1 //===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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/MCObjectWriter.h"
18 #include "llvm/MC/MCSymbol.h"
19 #include "llvm/MC/MCValue.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #include "llvm/Support/raw_ostream.h"
27 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
31 void MCExpr::print(raw_ostream &OS) const {
34 return cast<MCTargetExpr>(this)->PrintImpl(OS);
35 case MCExpr::Constant:
36 OS << cast<MCConstantExpr>(*this).getValue();
39 case MCExpr::SymbolRef: {
40 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
41 const MCSymbol &Sym = SRE.getSymbol();
42 // Parenthesize names that start with $ so that they don't look like
44 bool UseParens = Sym.getName()[0] == '$';
46 if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_HA16 ||
47 SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_LO16) {
48 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
53 OS << '(' << Sym << ')';
57 if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_NONE ||
58 SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT ||
59 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD ||
60 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT ||
61 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF ||
62 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF ||
63 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF ||
64 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET1 ||
65 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET2 ||
66 SRE.getKind() == MCSymbolRefExpr::VK_ARM_PREL31)
67 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
68 else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
69 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 &&
70 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_LO16)
71 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
77 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
78 switch (UE.getOpcode()) {
79 case MCUnaryExpr::LNot: OS << '!'; break;
80 case MCUnaryExpr::Minus: OS << '-'; break;
81 case MCUnaryExpr::Not: OS << '~'; break;
82 case MCUnaryExpr::Plus: OS << '+'; break;
84 OS << *UE.getSubExpr();
88 case MCExpr::Binary: {
89 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
91 // Only print parens around the LHS if it is non-trivial.
92 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
95 OS << '(' << *BE.getLHS() << ')';
98 switch (BE.getOpcode()) {
99 case MCBinaryExpr::Add:
100 // Print "X-42" instead of "X+-42".
101 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
102 if (RHSC->getValue() < 0) {
103 OS << RHSC->getValue();
110 case MCBinaryExpr::And: OS << '&'; break;
111 case MCBinaryExpr::Div: OS << '/'; break;
112 case MCBinaryExpr::EQ: OS << "=="; break;
113 case MCBinaryExpr::GT: OS << '>'; break;
114 case MCBinaryExpr::GTE: OS << ">="; break;
115 case MCBinaryExpr::LAnd: OS << "&&"; break;
116 case MCBinaryExpr::LOr: OS << "||"; break;
117 case MCBinaryExpr::LT: OS << '<'; break;
118 case MCBinaryExpr::LTE: OS << "<="; break;
119 case MCBinaryExpr::Mod: OS << '%'; break;
120 case MCBinaryExpr::Mul: OS << '*'; break;
121 case MCBinaryExpr::NE: OS << "!="; break;
122 case MCBinaryExpr::Or: OS << '|'; break;
123 case MCBinaryExpr::Shl: OS << "<<"; break;
124 case MCBinaryExpr::Shr: OS << ">>"; break;
125 case MCBinaryExpr::Sub: OS << '-'; break;
126 case MCBinaryExpr::Xor: OS << '^'; break;
129 // Only print parens around the LHS if it is non-trivial.
130 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
133 OS << '(' << *BE.getRHS() << ')';
139 llvm_unreachable("Invalid expression kind!");
142 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
143 void MCExpr::dump() const {
151 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS,
152 const MCExpr *RHS, MCContext &Ctx) {
153 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
156 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
158 return new (Ctx) MCUnaryExpr(Opc, Expr);
161 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
162 return new (Ctx) MCConstantExpr(Value);
167 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
170 return new (Ctx) MCSymbolRefExpr(Sym, Kind);
173 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
175 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
178 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
180 case VK_Invalid: return "<<invalid>>";
181 case VK_None: return "<<none>>";
183 case VK_GOT: return "GOT";
184 case VK_GOTOFF: return "GOTOFF";
185 case VK_GOTPCREL: return "GOTPCREL";
186 case VK_GOTTPOFF: return "GOTTPOFF";
187 case VK_INDNTPOFF: return "INDNTPOFF";
188 case VK_NTPOFF: return "NTPOFF";
189 case VK_GOTNTPOFF: return "GOTNTPOFF";
190 case VK_PLT: return "PLT";
191 case VK_TLSGD: return "TLSGD";
192 case VK_TLSLD: return "TLSLD";
193 case VK_TLSLDM: return "TLSLDM";
194 case VK_TPOFF: return "TPOFF";
195 case VK_DTPOFF: return "DTPOFF";
196 case VK_TLVP: return "TLVP";
197 case VK_SECREL: return "SECREL32";
198 case VK_ARM_NONE: return "(NONE)";
199 case VK_ARM_PLT: return "(PLT)";
200 case VK_ARM_GOT: return "(GOT)";
201 case VK_ARM_GOTOFF: return "(GOTOFF)";
202 case VK_ARM_TPOFF: return "(tpoff)";
203 case VK_ARM_GOTTPOFF: return "(gottpoff)";
204 case VK_ARM_TLSGD: return "(tlsgd)";
205 case VK_ARM_TARGET1: return "(target1)";
206 case VK_ARM_TARGET2: return "(target2)";
207 case VK_ARM_PREL31: return "(prel31)";
208 case VK_PPC_TOC: return "tocbase";
209 case VK_PPC_TOC_ENTRY: return "toc";
210 case VK_PPC_DARWIN_HA16: return "ha16";
211 case VK_PPC_DARWIN_LO16: return "lo16";
212 case VK_PPC_GAS_HA16: return "ha";
213 case VK_PPC_GAS_LO16: return "l";
214 case VK_PPC_TPREL16_HA: return "tprel@ha";
215 case VK_PPC_TPREL16_LO: return "tprel@l";
216 case VK_PPC_DTPREL16_HA: return "dtprel@ha";
217 case VK_PPC_DTPREL16_LO: return "dtprel@l";
218 case VK_PPC_TOC16_HA: return "toc@ha";
219 case VK_PPC_TOC16_LO: return "toc@l";
220 case VK_PPC_GOT_TPREL16_HA: return "got@tprel@ha";
221 case VK_PPC_GOT_TPREL16_LO: return "got@tprel@l";
222 case VK_PPC_TLS: return "tls";
223 case VK_PPC_GOT_TLSGD16_HA: return "got@tlsgd@ha";
224 case VK_PPC_GOT_TLSGD16_LO: return "got@tlsgd@l";
225 case VK_PPC_GOT_TLSLD16_HA: return "got@tlsld@ha";
226 case VK_PPC_GOT_TLSLD16_LO: return "got@tlsld@l";
227 case VK_PPC_TLSGD: return "tlsgd";
228 case VK_PPC_TLSLD: return "tlsld";
229 case VK_Mips_GPREL: return "GPREL";
230 case VK_Mips_GOT_CALL: return "GOT_CALL";
231 case VK_Mips_GOT16: return "GOT16";
232 case VK_Mips_GOT: return "GOT";
233 case VK_Mips_ABS_HI: return "ABS_HI";
234 case VK_Mips_ABS_LO: return "ABS_LO";
235 case VK_Mips_TLSGD: return "TLSGD";
236 case VK_Mips_TLSLDM: return "TLSLDM";
237 case VK_Mips_DTPREL_HI: return "DTPREL_HI";
238 case VK_Mips_DTPREL_LO: return "DTPREL_LO";
239 case VK_Mips_GOTTPREL: return "GOTTPREL";
240 case VK_Mips_TPREL_HI: return "TPREL_HI";
241 case VK_Mips_TPREL_LO: return "TPREL_LO";
242 case VK_Mips_GPOFF_HI: return "GPOFF_HI";
243 case VK_Mips_GPOFF_LO: return "GPOFF_LO";
244 case VK_Mips_GOT_DISP: return "GOT_DISP";
245 case VK_Mips_GOT_PAGE: return "GOT_PAGE";
246 case VK_Mips_GOT_OFST: return "GOT_OFST";
247 case VK_Mips_HIGHER: return "HIGHER";
248 case VK_Mips_HIGHEST: return "HIGHEST";
249 case VK_Mips_GOT_HI16: return "GOT_HI16";
250 case VK_Mips_GOT_LO16: return "GOT_LO16";
251 case VK_Mips_CALL_HI16: return "CALL_HI16";
252 case VK_Mips_CALL_LO16: return "CALL_LO16";
253 case VK_COFF_IMGREL32: return "IMGREL32";
255 llvm_unreachable("Invalid variant kind");
258 MCSymbolRefExpr::VariantKind
259 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
260 return StringSwitch<VariantKind>(Name)
263 .Case("GOTOFF", VK_GOTOFF)
264 .Case("gotoff", VK_GOTOFF)
265 .Case("GOTPCREL", VK_GOTPCREL)
266 .Case("gotpcrel", VK_GOTPCREL)
267 .Case("GOTTPOFF", VK_GOTTPOFF)
268 .Case("gottpoff", VK_GOTTPOFF)
269 .Case("INDNTPOFF", VK_INDNTPOFF)
270 .Case("indntpoff", VK_INDNTPOFF)
271 .Case("NTPOFF", VK_NTPOFF)
272 .Case("ntpoff", VK_NTPOFF)
273 .Case("GOTNTPOFF", VK_GOTNTPOFF)
274 .Case("gotntpoff", VK_GOTNTPOFF)
277 .Case("TLSGD", VK_TLSGD)
278 .Case("tlsgd", VK_TLSGD)
279 .Case("TLSLD", VK_TLSLD)
280 .Case("tlsld", VK_TLSLD)
281 .Case("TLSLDM", VK_TLSLDM)
282 .Case("tlsldm", VK_TLSLDM)
283 .Case("TPOFF", VK_TPOFF)
284 .Case("tpoff", VK_TPOFF)
285 .Case("DTPOFF", VK_DTPOFF)
286 .Case("dtpoff", VK_DTPOFF)
287 .Case("TLVP", VK_TLVP)
288 .Case("tlvp", VK_TLVP)
289 .Case("IMGREL", VK_COFF_IMGREL32)
290 .Case("imgrel", VK_COFF_IMGREL32)
291 .Default(VK_Invalid);
296 void MCTargetExpr::anchor() {}
300 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
301 return EvaluateAsAbsolute(Res, 0, 0, 0);
304 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
305 const MCAsmLayout &Layout) const {
306 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0);
309 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
310 const MCAsmLayout &Layout,
311 const SectionAddrMap &Addrs) const {
312 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
315 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
316 return EvaluateAsAbsolute(Res, &Asm, 0, 0);
319 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
320 const MCAsmLayout *Layout,
321 const SectionAddrMap *Addrs) const {
324 // Fast path constants.
325 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
326 Res = CE->getValue();
330 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
331 // absolutize differences across sections and that is what the MachO writer
334 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs);
336 // Record the current value.
337 Res = Value.getConstant();
339 return IsRelocatable && Value.isAbsolute();
342 /// \brief Helper method for \see EvaluateSymbolAdd().
343 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm,
344 const MCAsmLayout *Layout,
345 const SectionAddrMap *Addrs,
347 const MCSymbolRefExpr *&A,
348 const MCSymbolRefExpr *&B,
353 const MCSymbol &SA = A->getSymbol();
354 const MCSymbol &SB = B->getSymbol();
356 if (SA.isUndefined() || SB.isUndefined())
359 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
362 MCSymbolData &AD = Asm->getSymbolData(SA);
363 MCSymbolData &BD = Asm->getSymbolData(SB);
365 if (AD.getFragment() == BD.getFragment()) {
366 Addend += (AD.getOffset() - BD.getOffset());
368 // Pointers to Thumb symbols need to have their low-bit set to allow
370 if (Asm->isThumbFunc(&SA))
373 // Clear the symbol expr pointers to indicate we have folded these
382 const MCSectionData &SecA = *AD.getFragment()->getParent();
383 const MCSectionData &SecB = *BD.getFragment()->getParent();
385 if ((&SecA != &SecB) && !Addrs)
389 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) -
390 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol())));
391 if (Addrs && (&SecA != &SecB))
392 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
394 // Pointers to Thumb symbols need to have their low-bit set to allow
396 if (Asm->isThumbFunc(&SA))
399 // Clear the symbol expr pointers to indicate we have folded these
404 /// \brief Evaluate the result of an add between (conceptually) two MCValues.
406 /// This routine conceptually attempts to construct an MCValue:
407 /// Result = (Result_A - Result_B + Result_Cst)
408 /// from two MCValue's LHS and RHS where
409 /// Result = LHS + RHS
411 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
413 /// This routine attempts to aggresively fold the operands such that the result
414 /// is representable in an MCValue, but may not always succeed.
416 /// \returns True on success, false if the result is not representable in an
419 /// NOTE: It is really important to have both the Asm and Layout arguments.
420 /// They might look redundant, but this function can be used before layout
421 /// is done (see the object streamer for example) and having the Asm argument
422 /// lets us avoid relaxations early.
423 static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
424 const MCAsmLayout *Layout,
425 const SectionAddrMap *Addrs,
427 const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
428 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
430 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
431 // about dealing with modifiers. This will ultimately bite us, one day.
432 const MCSymbolRefExpr *LHS_A = LHS.getSymA();
433 const MCSymbolRefExpr *LHS_B = LHS.getSymB();
434 int64_t LHS_Cst = LHS.getConstant();
436 // Fold the result constant immediately.
437 int64_t Result_Cst = LHS_Cst + RHS_Cst;
439 assert((!Layout || Asm) &&
440 "Must have an assembler object if layout is given!");
442 // If we have a layout, we can fold resolved differences.
444 // First, fold out any differences which are fully resolved. By
445 // reassociating terms in
446 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
447 // we have the four possible differences:
452 // Since we are attempting to be as aggressive as possible about folding, we
453 // attempt to evaluate each possible alternative.
454 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
456 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
458 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
460 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
464 // We can't represent the addition or subtraction of two symbols.
465 if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
468 // At this point, we have at most one additive symbol and one subtractive
469 // symbol -- find them.
470 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
471 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
473 // If we have a negated symbol, then we must have also have a non-negated
474 // symbol in order to encode the expression.
478 Res = MCValue::get(A, B, Result_Cst);
482 bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
483 const MCAsmLayout &Layout) const {
484 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout,
488 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
489 const MCAssembler *Asm,
490 const MCAsmLayout *Layout,
491 const SectionAddrMap *Addrs,
493 ++stats::MCExprEvaluate;
497 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
500 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
504 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
505 const MCSymbol &Sym = SRE->getSymbol();
507 // Evaluate recursively if this is a variable.
508 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
509 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
513 // If we failed to simplify this to a constant, let the target
515 if (Ret && !Res.getSymA() && !Res.getSymB())
519 Res = MCValue::get(SRE, 0, 0);
524 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
527 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
531 switch (AUE->getOpcode()) {
532 case MCUnaryExpr::LNot:
533 if (!Value.isAbsolute())
535 Res = MCValue::get(!Value.getConstant());
537 case MCUnaryExpr::Minus:
538 /// -(a - b + const) ==> (b - a - const)
539 if (Value.getSymA() && !Value.getSymB())
541 Res = MCValue::get(Value.getSymB(), Value.getSymA(),
542 -Value.getConstant());
544 case MCUnaryExpr::Not:
545 if (!Value.isAbsolute())
547 Res = MCValue::get(~Value.getConstant());
549 case MCUnaryExpr::Plus:
558 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
559 MCValue LHSValue, RHSValue;
561 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
563 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
567 // We only support a few operations on non-constant expressions, handle
569 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
570 switch (ABE->getOpcode()) {
573 case MCBinaryExpr::Sub:
574 // Negate RHS and add.
575 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
576 RHSValue.getSymB(), RHSValue.getSymA(),
577 -RHSValue.getConstant(),
580 case MCBinaryExpr::Add:
581 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
582 RHSValue.getSymA(), RHSValue.getSymB(),
583 RHSValue.getConstant(),
588 // FIXME: We need target hooks for the evaluation. It may be limited in
589 // width, and gas defines the result of comparisons and right shifts
590 // differently from Apple as.
591 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
593 switch (ABE->getOpcode()) {
594 case MCBinaryExpr::Add: Result = LHS + RHS; break;
595 case MCBinaryExpr::And: Result = LHS & RHS; break;
596 case MCBinaryExpr::Div: Result = LHS / RHS; break;
597 case MCBinaryExpr::EQ: Result = LHS == RHS; break;
598 case MCBinaryExpr::GT: Result = LHS > RHS; break;
599 case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
600 case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
601 case MCBinaryExpr::LOr: Result = LHS || RHS; break;
602 case MCBinaryExpr::LT: Result = LHS < RHS; break;
603 case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
604 case MCBinaryExpr::Mod: Result = LHS % RHS; break;
605 case MCBinaryExpr::Mul: Result = LHS * RHS; break;
606 case MCBinaryExpr::NE: Result = LHS != RHS; break;
607 case MCBinaryExpr::Or: Result = LHS | RHS; break;
608 case MCBinaryExpr::Shl: Result = LHS << RHS; break;
609 case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
610 case MCBinaryExpr::Sub: Result = LHS - RHS; break;
611 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
614 Res = MCValue::get(Result);
619 llvm_unreachable("Invalid assembly expression kind!");
622 const MCSection *MCExpr::FindAssociatedSection() const {
625 // We never look through target specific expressions.
626 return cast<MCTargetExpr>(this)->FindAssociatedSection();
629 return MCSymbol::AbsolutePseudoSection;
632 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
633 const MCSymbol &Sym = SRE->getSymbol();
636 return &Sym.getSection();
642 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection();
645 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
646 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection();
647 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection();
649 // If either section is absolute, return the other.
650 if (LHS_S == MCSymbol::AbsolutePseudoSection)
652 if (RHS_S == MCSymbol::AbsolutePseudoSection)
655 // Otherwise, return the first non-null section.
656 return LHS_S ? LHS_S : RHS_S;
660 llvm_unreachable("Invalid assembly expression kind!");