gcc/testsuite/gcc.dg/tree-ssa/bitcmp-6.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -fdump-tree-optimized" } */
   3 /* PR tree-optimization/101590 */
   4
   5 /* These are the signed integer versions
   6    of `(a & b) CMP a` and `(a | b) CMP a`
   7    which can be optimized to 0. */
   8
   9 #if __SIZEOF_INT__ < 4
  10 #define int __INT32_TYPE__
  11 #endif
  12
  13 /* For `&`, the non-negativeness of b is not taken into account. */
  14 int f_and_gt(int len) {
  15   len &= 0xfffff;
  16   const int N = 4;
  17   int newlen = len & -N;
  18   return newlen > len; // return 0
  19 }
  20 int f_and_gt_(int len, int N) {
  21   len &= 0xfffff;
  22   int newlen = len & -N;
  23   return newlen > len; // return 0
  24 }
  25
  26 /* For `|`, to get a known value, b either needs to be non-negative
  27    or a constant.  For the negative constant case, we swap around the comparison. */
  28 int f_or_lt_(int len, int N) {
  29   len &= 0xfffff;
  30   N &= 0xffff;
  31   int newlen = len | N;
  32   return newlen < len; // return 0
  33 }
  34 int f_or_ge(int len) {
  35   len &= 0xfffff;
  36   const int N = 4;
  37   int newlen = len | -N;
  38   return newlen >= len; // return 0
  39 }
  40
  41 /* { dg-final { scan-tree-dump-not " > " "optimized" } } */
  42 /* { dg-final { scan-tree-dump-not " < " "optimized" } } */
  43 /* { dg-final { scan-tree-dump-not " & "  "optimized" } } */
  44 /* { dg-final { scan-tree-dump-not " \\\| " "optimized" } } */
  45 /* { dg-final { scan-tree-dump-times "return 0;" 4 "optimized" } } */