| blob | ea16eae741b7fb7d4ac3ce3093f26cf930631b6f |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
21 02110-1301, USA. */
23 /*@@ This file should be rewritten to use an arbitrary precision
24 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
25 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
26 @@ The routines that translate from the ap rep should
27 @@ warn if precision et. al. is lost.
28 @@ This would also make life easier when this technology is used
29 @@ for cross-compilers. */
31 /* The entry points in this file are fold, size_int_wide, size_binop
32 and force_fit_type.
34 fold takes a tree as argument and returns a simplified tree.
36 size_binop takes a tree code for an arithmetic operation
37 and two operands that are trees, and produces a tree for the
38 result, assuming the type comes from `sizetype'.
40 size_int takes an integer value, and creates a tree constant
41 with type from `sizetype'.
43 force_fit_type takes a constant, an overflowable flag and prior
44 overflow indicators. It forces the value to fit the type and sets
45 TREE_OVERFLOW and TREE_CONSTANT_OVERFLOW as appropriate. */
64 /* Non-zero if we are folding constants inside an initializer; zero
65 otherwise. */
68 /* The following constants represent a bit based encoding of GCC's
69 comparison operators. This encoding simplifies transformations
70 on relational comparison operators, such as AND and OR. */
88 };
122 tree);
147 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
148 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
149 and SUM1. Then this yields nonzero if overflow occurred during the
150 addition.
152 Overflow occurs if A and B have the same sign, but A and SUM differ in
153 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
154 sign. */
155 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
156 \f
157 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
158 We do that by representing the two-word integer in 4 words, with only
159 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
160 number. The value of the word is LOWPART + HIGHPART * BASE. */
162 #define LOWPART(x) \
163 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
164 #define HIGHPART(x) \
165 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
166 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
168 /* Unpack a two-word integer into 4 words.
169 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
170 WORDS points to the array of HOST_WIDE_INTs. */
172 static void
174 {
179 }
181 /* Pack an array of 4 words into a two-word integer.
182 WORDS points to the array of words.
183 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
185 static void
188 {
191 }
192 \f
193 /* T is an INT_CST node. OVERFLOWABLE indicates if we are interested
194 in overflow of the value, when >0 we are only interested in signed
195 overflow, for <0 we are interested in any overflow. OVERFLOWED
196 indicates whether overflow has already occurred. CONST_OVERFLOWED
197 indicates whether constant overflow has already occurred. We force
198 T's value to be within range of T's type (by setting to 0 or 1 all
199 the bits outside the type's range). We set TREE_OVERFLOWED if,
200 OVERFLOWED is nonzero,
201 or OVERFLOWABLE is >0 and signed overflow occurs
202 or OVERFLOWABLE is <0 and any overflow occurs
203 We set TREE_CONSTANT_OVERFLOWED if,
204 CONST_OVERFLOWED is nonzero
205 or we set TREE_OVERFLOWED.
206 We return either the original T, or a copy. */
208 tree
211 {
213 HOST_WIDE_INT high;
225 else
227 /* Size types *are* sign extended. */
232 /* First clear all bits that are beyond the type's precision. */
235 ;
238 else
239 {
243 }
250 {
251 /* Sign extend top half? */
255 }
257 {
260 }
261 else
262 {
263 /* Sign extend bottom half? */
265 {
268 }
269 }
271 /* If the value changed, return a new node. */
274 {
280 {
284 }
286 {
289 }
290 }
293 }
294 \f
295 /* Add two doubleword integers with doubleword result.
296 Return nonzero if the operation overflows according to UNSIGNED_P.
297 Each argument is given as two `HOST_WIDE_INT' pieces.
298 One argument is L1 and H1; the other, L2 and H2.
299 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
301 int
306 {
308 HOST_WIDE_INT h;
318 else
320 }
322 /* Negate a doubleword integer with doubleword result.
323 Return nonzero if the operation overflows, assuming it's signed.
324 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
325 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
327 int
330 {
332 {
336 }
337 else
338 {
342 }
343 }
344 \f
345 /* Multiply two doubleword integers with doubleword result.
346 Return nonzero if the operation overflows according to UNSIGNED_P.
347 Each argument is given as two `HOST_WIDE_INT' pieces.
348 One argument is L1 and H1; the other, L2 and H2.
349 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
351 int
356 {
371 {
374 {
376 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
378 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
382 }
384 }
389 /* Unsigned overflow is immediate. */
393 /* Check for signed overflow by calculating the signed representation of the
394 top half of the result; it should agree with the low half's sign bit. */
396 {
399 }
401 {
404 }
406 }
407 \f
408 /* Shift the doubleword integer in L1, H1 left by COUNT places
409 keeping only PREC bits of result.
410 Shift right if COUNT is negative.
411 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
412 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
414 void
418 {
422 {
425 }
431 {
432 /* Shifting by the host word size is undefined according to the
433 ANSI standard, so we must handle this as a special case. */
436 }
438 {
441 }
442 else
443 {
447 }
449 /* Sign extend all bits that are beyond the precision. */
457 ;
459 {
462 }
463 else
464 {
468 }
469 }
471 /* Shift the doubleword integer in L1, H1 right by COUNT places
472 keeping only PREC bits of result. COUNT must be positive.
473 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
474 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
476 void
481 {
484 signmask = (arith
492 {
493 /* Shifting by the host word size is undefined according to the
494 ANSI standard, so we must handle this as a special case. */
497 }
499 {
502 }
503 else
504 {
508 }
510 /* Zero / sign extend all bits that are beyond the precision. */
513 {
516 }
518 ;
520 {
523 }
524 else
525 {
529 }
530 }
531 \f
532 /* Rotate the doubleword integer in L1, H1 left by COUNT places
533 keeping only PREC bits of result.
534 Rotate right if COUNT is negative.
535 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
537 void
541 {
553 }
555 /* Rotate the doubleword integer in L1, H1 left by COUNT places
556 keeping only PREC bits of result. COUNT must be positive.
557 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
559 void
563 {
575 }
576 \f
577 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
578 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
579 CODE is a tree code for a kind of division, one of
580 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
581 or EXACT_DIV_EXPR
582 It controls how the quotient is rounded to an integer.
583 Return nonzero if the operation overflows.
584 UNS nonzero says do unsigned division. */
586 int
589 HOST_WIDE_INT hnum_orig,
591 HOST_WIDE_INT hden_orig,
595 {
611 /* Calculate quotient sign and convert operands to unsigned. */
613 {
615 {
617 /* (minimum integer) / (-1) is the only overflow case. */
621 }
623 {
626 }
627 }
632 /* This unsigned division rounds toward zero. */
635 }
639 /* hden != 0 already checked. */
644 }
654 /* Special code for when the divisor < BASE. */
656 {
657 /* hnum != 0 already checked. */
659 {
663 }
664 }
665 else
666 {
667 /* Full double precision division,
668 with thanks to Don Knuth's "Seminumerical Algorithms". */
672 /* Find the highest nonzero divisor digit. */
675 {
678 }
680 /* Insure that the first digit of the divisor is at least BASE/2.
681 This is required by the quotient digit estimation algorithm. */
688 {
692 }
697 {
702 }
703 }
707 /* Main loop */
709 {
710 /* Guess the next quotient digit, quo_est, by dividing the first
711 two remaining dividend digits by the high order quotient digit.
712 quo_est is never low and is at most 2 high. */
719 else
722 /* Refine quo_est so it's usually correct, and at most one high. */
727 quo_est--;
729 /* Try QUO_EST as the quotient digit, by multiplying the
730 divisor by QUO_EST and subtracting from the remaining dividend.
731 Keep in mind that QUO_EST is the I - 1st digit. */
735 {
741 }
743 /* If quo_est was high by one, then num[i] went negative and
744 we need to correct things. */
746 {
747 quo_est--;
750 {
754 }
757 }
759 /* Store the quotient digit. */
761 }
762 }
766 finish_up:
767 /* If result is negative, make it so. */
771 /* Compute trial remainder: rem = num - (quo * den) */
777 {
786 {
787 /* quo = quo - 1; */
790 }
791 else
798 {
801 }
802 else
808 {
814 /* Get absolute values. */
820 /* If (2 * abs (lrem) >= abs (lden)) */
829 {
831 /* quo = quo - 1; */
834 else
835 /* quo = quo + 1; */
838 }
839 else
841 }
846 }
848 /* Compute true remainder: rem = num - (quo * den) */
853 }
855 /* If ARG2 divides ARG1 with zero remainder, carries out the division
856 of type CODE and returns the quotient.
857 Otherwise returns NULL_TREE. */
859 static tree
861 {
880 }
881 \f
882 /* This is non-zero if we should defer warnings about undefined
883 overflow. This facility exists because these warnings are a
884 special case. The code to estimate loop iterations does not want
885 to issue any warnings, since it works with expressions which do not
886 occur in user code. Various bits of cleanup code call fold(), but
887 only use the result if it has certain characteristics (e.g., is a
888 constant); that code only wants to issue a warning if the result is
889 used. */
893 /* If a warning about undefined overflow is deferred, this is the
894 warning. Note that this may cause us to turn two warnings into
895 one, but that is fine since it is sufficient to only give one
896 warning per expression. */
900 /* If a warning about undefined overflow is deferred, this is the
901 level at which the warning should be emitted. */
905 /* Start deferring overflow warnings. We could use a stack here to
906 permit nested calls, but at present it is not necessary. */
908 void
910 {
912 }
914 /* Stop deferring overflow warnings. If there is a pending warning,
915 and ISSUE is true, then issue the warning if appropriate. STMT is
916 the statement with which the warning should be associated (used for
917 location information); STMT may be NULL. CODE is the level of the
918 warning--a warn_strict_overflow_code value. This function will use
919 the smaller of CODE and the deferred code when deciding whether to
920 issue the warning. CODE may be zero to mean to always use the
921 deferred code. */
923 void
925 {
927 location_t locus;
932 {
938 }
946 /* Use the smallest code level when deciding to issue the
947 warning. */
956 else
959 }
961 /* Stop deferring overflow warnings, ignoring any deferred
962 warnings. */
964 void
966 {
968 }
970 /* Whether we are deferring overflow warnings. */
972 bool
974 {
976 }
978 /* This is called when we fold something based on the fact that signed
979 overflow is undefined. */
981 static void
983 {
986 {
989 {
992 }
993 }
996 }
997 \f
998 /* Return true if the built-in mathematical function specified by CODE
999 is odd, i.e. -f(x) == f(-x). */
1001 static bool
1003 {
1005 {
1019 }
1021 }
1023 /* Check whether we may negate an integer constant T without causing
1024 overflow. */
1026 bool
1028 {
1031 tree type;
1041 {
1046 }
1047 else
1052 }
1054 /* Determine whether an expression T can be cheaply negated using
1055 the function negate_expr without introducing undefined overflow. */
1057 static bool
1059 {
1060 tree type;
1069 {
1074 /* Check that -CST will not overflow type. */
1091 /* -(A + B) -> (-B) - A. */
1096 /* -(A + B) -> (-A) - B. */
1100 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1109 /* Fall through. */
1122 /* In general we can't negate A / B, because if A is INT_MIN and
1123 B is 1, we may turn this into INT_MIN / -1 which is undefined
1124 and actually traps on some architectures. But if overflow is
1125 undefined, we can negate, because - (INT_MIN / 1) is an
1126 overflow. */
1134 /* Negate -((double)float) as (double)(-float). */
1136 {
1140 }
1144 /* Negate -f(x) as f(-x). */
1150 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1152 {
1158 }
1163 }
1165 }
1167 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1168 simplification is possible.
1169 If negate_expr_p would return true for T, NULL_TREE will never be
1170 returned. */
1172 static tree
1174 {
1176 tree tem;
1179 {
1180 /* Convert - (~A) to A + 1. */
1196 /* Two's complement FP formats, such as c4x, may overflow. */
1202 {
1211 }
1219 {
1220 /* -(A + B) -> (-B) - A. */
1224 {
1228 }
1230 /* -(A + B) -> (-A) - B. */
1232 {
1236 }
1237 }
1241 /* - (A - B) -> B - A */
1252 /* Fall through. */
1256 {
1265 }
1273 /* In general we can't negate A / B, because if A is INT_MIN and
1274 B is 1, we may turn this into INT_MIN / -1 which is undefined
1275 and actually traps on some architectures. But if overflow is
1276 undefined, we can negate, because - (INT_MIN / 1) is an
1277 overflow. */
1279 {
1284 {
1291 }
1294 {
1301 }
1302 }
1306 /* Convert -((double)float) into (double)(-float). */
1308 {
1312 }
1316 /* Negate -f(x) as f(-x). */
1319 {
1326 }
1330 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1332 {
1337 {
1344 }
1345 }
1350 }
1353 }
1355 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1356 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1357 return NULL_TREE. */
1359 static tree
1361 {
1374 }
1375 \f
1376 /* Split a tree IN into a constant, literal and variable parts that could be
1377 combined with CODE to make IN. "constant" means an expression with
1378 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1379 commutative arithmetic operation. Store the constant part into *CONP,
1380 the literal in *LITP and return the variable part. If a part isn't
1381 present, set it to null. If the tree does not decompose in this way,
1382 return the entire tree as the variable part and the other parts as null.
1384 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1385 case, we negate an operand that was subtracted. Except if it is a
1386 literal for which we use *MINUS_LITP instead.
1388 If NEGATE_P is true, we are negating all of IN, again except a literal
1389 for which we use *MINUS_LITP instead.
1391 If IN is itself a literal or constant, return it as appropriate.
1393 Note that we do not guarantee that any of the three values will be the
1394 same type as IN, but they will have the same signedness and mode. */
1396 static tree
1399 {
1406 /* Strip any conversions that don't change the machine mode or signedness. */
1413 /* We can associate addition and subtraction together (even
1414 though the C standard doesn't say so) for integers because
1415 the value is not affected. For reals, the value might be
1416 affected, so we can't. */
1419 {
1425 /* First see if either of the operands is a literal, then a constant. */
1436 /* If we haven't dealt with either operand, this is not a case we can
1437 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1442 else
1445 /* Now do any needed negations. */
1452 }
1455 else
1459 {
1466 }
1469 }
1471 /* Re-associate trees split by the above function. T1 and T2 are either
1472 expressions to associate or null. Return the new expression, if any. If
1473 we build an operation, do it in TYPE and with CODE. */
1475 static tree
1477 {
1483 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1484 try to fold this since we will have infinite recursion. But do
1485 deal with any NEGATE_EXPRs. */
1488 {
1490 {
1499 }
1501 {
1504 }
1508 }
1512 }
1513 \f
1514 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1515 to produce a new constant. Return NULL_TREE if we don't know how
1516 to evaluate CODE at compile-time.
1518 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1520 tree
1522 {
1526 HOST_WIDE_INT hi;
1528 HOST_WIDE_INT garbageh;
1529 tree t;
1532 int is_sizetype
1542 {
1558 /* It's unclear from the C standard whether shifts can overflow.
1559 The following code ignores overflow; perhaps a C standard
1560 interpretation ruling is needed. */
1589 /* This is a shortcut for a common special case. */
1594 {
1600 }
1602 /* ... fall through ... */
1608 {
1611 }
1614 {
1617 }
1624 /* This is a shortcut for a common special case. */
1629 {
1634 }
1636 /* ... fall through ... */
1654 else
1660 else
1666 }
1671 {
1672 /* Propagate overflow flags ourselves. */
1675 {
1679 }
1681 {
1684 }
1685 }
1686 else
1694 }
1696 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1697 constant. We assume ARG1 and ARG2 have the same data type, or at least
1698 are the same kind of constant and the same machine mode. Return zero if
1699 combining the constants is not allowed in the current operating mode.
1701 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1703 static tree
1705 {
1706 /* Sanity check for the recursive cases. */
1717 {
1719 REAL_VALUE_TYPE d1;
1720 REAL_VALUE_TYPE d2;
1721 REAL_VALUE_TYPE value;
1722 REAL_VALUE_TYPE result;
1726 /* The following codes are handled by real_arithmetic. */
1728 {
1739 }
1747 /* Don't perform operation if we honor signaling NaNs and
1748 either operand is a NaN. */
1753 /* Don't perform operation if it would raise a division
1754 by zero exception. */
1760 /* If either operand is a NaN, just return it. Otherwise, set up
1761 for floating-point trap; we return an overflow. */
1770 /* Don't constant fold this floating point operation if
1771 the result has overflowed and flag_trapping_math. */
1779 /* Don't constant fold this floating point operation if the
1780 result may dependent upon the run-time rounding mode and
1781 flag_rounding_math is set, or if GCC's software emulation
1782 is unable to accurately represent the result. */
1797 }
1800 {
1809 {
1820 notrunc);
1824 notrunc);
1828 {
1829 tree magsquared
1833 notrunc);
1834 tree t1
1838 notrunc);
1839 tree t2
1843 notrunc);
1850 }
1855 }
1859 }
1862 }
1864 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1865 indicates which particular sizetype to create. */
1867 tree
1869 {
1871 }
1872 \f
1873 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1874 is a tree code. The type of the result is taken from the operands.
1875 Both must be the same type integer type and it must be a size type.
1876 If the operands are constant, so is the result. */
1878 tree
1880 {
1889 /* Handle the special case of two integer constants faster. */
1891 {
1892 /* And some specific cases even faster than that. */
1901 /* Handle general case of two integer constants. */
1903 }
1906 }
1908 /* Given two values, either both of sizetype or both of bitsizetype,
1909 compute the difference between the two values. Return the value
1910 in signed type corresponding to the type of the operands. */
1912 tree
1914 {
1916 tree ctype;
1921 /* If the type is already signed, just do the simple thing. */
1927 /* If either operand is not a constant, do the conversions to the signed
1928 type and subtract. The hardware will do the right thing with any
1929 overflow in the subtraction. */
1934 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1935 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1936 overflow) and negate (which can't either). Special-case a result
1937 of zero while we're here. */
1942 else
1946 }
1947 \f
1948 /* A subroutine of fold_convert_const handling conversions of an
1949 INTEGER_CST to another integer type. */
1951 static tree
1953 {
1954 tree t;
1956 /* Given an integer constant, make new constant with new type,
1957 appropriately sign-extended or truncated. */
1962 /* Don't set the overflow when
1963 converting a pointer */
1972 }
1974 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1975 to an integer type. */
1977 static tree
1979 {
1981 tree t;
1983 /* The following code implements the floating point to integer
1984 conversion rules required by the Java Language Specification,
1985 that IEEE NaNs are mapped to zero and values that overflow
1986 the target precision saturate, i.e. values greater than
1987 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1988 are mapped to INT_MIN. These semantics are allowed by the
1989 C and C++ standards that simply state that the behavior of
1990 FP-to-integer conversion is unspecified upon overflow. */
1993 REAL_VALUE_TYPE r;
1997 {
2016 }
2018 /* If R is NaN, return zero and show we have an overflow. */
2020 {
2024 }
2026 /* See if R is less than the lower bound or greater than the
2027 upper bound. */
2030 {
2034 {
2038 }
2039 }
2042 {
2045 {
2048 {
2052 }
2053 }
2054 }
2064 }
2066 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2067 to another floating point type. */
2069 static tree
2071 {
2072 REAL_VALUE_TYPE value;
2073 tree t;
2082 }
2084 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2085 type TYPE. If no simplification can be done return NULL_TREE. */
2087 static tree
2089 {
2094 {
2099 }
2101 {
2106 }
2108 }
2110 /* Construct a vector of zero elements of vector type TYPE. */
2112 static tree
2114 {
2125 }
2127 /* Convert expression ARG to type TYPE. Used by the middle-end for
2128 simple conversions in preference to calling the front-end's convert. */
2130 tree
2132 {
2134 tree tem;
2150 {
2155 {
2159 }
2164 {
2167 }
2174 {
2178 }
2180 {
2184 }
2187 {
2202 }
2206 {
2215 {
2219 {
2223 }
2231 }
2235 }
2250 }
2251 }
2252 \f
2253 /* Return false if expr can be assumed not to be an lvalue, true
2254 otherwise. */
2256 static bool
2258 {
2259 /* We only need to wrap lvalue tree codes. */
2261 {
2295 /* Assume the worst for front-end tree codes. */
2299 }
2302 }
2304 /* Return an expr equal to X but certainly not valid as an lvalue. */
2306 tree
2308 {
2309 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2310 us. */
2317 }
2319 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2320 Zero means allow extended lvalues. */
2324 /* When pedantic, return an expr equal to X but certainly not valid as a
2325 pedantic lvalue. Otherwise, return X. */
2327 static tree
2329 {
2332 else
2334 }
2335 \f
2336 /* Given a tree comparison code, return the code that is the logical inverse
2337 of the given code. It is not safe to do this for floating-point
2338 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2339 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2341 enum tree_code
2343 {
2348 {
2379 }
2380 }
2382 /* Similar, but return the comparison that results if the operands are
2383 swapped. This is safe for floating-point. */
2385 enum tree_code
2387 {
2389 {
2415 }
2416 }
2419 /* Convert a comparison tree code from an enum tree_code representation
2420 into a compcode bit-based encoding. This function is the inverse of
2421 compcode_to_comparison. */
2423 static enum comparison_code
2425 {
2427 {
2458 }
2459 }
2461 /* Convert a compcode bit-based encoding of a comparison operator back
2462 to GCC's enum tree_code representation. This function is the
2463 inverse of comparison_to_compcode. */
2465 static enum tree_code
2467 {
2469 {
2500 }
2501 }
2503 /* Return a tree for the comparison which is the combination of
2504 doing the AND or OR (depending on CODE) of the two operations LCODE
2505 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2506 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2507 if this makes the transformation invalid. */
2509 tree
2513 {
2520 {
2531 }
2534 {
2535 /* Eliminate unordered comparisons, as well as LTGT and ORD
2536 which are not used unless the mode has NaNs. */
2542 }
2544 {
2545 /* Check that the original operation and the optimized ones will trap
2546 under the same condition. */
2557 /* In a short-circuited boolean expression the LHS might be
2558 such that the RHS, if evaluated, will never trap. For
2559 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2560 if neither x nor y is NaN. (This is a mixed blessing: for
2561 example, the expression above will never trap, hence
2562 optimizing it to x < y would be invalid). */
2567 /* If the comparison was short-circuited, and only the RHS
2568 trapped, we may now generate a spurious trap. */
2573 /* If we changed the conditions that cause a trap, we lose. */
2576 }
2582 else
2585 }
2587 /* Return nonzero if CODE is a tree code that represents a truth value. */
2589 static int
2591 {
2596 }
2597 \f
2598 /* Return nonzero if two operands (typically of the same tree node)
2599 are necessarily equal. If either argument has side-effects this
2600 function returns zero. FLAGS modifies behavior as follows:
2602 If OEP_ONLY_CONST is set, only return nonzero for constants.
2603 This function tests whether the operands are indistinguishable;
2604 it does not test whether they are equal using C's == operation.
2605 The distinction is important for IEEE floating point, because
2606 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2607 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2609 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2610 even though it may hold multiple values during a function.
2611 This is because a GCC tree node guarantees that nothing else is
2612 executed between the evaluation of its "operands" (which may often
2613 be evaluated in arbitrary order). Hence if the operands themselves
2614 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2615 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2616 unset means assuming isochronic (or instantaneous) tree equivalence.
2617 Unless comparing arbitrary expression trees, such as from different
2618 statements, this flag can usually be left unset.
2620 If OEP_PURE_SAME is set, then pure functions with identical arguments
2621 are considered the same. It is used when the caller has other ways
2622 to ensure that global memory is unchanged in between. */
2624 int
2626 {
2627 /* If either is ERROR_MARK, they aren't equal. */
2631 /* If both types don't have the same signedness, then we can't consider
2632 them equal. We must check this before the STRIP_NOPS calls
2633 because they may change the signedness of the arguments. */
2637 /* If both types don't have the same precision, then it is not safe
2638 to strip NOPs. */
2645 /* In case both args are comparisons but with different comparison
2646 code, try to swap the comparison operands of one arg to produce
2647 a match and compare that variant. */
2651 {
2659 }
2662 /* This is needed for conversions and for COMPONENT_REF.
2663 Might as well play it safe and always test this. */
2669 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2670 We don't care about side effects in that case because the SAVE_EXPR
2671 takes care of that for us. In all other cases, two expressions are
2672 equal if they have no side effects. If we have two identical
2673 expressions with side effects that should be treated the same due
2674 to the only side effects being identical SAVE_EXPR's, that will
2675 be detected in the recursive calls below. */
2681 /* Next handle constant cases, those for which we can return 1 even
2682 if ONLY_CONST is set. */
2685 {
2698 {
2708 {
2710 flags))
2714 }
2717 }
2721 flags)
2723 flags));
2736 }
2741 /* Define macros to test an operand from arg0 and arg1 for equality and a
2742 variant that allows null and views null as being different from any
2743 non-null value. In the latter case, if either is null, the both
2744 must be; otherwise, do the normal comparison. */
2745 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2746 TREE_OPERAND (arg1, N), flags)
2748 #define OP_SAME_WITH_NULL(N) \
2749 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2750 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2753 {
2755 /* Two conversions are equal only if signedness and modes match. */
2757 {
2770 }
2780 /* For commutative ops, allow the other order. */
2788 /* If either of the pointer (or reference) expressions we are
2789 dereferencing contain a side effect, these cannot be equal. */
2795 {
2805 /* Operands 2 and 3 may be null. */
2812 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2813 may be NULL when we're called to compare MEM_EXPRs. */
2823 }
2827 {
2842 /* Otherwise take into account this is a commutative operation. */
2849 /* If the CALL_EXPRs call different functions, then they
2850 clearly can not be equal. */
2854 {
2858 else
2862 }
2864 /* Now see if all the arguments are the same. operand_equal_p
2865 does not handle TREE_LIST, so we walk the operands here
2866 feeding them to operand_equal_p. */
2870 {
2872 flags))
2877 }
2879 /* If we get here and both argument lists are exhausted
2880 then the CALL_EXPRs are equal. */
2885 }
2888 /* Consider __builtin_sqrt equal to sqrt. */
2896 }
2898 #undef OP_SAME
2899 #undef OP_SAME_WITH_NULL
2900 }
2901 \f
2902 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2903 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2905 When in doubt, return 0. */
2907 static int
2909 {
2921 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2922 and see if the inner values are the same. This removes any
2923 signedness comparison, which doesn't matter here. */
2930 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2931 actual comparison operand, ARG0.
2933 First throw away any conversions to wider types
2934 already present in the operands. */
2943 {
2946 /* Make sure shorter operand is extended the right way
2947 to match the longer operand. */
2953 }
2956 }
2957 \f
2958 /* See if ARG is an expression that is either a comparison or is performing
2959 arithmetic on comparisons. The comparisons must only be comparing
2960 two different values, which will be stored in *CVAL1 and *CVAL2; if
2961 they are nonzero it means that some operands have already been found.
2962 No variables may be used anywhere else in the expression except in the
2963 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2964 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2966 If this is true, return 1. Otherwise, return zero. */
2968 static int
2970 {
2974 /* We can handle some of the tcc_expression cases here. */
2984 {
2985 /* If we've already found a CVAL1 or CVAL2, this expression is
2986 two complex to handle. */
2992 }
2995 {
3018 /* First see if we can handle the first operand, then the second. For
3019 the second operand, we know *CVAL1 can't be zero. It must be that
3020 one side of the comparison is each of the values; test for the
3021 case where this isn't true by failing if the two operands
3022 are the same. */
3031 ;
3035 ;
3036 else
3040 ;
3044 ;
3045 else
3052 }
3053 }
3054 \f
3055 /* ARG is a tree that is known to contain just arithmetic operations and
3056 comparisons. Evaluate the operations in the tree substituting NEW0 for
3057 any occurrence of OLD0 as an operand of a comparison and likewise for
3058 NEW1 and OLD1. */
3060 static tree
3062 {
3067 /* We can handle some of the tcc_expression cases here. */
3075 {
3090 {
3107 }
3108 /* Fall through - ??? */
3111 {
3115 /* We need to check both for exact equality and tree equality. The
3116 former will be true if the operand has a side-effect. In that
3117 case, we know the operand occurred exactly once. */
3130 }
3134 }
3135 }
3136 \f
3137 /* Return a tree for the case when the result of an expression is RESULT
3138 converted to TYPE and OMITTED was previously an operand of the expression
3139 but is now not needed (e.g., we folded OMITTED * 0).
3141 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3142 the conversion of RESULT to TYPE. */
3144 tree
3146 {
3153 }
3155 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3157 static tree
3159 {
3166 }
3168 /* Return a tree for the case when the result of an expression is RESULT
3169 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3170 of the expression but are now not needed.
3172 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3173 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3174 evaluated before OMITTED2. Otherwise, if neither has side effects,
3175 just do the conversion of RESULT to TYPE. */
3177 tree
3179 {
3188 }
3190 \f
3191 /* Return a simplified tree node for the truth-negation of ARG. This
3192 never alters ARG itself. We assume that ARG is an operation that
3193 returns a truth value (0 or 1).
3195 FIXME: one would think we would fold the result, but it causes
3196 problems with the dominator optimizer. */
3198 tree
3200 {
3204 /* If this is a comparison, we can simply invert it, except for
3205 floating-point non-equality comparisons, in which case we just
3206 enclose a TRUTH_NOT_EXPR around what we have. */
3209 {
3212 && flag_trapping_math
3216 else
3217 {
3222 else
3225 }
3226 }
3229 {
3244 /* Here we can invert either operand. We invert the first operand
3245 unless the second operand is a TRUTH_NOT_EXPR in which case our
3246 result is the XOR of the first operand with the inside of the
3247 negation of the second operand. */
3252 else
3271 {
3274 /* A COND_EXPR may have a throw as one operand, which
3275 then has void type. Just leave void operands
3276 as they are. */
3282 }
3315 }
3318 }
3320 /* Return a simplified tree node for the truth-negation of ARG. This
3321 never alters ARG itself. We assume that ARG is an operation that
3322 returns a truth value (0 or 1).
3324 FIXME: one would think we would fold the result, but it causes
3325 problems with the dominator optimizer. */
3327 tree
3329 {
3330 tree tem;
3340 }
3342 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3343 operands are another bit-wise operation with a common input. If so,
3344 distribute the bit operations to save an operation and possibly two if
3345 constants are involved. For example, convert
3346 (A | B) & (A | C) into A | (B & C)
3347 Further simplification will occur if B and C are constants.
3349 If this optimization cannot be done, 0 will be returned. */
3351 static tree
3353 {
3354 tree common;
3364 {
3368 }
3370 {
3374 }
3376 {
3380 }
3382 {
3386 }
3387 else
3392 }
3394 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3395 with code CODE. This optimization is unsafe. */
3396 static tree
3398 {
3402 /* (A / C) +- (B / C) -> (A +- B) / C. */
3412 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3417 {
3429 }
3432 }
3433 \f
3434 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3435 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3437 static tree
3440 {
3441 tree result;
3444 {
3451 }
3459 }
3461 /* Optimize a bit-field compare.
3463 There are two cases: First is a compare against a constant and the
3464 second is a comparison of two items where the fields are at the same
3465 bit position relative to the start of a chunk (byte, halfword, word)
3466 large enough to contain it. In these cases we can avoid the shift
3467 implicit in bitfield extractions.
3469 For constants, we emit a compare of the shifted constant with the
3470 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3471 compared. For two fields at the same position, we do the ANDs with the
3472 similar mask and compare the result of the ANDs.
3474 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3475 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3476 are the left and right operands of the comparison, respectively.
3478 If the optimization described above can be done, we return the resulting
3479 tree. Otherwise we return zero. */
3481 static tree
3484 {
3493 tree mask;
3494 tree offset;
3496 /* Get all the information about the extractions being done. If the bit size
3497 if the same as the size of the underlying object, we aren't doing an
3498 extraction at all and so can do nothing. We also don't want to
3499 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3500 then will no longer be able to replace it. */
3508 {
3509 /* If this is not a constant, we can only do something if bit positions,
3510 sizes, and signedness are the same. */
3518 }
3520 /* See if we can find a mode to refer to this field. We should be able to,
3521 but fail if we can't. */
3530 /* Set signed and unsigned types of the precision of this mode for the
3531 shifts below. */
3535 /* Compute the bit position and size for the new reference and our offset
3536 within it. If the new reference is the same size as the original, we
3537 won't optimize anything, so return zero. */
3547 /* Make the mask to be used against the extracted field. */
3556 /* If not comparing with constant, just rework the comparison
3557 and return. */
3562 mask),
3566 mask));
3568 /* Otherwise, we are handling the constant case. See if the constant is too
3569 big for the field. Warn and return a tree of for 0 (false) if so. We do
3570 this not only for its own sake, but to avoid having to test for this
3571 error case below. If we didn't, we might generate wrong code.
3573 For unsigned fields, the constant shifted right by the field length should
3574 be all zero. For signed fields, the high-order bits should agree with
3575 the sign bit. */
3578 {
3582 {
3586 }
3587 }
3588 else
3589 {
3593 {
3597 }
3598 }
3600 /* Single-bit compares should always be against zero. */
3602 {
3605 }
3607 /* Make a new bitfield reference, shift the constant over the
3608 appropriate number of bits and mask it with the computed mask
3609 (in case this was a signed field). If we changed it, make a new one. */
3612 {
3615 }
3625 rhs);
3626 }
3627 \f
3628 /* Subroutine for fold_truthop: decode a field reference.
3630 If EXP is a comparison reference, we return the innermost reference.
3632 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3633 set to the starting bit number.
3635 If the innermost field can be completely contained in a mode-sized
3636 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3638 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3639 otherwise it is not changed.
3641 *PUNSIGNEDP is set to the signedness of the field.
3643 *PMASK is set to the mask used. This is either contained in a
3644 BIT_AND_EXPR or derived from the width of the field.
3646 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3648 Return 0 if this is not a component reference or is one that we can't
3649 do anything with. */
3651 static tree
3656 {
3660 tree unsigned_type;
3663 /* All the optimizations using this function assume integer fields.
3664 There are problems with FP fields since the type_for_size call
3665 below can fail for, e.g., XFmode. */
3669 /* We are interested in the bare arrangement of bits, so strip everything
3670 that doesn't affect the machine mode. However, record the type of the
3671 outermost expression if it may matter below. */
3679 {
3685 }
3694 /* If the number of bits in the reference is the same as the bitsize of
3695 the outer type, then the outer type gives the signedness. Otherwise
3696 (in case of a small bitfield) the signedness is unchanged. */
3700 /* Compute the mask to access the bitfield. */
3710 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3718 }
3720 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3721 bit positions. */
3723 static int
3725 {
3728 tree tmask;
3733 return
3740 }
3742 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3743 represents the sign bit of EXP's type. If EXP represents a sign
3744 or zero extension, also test VAL against the unextended type.
3745 The return value is the (sub)expression whose sign bit is VAL,
3746 or NULL_TREE otherwise. */
3748 static tree
3750 {
3754 tree t;
3756 /* Tree EXP must have an integral type. */
3761 /* Tree VAL must be an integer constant. */
3768 {
3775 }
3776 else
3777 {
3784 }
3786 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3787 treat VAL as if it were unsigned. */
3792 /* Handle extension from a narrower type. */
3798 }
3800 /* Subroutine for fold_truthop: determine if an operand is simple enough
3801 to be evaluated unconditionally. */
3803 static int
3805 {
3806 /* Strip any conversions that don't change the machine mode. */
3815 /* Don't regard global variables as simple. They may be
3816 allocated in ways unknown to the compiler (shared memory,
3817 #pragma weak, etc). */
3820 /* Loading a static variable is unduly expensive, but global
3821 registers aren't expensive. */
3823 }
3824 \f
3825 /* The following functions are subroutines to fold_range_test and allow it to
3826 try to change a logical combination of comparisons into a range test.
3828 For example, both
3829 X == 2 || X == 3 || X == 4 || X == 5
3830 and
3831 X >= 2 && X <= 5
3832 are converted to
3833 (unsigned) (X - 2) <= 3
3835 We describe each set of comparisons as being either inside or outside
3836 a range, using a variable named like IN_P, and then describe the
3837 range with a lower and upper bound. If one of the bounds is omitted,
3838 it represents either the highest or lowest value of the type.
3840 In the comments below, we represent a range by two numbers in brackets
3841 preceded by a "+" to designate being inside that range, or a "-" to
3842 designate being outside that range, so the condition can be inverted by
3843 flipping the prefix. An omitted bound is represented by a "-". For
3844 example, "- [-, 10]" means being outside the range starting at the lowest
3845 possible value and ending at 10, in other words, being greater than 10.
3846 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3847 always false.
3849 We set up things so that the missing bounds are handled in a consistent
3850 manner so neither a missing bound nor "true" and "false" need to be
3851 handled using a special case. */
3853 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3854 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3855 and UPPER1_P are nonzero if the respective argument is an upper bound
3856 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3857 must be specified for a comparison. ARG1 will be converted to ARG0's
3858 type if both are specified. */
3860 static tree
3863 {
3864 tree tem;
3868 /* If neither arg represents infinity, do the normal operation.
3869 Else, if not a comparison, return infinity. Else handle the special
3870 comparison rules. Note that most of the cases below won't occur, but
3871 are handled for consistency. */
3874 {
3879 }
3884 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3885 for neither. In real maths, we cannot assume open ended ranges are
3886 the same. But, this is computer arithmetic, where numbers are finite.
3887 We can therefore make the transformation of any unbounded range with
3888 the value Z, Z being greater than any representable number. This permits
3889 us to treat unbounded ranges as equal. */
3893 {
3914 }
3917 }
3918 \f
3919 /* Given EXP, a logical expression, set the range it is testing into
3920 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
3921 actually being tested. *PLOW and *PHIGH will be made of the same
3922 type as the returned expression. If EXP is not a comparison, we
3923 will most likely not be returning a useful value and range. Set
3924 *STRICT_OVERFLOW_P to true if the return value is only valid
3925 because signed overflow is undefined; otherwise, do not change
3926 *STRICT_OVERFLOW_P. */
3928 static tree
3931 {
3938 /* Start with simply saying "EXP != 0" and then look at the code of EXP
3939 and see if we can refine the range. Some of the cases below may not
3940 happen, but it doesn't seem worth worrying about this. We "continue"
3941 the outer loop when we've changed something; otherwise we "break"
3942 the switch, which will "break" the while. */
3948 {
3953 {
3965 }
3968 {
3975 /* We can only do something if the range is testing for zero
3976 and if the second operand is an integer constant. Note that
3977 saying something is "in" the range we make is done by
3978 complementing IN_P since it will set in the initial case of
3979 being not equal to zero; "out" is leaving it alone. */
3986 {
4007 }
4009 /* If this is an unsigned comparison, we also know that EXP is
4010 greater than or equal to zero. We base the range tests we make
4011 on that fact, so we record it here so we can parse existing
4012 range tests. We test arg0_type since often the return type
4013 of, e.g. EQ_EXPR, is boolean. */
4015 {
4019 NULL_TREE))
4024 /* If the high bound is missing, but we have a nonzero low
4025 bound, reverse the range so it goes from zero to the low bound
4026 minus 1. */
4028 {
4033 }
4034 }
4040 /* (-x) IN [a,b] -> x in [-b, -a] */
4052 /* ~ X -> -X - 1 */
4061 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4062 move a constant to the other side. */
4067 /* If EXP is signed, any overflow in the computation is undefined,
4068 so we don't worry about it so long as our computations on
4069 the bounds don't overflow. For unsigned, overflow is defined
4070 and this is exactly the right thing. */
4082 /* Check for an unsigned range which has wrapped around the maximum
4083 value thus making n_high < n_low, and normalize it. */
4085 {
4091 /* If the range is of the form +/- [ x+1, x ], we won't
4092 be able to normalize it. But then, it represents the
4093 whole range or the empty set, so make it
4094 +/- [ -, - ]. */
4098 else
4100 }
4101 else
4125 /* If we're converting arg0 from an unsigned type, to exp,
4126 a signed type, we will be doing the comparison as unsigned.
4127 The tests above have already verified that LOW and HIGH
4128 are both positive.
4130 So we have to ensure that we will handle large unsigned
4131 values the same way that the current signed bounds treat
4132 negative values. */
4135 {
4136 tree high_positive;
4140 /* A range without an upper bound is, naturally, unbounded.
4141 Since convert would have cropped a very large value, use
4142 the max value for the destination type. */
4143 high_positive
4150 high_positive),
4152 integer_one_node));
4154 /* If the low bound is specified, "and" the range with the
4155 range for which the original unsigned value will be
4156 positive. */
4158 {
4162 integer_zero_node),
4163 high_positive))
4167 }
4168 else
4169 {
4170 /* Otherwise, "or" the range with the range of the input
4171 that will be interpreted as negative. */
4175 integer_zero_node),
4176 high_positive))
4180 }
4181 }
4189 }
4192 }
4194 /* If EXP is a constant, we can evaluate whether this is true or false. */
4196 {
4203 }
4207 }
4208 \f
4209 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4210 type, TYPE, return an expression to test if EXP is in (or out of, depending
4211 on IN_P) the range. Return 0 if the test couldn't be created. */
4213 static tree
4215 {
4217 tree value;
4219 #ifdef HAVE_canonicalize_funcptr_for_compare
4220 /* Disable this optimization for function pointer expressions
4221 on targets that require function pointer canonicalization. */
4226 #endif
4229 {
4235 }
4253 {
4255 {
4259 }
4261 }
4263 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4265 {
4267 HOST_WIDE_INT hi;
4272 {
4275 }
4276 else
4277 {
4280 }
4283 {
4285 {
4288 }
4291 }
4292 }
4294 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4295 This requires wrap-around arithmetics for the type of the expression. */
4297 {
4299 /* There is no requirement that LOW be within the range of ETYPE
4300 if the latter is a subtype. It must, however, be within the base
4301 type of ETYPE. So be sure we do the subtraction in that type. */
4314 }
4316 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4319 {
4322 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4323 for the type in question, as we rely on this here. */
4333 else
4335 }
4349 }
4350 \f
4351 /* Return the predecessor of VAL in its type, handling the infinite case. */
4353 static tree
4355 {
4361 else
4363 }
4365 /* Return the successor of VAL in its type, handling the infinite case. */
4367 static tree
4369 {
4375 else
4377 }
4379 /* Given two ranges, see if we can merge them into one. Return 1 if we
4380 can, 0 if we can't. Set the output range into the specified parameters. */
4382 static int
4385 {
4389 tree tem;
4399 /* Make range 0 be the range that starts first, or ends last if they
4400 start at the same value. Swap them if it isn't. */
4403 || (lowequal
4406 {
4410 }
4412 /* Now flag two cases, whether the ranges are disjoint or whether the
4413 second range is totally subsumed in the first. Note that the tests
4414 below are simplified by the ones above. */
4420 /* We now have four cases, depending on whether we are including or
4421 excluding the two ranges. */
4423 {
4424 /* If they don't overlap, the result is false. If the second range
4425 is a subset it is the result. Otherwise, the range is from the start
4426 of the second to the end of the first. */
4431 else
4433 }
4436 {
4437 /* If they don't overlap, the result is the first range. If they are
4438 equal, the result is false. If the second range is a subset of the
4439 first, and the ranges begin at the same place, we go from just after
4440 the end of the second range to the end of the first. If the second
4441 range is not a subset of the first, or if it is a subset and both
4442 ranges end at the same place, the range starts at the start of the
4443 first range and ends just before the second range.
4444 Otherwise, we can't describe this as a single range. */
4450 {
4455 {
4456 /* We are in the weird situation where high0 > high1 but
4457 high1 has no successor. Punt. */
4459 }
4460 }
4462 {
4467 {
4468 /* low0 < low1 but low1 has no predecessor. Punt. */
4470 }
4471 }
4472 else
4474 }
4477 {
4478 /* If they don't overlap, the result is the second range. If the second
4479 is a subset of the first, the result is false. Otherwise,
4480 the range starts just after the first range and ends at the
4481 end of the second. */
4486 else
4487 {
4492 {
4493 /* high1 > high0 but high0 has no successor. Punt. */
4495 }
4496 }
4497 }
4499 else
4500 {
4501 /* The case where we are excluding both ranges. Here the complex case
4502 is if they don't overlap. In that case, the only time we have a
4503 range is if they are adjacent. If the second is a subset of the
4504 first, the result is the first. Otherwise, the range to exclude
4505 starts at the beginning of the first range and ends at the end of the
4506 second. */
4508 {
4513 else
4514 {
4515 /* Canonicalize - [min, x] into - [-, x]. */
4518 {
4523 /* FALLTHROUGH */
4536 }
4538 /* Canonicalize - [x, max] into - [x, -]. */
4541 {
4546 /* FALLTHROUGH */
4561 }
4563 /* The ranges might be also adjacent between the maximum and
4564 minimum values of the given type. For
4565 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4566 return + [x + 1, y - 1]. */
4568 {
4575 }
4576 else
4578 }
4579 }
4582 else
4584 }
4588 }
4589 \f
4591 /* Subroutine of fold, looking inside expressions of the form
4592 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4593 of the COND_EXPR. This function is being used also to optimize
4594 A op B ? C : A, by reversing the comparison first.
4596 Return a folded expression whose code is not a COND_EXPR
4597 anymore, or NULL_TREE if no folding opportunity is found. */
4599 static tree
4601 {
4606 tree tem;
4611 /* If we have A op 0 ? A : -A, consider applying the following
4612 transformations:
4614 A == 0? A : -A same as -A
4615 A != 0? A : -A same as A
4616 A >= 0? A : -A same as abs (A)
4617 A > 0? A : -A same as abs (A)
4618 A <= 0? A : -A same as -abs (A)
4619 A < 0? A : -A same as -abs (A)
4621 None of these transformations work for modes with signed
4622 zeros. If A is +/-0, the first two transformations will
4623 change the sign of the result (from +0 to -0, or vice
4624 versa). The last four will fix the sign of the result,
4625 even though the original expressions could be positive or
4626 negative, depending on the sign of A.
4628 Note that all these transformations are correct if A is
4629 NaN, since the two alternatives (A and -A) are also NaNs. */
4635 /* In the case that A is of the form X-Y, '-A' (arg2) may
4636 have already been folded to Y-X, check for that. */
4644 {
4656 /* Fall through. */
4678 }
4680 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4681 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4682 both transformations are correct when A is NaN: A != 0
4683 is then true, and A == 0 is false. */
4686 {
4691 }
4693 /* Try some transformations of A op B ? A : B.
4695 A == B? A : B same as B
4696 A != B? A : B same as A
4697 A >= B? A : B same as max (A, B)
4698 A > B? A : B same as max (B, A)
4699 A <= B? A : B same as min (A, B)
4700 A < B? A : B same as min (B, A)
4702 As above, these transformations don't work in the presence
4703 of signed zeros. For example, if A and B are zeros of
4704 opposite sign, the first two transformations will change
4705 the sign of the result. In the last four, the original
4706 expressions give different results for (A=+0, B=-0) and
4707 (A=-0, B=+0), but the transformed expressions do not.
4709 The first two transformations are correct if either A or B
4710 is a NaN. In the first transformation, the condition will
4711 be false, and B will indeed be chosen. In the case of the
4712 second transformation, the condition A != B will be true,
4713 and A will be chosen.
4715 The conversions to max() and min() are not correct if B is
4716 a number and A is not. The conditions in the original
4717 expressions will be false, so all four give B. The min()
4718 and max() versions would give a NaN instead. */
4720 /* Avoid these transformations if the COND_EXPR may be used
4721 as an lvalue in the C++ front-end. PR c++/19199. */
4722 && (in_gimple_form
4727 {
4732 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4734 {
4738 }
4741 {
4750 /* In C++ a ?: expression can be an lvalue, so put the
4751 operand which will be used if they are equal first
4752 so that we can convert this back to the
4753 corresponding COND_EXPR. */
4755 {
4762 }
4769 {
4776 }
4789 }
4790 }
4792 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4793 we might still be able to simplify this. For example,
4794 if C1 is one less or one more than C2, this might have started
4795 out as a MIN or MAX and been transformed by this function.
4796 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4802 {
4804 /* We can replace A with C1 in this case. */
4809 /* If C1 is C2 + 1, this is min(A, C2). */
4811 OEP_ONLY_CONST)
4815 OEP_ONLY_CONST))
4821 /* If C1 is C2 - 1, this is min(A, C2). */
4823 OEP_ONLY_CONST)
4827 OEP_ONLY_CONST))
4833 /* If C1 is C2 - 1, this is max(A, C2). */
4835 OEP_ONLY_CONST)
4839 OEP_ONLY_CONST))
4845 /* If C1 is C2 + 1, this is max(A, C2). */
4847 OEP_ONLY_CONST)
4851 OEP_ONLY_CONST))
4859 }
4862 }
4865 \f
4866 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4867 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4868 #endif
4870 /* EXP is some logical combination of boolean tests. See if we can
4871 merge it into some range test. Return the new tree if so. */
4873 static tree
4875 {
4883 tree tem;
4887 /* If this is an OR operation, invert both sides; we will invert
4888 again at the end. */
4892 /* If both expressions are the same, if we can merge the ranges, and we
4893 can build the range test, return it or it inverted. If one of the
4894 ranges is always true or always false, consider it to be the same
4895 expression as the other. */
4903 {
4907 }
4909 /* On machines where the branch cost is expensive, if this is a
4910 short-circuited branch and the underlying object on both sides
4911 is the same, make a non-short-circuit operation. */
4917 {
4918 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4919 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4920 which cases we can't do this. */
4928 {
4937 {
4940 WARN_STRICT_OVERFLOW_COMPARISON);
4944 }
4945 }
4946 }
4949 }
4950 \f
4951 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
4952 bit value. Arrange things so the extra bits will be set to zero if and
4953 only if C is signed-extended to its full width. If MASK is nonzero,
4954 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4956 static tree
4958 {
4961 tree temp;
4966 /* We work by getting just the sign bit into the low-order bit, then
4967 into the high-order bit, then sign-extend. We then XOR that value
4968 with C. */
4972 /* We must use a signed type in order to get an arithmetic right shift.
4973 However, we must also avoid introducing accidental overflows, so that
4974 a subsequent call to integer_zerop will work. Hence we must
4975 do the type conversion here. At this point, the constant is either
4976 zero or one, and the conversion to a signed type can never overflow.
4977 We could get an overflow if this conversion is done anywhere else. */
4986 /* If necessary, convert the type back to match the type of C. */
4991 }
4992 \f
4993 /* Find ways of folding logical expressions of LHS and RHS:
4994 Try to merge two comparisons to the same innermost item.
4995 Look for range tests like "ch >= '0' && ch <= '9'".
4996 Look for combinations of simple terms on machines with expensive branches
4997 and evaluate the RHS unconditionally.
4999 For example, if we have p->a == 2 && p->b == 4 and we can make an
5000 object large enough to span both A and B, we can do this with a comparison
5001 against the object ANDed with the a mask.
5003 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5004 operations to do this with one comparison.
5006 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5007 function and the one above.
5009 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5010 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5012 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5013 two operands.
5015 We return the simplified tree or 0 if no optimization is possible. */
5017 static tree
5019 {
5020 /* If this is the "or" of two comparisons, we can do something if
5021 the comparisons are NE_EXPR. If this is the "and", we can do something
5022 if the comparisons are EQ_EXPR. I.e.,
5023 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5025 WANTED_CODE is this operation code. For single bit fields, we can
5026 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5027 comparison for one-bit fields. */
5049 /* Start by getting the comparison codes. Fail if anything is volatile.
5050 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5051 it were surrounded with a NE_EXPR. */
5060 {
5064 }
5067 {
5071 }
5082 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5085 {
5086 tree result;
5089 {
5094 }
5097 {
5103 }
5104 }
5109 /* If the RHS can be evaluated unconditionally and its operands are
5110 simple, it wins to evaluate the RHS unconditionally on machines
5111 with expensive branches. In this case, this isn't a comparison
5112 that can be merged. Avoid doing this if the RHS is a floating-point
5113 comparison since those can trap. */
5119 {
5120 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5130 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5141 {
5145 }
5146 }
5148 /* See if the comparisons can be merged. Then get all the parameters for
5149 each side. */
5173 /* It must be true that the inner operation on the lhs of each
5174 comparison must be the same if we are to be able to do anything.
5175 Then see if we have constants. If not, the same must be true for
5176 the rhs's. */
5187 else
5190 /* If either comparison code is not correct for our logical operation,
5191 fail. However, we can convert a one-bit comparison against zero into
5192 the opposite comparison against that bit being set in the field. */
5196 {
5198 {
5199 /* Make the left operand unsigned, since we are only interested
5200 in the value of one bit. Otherwise we are doing the wrong
5201 thing below. */
5204 }
5205 else
5207 }
5209 /* This is analogous to the code for l_const above. */
5211 {
5213 {
5216 }
5217 else
5219 }
5221 /* After this point all optimizations will generate bit-field
5222 references, which we might not want. */
5226 /* See if we can find a mode that contains both fields being compared on
5227 the left. If we can't, fail. Otherwise, update all constants and masks
5228 to be relative to a field of that size. */
5233 volatilep);
5243 {
5246 }
5254 {
5262 {
5266 }
5267 }
5269 {
5277 {
5281 }
5282 }
5284 /* If the right sides are not constant, do the same for it. Also,
5285 disallow this optimization if a size or signedness mismatch occurs
5286 between the left and right sides. */
5288 {
5291 /* Make sure the two fields on the right
5292 correspond to the left without being swapped. */
5300 volatilep);
5310 {
5313 }
5320 /* Make a mask that corresponds to both fields being compared.
5321 Do this for both items being compared. If the operands are the
5322 same size and the bits being compared are in the same position
5323 then we can do this by masking both and comparing the masked
5324 results. */
5328 {
5340 }
5342 /* There is still another way we can do something: If both pairs of
5343 fields being compared are adjacent, we may be able to make a wider
5344 field containing them both.
5346 Note that we still must mask the lhs/rhs expressions. Furthermore,
5347 the mask must be shifted to account for the shift done by
5348 make_bit_field_ref. */
5353 {
5354 tree type;
5366 /* Convert to the smaller type before masking out unwanted bits. */
5369 {
5371 {
5375 }
5377 {
5381 }
5382 }
5391 }
5394 }
5396 /* Handle the case of comparisons with constants. If there is something in
5397 common between the masks, those bits of the constants must be the same.
5398 If not, the condition is always false. Test for this to avoid generating
5399 incorrect code below. */
5404 {
5406 {
5409 }
5410 else
5411 {
5414 }
5415 }
5417 /* Construct the expression we will return. First get the component
5418 reference we will make. Unless the mask is all ones the width of
5419 that field, perform the mask operation. Then compare with the
5420 merged constant. */
5430 }
5431 \f
5432 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5433 constant. */
5435 static tree
5437 {
5441 tree minmax_const;
5443 tree inner;
5453 /* If something does not permit us to optimize, return the original tree. */
5461 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5462 and GT_EXPR, doing the rest with recursive calls using logical
5463 simplifications. */
5465 {
5467 {
5473 }
5476 return
5478 optimize_minmax_comparison
5480 optimize_minmax_comparison
5485 /* MAX (X, 0) == 0 -> X <= 0 */
5489 /* MAX (X, 0) == 5 -> X == 5 */
5493 /* MAX (X, 0) == -1 -> false */
5497 /* MIN (X, 0) == 0 -> X >= 0 */
5501 /* MIN (X, 0) == 5 -> false */
5504 else
5505 /* MIN (X, 0) == -1 -> X == -1 */
5510 /* MAX (X, 0) > 0 -> X > 0
5511 MAX (X, 0) > 5 -> X > 5 */
5515 /* MAX (X, 0) > -1 -> true */
5519 /* MIN (X, 0) > 0 -> false
5520 MIN (X, 0) > 5 -> false */
5523 else
5524 /* MIN (X, 0) > -1 -> X > -1 */
5529 }
5530 }
5531 \f
5532 /* T is an integer expression that is being multiplied, divided, or taken a
5533 modulus (CODE says which and what kind of divide or modulus) by a
5534 constant C. See if we can eliminate that operation by folding it with
5535 other operations already in T. WIDE_TYPE, if non-null, is a type that
5536 should be used for the computation if wider than our type.
5538 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5539 (X * 2) + (Y * 4). We must, however, be assured that either the original
5540 expression would not overflow or that overflow is undefined for the type
5541 in the language in question.
5543 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5544 the machine has a multiply-accumulate insn or that this is part of an
5545 addressing calculation.
5547 If we return a non-null expression, it is an equivalent form of the
5548 original computation, but need not be in the original type.
5550 We set *STRICT_OVERFLOW_P to true if the return values depends on
5551 signed overflow being undefined. Otherwise we do not change
5552 *STRICT_OVERFLOW_P. */
5554 static tree
5557 {
5558 /* To avoid exponential search depth, refuse to allow recursion past
5559 three levels. Beyond that (1) it's highly unlikely that we'll find
5560 something interesting and (2) we've probably processed it before
5561 when we built the inner expression. */
5564 tree ret;
5569 depth++;
5571 depth--;
5574 }
5576 static tree
5579 {
5590 /* Don't deal with constants of zero here; they confuse the code below. */
5600 /* Note that we need not handle conditional operations here since fold
5601 already handles those cases. So just do arithmetic here. */
5603 {
5605 /* For a constant, we can always simplify if we are a multiply
5606 or (for divide and modulus) if it is a multiple of our constant. */
5614 /* If op0 is an expression ... */
5619 /* ... and is unsigned, and its type is smaller than ctype,
5620 then we cannot pass through as widening. */
5626 /* ... or this is a truncation (t is narrower than op0),
5627 then we cannot pass through this narrowing. */
5630 /* ... or signedness changes for division or modulus,
5631 then we cannot pass through this conversion. */
5637 /* Pass the constant down and see if we can make a simplification. If
5638 we can, replace this expression with the inner simplification for
5639 possible later conversion to our or some other type. */
5644 code == MULT_EXPR
5646 strict_overflow_p))))
5651 /* If widening the type changes it from signed to unsigned, then we
5652 must avoid building ABS_EXPR itself as unsigned. */
5654 {
5658 {
5661 }
5663 }
5664 /* If the constant is negative, we cannot simplify this. */
5667 /* FALLTHROUGH */
5675 /* If widening the type changes the signedness, then we can't perform
5676 this optimization as that changes the result. */
5680 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5686 {
5693 }
5697 /* If the second operand is constant, this is a multiplication
5698 or floor division, by a power of two, so we can treat it that
5699 way unless the multiplier or divisor overflows. Signed
5700 left-shift overflow is implementation-defined rather than
5701 undefined in C90, so do not convert signed left shift into
5702 multiplication. */
5705 /* const_binop may not detect overflow correctly,
5706 so check for it explicitly here. */
5711 size_one_node,
5721 /* See if we can eliminate the operation on both sides. If we can, we
5722 can return a new PLUS or MINUS. If we can't, the only remaining
5723 cases where we can do anything are if the second operand is a
5724 constant. */
5730 /* If not multiplication, we can only do this if both operands
5731 are divisible by c. */
5734 {
5739 }
5741 /* If this was a subtraction, negate OP1 and set it to be an addition.
5742 This simplifies the logic below. */
5749 /* If either OP1 or C are negative, this optimization is not safe for
5750 some of the division and remainder types while for others we need
5751 to change the code. */
5753 {
5761 }
5763 /* If it's a multiply or a division/modulus operation of a multiple
5764 of our constant, do the operation and verify it doesn't overflow. */
5767 {
5770 /* We allow the constant to overflow with wrapping semantics. */
5774 }
5775 else
5778 /* If we have an unsigned type is not a sizetype, we cannot widen
5779 the operation since it will change the result if the original
5780 computation overflowed. */
5786 /* If we were able to eliminate our operation from the first side,
5787 apply our operation to the second side and reform the PLUS. */
5791 /* The last case is if we are a multiply. In that case, we can
5792 apply the distributive law to commute the multiply and addition
5793 if the multiplication of the constants doesn't overflow. */
5799 op1);
5804 /* We have a special case here if we are doing something like
5805 (C * 8) % 4 since we know that's zero. */
5812 /* ... fall through ... */
5816 /* If we can extract our operation from the LHS, do so and return a
5817 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5818 do something only if the second operand is a constant. */
5832 /* If these are the same operation types, we can associate them
5833 assuming no overflow. */
5840 /* If these operations "cancel" each other, we have the main
5841 optimizations of this pass, which occur when either constant is a
5842 multiple of the other, in which case we replace this with either an
5843 operation or CODE or TCODE.
5845 If we have an unsigned type that is not a sizetype, we cannot do
5846 this since it will change the result if the original computation
5847 overflowed. */
5854 {
5856 {
5863 }
5865 {
5872 }
5873 }
5878 }
5881 }
5882 \f
5883 /* Return a node which has the indicated constant VALUE (either 0 or
5884 1), and is of the indicated TYPE. */
5886 tree
5888 {
5893 else
5895 }
5898 /* Return true if expr looks like an ARRAY_REF and set base and
5899 offset to the appropriate trees. If there is no offset,
5900 offset is set to NULL_TREE. Base will be canonicalized to
5901 something you can get the element type from using
5902 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5903 in bytes to the base. */
5905 static bool
5907 {
5908 /* One canonical form is a PLUS_EXPR with the first
5909 argument being an ADDR_EXPR with a possible NOP_EXPR
5910 attached. */
5912 {
5915 /* Strip NOP_EXPRs here because the C frontends and/or
5916 folders present us (int *)&x.a + 4B possibly. */
5919 {
5923 else
5927 }
5928 }
5929 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5930 which we transform into an ADDR_EXPR with appropriate
5931 offset. For other arguments to the ADDR_EXPR we assume
5932 zero offset and as such do not care about the ADDR_EXPR
5933 type and strip possible nops from it. */
5935 {
5938 {
5943 }
5944 else
5945 {
5946 /* Handle array-to-pointer decay as &a. */
5949 else
5952 }
5954 }
5955 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
5958 {
5962 }
5965 }
5968 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
5969 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
5970 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
5971 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
5972 COND is the first argument to CODE; otherwise (as in the example
5973 given here), it is the second argument. TYPE is the type of the
5974 original expression. Return NULL_TREE if no simplification is
5975 possible. */
5977 static tree
5981 {
5988 /* This transformation is only worthwhile if we don't have to wrap
5989 arg in a SAVE_EXPR, and the operation can be simplified on at least
5990 one of the branches once its pushed inside the COND_EXPR. */
5995 {
5999 /* If this operand throws an expression, then it does not make
6000 sense to try to perform a logical or arithmetic operation
6001 involving it. */
6006 }
6007 else
6008 {
6013 }
6017 {
6021 else
6023 }
6025 {
6029 else
6031 }
6035 }
6037 \f
6038 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6040 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6041 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6042 ADDEND is the same as X.
6044 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6045 and finite. The problematic cases are when X is zero, and its mode
6046 has signed zeros. In the case of rounding towards -infinity,
6047 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6048 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6050 static bool
6052 {
6056 /* Don't allow the fold with -fsignaling-nans. */
6060 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6064 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6069 /* The mode has signed zeros, and we have to honor their sign.
6070 In this situation, there is only one case we can return true for.
6071 X - 0 is the same as X unless rounding towards -infinity is
6072 supported. */
6074 }
6076 /* Subroutine of fold() that checks comparisons of built-in math
6077 functions against real constants.
6079 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6080 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6081 is the type of the result and ARG0 and ARG1 are the operands of the
6082 comparison. ARG1 must be a TREE_REAL_CST.
6084 The function returns the constant folded tree if a simplification
6085 can be made, and NULL_TREE otherwise. */
6087 static tree
6090 {
6091 REAL_VALUE_TYPE c;
6094 {
6100 {
6101 /* sqrt(x) < y is always false, if y is negative. */
6105 /* sqrt(x) > y is always true, if y is negative and we
6106 don't care about NaNs, i.e. negative values of x. */
6110 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6113 }
6115 {
6116 REAL_VALUE_TYPE c2;
6122 {
6123 /* sqrt(x) > y is x == +Inf, when y is very large. */
6128 /* sqrt(x) > y is always false, when y is very large
6129 and we don't care about infinities. */
6131 }
6133 /* sqrt(x) > c is the same as x > c*c. */
6136 }
6138 {
6139 REAL_VALUE_TYPE c2;
6145 {
6146 /* sqrt(x) < y is always true, when y is a very large
6147 value and we don't care about NaNs or Infinities. */
6151 /* sqrt(x) < y is x != +Inf when y is very large and we
6152 don't care about NaNs. */
6157 /* sqrt(x) < y is x >= 0 when y is very large and we
6158 don't care about Infinities. */
6163 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6172 dconst0)),
6175 c2)));
6176 }
6178 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6183 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6186 {
6191 dconst0)),
6194 c2)));
6195 }
6196 }
6197 }
6200 }
6202 /* Subroutine of fold() that optimizes comparisons against Infinities,
6203 either +Inf or -Inf.
6205 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6206 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6207 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6209 The function returns the constant folded tree if a simplification
6210 can be made, and NULL_TREE otherwise. */
6212 static tree
6214 {
6216 REAL_VALUE_TYPE max;
6217 tree temp;
6222 /* For negative infinity swap the sense of the comparison. */
6228 {
6230 /* x > +Inf is always false, if with ignore sNANs. */
6236 /* x <= +Inf is always true, if we don't case about NaNs. */
6240 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6243 {
6246 }
6251 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6257 /* x < +Inf is always equal to x <= DBL_MAX. */
6263 /* x != +Inf is always equal to !(x > DBL_MAX). */
6269 /* The transformation below creates non-gimple code and thus is
6270 not appropriate if we are in gimple form. */
6280 }
6283 }
6285 /* Subroutine of fold() that optimizes comparisons of a division by
6286 a nonzero integer constant against an integer constant, i.e.
6287 X/C1 op C2.
6289 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6290 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6291 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6293 The function returns the constant folded tree if a simplification
6294 can be made, and NULL_TREE otherwise. */
6296 static tree
6298 {
6303 HOST_WIDE_INT hpart;
6308 /* We have to do this the hard way to detect unsigned overflow.
6309 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6320 {
6324 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6333 }
6335 {
6338 {
6357 }
6358 }
6359 else
6360 {
6361 /* A negative divisor reverses the relational operators. */
6366 {
6385 }
6386 }
6389 {
6410 {
6413 }
6418 {
6421 }
6426 {
6429 }
6434 {
6437 }
6442 }
6445 }
6448 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6449 equality/inequality test, then return a simplified form of the test
6450 using a sign testing. Otherwise return NULL. TYPE is the desired
6451 result type. */
6453 static tree
6455 tree result_type)
6456 {
6457 /* If this is testing a single bit, we can optimize the test. */
6461 {
6462 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6463 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6467 /* This is only a win if casting to a signed type is cheap,
6468 i.e. when arg00's type is not a partial mode. */
6471 {
6476 }
6477 }
6480 }
6482 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6483 equality/inequality test, then return a simplified form of
6484 the test using shifts and logical operations. Otherwise return
6485 NULL. TYPE is the desired result type. */
6487 tree
6489 tree result_type)
6490 {
6491 /* If this is testing a single bit, we can optimize the test. */
6495 {
6502 tree tem;
6504 /* First, see if we can fold the single bit test into a sign-bit
6505 test. */
6507 result_type);
6511 /* Otherwise we have (A & C) != 0 where C is a single bit,
6512 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6513 Similarly for (A & C) == 0. */
6515 /* If INNER is a right shift of a constant and it plus BITNUM does
6516 not overflow, adjust BITNUM and INNER. */
6523 {
6526 }
6528 /* If we are going to be able to omit the AND below, we must do our
6529 operations as unsigned. If we must use the AND, we have a choice.
6530 Normally unsigned is faster, but for some machines signed is. */
6531 #ifdef LOAD_EXTEND_OP
6534 #else
6536 #endif
6551 /* Put the AND last so it can combine with more things. */
6555 /* Make sure to return the proper type. */
6559 }
6561 }
6563 /* Check whether we are allowed to reorder operands arg0 and arg1,
6564 such that the evaluation of arg1 occurs before arg0. */
6566 static bool
6568 {
6575 }
6577 /* Test whether it is preferable two swap two operands, ARG0 and
6578 ARG1, for example because ARG0 is an integer constant and ARG1
6579 isn't. If REORDER is true, only recommend swapping if we can
6580 evaluate the operands in reverse order. */
6582 bool
6584 {
6620 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6621 for commutative and comparison operators. Ensuring a canonical
6622 form allows the optimizers to find additional redundancies without
6623 having to explicitly check for both orderings. */
6630 }
6632 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6633 ARG0 is extended to a wider type. */
6635 static tree
6637 {
6639 tree arg1_unw;
6648 #ifdef HAVE_canonicalize_funcptr_for_compare
6649 /* Disable this optimization if we're casting a function pointer
6650 type on targets that require function pointer canonicalization. */
6655 #endif
6662 /* If possible, express the comparison in the shorter mode. */
6678 /* If we are comparing with the integer that does not fit into the range
6679 of the shorter type, the result is known. */
6690 {
6717 }
6720 }
6722 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6723 ARG0 just the signedness is changed. */
6725 static tree
6728 {
6740 #ifdef HAVE_canonicalize_funcptr_for_compare
6741 /* Disable this optimization if we're casting a function pointer
6742 type on targets that require function pointer canonicalization. */
6747 #endif
6764 {
6771 }
6772 else
6776 }
6778 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6779 step of the array. Reconstructs s and delta in the case of s * delta
6780 being an integer constant (and thus already folded).
6781 ADDR is the address. MULT is the multiplicative expression.
6782 If the function succeeds, the new address expression is returned. Otherwise
6783 NULL_TREE is returned. */
6785 static tree
6787 {
6791 tree itype;
6793 /* Canonicalize op1 into a possibly non-constant delta
6794 and an INTEGER_CST s. */
6796 {
6803 {
6806 }
6808 {
6811 }
6812 else
6814 }
6816 {
6819 }
6820 else
6821 {
6822 /* Simulate we are delta * 1. */
6825 }
6828 {
6830 {
6840 {
6843 }
6844 else
6845 {
6846 /* Try if delta is a multiple of step. */
6851 }
6854 }
6858 }
6860 /* We found the suitable array reference. So copy everything up to it,
6861 and replace the index. */
6868 {
6872 }
6880 }
6883 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6884 means A >= Y && A != MAX, but in this case we know that
6885 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6887 static tree
6889 {
6896 else
6905 {
6908 }
6910 {
6913 }
6914 else
6925 }
6927 /* Fold a sum or difference of at least one multiplication.
6928 Returns the folded tree or NULL if no simplification could be made. */
6930 static tree
6932 {
6936 /* (A * C) +- (B * C) -> (A+-B) * C.
6937 (A * C) +- A -> A * (C+-1).
6938 We are most concerned about the case where C is a constant,
6939 but other combinations show up during loop reduction. Since
6940 it is not difficult, try all four possibilities. */
6943 {
6946 }
6947 else
6948 {
6951 }
6953 {
6956 }
6957 else
6958 {
6961 }
6973 /* No identical multiplicands; see if we can find a common
6974 power-of-two factor in non-power-of-two multiplies. This
6975 can help in multi-dimensional array access. */
6978 {
6981 tree maybe_same;
6985 /* Move min of absolute values to int11. */
6988 {
6993 }
6994 else
6998 {
7006 }
7007 }
7017 }
7019 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7020 specified by EXPR into the buffer PTR of length LEN bytes.
7021 Return the number of bytes placed in the buffer, or zero
7022 upon failure. */
7024 static int
7026 {
7037 {
7041 else
7046 {
7053 else
7055 }
7056 else
7059 }
7061 }
7064 /* Subroutine of native_encode_expr. Encode the REAL_CST
7065 specified by EXPR into the buffer PTR of length LEN bytes.
7066 Return the number of bytes placed in the buffer, or zero
7067 upon failure. */
7069 static int
7071 {
7077 /* There are always 32 bits in each long, no matter the size of
7078 the hosts long. We handle floating point representations with
7079 up to 192 bits. */
7090 {
7095 {
7102 else
7104 }
7105 else
7108 }
7110 }
7112 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7113 specified by EXPR into the buffer PTR of length LEN bytes.
7114 Return the number of bytes placed in the buffer, or zero
7115 upon failure. */
7117 static int
7119 {
7121 tree part;
7132 }
7135 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7136 specified by EXPR into the buffer PTR of length LEN bytes.
7137 Return the number of bytes placed in the buffer, or zero
7138 upon failure. */
7140 static int
7142 {
7152 {
7154 {
7157 }
7158 else
7162 {
7165 }
7166 else
7167 {
7171 }
7173 }
7175 }
7178 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7179 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7180 buffer PTR of length LEN bytes. Return the number of bytes
7181 placed in the buffer, or zero upon failure. */
7183 static int
7185 {
7187 {
7202 }
7203 }
7206 /* Subroutine of native_interpret_expr. Interpret the contents of
7207 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7208 If the buffer cannot be interpreted, return NULL_TREE. */
7210 static tree
7212 {
7226 {
7229 {
7236 else
7238 }
7239 else
7245 else
7248 }
7252 }
7255 /* Subroutine of native_interpret_expr. Interpret the contents of
7256 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7257 If the buffer cannot be interpreted, return NULL_TREE. */
7259 static tree
7261 {
7266 /* There are always 32 bits in each long, no matter the size of
7267 the hosts long. We handle floating point representations with
7268 up to 192 bits. */
7269 REAL_VALUE_TYPE r;
7280 {
7283 {
7290 else
7292 }
7293 else
7298 }
7302 }
7305 /* Subroutine of native_interpret_expr. Interpret the contents of
7306 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7307 If the buffer cannot be interpreted, return NULL_TREE. */
7309 static tree
7311 {
7326 }
7329 /* Subroutine of native_interpret_expr. Interpret the contents of
7330 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7331 If the buffer cannot be interpreted, return NULL_TREE. */
7333 static tree
7335 {
7347 {
7352 }
7354 }
7357 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7358 the buffer PTR of length LEN as a constant of type TYPE. For
7359 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7360 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7361 return NULL_TREE. */
7363 static tree
7365 {
7367 {
7384 }
7385 }
7388 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7389 TYPE at compile-time. If we're unable to perform the conversion
7390 return NULL_TREE. */
7392 static tree
7394 {
7395 /* We support up to 512-bit values (for V8DFmode). */
7399 /* Check that the host and target are sane. */
7408 }
7411 /* Fold a unary expression of code CODE and type TYPE with operand
7412 OP0. Return the folded expression if folding is successful.
7413 Otherwise, return NULL_TREE. */
7415 tree
7417 {
7418 tree tem;
7419 tree arg0;
7427 {
7430 {
7431 /* Don't use STRIP_NOPS, because signedness of argument type
7432 matters. */
7434 }
7435 else
7436 {
7437 /* Strip any conversions that don't change the mode. This
7438 is safe for every expression, except for a comparison
7439 expression because its signedness is derived from its
7440 operands.
7442 Note that this is done as an internal manipulation within
7443 the constant folder, in order to find the simplest
7444 representation of the arguments so that their form can be
7445 studied. In any cases, the appropriate type conversions
7446 should be put back in the tree that will get out of the
7447 constant folder. */
7449 }
7450 }
7453 {
7458 {
7468 /* If this was a conversion, and all we did was to move into
7469 inside the COND_EXPR, bring it back out. But leave it if
7470 it is a conversion from integer to integer and the
7471 result precision is no wider than a word since such a
7472 conversion is cheap and may be optimized away by combine,
7473 while it couldn't if it were outside the COND_EXPR. Then return
7474 so we don't get into an infinite recursion loop taking the
7475 conversion out and then back in. */
7487 && (INTEGRAL_TYPE_P
7499 }
7501 {
7503 {
7507 }
7511 integer_one_node),
7513 integer_zero_node));
7514 }
7515 }
7518 {
7529 /* If we have (type) (a CMP b) and type is an integral type, return
7530 new expression involving the new type. */
7535 /* Handle cases of two conversions in a row. */
7538 {
7560 /* In addition to the cases of two conversions in a row
7561 handled below, if we are converting something to its own
7562 type via an object of identical or wider precision, neither
7563 conversion is needed. */
7570 /* Likewise, if the intermediate and final types are either both
7571 float or both integer, we don't need the middle conversion if
7572 it is wider than the final type and doesn't change the signedness
7573 (for integers). Avoid this if the final type is a pointer
7574 since then we sometimes need the inner conversion. Likewise if
7575 the outer has a precision not equal to the size of its mode. */
7584 && ! final_ptr
7588 /* If we have a sign-extension of a zero-extended value, we can
7589 replace that by a single zero-extension. */
7595 /* Two conversions in a row are not needed unless:
7596 - some conversion is floating-point (overstrict for now), or
7597 - some conversion is a vector (overstrict for now), or
7598 - the intermediate type is narrower than both initial and
7599 final, or
7600 - the intermediate type and innermost type differ in signedness,
7601 and the outermost type is wider than the intermediate, or
7602 - the initial type is a pointer type and the precisions of the
7603 intermediate and final types differ, or
7604 - the final type is a pointer type and the precisions of the
7605 initial and intermediate types differ.
7606 - the final type is a pointer type and the initial type not
7607 - the initial type is a pointer to an array and the final type
7608 not. */
7609 /* Java pointer type conversions generate checks in some
7610 cases, so we explicitly disallow this optimization. */
7624 && ! (inside_ptr
7630 }
7632 /* Handle (T *)&A.B.C for A being of type T and B and C
7633 living at offset zero. This occurs frequently in
7634 C++ upcasting and then accessing the base. */
7638 {
7640 tree offset;
7646 /* If the reference was to a (constant) zero offset, we can use
7647 the address of the base if it has the same base type
7648 as the result type. */
7653 }
7657 /* Detect assigning a bitfield. */
7660 {
7661 /* Don't leave an assignment inside a conversion
7662 unless assigning a bitfield. */
7664 /* First do the assignment, then return converted constant. */
7669 }
7671 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7672 constants (if x has signed type, the sign bit cannot be set
7673 in c). This folds extension into the BIT_AND_EXPR. */
7678 {
7688 <= HOST_BITS_PER_WIDE_INT
7690 {
7697 #ifdef LOAD_EXTEND_OP
7699 && !flag_syntax_only
7702 {
7706 }
7707 #endif
7708 }
7710 {
7717 }
7718 }
7720 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
7721 T2 being pointers to types of the same size. */
7726 {
7738 }
7740 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7741 of the same precision, and X is a integer type not narrower than
7742 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7749 {
7754 }
7775 /* Convert fabs((double)float) into (double)fabsf(float). */
7778 {
7783 targ0));
7784 }
7785 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7791 /* Strip sign ops from argument. */
7793 {
7797 }
7804 {
7809 }
7811 {
7816 }
7826 /* Convert ~ (-A) to A - 1. */
7830 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7837 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7854 /* The argument to invert_truthvalue must have Boolean type. */
7858 /* Note that the operand of this must be an int
7859 and its values must be 0 or 1.
7860 ("true" is a fixed value perhaps depending on the language,
7861 but we don't handle values other than 1 correctly yet.) */
7876 {
7884 }
7886 {
7890 }
7902 {
7910 }
7912 {
7916 }
7922 }
7924 /* Fold a binary expression of code CODE and type TYPE with operands
7925 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
7926 Return the folded expression if folding is successful. Otherwise,
7927 return NULL_TREE. */
7929 static tree
7931 {
7938 else
7941 /* MIN (MAX (a, b), b) == b. */
7946 /* MIN (MAX (b, a), b) == b. */
7952 /* MIN (a, MAX (a, b)) == a. */
7958 /* MIN (a, MAX (b, a)) == a. */
7965 }
7967 /* Subroutine of fold_binary. This routine performs all of the
7968 transformations that are common to the equality/inequality
7969 operators (EQ_EXPR and NE_EXPR) and the ordering operators
7970 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
7971 fold_binary should call fold_binary. Fold a comparison with
7972 tree code CODE and type TYPE with operands OP0 and OP1. Return
7973 the folded comparison or NULL_TREE. */
7975 static tree
7977 {
7990 /* If one arg is a real or integer constant, put it last. */
7994 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8001 {
8005 tree lhs;
8014 {
8016 "when changing X +- C1 cmp C2 to "
8018 WARN_STRICT_OVERFLOW_COMPARISON);
8020 }
8021 }
8023 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8024 same object, then we can fold this to a comparison of the two offsets in
8025 signed size type. This is possible because pointer arithmetic is
8026 restricted to retain within an object and overflow on pointer differences
8027 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8029 We check flag_wrapv directly because pointers types are unsigned,
8030 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8031 normally what we want to avoid certain odd overflow cases, but
8032 not here. */
8034 && !flag_wrapv
8036 {
8042 {
8043 tree signed_size_type_node;
8046 /* By converting to signed size type we cover middle-end pointer
8047 arithmetic which operates on unsigned pointer types of size
8048 type size and ARRAY_REF offsets which are properly sign or
8049 zero extended from their type in case it is narrower than
8050 size type. */
8053 else
8057 else
8061 }
8062 }
8065 {
8073 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8078 /* (-a) CMP (-b) -> b CMP a */
8085 {
8086 REAL_VALUE_TYPE cst;
8089 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8096 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8097 /* a CMP (-0) -> a CMP 0 */
8102 /* x != NaN is always true, other ops are always false. */
8105 {
8108 }
8110 /* Fold comparisons against infinity. */
8112 {
8116 }
8117 }
8119 /* If this is a comparison of a real constant with a PLUS_EXPR
8120 or a MINUS_EXPR of a real constant, we can convert it into a
8121 comparison with a revised real constant as long as no overflow
8122 occurs when unsafe_math_optimizations are enabled. */
8134 /* Likewise, we can simplify a comparison of a real constant with
8135 a MINUS_EXPR whose first operand is also a real constant, i.e.
8136 (c1 - x) < c2 becomes x > c1-c2. */
8147 /* Fold comparisons against built-in math functions. */
8149 && flag_unsafe_math_optimizations
8151 {
8155 {
8159 }
8160 }
8161 }
8163 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
8167 /* This optimization is invalid for ordered comparisons
8168 if CONST+INCR overflows or if foo+incr might overflow.
8169 This optimization is invalid for floating point due to rounding.
8170 For pointer types we assume overflow doesn't happen. */
8174 {
8178 {
8184 }
8185 else
8186 {
8192 }
8195 /* If VAROP is a reference to a bitfield, we must mask
8196 the constant by the width of the field. */
8201 {
8206 /* First check whether the comparison would come out
8207 always the same. If we don't do that we would
8208 change the meaning with the masking. */
8221 }
8224 }
8229 {
8230 /* If we are widening one operand of an integer comparison,
8231 see if the other operand is similarly being widened. Perhaps we
8232 can do the comparison in the narrower type. */
8237 /* Or if we are changing signedness. */
8241 }
8243 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8244 constant, we can simplify it. */
8249 {
8253 }
8255 /* Simplify comparison of something with itself. (For IEEE
8256 floating-point, we can only do some of these simplifications.) */
8258 {
8260 {
8275 /* For NE, we can only do this simplification if integer
8276 or we don't honor IEEE floating point NaNs. */
8280 /* ... fall through ... */
8286 }
8287 }
8289 /* If we are comparing an expression that just has comparisons
8290 of two integer values, arithmetic expressions of those comparisons,
8291 and constants, we can simplify it. There are only three cases
8292 to check: the two values can either be equal, the first can be
8293 greater, or the second can be greater. Fold the expression for
8294 those three values. Since each value must be 0 or 1, we have
8295 eight possibilities, each of which corresponds to the constant 0
8296 or 1 or one of the six possible comparisons.
8298 This handles common cases like (a > b) == 0 but also handles
8299 expressions like ((x > y) - (y > x)) > 0, which supposedly
8300 occur in macroized code. */
8303 {
8308 /* Don't handle degenerate cases here; they should already
8309 have been handled anyway. */
8318 {
8322 /* We can't just pass T to eval_subst in case cval1 or cval2
8323 was the same as ARG1. */
8325 tree high_result
8329 arg1);
8330 tree equal_result
8334 arg1);
8335 tree low_result
8339 arg1);
8341 /* All three of these results should be 0 or 1. Confirm they are.
8342 Then use those values to select the proper code to use. */
8347 {
8348 /* Make a 3-bit mask with the high-order bit being the
8349 value for `>', the next for '=', and the low for '<'. */
8353 {
8355 /* Always false. */
8376 /* Always true. */
8378 }
8383 }
8384 }
8385 }
8387 /* Fold a comparison of the address of COMPONENT_REFs with the same
8388 type and component to a comparison of the address of the base
8389 object. In short, &x->a OP &y->a to x OP y and
8390 &x->a OP &y.a to x OP &y */
8395 {
8399 {
8405 }
8406 }
8408 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8409 into a single range test. */
8417 {
8421 }
8424 }
8427 /* Subroutine of fold_binary. Optimize complex multiplications of the
8428 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8429 argument EXPR represents the expression "z" of type TYPE. */
8431 static tree
8433 {
8438 {
8441 }
8443 {
8446 }
8447 else
8448 {
8452 }
8461 }
8464 /* Fold a binary expression of code CODE and type TYPE with operands
8465 OP0 and OP1. Return the folded expression if folding is
8466 successful. Otherwise, return NULL_TREE. */
8468 tree
8470 {
8484 /* Strip any conversions that don't change the mode. This is
8485 safe for every expression, except for a comparison expression
8486 because its signedness is derived from its operands. So, in
8487 the latter case, only strip conversions that don't change the
8488 signedness.
8490 Note that this is done as an internal manipulation within the
8491 constant folder, in order to find the simplest representation
8492 of the arguments so that their form can be studied. In any
8493 cases, the appropriate type conversions should be put back in
8494 the tree that will get out of the constant folder. */
8497 {
8500 }
8501 else
8502 {
8505 }
8507 /* Note that TREE_CONSTANT isn't enough: static var addresses are
8508 constant but we can't do arithmetic on them. */
8513 {
8518 else
8522 {
8526 }
8527 }
8529 /* If this is a commutative operation, and ARG0 is a constant, move it
8530 to ARG1 to reduce the number of tests below. */
8535 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
8537 First check for cases where an arithmetic operation is applied to a
8538 compound, conditional, or comparison operation. Push the arithmetic
8539 operation inside the compound or conditional to see if any folding
8540 can then be done. Convert comparison to conditional for this purpose.
8541 The also optimizes non-constant cases that used to be done in
8542 expand_expr.
8544 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
8545 one of the operands is a comparison and the other is a comparison, a
8546 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
8547 code below would make the expression more complex. Change it to a
8548 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
8549 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
8561 {
8565 boolean_type_node,
8573 }
8577 {
8589 {
8595 }
8598 {
8604 }
8605 }
8608 {
8610 /* A + (-B) -> A - B */
8615 /* (-A) + B -> B - A */
8621 /* Convert ~A + 1 to -A. */
8627 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
8628 same or one. */
8632 {
8636 }
8639 {
8643 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
8644 with a constant, and the two constants have no bits in common,
8645 we should treat this as a BIT_IOR_EXPR since this may produce more
8646 simplifications. */
8654 {
8657 }
8659 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
8660 (plus (plus (mult) (mult)) (foo)) so that we can
8661 take advantage of the factoring cases below. */
8668 {
8674 else
8696 parg1)));
8697 }
8699 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
8700 of the array. Loop optimizer sometimes produce this type of
8701 expressions. */
8703 {
8707 }
8709 {
8713 }
8714 }
8715 else
8716 {
8717 /* See if ARG1 is zero and X + ARG1 reduces to X. */
8721 /* Likewise if the operands are reversed. */
8725 /* Convert X + -C into X - C. */
8728 {
8734 }
8742 /* Convert x+x into x*2.0. */
8748 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
8752 {
8757 {
8758 tree tree0;
8761 }
8762 }
8763 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
8767 {
8772 {
8773 tree tree0;
8776 }
8777 }
8778 }
8780 bit_rotate:
8781 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
8782 is a rotate of A by C1 bits. */
8783 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
8784 is a rotate of A by B bits. */
8785 {
8794 {
8813 {
8821 TYPE_PRECISION
8826 ? LROTATE_EXPR
8829 }
8831 {
8839 TYPE_PRECISION
8844 ? LROTATE_EXPR
8847 }
8848 }
8849 }
8851 associate:
8852 /* In most languages, can't associate operations on floats through
8853 parentheses. Rather than remember where the parentheses were, we
8854 don't associate floats at all, unless the user has specified
8855 -funsafe-math-optimizations. */
8858 {
8863 /* Split both trees into variables, constants, and literals. Then
8864 associate each group together, the constants with literals,
8865 then the result with variables. This increases the chances of
8866 literals being recombined later and of generating relocatable
8867 expressions for the sum of a constant and literal. */
8872 /* With undefined overflow we can only associate constants
8873 with one variable. */
8878 {
8886 /* The only case we can still associate with two variables
8887 is if they are the same, modulo negation. */
8890 }
8892 /* Only do something if we found more than two objects. Otherwise,
8893 nothing has changed and we risk infinite recursion. */
8899 {
8900 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
8909 /* Preserve the MINUS_EXPR if the negative part of the literal is
8910 greater than the positive part. Otherwise, the multiplicative
8911 folding code (i.e extract_muldiv) may be fooled in case
8912 unsigned constants are subtracted, like in the following
8913 example: ((X*2 + 4) - 8U)/2. */
8915 {
8919 {
8923 }
8924 else
8925 {
8929 }
8930 }
8932 {
8937 else
8938 {
8944 }
8945 }
8950 }
8951 }
8956 /* A - (-B) -> A + B */
8959 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
8967 /* Convert -A - 1 to ~A. */
8974 /* Convert -1 - A to ~A. */
8980 {
8986 /* Fold A - (A & B) into ~B & A. */
8989 {
8994 arg0);
8999 arg0);
9000 }
9002 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9003 any power of 2 minus 1. */
9008 {
9014 {
9018 }
9019 }
9020 }
9022 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9026 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9027 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9028 (-ARG1 + ARG0) reduces to -ARG1. */
9032 /* Fold &x - &x. This can happen from &x.foo - &x.
9033 This is unsafe for certain floats even in non-IEEE formats.
9034 In IEEE, it is unsafe because it does wrong for NaNs.
9035 Also note that operand_equal_p is always false if an operand
9036 is volatile. */
9042 /* A - B -> A + (-B) if B is easily negatable. */
9045 /* Avoid this transformation if B is a positive REAL_CST. */
9053 /* Try folding difference of addresses. */
9054 {
9055 HOST_WIDE_INT diff;
9061 }
9063 /* Fold &a[i] - &a[j] to i-j. */
9068 {
9073 {
9081 }
9082 }
9084 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9085 of the array. Loop optimizer sometimes produce this type of
9086 expressions. */
9088 {
9092 }
9100 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9101 same or one. */
9105 {
9109 }
9114 /* (-A) * (-B) -> A * B */
9125 {
9130 /* Transform x * -1 into -x. */
9134 /* (a * (1 << b)) is (a << b) */
9150 {
9153 "occur when simplifying "
9155 WARN_STRICT_OVERFLOW_MISC);
9157 }
9159 /* Optimize z * conj(z) for integer complex numbers. */
9166 }
9167 else
9168 {
9169 /* Maybe fold x * 0 to 0. The expressions aren't the same
9170 when x is NaN, since x * 0 is also NaN. Nor are they the
9171 same in modes with signed zeros, since multiplying a
9172 negative value by 0 gives -0, not +0. */
9177 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9182 /* Transform x * -1.0 into -x. */
9187 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9192 {
9198 }
9200 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9202 {
9205 {
9208 }
9209 }
9211 /* Optimize z * conj(z) for floating point complex numbers.
9212 Guarded by flag_unsafe_math_optimizations as non-finite
9213 imaginary components don't produce scalar results. */
9224 {
9228 /* Optimizations of root(...)*root(...). */
9230 {
9235 /* Optimize sqrt(x)*sqrt(x) as x. */
9241 /* Optimize root(x)*root(y) as root(x*y). */
9246 }
9248 /* Optimize expN(x)*expN(y) as expN(x+y). */
9250 {
9257 }
9259 /* Optimizations of pow(...)*pow(...). */
9263 {
9271 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9273 {
9278 arg01));
9280 }
9282 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9284 {
9289 arg));
9291 }
9292 }
9294 /* Optimize tan(x)*cos(x) as sin(x). */
9303 {
9309 }
9311 /* Optimize x*pow(x,c) as pow(x,c+1). */
9315 {
9322 {
9324 REAL_VALUE_TYPE c;
9333 }
9334 }
9336 /* Optimize pow(x,c)*x as pow(x,c+1). */
9340 {
9347 {
9349 REAL_VALUE_TYPE c;
9358 }
9359 }
9361 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9364 {
9368 {
9373 }
9374 }
9375 }
9376 }
9380 bit_ior:
9388 /* ~X | X is -1. */
9391 {
9395 }
9397 /* X | ~X is -1. */
9400 {
9404 }
9406 /* Canonicalize (X & C1) | C2. */
9410 {
9418 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9423 {
9427 }
9428 else
9429 {
9433 }
9435 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9440 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
9450 arg1);
9451 }
9453 /* (X & Y) | Y is (X, Y). */
9457 /* (X & Y) | X is (Y, X). */
9462 /* X | (X & Y) is (Y, X). */
9467 /* X | (Y & X) is (Y, X). */
9477 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
9479 This results in more efficient code for machines without a NAND
9480 instruction. Combine will canonicalize to the first form
9481 which will allow use of NAND instructions provided by the
9482 backend if they exist. */
9485 {
9490 }
9492 /* See if this can be simplified into a rotate first. If that
9493 is unsuccessful continue in the association code. */
9504 /* ~X ^ X is -1. */
9507 {
9511 }
9513 /* X ^ ~X is -1. */
9516 {
9520 }
9522 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
9523 with a constant, and the two constants have no bits in common,
9524 we should treat this as a BIT_IOR_EXPR since this may produce more
9525 simplifications. */
9533 {
9536 }
9538 /* (X | Y) ^ X -> Y & ~ X*/
9541 {
9544 arg1);
9548 }
9550 /* (Y | X) ^ X -> Y & ~ X*/
9553 {
9556 arg1);
9560 }
9562 /* X ^ (X | Y) -> Y & ~ X*/
9565 {
9568 arg0);
9572 }
9574 /* X ^ (Y | X) -> Y & ~ X*/
9577 {
9580 arg0);
9584 }
9586 /* Convert ~X ^ ~Y to X ^ Y. */
9593 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9600 /* Fold (X & Y) ^ Y as ~X & Y. */
9603 {
9608 }
9609 /* Fold (X & Y) ^ X as ~Y & X. */
9613 {
9618 }
9619 /* Fold X ^ (X & Y) as X & ~Y. */
9622 {
9627 }
9628 /* Fold X ^ (Y & X) as ~Y & X. */
9632 {
9637 }
9639 /* See if this can be simplified into a rotate first. If that
9640 is unsuccessful continue in the association code. */
9651 /* ~X & X is always zero. */
9656 /* X & ~X is always zero. */
9661 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
9671 /* (X | Y) & Y is (X, Y). */
9675 /* (X | Y) & X is (Y, X). */
9680 /* X & (X | Y) is (Y, X). */
9685 /* X & (Y | X) is (Y, X). */
9691 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9695 {
9701 }
9702 /* Fold ~X & 1 as (X & 1) == 0. */
9705 {
9711 }
9713 /* Fold (X ^ Y) & Y as ~X & Y. */
9716 {
9721 }
9722 /* Fold (X ^ Y) & X as ~Y & X. */
9726 {
9731 }
9732 /* Fold X & (X ^ Y) as X & ~Y. */
9735 {
9740 }
9741 /* Fold X & (Y ^ X) as ~Y & X. */
9745 {
9750 }
9755 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
9758 {
9759 unsigned int prec
9766 }
9768 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
9770 This results in more efficient code for machines without a NOR
9771 instruction. Combine will canonicalize to the first form
9772 which will allow use of NOR instructions provided by the
9773 backend if they exist. */
9776 {
9781 }
9786 /* Don't touch a floating-point divide by zero unless the mode
9787 of the constant can represent infinity. */
9793 /* Optimize A / A to 1.0 if we don't care about
9794 NaNs or Infinities. Skip the transformation
9795 for non-real operands. */
9800 {
9804 }
9806 /* The complex version of the above A / A optimization. */
9809 {
9813 {
9815 /* omit_two_operands will call fold_convert for us. */
9817 }
9818 }
9820 /* (-A) / (-B) -> A / B */
9830 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
9835 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
9840 /* If ARG1 is a constant, we can convert this to a multiply by the
9841 reciprocal. This does not have the same rounding properties,
9842 so only do this if -funsafe-math-optimizations. We can actually
9843 always safely do it if ARG1 is a power of two, but it's hard to
9844 tell if it is or not in a portable manner. */
9846 {
9851 /* Find the reciprocal if optimizing and the result is exact. */
9853 {
9854 REAL_VALUE_TYPE r;
9857 {
9861 }
9862 }
9863 }
9864 /* Convert A/B/C to A/(B*C). */
9871 /* Convert A/(B/C) to (A/B)*C. */
9879 /* Convert C1/(X*C2) into (C1/C2)/X. */
9884 {
9890 }
9893 {
9897 /* Optimize sin(x)/cos(x) as tan(x). */
9903 {
9909 }
9911 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
9917 {
9921 {
9926 }
9927 }
9929 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
9930 NaNs or Infinities. */
9934 {
9941 {
9947 }
9948 }
9950 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
9951 NaNs or Infinities. */
9955 {
9962 {
9966 {
9971 tmp);
9972 }
9973 }
9974 }
9976 /* Optimize pow(x,c)/x as pow(x,c-1). */
9980 {
9986 {
9988 REAL_VALUE_TYPE c;
9997 }
9998 }
10000 /* Optimize x/expN(y) into x*expN(-y). */
10002 {
10009 }
10011 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10015 {
10024 }
10025 }
10030 /* Simplify A / (B << N) where A and B are positive and B is
10031 a power of 2, to A >> (N + log2(B)). */
10036 {
10039 {
10046 WARN_STRICT_OVERFLOW_MISC);
10052 }
10053 }
10054 /* Fall thru */
10063 /* X / -1 is -X. */
10070 /* Convert -A / -B to A / B when the type is signed and overflow is
10071 undefined. */
10075 {
10078 "when distributing negation across "
10080 WARN_STRICT_OVERFLOW_MISC);
10083 }
10087 {
10090 "when distributing negation across "
10092 WARN_STRICT_OVERFLOW_MISC);
10095 }
10097 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10098 operation, EXACT_DIV_EXPR.
10100 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10101 At one time others generated faster code, it's not clear if they do
10102 after the last round to changes to the DIV code in expmed.c. */
10111 {
10115 WARN_STRICT_OVERFLOW_MISC);
10117 }
10125 /* X % 1 is always zero, but be sure to preserve any side
10126 effects in X. */
10130 /* X % 0, return X % 0 unchanged so that we can get the
10131 proper warnings and errors. */
10135 /* 0 % X is always zero, but be sure to preserve any side
10136 effects in X. Place this after checking for X == 0. */
10140 /* X % -1 is zero. */
10147 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10148 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10153 {
10155 /* Also optimize A % (C << N) where C is a power of 2,
10156 to A & ((C << N) - 1). */
10161 {
10166 "occur when simplifying "
10168 WARN_STRICT_OVERFLOW_MISC);
10172 }
10173 }
10175 /* X % -C is the same as X % C. */
10182 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10187 /* X % -Y is the same as X % Y. */
10198 {
10202 WARN_STRICT_OVERFLOW_MISC);
10204 }
10215 /* Optimize -1 >> x for arithmetic right shifts. */
10218 /* ... fall through ... */
10221 shift:
10227 /* Since negative shift count is not well-defined,
10228 don't try to compute it in the compiler. */
10232 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10237 {
10241 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10242 being well defined. */
10244 {
10249 else
10251 }
10255 }
10257 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10258 into x & ((unsigned)-1 >> c) for unsigned types. */
10266 {
10269 tree lshift;
10270 tree arg00;
10273 {
10280 }
10281 }
10283 /* Rewrite an LROTATE_EXPR by a constant into an
10284 RROTATE_EXPR by a new constant. */
10286 {
10292 }
10294 /* If we have a rotate of a bit operation with the rotate count and
10295 the second operand of the bit operation both constant,
10296 permute the two operations. */
10308 /* Two consecutive rotates adding up to the width of the mode can
10309 be ignored. */
10346 /* Note that the operands of this must be ints
10347 and their values must be 0 or 1.
10348 ("true" is a fixed value perhaps depending on the language.) */
10349 /* If first arg is constant zero, return it. */
10353 /* If either arg is constant true, drop it. */
10357 /* Preserve sequence points. */
10360 /* If second arg is constant zero, result is zero, but first arg
10361 must be evaluated. */
10364 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10365 case will be handled here. */
10369 /* !X && X is always false. */
10373 /* X && !X is always false. */
10378 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10379 means A >= Y && A != MAX, but in this case we know that
10380 A < X <= MAX. */
10384 {
10392 }
10394 truth_andor:
10395 /* We only do these simplifications if we are optimizing. */
10399 /* Check for things like (A || B) && (A || C). We can convert this
10400 to A || (B && C). Note that either operator can be any of the four
10401 truth and/or operations and the transformation will still be
10402 valid. Also note that we only care about order for the
10403 ANDIF and ORIF operators. If B contains side effects, this
10404 might change the truth-value of A. */
10411 {
10431 /* This case if tricky because we must either have commutative
10432 operators or else A10 must not have side-effects. */
10438 a01);
10439 }
10441 /* See if we can build a range comparison. */
10445 /* Check for the possibility of merging component references. If our
10446 lhs is another similar operation, try to merge its rhs with our
10447 rhs. Then try to merge our lhs and rhs. */
10459 /* Note that the operands of this must be ints
10460 and their values must be 0 or true.
10461 ("true" is a fixed value perhaps depending on the language.) */
10462 /* If first arg is constant true, return it. */
10466 /* If either arg is constant zero, drop it. */
10470 /* Preserve sequence points. */
10473 /* If second arg is constant true, result is true, but we must
10474 evaluate first arg. */
10477 /* Likewise for first arg, but note this only occurs here for
10478 TRUTH_OR_EXPR. */
10482 /* !X || X is always true. */
10486 /* X || !X is always true. */
10494 /* If the second arg is constant zero, drop it. */
10497 /* If the second arg is constant true, this is a logical inversion. */
10499 {
10500 /* Only call invert_truthvalue if operand is a truth value. */
10503 else
10506 }
10507 /* Identical arguments cancel to zero. */
10511 /* !X ^ X is always true. */
10516 /* X ^ !X is always true. */
10529 /* bool_var != 0 becomes bool_var. */
10534 /* bool_var == 1 becomes bool_var. */
10539 /* bool_var != 1 becomes !bool_var. */
10544 /* bool_var == 0 becomes !bool_var. */
10549 /* ~a != C becomes a != ~C where C is a constant. Likewise for ==. */
10552 {
10557 }
10559 /* If this is an equality comparison of the address of a non-weak
10560 object against zero, then we know the result. */
10567 /* If this is an equality comparison of the address of two non-weak,
10568 unaliased symbols neither of which are extern (since we do not
10569 have access to attributes for externs), then we know the result. */
10582 {
10583 /* We know that we're looking at the address of two
10584 non-weak, unaliased, static _DECL nodes.
10586 It is both wasteful and incorrect to call operand_equal_p
10587 to compare the two ADDR_EXPR nodes. It is wasteful in that
10588 all we need to do is test pointer equality for the arguments
10589 to the two ADDR_EXPR nodes. It is incorrect to use
10590 operand_equal_p as that function is NOT equivalent to a
10591 C equality test. It can in fact return false for two
10592 objects which would test as equal using the C equality
10593 operator. */
10597 type);
10598 }
10600 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
10601 a MINUS_EXPR of a constant, we can convert it into a comparison with
10602 a revised constant as long as no overflow occurs. */
10614 /* Similarly for a NEGATE_EXPR. */
10622 /* If we have X - Y == 0, we can convert that to X == Y and similarly
10623 for !=. Don't do this for ordered comparisons due to overflow. */
10629 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
10634 /* If this is an EQ or NE comparison with zero and ARG0 is
10635 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10636 two operations, but the latter can be done in one less insn
10637 on machines that have only two-operand insns or on which a
10638 constant cannot be the first operand. */
10641 {
10646 return
10652 integer_one_node)),
10653 arg1);
10656 return
10662 integer_one_node)),
10663 arg1);
10664 }
10666 /* If this is an NE or EQ comparison of zero against the result of a
10667 signed MOD operation whose second operand is a power of 2, make
10668 the MOD operation unsigned since it is simpler and equivalent. */
10676 {
10686 }
10688 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10689 C1 is a valid shift constant, and C2 is a power of two, i.e.
10690 a single bit. */
10694 == INTEGER_CST
10697 {
10702 /* Check for a valid shift count. */
10705 {
10709 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10710 can be rewritten as (X & (C2 << C1)) != 0. */
10712 {
10716 }
10717 /* Otherwise, for signed (arithmetic) shifts,
10718 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10719 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10723 /* Otherwise, of unsigned (logical) shifts,
10724 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10725 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10726 else
10730 arg000);
10731 }
10732 }
10734 /* If this is an NE comparison of zero with an AND of one, remove the
10735 comparison since the AND will give the correct value. */
10742 /* If we have (A & C) == C where C is a power of 2, convert this into
10743 (A & C) != 0. Similarly for NE_EXPR. */
10749 integer_zero_node));
10751 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
10752 bit, then fold the expression into A < 0 or A >= 0. */
10757 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10758 Similarly for NE_EXPR. */
10762 {
10771 }
10773 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
10774 Similarly for NE_EXPR. */
10778 {
10785 }
10787 /* If this is a comparison of a field, we may be able to simplify it. */
10791 /* Handle the constant case even without -O
10792 to make sure the warnings are given. */
10794 {
10798 }
10800 /* Optimize comparisons of strlen vs zero to a compare of the
10801 first character of the string vs zero. To wit,
10802 strlen(ptr) == 0 => *ptr == 0
10803 strlen(ptr) != 0 => *ptr != 0
10804 Other cases should reduce to one of these two (or a constant)
10805 due to the return value of strlen being unsigned. */
10808 {
10810 tree arglist;
10818 {
10822 }
10823 }
10825 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10826 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10830 {
10837 {
10839 {
10842 }
10845 }
10846 }
10848 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
10854 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
10859 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
10866 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
10874 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10875 (X & C) == 0 when C is a single bit. */
10880 {
10886 }
10888 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10889 constant C is a power of two, i.e. a single bit. */
10896 {
10900 }
10902 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10903 when is C is a power of two, i.e. a single bit. */
10910 {
10916 }
10920 {
10923 }
10934 /* Transform comparisons of the form X +- C CMP X. */
10941 {
10948 else
10951 /* (X - c) > X becomes false. */
10955 {
10959 "occur when assuming that (X - c) > X "
10961 WARN_STRICT_OVERFLOW_ALL);
10963 }
10965 /* Likewise (X + c) < X becomes false. */
10969 {
10973 "occur when assuming that "
10975 WARN_STRICT_OVERFLOW_ALL);
10977 }
10979 /* Convert (X - c) <= X to true. */
10984 {
10988 "occur when assuming that "
10990 WARN_STRICT_OVERFLOW_ALL);
10992 }
10994 /* Convert (X + c) >= X to true. */
10999 {
11003 "occur when assuming that "
11005 WARN_STRICT_OVERFLOW_ALL);
11007 }
11010 {
11011 /* Convert X + c > X and X - c < X to true for integers. */
11015 {
11018 "not occur when assuming that "
11020 WARN_STRICT_OVERFLOW_ALL);
11022 }
11027 {
11030 "not occur when assuming that "
11032 WARN_STRICT_OVERFLOW_ALL);
11034 }
11036 /* Convert X + c <= X and X - c >= X to false for integers. */
11040 {
11043 "not occur when assuming that "
11045 WARN_STRICT_OVERFLOW_ALL);
11047 }
11052 {
11055 "not occur when assuming that "
11057 WARN_STRICT_OVERFLOW_ALL);
11059 }
11060 }
11061 }
11063 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11064 This transformation affects the cases which are handled in later
11065 optimizations involving comparisons with non-negative constants. */
11069 {
11071 {
11076 }
11078 {
11083 }
11084 }
11086 /* Comparisons with the highest or lowest possible integer of
11087 the specified size will have known values. */
11088 {
11096 {
11097 HOST_WIDE_INT signed_max_hi;
11102 {
11109 {
11113 }
11114 else
11115 {
11119 }
11120 }
11121 else
11122 {
11131 {
11134 }
11135 else
11136 {
11139 }
11140 }
11145 {
11158 /* The GE_EXPR and LT_EXPR cases above are not normally
11159 reached because of previous transformations. */
11163 }
11165 == max_hi
11168 {
11173 arg1);
11178 arg1);
11181 }
11183 == min_hi
11186 {
11201 }
11203 == min_hi
11206 {
11211 arg1);
11216 arg1);
11219 }
11225 /* signed_type does not work on pointer types. */
11227 {
11228 /* The following case also applies to X < signed_max+1
11229 and X >= signed_max+1 because previous transformations. */
11231 {
11232 tree st;
11237 }
11238 }
11239 }
11240 }
11242 /* If we are comparing an ABS_EXPR with a constant, we can
11243 convert all the cases into explicit comparisons, but they may
11244 well not be faster than doing the ABS and one comparison.
11245 But ABS (X) <= C is a range comparison, which becomes a subtraction
11246 and a comparison, and is probably faster. */
11260 /* Convert ABS_EXPR<x> >= 0 to true. */
11267 {
11270 "when simplifying comparison of "
11272 WARN_STRICT_OVERFLOW_CONDITIONAL);
11274 }
11276 /* Convert ABS_EXPR<x> < 0 to false. */
11281 {
11284 "when simplifying comparison of "
11286 WARN_STRICT_OVERFLOW_CONDITIONAL);
11288 }
11290 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11291 and similarly for >= into !=. */
11307 return
11326 {
11330 }
11332 /* If the first operand is NaN, the result is constant. */
11336 {
11338 ? integer_zero_node
11341 }
11343 /* If the second operand is NaN, the result is constant. */
11347 {
11349 ? integer_zero_node
11352 }
11354 /* Simplify unordered comparison of something with itself. */
11360 && !flag_trapping_math
11364 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11365 {
11376 }
11381 /* When pedantic, a compound expression can be neither an lvalue
11382 nor an integer constant expression. */
11385 /* Don't let (0, 0) be null pointer constant. */
11399 /* An ASSERT_EXPR should never be passed to fold_binary. */
11405 }
11407 /* Callback for walk_tree, looking for LABEL_EXPR.
11408 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
11409 Do not check the sub-tree of GOTO_EXPR. */
11411 static tree
11415 {
11417 {
11422 /* no break */
11425 }
11426 }
11428 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
11429 accessible from outside the sub-tree. Returns NULL_TREE if no
11430 addressable label is found. */
11432 static bool
11434 {
11436 }
11438 /* Fold a ternary expression of code CODE and type TYPE with operands
11439 OP0, OP1, and OP2. Return the folded expression if folding is
11440 successful. Otherwise, return NULL_TREE. */
11442 tree
11444 {
11445 tree tem;
11452 /* Strip any conversions that don't change the mode. This is safe
11453 for every expression, except for a comparison expression because
11454 its signedness is derived from its operands. So, in the latter
11455 case, only strip conversions that don't change the signedness.
11457 Note that this is done as an internal manipulation within the
11458 constant folder, in order to find the simplest representation of
11459 the arguments so that their form can be studied. In any cases,
11460 the appropriate type conversions should be put back in the tree
11461 that will get out of the constant folder. */
11463 {
11466 }
11469 {
11472 }
11475 {
11479 {
11485 }
11489 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11490 so all simple results must be passed through pedantic_non_lvalue. */
11492 {
11495 /* Only optimize constant conditions when the selected branch
11496 has the same type as the COND_EXPR. This avoids optimizing
11497 away "c ? x : throw", where the throw has a void type.
11498 Avoid throwing away that operand which contains label. */
11505 }
11509 /* If we have A op B ? A : C, we may be able to convert this to a
11510 simpler expression, depending on the operation and the values
11511 of B and C. Signed zeros prevent all of these transformations,
11512 for reasons given above each one.
11514 Also try swapping the arguments and inverting the conditional. */
11519 {
11523 }
11527 op2,
11530 {
11533 {
11537 }
11538 }
11540 /* If the second operand is simpler than the third, swap them
11541 since that produces better jump optimization results. */
11544 {
11545 /* See if this can be inverted. If it can't, possibly because
11546 it was a floating-point inequality comparison, don't do
11547 anything. */
11551 }
11553 /* Convert A ? 1 : 0 to simply A. */
11556 /* If we try to convert OP0 to our type, the
11557 call to fold will try to move the conversion inside
11558 a COND, which will recurse. In that case, the COND_EXPR
11559 is probably the best choice, so leave it alone. */
11563 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11564 over COND_EXPR in cases such as floating point comparisons. */
11571 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11576 {
11577 /* sign_bit_p only checks ARG1 bits within A's precision.
11578 If <sign bit of A> has wider type than A, bits outside
11579 of A's precision in <sign bit of A> need to be checked.
11580 If they are all 0, this optimization needs to be done
11581 in unsigned A's type, if they are all 1 in signed A's type,
11582 otherwise this can't be done. */
11587 {
11589 HOST_WIDE_INT mask_hi;
11591 tree tem_type;
11599 {
11603 }
11604 else
11605 {
11609 }
11611 {
11615 }
11616 else
11622 {
11625 }
11628 {
11631 }
11632 else
11634 }
11641 arg1)));
11642 }
11644 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11645 already handled above. */
11650 {
11659 }
11661 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11662 is probably obsolete because the first operand should be a
11663 truth value (that's why we have the two cases above), but let's
11664 leave it in until we can confirm this for all front-ends. */
11675 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11681 arg1);
11683 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11687 {
11688 /* Only perform transformation if ARG0 is easily inverted. */
11693 arg1);
11694 }
11696 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11700 {
11701 /* Only perform transformation if ARG0 is easily inverted. */
11706 op2);
11707 }
11709 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11715 op2);
11720 /* Check for a built-in function. */
11732 {
11741 {
11747 else
11749 }
11750 }
11756 }
11758 /* Perform constant folding and related simplification of EXPR.
11759 The related simplifications include x*1 => x, x*0 => 0, etc.,
11760 and application of the associative law.
11761 NOP_EXPR conversions may be removed freely (as long as we
11762 are careful not to change the type of the overall expression).
11763 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11764 but we can constant-fold them if they have constant operands. */
11766 #ifdef ENABLE_FOLD_CHECKING
11767 # define fold(x) fold_1 (x)
11769 static
11770 #endif
11771 tree
11773 {
11777 tree tem;
11779 /* Return right away if a constant. */
11784 {
11789 {
11807 }
11808 }
11811 {
11818 }
11820 #ifdef ENABLE_FOLD_CHECKING
11821 #undef fold
11827 /* When --enable-checking=fold, compute a digest of expr before
11828 and after actual fold call to see if fold did not accidentally
11829 change original expr. */
11831 tree
11833 {
11834 tree ret;
11837 htab_t ht;
11856 }
11858 void
11860 {
11863 htab_t ht;
11873 }
11875 static void
11877 {
11879 }
11881 static void
11883 {
11889 recursive_label:
11903 {
11904 /* Allow DECL_ASSEMBLER_NAME to be modified. */
11908 }
11913 {
11914 /* Allow these fields to be modified. */
11921 {
11924 }
11925 }
11933 {
11936 {
11950 }
11954 {
11967 }
11983 {
11989 }
11994 {
11998 }
12009 {
12012 }
12022 }
12023 }
12025 #endif
12027 /* Fold a unary tree expression with code CODE of type TYPE with an
12028 operand OP0. Return a folded expression if successful. Otherwise,
12029 return a tree expression with code CODE of type TYPE with an
12030 operand OP0. */
12032 tree
12034 {
12035 tree tem;
12036 #ifdef ENABLE_FOLD_CHECKING
12039 htab_t ht;
12046 #endif
12052 #ifdef ENABLE_FOLD_CHECKING
12060 #endif
12062 }
12064 /* Fold a binary tree expression with code CODE of type TYPE with
12065 operands OP0 and OP1. Return a folded expression if successful.
12066 Otherwise, return a tree expression with code CODE of type TYPE
12067 with operands OP0 and OP1. */
12069 tree
12071 MEM_STAT_DECL)
12072 {
12073 tree tem;
12074 #ifdef ENABLE_FOLD_CHECKING
12080 htab_t ht;
12092 #endif
12098 #ifdef ENABLE_FOLD_CHECKING
12114 #endif
12116 }
12118 /* Fold a ternary tree expression with code CODE of type TYPE with
12119 operands OP0, OP1, and OP2. Return a folded expression if
12120 successful. Otherwise, return a tree expression with code CODE of
12121 type TYPE with operands OP0, OP1, and OP2. */
12123 tree
12125 MEM_STAT_DECL)
12126 {
12127 tree tem;
12128 #ifdef ENABLE_FOLD_CHECKING
12136 htab_t ht;
12153 #endif
12159 #ifdef ENABLE_FOLD_CHECKING
12183 #endif
12185 }
12187 /* Perform constant folding and related simplification of initializer
12188 expression EXPR. These behave identically to "fold_buildN" but ignore
12189 potential run-time traps and exceptions that fold must preserve. */
12191 #define START_FOLD_INIT \
12192 int saved_signaling_nans = flag_signaling_nans;\
12193 int saved_trapping_math = flag_trapping_math;\
12194 int saved_rounding_math = flag_rounding_math;\
12195 int saved_trapv = flag_trapv;\
12196 int saved_folding_initializer = folding_initializer;\
12197 flag_signaling_nans = 0;\
12198 flag_trapping_math = 0;\
12199 flag_rounding_math = 0;\
12200 flag_trapv = 0;\
12201 folding_initializer = 1;
12203 #define END_FOLD_INIT \
12204 flag_signaling_nans = saved_signaling_nans;\
12205 flag_trapping_math = saved_trapping_math;\
12206 flag_rounding_math = saved_rounding_math;\
12207 flag_trapv = saved_trapv;\
12208 folding_initializer = saved_folding_initializer;
12210 tree
12212 {
12213 tree result;
12214 START_FOLD_INIT;
12218 END_FOLD_INIT;
12220 }
12222 tree
12224 {
12225 tree result;
12226 START_FOLD_INIT;
12230 END_FOLD_INIT;
12232 }
12234 tree
12236 tree op2)
12237 {
12238 tree result;
12239 START_FOLD_INIT;
12243 END_FOLD_INIT;
12245 }
12247 #undef START_FOLD_INIT
12248 #undef END_FOLD_INIT
12250 /* Determine if first argument is a multiple of second argument. Return 0 if
12251 it is not, or we cannot easily determined it to be.
12253 An example of the sort of thing we care about (at this point; this routine
12254 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12255 fold cases do now) is discovering that
12257 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12259 is a multiple of
12261 SAVE_EXPR (J * 8)
12263 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12265 This code also handles discovering that
12267 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12269 is a multiple of 8 so we don't have to worry about dealing with a
12270 possible remainder.
12272 Note that we *look* inside a SAVE_EXPR only to determine how it was
12273 calculated; it is not safe for fold to do much of anything else with the
12274 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12275 at run time. For example, the latter example above *cannot* be implemented
12276 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12277 evaluation time of the original SAVE_EXPR is not necessarily the same at
12278 the time the new expression is evaluated. The only optimization of this
12279 sort that would be valid is changing
12281 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12283 divided by 8 to
12285 SAVE_EXPR (I) * SAVE_EXPR (J)
12287 (where the same SAVE_EXPR (J) is used in the original and the
12288 transformed version). */
12290 static int
12292 {
12300 {
12302 /* Bitwise and provides a power of two multiple. If the mask is
12303 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12306 /* FALLTHRU */
12319 {
12323 /* const_binop may not detect overflow correctly,
12324 so check for it explicitly here. */
12330 size_one_node,
12334 }
12338 /* Can't handle conversions from non-integral or wider integral type. */
12344 /* .. fall through ... */
12360 }
12361 }
12363 /* Return true if `t' is known to be non-negative. If the return
12364 value is based on the assumption that signed overflow is undefined,
12365 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12366 *STRICT_OVERFLOW_P. */
12368 int
12370 {
12378 {
12380 /* Query VRP to see if it has recorded any information about
12381 the range of this object. */
12385 /* We can't return 1 if flag_wrapv is set because
12386 ABS_EXPR<INT_MIN> = INT_MIN. */
12390 {
12393 }
12405 strict_overflow_p)
12407 strict_overflow_p));
12409 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12410 both unsigned and at least 2 bits shorter than the result. */
12414 {
12419 {
12423 }
12424 }
12429 {
12430 /* x * x for floating point x is always non-negative. */
12434 strict_overflow_p)
12436 strict_overflow_p));
12437 }
12439 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12440 both unsigned and their total bits is shorter than the result. */
12444 {
12451 }
12457 strict_overflow_p)
12459 strict_overflow_p));
12470 strict_overflow_p)
12472 strict_overflow_p));
12483 strict_overflow_p);
12488 strict_overflow_p);
12492 strict_overflow_p);
12496 strict_overflow_p)
12498 strict_overflow_p));
12501 {
12506 {
12509 strict_overflow_p);
12511 {
12515 strict_overflow_p);
12516 }
12517 }
12519 {
12522 strict_overflow_p);
12526 }
12527 }
12531 {
12535 /* If the initializer is non-void, then it's a normal expression
12536 that will be assigned to the slot. */
12540 /* Otherwise, the initializer sets the slot in some way. One common
12541 way is an assignment statement at the end of the initializer. */
12543 {
12551 else
12553 }
12557 strict_overflow_p);
12560 }
12563 {
12568 {
12584 /* Always true. */
12588 /* sqrt(-0.0) is -0.0. */
12592 strict_overflow_p);
12622 /* True if the 1st argument is nonnegative. */
12624 strict_overflow_p);
12627 /* True if the 1st OR 2nd arguments are nonnegative. */
12629 strict_overflow_p)
12630 || (tree_expr_nonnegative_warnv_p
12632 strict_overflow_p)));
12635 /* True if the 1st AND 2nd arguments are nonnegative. */
12637 strict_overflow_p)
12638 && (tree_expr_nonnegative_warnv_p
12640 strict_overflow_p)));
12643 /* True if the 2nd argument is nonnegative. */
12646 strict_overflow_p));
12650 }
12651 }
12653 /* ... fall through ... */
12656 {
12660 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12661 have a signed:1 type (where the value is -1 and 0). */
12663 }
12664 }
12666 /* We don't know sign of `t', so be conservative and return false. */
12668 }
12670 /* Return true if `t' is known to be non-negative. Handle warnings
12671 about undefined signed overflow. */
12673 int
12675 {
12683 "determining that expression is always "
12685 WARN_STRICT_OVERFLOW_MISC);
12687 }
12689 /* Return true when T is an address and is known to be nonzero.
12690 For floating point we further ensure that T is not denormal.
12691 Similar logic is present in nonzero_address in rtlanal.h.
12693 If the return value is based on the assumption that signed overflow
12694 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
12695 change *STRICT_OVERFLOW_P. */
12697 bool
12699 {
12703 /* Doing something useful for floating point would need more work. */
12708 {
12710 /* Query VRP to see if it has recorded any information about
12711 the range of this object. */
12716 strict_overflow_p);
12719 /* We used to test for !integer_zerop here. This does not work correctly
12720 if TREE_CONSTANT_OVERFLOW (t). */
12726 {
12727 /* With the presence of negative values it is hard
12728 to say something. */
12735 /* One of operands must be positive and the other non-negative. */
12736 /* We don't set *STRICT_OVERFLOW_P here: even if this value
12737 overflows, on a twos-complement machine the sum of two
12738 nonnegative numbers can never be zero. */
12740 strict_overflow_p)
12742 strict_overflow_p));
12743 }
12748 {
12750 strict_overflow_p)
12752 strict_overflow_p))
12753 {
12756 }
12757 }
12761 {
12767 strict_overflow_p));
12768 }
12772 {
12778 /* Weak declarations may link to NULL. */
12782 /* Constants are never weak. */
12787 }
12795 {
12799 }
12808 {
12811 }
12818 {
12822 /* When both operands are nonzero, then MAX must be too. */
12824 strict_overflow_p))
12827 /* MAX where operand 0 is positive is positive. */
12829 strict_overflow_p);
12830 }
12831 /* MAX where operand 1 is positive is positive. */
12836 {
12840 }
12847 strict_overflow_p);
12852 strict_overflow_p);
12856 strict_overflow_p)
12858 strict_overflow_p));
12865 }
12867 }
12869 /* Return true when T is an address and is known to be nonzero.
12870 Handle warnings about undefined signed overflow. */
12872 bool
12874 {
12881 "determining that expression is always "
12883 WARN_STRICT_OVERFLOW_MISC);
12885 }
12887 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
12888 attempt to fold the expression to a constant without modifying TYPE,
12889 OP0 or OP1.
12891 If the expression could be simplified to a constant, then return
12892 the constant. If the expression would not be simplified to a
12893 constant, then return NULL_TREE. */
12895 tree
12897 {
12900 }
12902 /* Given the components of a unary expression CODE, TYPE and OP0,
12903 attempt to fold the expression to a constant without modifying
12904 TYPE or OP0.
12906 If the expression could be simplified to a constant, then return
12907 the constant. If the expression would not be simplified to a
12908 constant, then return NULL_TREE. */
12910 tree
12912 {
12915 }
12917 /* If EXP represents referencing an element in a constant string
12918 (either via pointer arithmetic or array indexing), return the
12919 tree representing the value accessed, otherwise return NULL. */
12921 tree
12923 {
12927 {
12929 tree index;
12930 tree string;
12934 else
12935 {
12939 /* Optimize the special-case of a zero lower bound.
12941 We convert the low_bound to sizetype to avoid some problems
12942 with constant folding. (E.g. suppose the lower bound is 1,
12943 and its mode is QI. Without the conversion,l (ARRAY
12944 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
12945 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
12950 }
12964 }
12966 }
12968 /* Return the tree for neg (ARG0) when ARG0 is known to be either
12969 an integer constant or real constant.
12971 TYPE is the type of the result. */
12973 static tree
12975 {
12979 {
12981 {
12983 HOST_WIDE_INT high;
12993 }
13001 }
13004 }
13006 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13007 an integer constant or real constant.
13009 TYPE is the type of the result. */
13011 tree
13013 {
13017 {
13019 /* If the value is unsigned, then the absolute value is
13020 the same as the ordinary value. */
13023 /* Similarly, if the value is non-negative. */
13026 /* If the value is negative, then the absolute value is
13027 its negation. */
13028 else
13029 {
13031 HOST_WIDE_INT high;
13038 }
13044 else
13050 }
13053 }
13055 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13056 constant. TYPE is the type of the result. */
13058 static tree
13060 {
13072 }
13074 /* Given CODE, a relational operator, the target type, TYPE and two
13075 constant operands OP0 and OP1, return the result of the
13076 relational operation. If the result is not a compile time
13077 constant, then return NULL_TREE. */
13079 static tree
13081 {
13084 /* From here on, the only cases we handle are when the result is
13085 known to be a constant. */
13088 {
13092 /* Handle the cases where either operand is a NaN. */
13094 {
13096 {
13124 }
13127 }
13130 }
13132 /* Handle equality/inequality of complex constants. */
13134 {
13145 else
13147 }
13149 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13151 To compute GT, swap the arguments and do LT.
13152 To compute GE, do LT and invert the result.
13153 To compute LE, swap the arguments, do LT and invert the result.
13154 To compute NE, do EQ and invert the result.
13156 Therefore, the code below must handle only EQ and LT. */
13159 {
13164 }
13166 /* Note that it is safe to invert for real values here because we
13167 have already handled the one case that it matters. */
13171 {
13174 }
13176 /* Compute a result for LT or EQ if args permit;
13177 Otherwise return T. */
13179 {
13184 else
13186 }
13187 else
13193 }
13195 /* Build an expression for the a clean point containing EXPR with type TYPE.
13196 Don't build a cleanup point expression for EXPR which don't have side
13197 effects. */
13199 tree
13201 {
13202 /* If the expression does not have side effects then we don't have to wrap
13203 it with a cleanup point expression. */
13207 /* If the expression is a return, check to see if the expression inside the
13208 return has no side effects or the right hand side of the modify expression
13209 inside the return. If either don't have side effects set we don't need to
13210 wrap the expression in a cleanup point expression. Note we don't check the
13211 left hand side of the modify because it should always be a return decl. */
13213 {
13220 }
13223 }
13225 /* Build an expression for the address of T. Folds away INDIRECT_REF to
13226 avoid confusing the gimplify process. */
13228 tree
13230 {
13231 /* The size of the object is not relevant when talking about its address. */
13235 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
13238 {
13242 }
13243 else
13244 {
13253 }
13256 }
13258 tree
13260 {
13262 }
13264 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13265 of an indirection through OP0, or NULL_TREE if no simplification is
13266 possible. */
13268 tree
13270 {
13272 tree subtype;
13280 {
13283 /* *&CONST_DECL -> to the value of the const decl. */
13286 /* *&p => p; make sure to handle *&"str"[cst] here. */
13288 {
13292 else
13294 }
13295 /* *(foo *)&fooarray => fooarray[0] */
13298 {
13304 }
13305 /* *(foo *)&complexfoo => __real__ complexfoo */
13309 }
13311 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13314 {
13317 tree op00type;
13324 {
13328 }
13329 }
13331 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
13334 {
13335 tree type_domain;
13342 }
13345 }
13347 /* Builds an expression for an indirection through T, simplifying some
13348 cases. */
13350 tree
13352 {
13358 else
13360 }
13362 /* Given an INDIRECT_REF T, return either T or a simplified version. */
13364 tree
13366 {
13371 else
13373 }
13375 /* Strip non-trapping, non-side-effecting tree nodes from an expression
13376 whose result is ignored. The type of the returned tree need not be
13377 the same as the original expression. */
13379 tree
13381 {
13387 {
13398 else
13404 {
13420 }
13425 }
13426 }
13428 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
13429 This can only be applied to objects of a sizetype. */
13431 tree
13433 {
13440 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
13441 have to do anything. Only do this when we are not given a const,
13442 because in that case, this check is more expensive than just
13443 doing it. */
13445 {
13450 }
13452 /* If divisor is a power of two, simplify this to bit manipulation. */
13454 {
13455 tree t;
13461 }
13462 else
13463 {
13468 }
13471 }
13473 /* Likewise, but round down. */
13475 tree
13477 {
13484 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
13485 have to do anything. Only do this when we are not given a const,
13486 because in that case, this check is more expensive than just
13487 doing it. */
13489 {
13494 }
13496 /* If divisor is a power of two, simplify this to bit manipulation. */
13498 {
13499 tree t;
13503 }
13504 else
13505 {
13510 }
13513 }
13515 /* Returns the pointer to the base of the object addressed by EXP and
13516 extracts the information about the offset of the access, storing it
13517 to PBITPOS and POFFSET. */
13519 static tree
13522 {
13523 tree core;
13526 HOST_WIDE_INT bitsize;
13529 {
13534 }
13535 else
13536 {
13540 }
13543 }
13545 /* Returns true if addresses of E1 and E2 differ by a constant, false
13546 otherwise. If they do, E1 - E2 is stored in *DIFF. */
13548 bool
13550 {
13564 {
13574 }
13576 {
13577 /* If only one of the offsets is non-constant, the difference cannot
13578 be a constant. */
13580 }
13581 else
13586 }
13588 /* Simplify the floating point expression EXP when the sign of the
13589 result is not significant. Return NULL_TREE if no simplification
13590 is possible. */
13592 tree
13594 {
13598 {
13618 }
13620 }