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 using namespace llvm;
22
23 namespace {
24 namespace stats {
25 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
26 }
27 }
28
print(raw_ostream & OS) const29 void MCExpr::print(raw_ostream &OS) const {
30 switch (getKind()) {
31 case MCExpr::Target:
32 return cast<MCTargetExpr>(this)->PrintImpl(OS);
33 case MCExpr::Constant:
34 OS << cast<MCConstantExpr>(*this).getValue();
35 return;
36
37 case MCExpr::SymbolRef: {
38 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
39 const MCSymbol &Sym = SRE.getSymbol();
40 // Parenthesize names that start with $ so that they don't look like
41 // absolute names.
42 bool UseParens = Sym.getName()[0] == '$';
43
44 if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_HA16 ||
45 SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_LO16) {
46 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
47 UseParens = true;
48 }
49
50 if (UseParens)
51 OS << '(' << Sym << ')';
52 else
53 OS << Sym;
54
55 if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT ||
56 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD ||
57 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT ||
58 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF ||
59 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF ||
60 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF)
61 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
62 else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
63 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 &&
64 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_LO16)
65 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
66
67 return;
68 }
69
70 case MCExpr::Unary: {
71 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
72 switch (UE.getOpcode()) {
73 default: assert(0 && "Invalid opcode!");
74 case MCUnaryExpr::LNot: OS << '!'; break;
75 case MCUnaryExpr::Minus: OS << '-'; break;
76 case MCUnaryExpr::Not: OS << '~'; break;
77 case MCUnaryExpr::Plus: OS << '+'; break;
78 }
79 OS << *UE.getSubExpr();
80 return;
81 }
82
83 case MCExpr::Binary: {
84 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
85
86 // Only print parens around the LHS if it is non-trivial.
87 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
88 OS << *BE.getLHS();
89 } else {
90 OS << '(' << *BE.getLHS() << ')';
91 }
92
93 switch (BE.getOpcode()) {
94 default: assert(0 && "Invalid opcode!");
95 case MCBinaryExpr::Add:
96 // Print "X-42" instead of "X+-42".
97 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
98 if (RHSC->getValue() < 0) {
99 OS << RHSC->getValue();
100 return;
101 }
102 }
103
104 OS << '+';
105 break;
106 case MCBinaryExpr::And: OS << '&'; break;
107 case MCBinaryExpr::Div: OS << '/'; break;
108 case MCBinaryExpr::EQ: OS << "=="; break;
109 case MCBinaryExpr::GT: OS << '>'; break;
110 case MCBinaryExpr::GTE: OS << ">="; break;
111 case MCBinaryExpr::LAnd: OS << "&&"; break;
112 case MCBinaryExpr::LOr: OS << "||"; break;
113 case MCBinaryExpr::LT: OS << '<'; break;
114 case MCBinaryExpr::LTE: OS << "<="; break;
115 case MCBinaryExpr::Mod: OS << '%'; break;
116 case MCBinaryExpr::Mul: OS << '*'; break;
117 case MCBinaryExpr::NE: OS << "!="; break;
118 case MCBinaryExpr::Or: OS << '|'; break;
119 case MCBinaryExpr::Shl: OS << "<<"; break;
120 case MCBinaryExpr::Shr: OS << ">>"; break;
121 case MCBinaryExpr::Sub: OS << '-'; break;
122 case MCBinaryExpr::Xor: OS << '^'; break;
123 }
124
125 // Only print parens around the LHS if it is non-trivial.
126 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
127 OS << *BE.getRHS();
128 } else {
129 OS << '(' << *BE.getRHS() << ')';
130 }
131 return;
132 }
133 }
134
135 assert(0 && "Invalid expression kind!");
136 }
137
dump() const138 void MCExpr::dump() const {
139 print(dbgs());
140 dbgs() << '\n';
141 }
142
143 /* *** */
144
Create(Opcode Opc,const MCExpr * LHS,const MCExpr * RHS,MCContext & Ctx)145 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS,
146 const MCExpr *RHS, MCContext &Ctx) {
147 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
148 }
149
Create(Opcode Opc,const MCExpr * Expr,MCContext & Ctx)150 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
151 MCContext &Ctx) {
152 return new (Ctx) MCUnaryExpr(Opc, Expr);
153 }
154
Create(int64_t Value,MCContext & Ctx)155 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
156 return new (Ctx) MCConstantExpr(Value);
157 }
158
159 /* *** */
160
Create(const MCSymbol * Sym,VariantKind Kind,MCContext & Ctx)161 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
162 VariantKind Kind,
163 MCContext &Ctx) {
164 return new (Ctx) MCSymbolRefExpr(Sym, Kind);
165 }
166
Create(StringRef Name,VariantKind Kind,MCContext & Ctx)167 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
168 MCContext &Ctx) {
169 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
170 }
171
getVariantKindName(VariantKind Kind)172 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
173 switch (Kind) {
174 default:
175 case VK_Invalid: return "<<invalid>>";
176 case VK_None: return "<<none>>";
177
178 case VK_GOT: return "GOT";
179 case VK_GOTOFF: return "GOTOFF";
180 case VK_GOTPCREL: return "GOTPCREL";
181 case VK_GOTTPOFF: return "GOTTPOFF";
182 case VK_INDNTPOFF: return "INDNTPOFF";
183 case VK_NTPOFF: return "NTPOFF";
184 case VK_GOTNTPOFF: return "GOTNTPOFF";
185 case VK_PLT: return "PLT";
186 case VK_TLSGD: return "TLSGD";
187 case VK_TLSLD: return "TLSLD";
188 case VK_TLSLDM: return "TLSLDM";
189 case VK_TPOFF: return "TPOFF";
190 case VK_DTPOFF: return "DTPOFF";
191 case VK_TLVP: return "TLVP";
192 case VK_ARM_PLT: return "(PLT)";
193 case VK_ARM_GOT: return "(GOT)";
194 case VK_ARM_GOTOFF: return "(GOTOFF)";
195 case VK_ARM_TPOFF: return "(tpoff)";
196 case VK_ARM_GOTTPOFF: return "(gottpoff)";
197 case VK_ARM_TLSGD: return "(tlsgd)";
198 case VK_PPC_TOC: return "toc";
199 case VK_PPC_DARWIN_HA16: return "ha16";
200 case VK_PPC_DARWIN_LO16: return "lo16";
201 case VK_PPC_GAS_HA16: return "ha";
202 case VK_PPC_GAS_LO16: return "l";
203 }
204 }
205
206 MCSymbolRefExpr::VariantKind
getVariantKindForName(StringRef Name)207 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
208 return StringSwitch<VariantKind>(Name)
209 .Case("GOT", VK_GOT)
210 .Case("got", VK_GOT)
211 .Case("GOTOFF", VK_GOTOFF)
212 .Case("gotoff", VK_GOTOFF)
213 .Case("GOTPCREL", VK_GOTPCREL)
214 .Case("gotpcrel", VK_GOTPCREL)
215 .Case("GOTTPOFF", VK_GOTTPOFF)
216 .Case("gottpoff", VK_GOTTPOFF)
217 .Case("INDNTPOFF", VK_INDNTPOFF)
218 .Case("indntpoff", VK_INDNTPOFF)
219 .Case("NTPOFF", VK_NTPOFF)
220 .Case("ntpoff", VK_NTPOFF)
221 .Case("GOTNTPOFF", VK_GOTNTPOFF)
222 .Case("gotntpoff", VK_GOTNTPOFF)
223 .Case("PLT", VK_PLT)
224 .Case("plt", VK_PLT)
225 .Case("TLSGD", VK_TLSGD)
226 .Case("tlsgd", VK_TLSGD)
227 .Case("TLSLD", VK_TLSLD)
228 .Case("tlsld", VK_TLSLD)
229 .Case("TLSLDM", VK_TLSLDM)
230 .Case("tlsldm", VK_TLSLDM)
231 .Case("TPOFF", VK_TPOFF)
232 .Case("tpoff", VK_TPOFF)
233 .Case("DTPOFF", VK_DTPOFF)
234 .Case("dtpoff", VK_DTPOFF)
235 .Case("TLVP", VK_TLVP)
236 .Case("tlvp", VK_TLVP)
237 .Default(VK_Invalid);
238 }
239
240 /* *** */
241
Anchor()242 void MCTargetExpr::Anchor() {}
243
244 /* *** */
245
EvaluateAsAbsolute(int64_t & Res) const246 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
247 return EvaluateAsAbsolute(Res, 0, 0, 0);
248 }
249
EvaluateAsAbsolute(int64_t & Res,const MCAsmLayout & Layout) const250 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
251 const MCAsmLayout &Layout) const {
252 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0);
253 }
254
EvaluateAsAbsolute(int64_t & Res,const MCAsmLayout & Layout,const SectionAddrMap & Addrs) const255 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
256 const MCAsmLayout &Layout,
257 const SectionAddrMap &Addrs) const {
258 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
259 }
260
EvaluateAsAbsolute(int64_t & Res,const MCAssembler & Asm) const261 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
262 return EvaluateAsAbsolute(Res, &Asm, 0, 0);
263 }
264
EvaluateAsAbsolute(int64_t & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs) const265 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
266 const MCAsmLayout *Layout,
267 const SectionAddrMap *Addrs) const {
268 MCValue Value;
269
270 // Fast path constants.
271 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
272 Res = CE->getValue();
273 return true;
274 }
275
276 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
277 // absolutize differences across sections and that is what the MachO writer
278 // uses Addrs for.
279 bool IsRelocatable =
280 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs);
281
282 // Record the current value.
283 Res = Value.getConstant();
284
285 return IsRelocatable && Value.isAbsolute();
286 }
287
288 /// \brief Helper method for \see EvaluateSymbolAdd().
AttemptToFoldSymbolOffsetDifference(const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs,bool InSet,const MCSymbolRefExpr * & A,const MCSymbolRefExpr * & B,int64_t & Addend)289 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm,
290 const MCAsmLayout *Layout,
291 const SectionAddrMap *Addrs,
292 bool InSet,
293 const MCSymbolRefExpr *&A,
294 const MCSymbolRefExpr *&B,
295 int64_t &Addend) {
296 if (!A || !B)
297 return;
298
299 const MCSymbol &SA = A->getSymbol();
300 const MCSymbol &SB = B->getSymbol();
301
302 if (SA.isUndefined() || SB.isUndefined())
303 return;
304
305 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
306 return;
307
308 MCSymbolData &AD = Asm->getSymbolData(SA);
309 MCSymbolData &BD = Asm->getSymbolData(SB);
310
311 if (AD.getFragment() == BD.getFragment()) {
312 Addend += (AD.getOffset() - BD.getOffset());
313
314 // Pointers to Thumb symbols need to have their low-bit set to allow
315 // for interworking.
316 if (Asm->isThumbFunc(&SA))
317 Addend |= 1;
318
319 // Clear the symbol expr pointers to indicate we have folded these
320 // operands.
321 A = B = 0;
322 return;
323 }
324
325 if (!Layout)
326 return;
327
328 const MCSectionData &SecA = *AD.getFragment()->getParent();
329 const MCSectionData &SecB = *BD.getFragment()->getParent();
330
331 if ((&SecA != &SecB) && !Addrs)
332 return;
333
334 // Eagerly evaluate.
335 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) -
336 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol())));
337 if (Addrs && (&SecA != &SecB))
338 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
339
340 // Clear the symbol expr pointers to indicate we have folded these
341 // operands.
342 A = B = 0;
343 }
344
345 /// \brief Evaluate the result of an add between (conceptually) two MCValues.
346 ///
347 /// This routine conceptually attempts to construct an MCValue:
348 /// Result = (Result_A - Result_B + Result_Cst)
349 /// from two MCValue's LHS and RHS where
350 /// Result = LHS + RHS
351 /// and
352 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
353 ///
354 /// This routine attempts to aggresively fold the operands such that the result
355 /// is representable in an MCValue, but may not always succeed.
356 ///
357 /// \returns True on success, false if the result is not representable in an
358 /// MCValue.
359
360 /// NOTE: It is really important to have both the Asm and Layout arguments.
361 /// They might look redundant, but this function can be used before layout
362 /// is done (see the object streamer for example) and having the Asm argument
363 /// lets us avoid relaxations early.
EvaluateSymbolicAdd(const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs,bool InSet,const MCValue & LHS,const MCSymbolRefExpr * RHS_A,const MCSymbolRefExpr * RHS_B,int64_t RHS_Cst,MCValue & Res)364 static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
365 const MCAsmLayout *Layout,
366 const SectionAddrMap *Addrs,
367 bool InSet,
368 const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
369 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
370 MCValue &Res) {
371 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
372 // about dealing with modifiers. This will ultimately bite us, one day.
373 const MCSymbolRefExpr *LHS_A = LHS.getSymA();
374 const MCSymbolRefExpr *LHS_B = LHS.getSymB();
375 int64_t LHS_Cst = LHS.getConstant();
376
377 // Fold the result constant immediately.
378 int64_t Result_Cst = LHS_Cst + RHS_Cst;
379
380 assert((!Layout || Asm) &&
381 "Must have an assembler object if layout is given!");
382
383 // If we have a layout, we can fold resolved differences.
384 if (Asm) {
385 // First, fold out any differences which are fully resolved. By
386 // reassociating terms in
387 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
388 // we have the four possible differences:
389 // (LHS_A - LHS_B),
390 // (LHS_A - RHS_B),
391 // (RHS_A - LHS_B),
392 // (RHS_A - RHS_B).
393 // Since we are attempting to be as aggressive as possible about folding, we
394 // attempt to evaluate each possible alternative.
395 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
396 Result_Cst);
397 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
398 Result_Cst);
399 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
400 Result_Cst);
401 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
402 Result_Cst);
403 }
404
405 // We can't represent the addition or subtraction of two symbols.
406 if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
407 return false;
408
409 // At this point, we have at most one additive symbol and one subtractive
410 // symbol -- find them.
411 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
412 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
413
414 // If we have a negated symbol, then we must have also have a non-negated
415 // symbol in order to encode the expression.
416 if (B && !A)
417 return false;
418
419 Res = MCValue::get(A, B, Result_Cst);
420 return true;
421 }
422
EvaluateAsRelocatable(MCValue & Res,const MCAsmLayout & Layout) const423 bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
424 const MCAsmLayout &Layout) const {
425 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout,
426 0, false);
427 }
428
EvaluateAsRelocatableImpl(MCValue & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs,bool InSet) const429 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
430 const MCAssembler *Asm,
431 const MCAsmLayout *Layout,
432 const SectionAddrMap *Addrs,
433 bool InSet) const {
434 ++stats::MCExprEvaluate;
435
436 switch (getKind()) {
437 case Target:
438 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
439
440 case Constant:
441 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
442 return true;
443
444 case SymbolRef: {
445 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
446 const MCSymbol &Sym = SRE->getSymbol();
447
448 // Evaluate recursively if this is a variable.
449 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
450 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
451 Layout,
452 Addrs,
453 true);
454 // If we failed to simplify this to a constant, let the target
455 // handle it.
456 if (Ret && !Res.getSymA() && !Res.getSymB())
457 return true;
458 }
459
460 Res = MCValue::get(SRE, 0, 0);
461 return true;
462 }
463
464 case Unary: {
465 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
466 MCValue Value;
467
468 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
469 Addrs, InSet))
470 return false;
471
472 switch (AUE->getOpcode()) {
473 case MCUnaryExpr::LNot:
474 if (!Value.isAbsolute())
475 return false;
476 Res = MCValue::get(!Value.getConstant());
477 break;
478 case MCUnaryExpr::Minus:
479 /// -(a - b + const) ==> (b - a - const)
480 if (Value.getSymA() && !Value.getSymB())
481 return false;
482 Res = MCValue::get(Value.getSymB(), Value.getSymA(),
483 -Value.getConstant());
484 break;
485 case MCUnaryExpr::Not:
486 if (!Value.isAbsolute())
487 return false;
488 Res = MCValue::get(~Value.getConstant());
489 break;
490 case MCUnaryExpr::Plus:
491 Res = Value;
492 break;
493 }
494
495 return true;
496 }
497
498 case Binary: {
499 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
500 MCValue LHSValue, RHSValue;
501
502 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
503 Addrs, InSet) ||
504 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
505 Addrs, InSet))
506 return false;
507
508 // We only support a few operations on non-constant expressions, handle
509 // those first.
510 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
511 switch (ABE->getOpcode()) {
512 default:
513 return false;
514 case MCBinaryExpr::Sub:
515 // Negate RHS and add.
516 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
517 RHSValue.getSymB(), RHSValue.getSymA(),
518 -RHSValue.getConstant(),
519 Res);
520
521 case MCBinaryExpr::Add:
522 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
523 RHSValue.getSymA(), RHSValue.getSymB(),
524 RHSValue.getConstant(),
525 Res);
526 }
527 }
528
529 // FIXME: We need target hooks for the evaluation. It may be limited in
530 // width, and gas defines the result of comparisons and right shifts
531 // differently from Apple as.
532 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
533 int64_t Result = 0;
534 switch (ABE->getOpcode()) {
535 case MCBinaryExpr::Add: Result = LHS + RHS; break;
536 case MCBinaryExpr::And: Result = LHS & RHS; break;
537 case MCBinaryExpr::Div: Result = LHS / RHS; break;
538 case MCBinaryExpr::EQ: Result = LHS == RHS; break;
539 case MCBinaryExpr::GT: Result = LHS > RHS; break;
540 case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
541 case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
542 case MCBinaryExpr::LOr: Result = LHS || RHS; break;
543 case MCBinaryExpr::LT: Result = LHS < RHS; break;
544 case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
545 case MCBinaryExpr::Mod: Result = LHS % RHS; break;
546 case MCBinaryExpr::Mul: Result = LHS * RHS; break;
547 case MCBinaryExpr::NE: Result = LHS != RHS; break;
548 case MCBinaryExpr::Or: Result = LHS | RHS; break;
549 case MCBinaryExpr::Shl: Result = LHS << RHS; break;
550 case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
551 case MCBinaryExpr::Sub: Result = LHS - RHS; break;
552 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
553 }
554
555 Res = MCValue::get(Result);
556 return true;
557 }
558 }
559
560 assert(0 && "Invalid assembly expression kind!");
561 return false;
562 }
563
FindAssociatedSection() const564 const MCSection *MCExpr::FindAssociatedSection() const {
565 switch (getKind()) {
566 case Target:
567 // We never look through target specific expressions.
568 return cast<MCTargetExpr>(this)->FindAssociatedSection();
569
570 case Constant:
571 return MCSymbol::AbsolutePseudoSection;
572
573 case SymbolRef: {
574 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
575 const MCSymbol &Sym = SRE->getSymbol();
576
577 if (Sym.isDefined())
578 return &Sym.getSection();
579
580 return 0;
581 }
582
583 case Unary:
584 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection();
585
586 case Binary: {
587 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
588 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection();
589 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection();
590
591 // If either section is absolute, return the other.
592 if (LHS_S == MCSymbol::AbsolutePseudoSection)
593 return RHS_S;
594 if (RHS_S == MCSymbol::AbsolutePseudoSection)
595 return LHS_S;
596
597 // Otherwise, return the first non-null section.
598 return LHS_S ? LHS_S : RHS_S;
599 }
600 }
601
602 assert(0 && "Invalid assembly expression kind!");
603 return 0;
604 }
605