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Silence -Wunused-variable in release builds.
[llvm/stm8.git] / lib / MC / MCExpr.cpp
blobfcf1aabb5a8629c5c58ba25a83dae24ca6c200d9
1 //===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #define DEBUG_TYPE "mcexpr"
11 #include "llvm/MC/MCExpr.h"
12 #include "llvm/ADT/Statistic.h"
13 #include "llvm/ADT/StringSwitch.h"
14 #include "llvm/MC/MCAsmLayout.h"
15 #include "llvm/MC/MCAssembler.h"
16 #include "llvm/MC/MCContext.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MCValue.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include "llvm/Target/TargetAsmBackend.h"
22 using namespace llvm;
23
24 namespace {
25 namespace stats {
26 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
27 }
28 }
29
30 void MCExpr::print(raw_ostream &OS) const {
31 switch (getKind()) {
32 case MCExpr::Target:
33 return cast<MCTargetExpr>(this)->PrintImpl(OS);
34 case MCExpr::Constant:
35 OS << cast<MCConstantExpr>(*this).getValue();
36 return;
37
38 case MCExpr::SymbolRef: {
39 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
40 const MCSymbol &Sym = SRE.getSymbol();
41 // Parenthesize names that start with $ so that they don't look like
42 // absolute names.
43 bool UseParens = Sym.getName()[0] == '$';
44
45 if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_HA16 ||
46 SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_LO16) {
47 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
48 UseParens = true;
49 }
50
51 if (UseParens)
52 OS << '(' << Sym << ')';
53 else
54 OS << Sym;
55
56 if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT ||
57 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD ||
58 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT ||
59 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF ||
60 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF ||
61 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF)
62 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
63 else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
64 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 &&
65 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_LO16)
66 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
67
68 return;
69 }
70
71 case MCExpr::Unary: {
72 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
73 switch (UE.getOpcode()) {
74 default: assert(0 && "Invalid opcode!");
75 case MCUnaryExpr::LNot: OS << '!'; break;
76 case MCUnaryExpr::Minus: OS << '-'; break;
77 case MCUnaryExpr::Not: OS << '~'; break;
78 case MCUnaryExpr::Plus: OS << '+'; break;
79 }
80 OS << *UE.getSubExpr();
81 return;
82 }
83
84 case MCExpr::Binary: {
85 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
86
87 // Only print parens around the LHS if it is non-trivial.
88 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
89 OS << *BE.getLHS();
90 } else {
91 OS << '(' << *BE.getLHS() << ')';
92 }
93
94 switch (BE.getOpcode()) {
95 default: assert(0 && "Invalid opcode!");
96 case MCBinaryExpr::Add:
97 // Print "X-42" instead of "X+-42".
98 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
99 if (RHSC->getValue() < 0) {
100 OS << RHSC->getValue();
101 return;
102 }
103 }
104
105 OS << '+';
106 break;
107 case MCBinaryExpr::And: OS << '&'; break;
108 case MCBinaryExpr::Div: OS << '/'; break;
109 case MCBinaryExpr::EQ: OS << "=="; break;
110 case MCBinaryExpr::GT: OS << '>'; break;
111 case MCBinaryExpr::GTE: OS << ">="; break;
112 case MCBinaryExpr::LAnd: OS << "&&"; break;
113 case MCBinaryExpr::LOr: OS << "||"; break;
114 case MCBinaryExpr::LT: OS << '<'; break;
115 case MCBinaryExpr::LTE: OS << "<="; break;
116 case MCBinaryExpr::Mod: OS << '%'; break;
117 case MCBinaryExpr::Mul: OS << '*'; break;
118 case MCBinaryExpr::NE: OS << "!="; break;
119 case MCBinaryExpr::Or: OS << '|'; break;
120 case MCBinaryExpr::Shl: OS << "<<"; break;
121 case MCBinaryExpr::Shr: OS << ">>"; break;
122 case MCBinaryExpr::Sub: OS << '-'; break;
123 case MCBinaryExpr::Xor: OS << '^'; break;
124 }
125
126 // Only print parens around the LHS if it is non-trivial.
127 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
128 OS << *BE.getRHS();
129 } else {
130 OS << '(' << *BE.getRHS() << ')';
131 }
132 return;
133 }
134 }
135
136 assert(0 && "Invalid expression kind!");
137 }
138
139 void MCExpr::dump() const {
140 print(dbgs());
141 dbgs() << '\n';
142 }
143
144 /* *** */
145
146 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS,
147 const MCExpr *RHS, MCContext &Ctx) {
148 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
149 }
150
151 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
152 MCContext &Ctx) {
153 return new (Ctx) MCUnaryExpr(Opc, Expr);
154 }
155
156 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
157 return new (Ctx) MCConstantExpr(Value);
158 }
159
160 /* *** */
161
162 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
163 VariantKind Kind,
164 MCContext &Ctx) {
165 return new (Ctx) MCSymbolRefExpr(Sym, Kind);
166 }
167
168 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
169 MCContext &Ctx) {
170 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
171 }
172
173 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
174 switch (Kind) {
175 default:
176 case VK_Invalid: return "<<invalid>>";
177 case VK_None: return "<<none>>";
178
179 case VK_GOT: return "GOT";
180 case VK_GOTOFF: return "GOTOFF";
181 case VK_GOTPCREL: return "GOTPCREL";
182 case VK_GOTTPOFF: return "GOTTPOFF";
183 case VK_INDNTPOFF: return "INDNTPOFF";
184 case VK_NTPOFF: return "NTPOFF";
185 case VK_GOTNTPOFF: return "GOTNTPOFF";
186 case VK_PLT: return "PLT";
187 case VK_TLSGD: return "TLSGD";
188 case VK_TLSLD: return "TLSLD";
189 case VK_TLSLDM: return "TLSLDM";
190 case VK_TPOFF: return "TPOFF";
191 case VK_DTPOFF: return "DTPOFF";
192 case VK_TLVP: return "TLVP";
193 case VK_ARM_PLT: return "(PLT)";
194 case VK_ARM_GOT: return "(GOT)";
195 case VK_ARM_GOTOFF: return "(GOTOFF)";
196 case VK_ARM_TPOFF: return "(tpoff)";
197 case VK_ARM_GOTTPOFF: return "(gottpoff)";
198 case VK_ARM_TLSGD: return "(tlsgd)";
199 case VK_PPC_TOC: return "toc";
200 case VK_PPC_DARWIN_HA16: return "ha16";
201 case VK_PPC_DARWIN_LO16: return "lo16";
202 case VK_PPC_GAS_HA16: return "ha";
203 case VK_PPC_GAS_LO16: return "l";
204 }
205 }
206
207 MCSymbolRefExpr::VariantKind
208 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
209 return StringSwitch<VariantKind>(Name)
210 .Case("GOT", VK_GOT)
211 .Case("got", VK_GOT)
212 .Case("GOTOFF", VK_GOTOFF)
213 .Case("gotoff", VK_GOTOFF)
214 .Case("GOTPCREL", VK_GOTPCREL)
215 .Case("gotpcrel", VK_GOTPCREL)
216 .Case("GOTTPOFF", VK_GOTTPOFF)
217 .Case("gottpoff", VK_GOTTPOFF)
218 .Case("INDNTPOFF", VK_INDNTPOFF)
219 .Case("indntpoff", VK_INDNTPOFF)
220 .Case("NTPOFF", VK_NTPOFF)
221 .Case("ntpoff", VK_NTPOFF)
222 .Case("GOTNTPOFF", VK_GOTNTPOFF)
223 .Case("gotntpoff", VK_GOTNTPOFF)
224 .Case("PLT", VK_PLT)
225 .Case("plt", VK_PLT)
226 .Case("TLSGD", VK_TLSGD)
227 .Case("tlsgd", VK_TLSGD)
228 .Case("TLSLD", VK_TLSLD)
229 .Case("tlsld", VK_TLSLD)
230 .Case("TLSLDM", VK_TLSLDM)
231 .Case("tlsldm", VK_TLSLDM)
232 .Case("TPOFF", VK_TPOFF)
233 .Case("tpoff", VK_TPOFF)
234 .Case("DTPOFF", VK_DTPOFF)
235 .Case("dtpoff", VK_DTPOFF)
236 .Case("TLVP", VK_TLVP)
237 .Case("tlvp", VK_TLVP)
238 .Default(VK_Invalid);
239 }
240
241 /* *** */
242
243 void MCTargetExpr::Anchor() {}
244
245 /* *** */
246
247 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
248 return EvaluateAsAbsolute(Res, 0, 0, 0);
249 }
250
251 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
252 const MCAsmLayout &Layout) const {
253 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0);
254 }
255
256 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
257 const MCAsmLayout &Layout,
258 const SectionAddrMap &Addrs) const {
259 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
260 }
261
262 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
263 return EvaluateAsAbsolute(Res, &Asm, 0, 0);
264 }
265
266 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
267 const MCAsmLayout *Layout,
268 const SectionAddrMap *Addrs) const {
269 MCValue Value;
270
271 // Fast path constants.
272 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
273 Res = CE->getValue();
274 return true;
275 }
276
277 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
278 // absolutize differences across sections and that is what the MachO writer
279 // uses Addrs for.
280 bool IsRelocatable =
281 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs);
282
283 // Record the current value.
284 Res = Value.getConstant();
285
286 return IsRelocatable && Value.isAbsolute();
287 }
288
289 /// \brief Helper method for \see EvaluateSymbolAdd().
290 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm,
291 const MCAsmLayout *Layout,
292 const SectionAddrMap *Addrs,
293 bool InSet,
294 const MCSymbolRefExpr *&A,
295 const MCSymbolRefExpr *&B,
296 int64_t &Addend) {
297 if (!A || !B)
298 return;
299
300 const MCSymbol &SA = A->getSymbol();
301 const MCSymbol &SB = B->getSymbol();
302
303 if (SA.isUndefined() || SB.isUndefined())
304 return;
305
306 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
307 return;
308
309 MCSymbolData &AD = Asm->getSymbolData(SA);
310 MCSymbolData &BD = Asm->getSymbolData(SB);
311
312 if (AD.getFragment() == BD.getFragment()) {
313 Addend += (AD.getOffset() - BD.getOffset());
314
315 // Pointers to Thumb symbols need to have their low-bit set to allow
316 // for interworking.
317 if (Asm->isThumbFunc(&SA))
318 Addend |= 1;
319
320 // Clear the symbol expr pointers to indicate we have folded these
321 // operands.
322 A = B = 0;
323 return;
324 }
325
326 if (!Layout)
327 return;
328
329 const MCSectionData &SecA = *AD.getFragment()->getParent();
330 const MCSectionData &SecB = *BD.getFragment()->getParent();
331
332 if ((&SecA != &SecB) && !Addrs)
333 return;
334
335 // Eagerly evaluate.
336 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) -
337 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol())));
338 if (Addrs && (&SecA != &SecB))
339 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
340
341 // Clear the symbol expr pointers to indicate we have folded these
342 // operands.
343 A = B = 0;
344 }
345
346 /// \brief Evaluate the result of an add between (conceptually) two MCValues.
347 ///
348 /// This routine conceptually attempts to construct an MCValue:
349 /// Result = (Result_A - Result_B + Result_Cst)
350 /// from two MCValue's LHS and RHS where
351 /// Result = LHS + RHS
352 /// and
353 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
354 ///
355 /// This routine attempts to aggresively fold the operands such that the result
356 /// is representable in an MCValue, but may not always succeed.
357 ///
358 /// \returns True on success, false if the result is not representable in an
359 /// MCValue.
360
361 /// NOTE: It is really important to have both the Asm and Layout arguments.
362 /// They might look redundant, but this function can be used before layout
363 /// is done (see the object streamer for example) and having the Asm argument
364 /// lets us avoid relaxations early.
365 static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
366 const MCAsmLayout *Layout,
367 const SectionAddrMap *Addrs,
368 bool InSet,
369 const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
370 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
371 MCValue &Res) {
372 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
373 // about dealing with modifiers. This will ultimately bite us, one day.
374 const MCSymbolRefExpr *LHS_A = LHS.getSymA();
375 const MCSymbolRefExpr *LHS_B = LHS.getSymB();
376 int64_t LHS_Cst = LHS.getConstant();
377
378 // Fold the result constant immediately.
379 int64_t Result_Cst = LHS_Cst + RHS_Cst;
380
381 assert((!Layout || Asm) &&
382 "Must have an assembler object if layout is given!");
383
384 // If we have a layout, we can fold resolved differences.
385 if (Asm) {
386 // First, fold out any differences which are fully resolved. By
387 // reassociating terms in
388 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
389 // we have the four possible differences:
390 // (LHS_A - LHS_B),
391 // (LHS_A - RHS_B),
392 // (RHS_A - LHS_B),
393 // (RHS_A - RHS_B).
394 // Since we are attempting to be as aggressive as possible about folding, we
395 // attempt to evaluate each possible alternative.
396 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
397 Result_Cst);
398 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
399 Result_Cst);
400 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
401 Result_Cst);
402 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
403 Result_Cst);
404 }
405
406 // We can't represent the addition or subtraction of two symbols.
407 if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
408 return false;
409
410 // At this point, we have at most one additive symbol and one subtractive
411 // symbol -- find them.
412 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
413 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
414
415 // If we have a negated symbol, then we must have also have a non-negated
416 // symbol in order to encode the expression.
417 if (B && !A)
418 return false;
419
420 Res = MCValue::get(A, B, Result_Cst);
421 return true;
422 }
423
424 bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
425 const MCAsmLayout &Layout) const {
426 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout,
427 0, false);
428 }
429
430 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
431 const MCAssembler *Asm,
432 const MCAsmLayout *Layout,
433 const SectionAddrMap *Addrs,
434 bool InSet) const {
435 ++stats::MCExprEvaluate;
436
437 switch (getKind()) {
438 case Target:
439 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
440
441 case Constant:
442 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
443 return true;
444
445 case SymbolRef: {
446 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
447 const MCSymbol &Sym = SRE->getSymbol();
448
449 // Evaluate recursively if this is a variable.
450 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
451 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
452 Layout,
453 Addrs,
454 true);
455 // If we failed to simplify this to a constant, let the target
456 // handle it.
457 if (Ret && !Res.getSymA() && !Res.getSymB())
458 return true;
459 }
460
461 Res = MCValue::get(SRE, 0, 0);
462 return true;
463 }
464
465 case Unary: {
466 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
467 MCValue Value;
468
469 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
470 Addrs, InSet))
471 return false;
472
473 switch (AUE->getOpcode()) {
474 case MCUnaryExpr::LNot:
475 if (!Value.isAbsolute())
476 return false;
477 Res = MCValue::get(!Value.getConstant());
478 break;
479 case MCUnaryExpr::Minus:
480 /// -(a - b + const) ==> (b - a - const)
481 if (Value.getSymA() && !Value.getSymB())
482 return false;
483 Res = MCValue::get(Value.getSymB(), Value.getSymA(),
484 -Value.getConstant());
485 break;
486 case MCUnaryExpr::Not:
487 if (!Value.isAbsolute())
488 return false;
489 Res = MCValue::get(~Value.getConstant());
490 break;
491 case MCUnaryExpr::Plus:
492 Res = Value;
493 break;
494 }
495
496 return true;
497 }
498
499 case Binary: {
500 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
501 MCValue LHSValue, RHSValue;
502
503 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
504 Addrs, InSet) ||
505 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
506 Addrs, InSet))
507 return false;
508
509 // We only support a few operations on non-constant expressions, handle
510 // those first.
511 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
512 switch (ABE->getOpcode()) {
513 default:
514 return false;
515 case MCBinaryExpr::Sub:
516 // Negate RHS and add.
517 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
518 RHSValue.getSymB(), RHSValue.getSymA(),
519 -RHSValue.getConstant(),
520 Res);
521
522 case MCBinaryExpr::Add:
523 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
524 RHSValue.getSymA(), RHSValue.getSymB(),
525 RHSValue.getConstant(),
526 Res);
527 }
528 }
529
530 // FIXME: We need target hooks for the evaluation. It may be limited in
531 // width, and gas defines the result of comparisons and right shifts
532 // differently from Apple as.
533 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
534 int64_t Result = 0;
535 switch (ABE->getOpcode()) {
536 case MCBinaryExpr::Add: Result = LHS + RHS; break;
537 case MCBinaryExpr::And: Result = LHS & RHS; break;
538 case MCBinaryExpr::Div: Result = LHS / RHS; break;
539 case MCBinaryExpr::EQ: Result = LHS == RHS; break;
540 case MCBinaryExpr::GT: Result = LHS > RHS; break;
541 case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
542 case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
543 case MCBinaryExpr::LOr: Result = LHS || RHS; break;
544 case MCBinaryExpr::LT: Result = LHS < RHS; break;
545 case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
546 case MCBinaryExpr::Mod: Result = LHS % RHS; break;
547 case MCBinaryExpr::Mul: Result = LHS * RHS; break;
548 case MCBinaryExpr::NE: Result = LHS != RHS; break;
549 case MCBinaryExpr::Or: Result = LHS | RHS; break;
550 case MCBinaryExpr::Shl: Result = LHS << RHS; break;
551 case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
552 case MCBinaryExpr::Sub: Result = LHS - RHS; break;
553 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
554 }
555
556 Res = MCValue::get(Result);
557 return true;
558 }
559 }
560
561 assert(0 && "Invalid assembly expression kind!");
562 return false;
563 }
564
565 const MCSection *MCExpr::FindAssociatedSection() const {
566 switch (getKind()) {
567 case Target:
568 // We never look through target specific expressions.
569 return cast<MCTargetExpr>(this)->FindAssociatedSection();
570
571 case Constant:
572 return MCSymbol::AbsolutePseudoSection;
573
574 case SymbolRef: {
575 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
576 const MCSymbol &Sym = SRE->getSymbol();
577
578 if (Sym.isDefined())
579 return &Sym.getSection();
580
581 return 0;
582 }
583
584 case Unary:
585 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection();
586
587 case Binary: {
588 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
589 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection();
590 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection();
591
592 // If either section is absolute, return the other.
593 if (LHS_S == MCSymbol::AbsolutePseudoSection)
594 return RHS_S;
595 if (RHS_S == MCSymbol::AbsolutePseudoSection)
596 return LHS_S;
597
598 // Otherwise, return the first non-null section.
599 return LHS_S ? LHS_S : RHS_S;
600 }
601 }
602
603 assert(0 && "Invalid assembly expression kind!");
604 return 0;
605 }
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