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/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"
23 using namespace llvm;
24
25 namespace {
26 namespace stats {
27 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
28 }
29 }
30
print(raw_ostream & OS) const31 void MCExpr::print(raw_ostream &OS) const {
32 switch (getKind()) {
33 case MCExpr::Target:
34 return cast<MCTargetExpr>(this)->PrintImpl(OS);
35 case MCExpr::Constant:
36 OS << cast<MCConstantExpr>(*this).getValue();
37 return;
38
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
43 // absolute names.
44 bool UseParens = Sym.getName()[0] == '$';
45
46 if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_HA16 ||
47 SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_LO16) {
48 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
49 UseParens = true;
50 }
51
52 if (UseParens)
53 OS << '(' << Sym << ')';
54 else
55 OS << Sym;
56
57 if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT ||
58 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD ||
59 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT ||
60 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF ||
61 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF ||
62 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF ||
63 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET1)
64 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
65 else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
66 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 &&
67 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_LO16)
68 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
69
70 return;
71 }
72
73 case MCExpr::Unary: {
74 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
75 switch (UE.getOpcode()) {
76 case MCUnaryExpr::LNot: OS << '!'; break;
77 case MCUnaryExpr::Minus: OS << '-'; break;
78 case MCUnaryExpr::Not: OS << '~'; break;
79 case MCUnaryExpr::Plus: OS << '+'; break;
80 }
81 OS << *UE.getSubExpr();
82 return;
83 }
84
85 case MCExpr::Binary: {
86 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
87
88 // Only print parens around the LHS if it is non-trivial.
89 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
90 OS << *BE.getLHS();
91 } else {
92 OS << '(' << *BE.getLHS() << ')';
93 }
94
95 switch (BE.getOpcode()) {
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 llvm_unreachable("Invalid expression kind!");
137 }
138
dump() const139 void MCExpr::dump() const {
140 print(dbgs());
141 dbgs() << '\n';
142 }
143
144 /* *** */
145
Create(Opcode Opc,const MCExpr * LHS,const MCExpr * RHS,MCContext & Ctx)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
Create(Opcode Opc,const MCExpr * Expr,MCContext & Ctx)151 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
152 MCContext &Ctx) {
153 return new (Ctx) MCUnaryExpr(Opc, Expr);
154 }
155
Create(int64_t Value,MCContext & Ctx)156 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
157 return new (Ctx) MCConstantExpr(Value);
158 }
159
160 /* *** */
161
Create(const MCSymbol * Sym,VariantKind Kind,MCContext & Ctx)162 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
163 VariantKind Kind,
164 MCContext &Ctx) {
165 return new (Ctx) MCSymbolRefExpr(Sym, Kind);
166 }
167
Create(StringRef Name,VariantKind Kind,MCContext & Ctx)168 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
169 MCContext &Ctx) {
170 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
171 }
172
getVariantKindName(VariantKind Kind)173 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
174 switch (Kind) {
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_SECREL: return "SECREL";
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_ARM_TARGET1: return "(target1)";
200 case VK_PPC_TOC: return "toc";
201 case VK_PPC_DARWIN_HA16: return "ha16";
202 case VK_PPC_DARWIN_LO16: return "lo16";
203 case VK_PPC_GAS_HA16: return "ha";
204 case VK_PPC_GAS_LO16: return "l";
205 case VK_Mips_GPREL: return "GPREL";
206 case VK_Mips_GOT_CALL: return "GOT_CALL";
207 case VK_Mips_GOT16: return "GOT16";
208 case VK_Mips_GOT: return "GOT";
209 case VK_Mips_ABS_HI: return "ABS_HI";
210 case VK_Mips_ABS_LO: return "ABS_LO";
211 case VK_Mips_TLSGD: return "TLSGD";
212 case VK_Mips_TLSLDM: return "TLSLDM";
213 case VK_Mips_DTPREL_HI: return "DTPREL_HI";
214 case VK_Mips_DTPREL_LO: return "DTPREL_LO";
215 case VK_Mips_GOTTPREL: return "GOTTPREL";
216 case VK_Mips_TPREL_HI: return "TPREL_HI";
217 case VK_Mips_TPREL_LO: return "TPREL_LO";
218 case VK_Mips_GPOFF_HI: return "GPOFF_HI";
219 case VK_Mips_GPOFF_LO: return "GPOFF_LO";
220 case VK_Mips_GOT_DISP: return "GOT_DISP";
221 case VK_Mips_GOT_PAGE: return "GOT_PAGE";
222 case VK_Mips_GOT_OFST: return "GOT_OFST";
223 }
224 llvm_unreachable("Invalid variant kind");
225 }
226
227 MCSymbolRefExpr::VariantKind
getVariantKindForName(StringRef Name)228 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
229 return StringSwitch<VariantKind>(Name)
230 .Case("GOT", VK_GOT)
231 .Case("got", VK_GOT)
232 .Case("GOTOFF", VK_GOTOFF)
233 .Case("gotoff", VK_GOTOFF)
234 .Case("GOTPCREL", VK_GOTPCREL)
235 .Case("gotpcrel", VK_GOTPCREL)
236 .Case("GOTTPOFF", VK_GOTTPOFF)
237 .Case("gottpoff", VK_GOTTPOFF)
238 .Case("INDNTPOFF", VK_INDNTPOFF)
239 .Case("indntpoff", VK_INDNTPOFF)
240 .Case("NTPOFF", VK_NTPOFF)
241 .Case("ntpoff", VK_NTPOFF)
242 .Case("GOTNTPOFF", VK_GOTNTPOFF)
243 .Case("gotntpoff", VK_GOTNTPOFF)
244 .Case("PLT", VK_PLT)
245 .Case("plt", VK_PLT)
246 .Case("TLSGD", VK_TLSGD)
247 .Case("tlsgd", VK_TLSGD)
248 .Case("TLSLD", VK_TLSLD)
249 .Case("tlsld", VK_TLSLD)
250 .Case("TLSLDM", VK_TLSLDM)
251 .Case("tlsldm", VK_TLSLDM)
252 .Case("TPOFF", VK_TPOFF)
253 .Case("tpoff", VK_TPOFF)
254 .Case("DTPOFF", VK_DTPOFF)
255 .Case("dtpoff", VK_DTPOFF)
256 .Case("TLVP", VK_TLVP)
257 .Case("tlvp", VK_TLVP)
258 .Default(VK_Invalid);
259 }
260
261 /* *** */
262
Anchor()263 void MCTargetExpr::Anchor() {}
264
265 /* *** */
266
EvaluateAsAbsolute(int64_t & Res) const267 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
268 return EvaluateAsAbsolute(Res, 0, 0, 0);
269 }
270
EvaluateAsAbsolute(int64_t & Res,const MCAsmLayout & Layout) const271 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
272 const MCAsmLayout &Layout) const {
273 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0);
274 }
275
EvaluateAsAbsolute(int64_t & Res,const MCAsmLayout & Layout,const SectionAddrMap & Addrs) const276 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
277 const MCAsmLayout &Layout,
278 const SectionAddrMap &Addrs) const {
279 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
280 }
281
EvaluateAsAbsolute(int64_t & Res,const MCAssembler & Asm) const282 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
283 return EvaluateAsAbsolute(Res, &Asm, 0, 0);
284 }
285
EvaluateAsAbsolute(int64_t & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs) const286 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
287 const MCAsmLayout *Layout,
288 const SectionAddrMap *Addrs) const {
289 MCValue Value;
290
291 // Fast path constants.
292 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
293 Res = CE->getValue();
294 return true;
295 }
296
297 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
298 // absolutize differences across sections and that is what the MachO writer
299 // uses Addrs for.
300 bool IsRelocatable =
301 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs);
302
303 // Record the current value.
304 Res = Value.getConstant();
305
306 return IsRelocatable && Value.isAbsolute();
307 }
308
309 /// \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)310 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm,
311 const MCAsmLayout *Layout,
312 const SectionAddrMap *Addrs,
313 bool InSet,
314 const MCSymbolRefExpr *&A,
315 const MCSymbolRefExpr *&B,
316 int64_t &Addend) {
317 if (!A || !B)
318 return;
319
320 const MCSymbol &SA = A->getSymbol();
321 const MCSymbol &SB = B->getSymbol();
322
323 if (SA.isUndefined() || SB.isUndefined())
324 return;
325
326 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
327 return;
328
329 MCSymbolData &AD = Asm->getSymbolData(SA);
330 MCSymbolData &BD = Asm->getSymbolData(SB);
331
332 if (AD.getFragment() == BD.getFragment()) {
333 Addend += (AD.getOffset() - BD.getOffset());
334
335 // Pointers to Thumb symbols need to have their low-bit set to allow
336 // for interworking.
337 if (Asm->isThumbFunc(&SA))
338 Addend |= 1;
339
340 // Clear the symbol expr pointers to indicate we have folded these
341 // operands.
342 A = B = 0;
343 return;
344 }
345
346 if (!Layout)
347 return;
348
349 const MCSectionData &SecA = *AD.getFragment()->getParent();
350 const MCSectionData &SecB = *BD.getFragment()->getParent();
351
352 if ((&SecA != &SecB) && !Addrs)
353 return;
354
355 // Eagerly evaluate.
356 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) -
357 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol())));
358 if (Addrs && (&SecA != &SecB))
359 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
360
361 // Pointers to Thumb symbols need to have their low-bit set to allow
362 // for interworking.
363 if (Asm->isThumbFunc(&SA))
364 Addend |= 1;
365
366 // Clear the symbol expr pointers to indicate we have folded these
367 // operands.
368 A = B = 0;
369 }
370
371 /// \brief Evaluate the result of an add between (conceptually) two MCValues.
372 ///
373 /// This routine conceptually attempts to construct an MCValue:
374 /// Result = (Result_A - Result_B + Result_Cst)
375 /// from two MCValue's LHS and RHS where
376 /// Result = LHS + RHS
377 /// and
378 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
379 ///
380 /// This routine attempts to aggresively fold the operands such that the result
381 /// is representable in an MCValue, but may not always succeed.
382 ///
383 /// \returns True on success, false if the result is not representable in an
384 /// MCValue.
385
386 /// NOTE: It is really important to have both the Asm and Layout arguments.
387 /// They might look redundant, but this function can be used before layout
388 /// is done (see the object streamer for example) and having the Asm argument
389 /// 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)390 static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
391 const MCAsmLayout *Layout,
392 const SectionAddrMap *Addrs,
393 bool InSet,
394 const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
395 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
396 MCValue &Res) {
397 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
398 // about dealing with modifiers. This will ultimately bite us, one day.
399 const MCSymbolRefExpr *LHS_A = LHS.getSymA();
400 const MCSymbolRefExpr *LHS_B = LHS.getSymB();
401 int64_t LHS_Cst = LHS.getConstant();
402
403 // Fold the result constant immediately.
404 int64_t Result_Cst = LHS_Cst + RHS_Cst;
405
406 assert((!Layout || Asm) &&
407 "Must have an assembler object if layout is given!");
408
409 // If we have a layout, we can fold resolved differences.
410 if (Asm) {
411 // First, fold out any differences which are fully resolved. By
412 // reassociating terms in
413 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
414 // we have the four possible differences:
415 // (LHS_A - LHS_B),
416 // (LHS_A - RHS_B),
417 // (RHS_A - LHS_B),
418 // (RHS_A - RHS_B).
419 // Since we are attempting to be as aggressive as possible about folding, we
420 // attempt to evaluate each possible alternative.
421 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
422 Result_Cst);
423 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
424 Result_Cst);
425 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
426 Result_Cst);
427 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
428 Result_Cst);
429 }
430
431 // We can't represent the addition or subtraction of two symbols.
432 if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
433 return false;
434
435 // At this point, we have at most one additive symbol and one subtractive
436 // symbol -- find them.
437 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
438 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
439
440 // If we have a negated symbol, then we must have also have a non-negated
441 // symbol in order to encode the expression.
442 if (B && !A)
443 return false;
444
445 Res = MCValue::get(A, B, Result_Cst);
446 return true;
447 }
448
EvaluateAsRelocatable(MCValue & Res,const MCAsmLayout & Layout) const449 bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
450 const MCAsmLayout &Layout) const {
451 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout,
452 0, false);
453 }
454
EvaluateAsRelocatableImpl(MCValue & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs,bool InSet) const455 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
456 const MCAssembler *Asm,
457 const MCAsmLayout *Layout,
458 const SectionAddrMap *Addrs,
459 bool InSet) const {
460 ++stats::MCExprEvaluate;
461
462 switch (getKind()) {
463 case Target:
464 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
465
466 case Constant:
467 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
468 return true;
469
470 case SymbolRef: {
471 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
472 const MCSymbol &Sym = SRE->getSymbol();
473
474 // Evaluate recursively if this is a variable.
475 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
476 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
477 Layout,
478 Addrs,
479 true);
480 // If we failed to simplify this to a constant, let the target
481 // handle it.
482 if (Ret && !Res.getSymA() && !Res.getSymB())
483 return true;
484 }
485
486 Res = MCValue::get(SRE, 0, 0);
487 return true;
488 }
489
490 case Unary: {
491 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
492 MCValue Value;
493
494 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
495 Addrs, InSet))
496 return false;
497
498 switch (AUE->getOpcode()) {
499 case MCUnaryExpr::LNot:
500 if (!Value.isAbsolute())
501 return false;
502 Res = MCValue::get(!Value.getConstant());
503 break;
504 case MCUnaryExpr::Minus:
505 /// -(a - b + const) ==> (b - a - const)
506 if (Value.getSymA() && !Value.getSymB())
507 return false;
508 Res = MCValue::get(Value.getSymB(), Value.getSymA(),
509 -Value.getConstant());
510 break;
511 case MCUnaryExpr::Not:
512 if (!Value.isAbsolute())
513 return false;
514 Res = MCValue::get(~Value.getConstant());
515 break;
516 case MCUnaryExpr::Plus:
517 Res = Value;
518 break;
519 }
520
521 return true;
522 }
523
524 case Binary: {
525 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
526 MCValue LHSValue, RHSValue;
527
528 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
529 Addrs, InSet) ||
530 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
531 Addrs, InSet))
532 return false;
533
534 // We only support a few operations on non-constant expressions, handle
535 // those first.
536 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
537 switch (ABE->getOpcode()) {
538 default:
539 return false;
540 case MCBinaryExpr::Sub:
541 // Negate RHS and add.
542 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
543 RHSValue.getSymB(), RHSValue.getSymA(),
544 -RHSValue.getConstant(),
545 Res);
546
547 case MCBinaryExpr::Add:
548 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
549 RHSValue.getSymA(), RHSValue.getSymB(),
550 RHSValue.getConstant(),
551 Res);
552 }
553 }
554
555 // FIXME: We need target hooks for the evaluation. It may be limited in
556 // width, and gas defines the result of comparisons and right shifts
557 // differently from Apple as.
558 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
559 int64_t Result = 0;
560 switch (ABE->getOpcode()) {
561 case MCBinaryExpr::Add: Result = LHS + RHS; break;
562 case MCBinaryExpr::And: Result = LHS & RHS; break;
563 case MCBinaryExpr::Div: Result = LHS / RHS; break;
564 case MCBinaryExpr::EQ: Result = LHS == RHS; break;
565 case MCBinaryExpr::GT: Result = LHS > RHS; break;
566 case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
567 case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
568 case MCBinaryExpr::LOr: Result = LHS || RHS; break;
569 case MCBinaryExpr::LT: Result = LHS < RHS; break;
570 case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
571 case MCBinaryExpr::Mod: Result = LHS % RHS; break;
572 case MCBinaryExpr::Mul: Result = LHS * RHS; break;
573 case MCBinaryExpr::NE: Result = LHS != RHS; break;
574 case MCBinaryExpr::Or: Result = LHS | RHS; break;
575 case MCBinaryExpr::Shl: Result = LHS << RHS; break;
576 case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
577 case MCBinaryExpr::Sub: Result = LHS - RHS; break;
578 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
579 }
580
581 Res = MCValue::get(Result);
582 return true;
583 }
584 }
585
586 llvm_unreachable("Invalid assembly expression kind!");
587 }
588
FindAssociatedSection() const589 const MCSection *MCExpr::FindAssociatedSection() const {
590 switch (getKind()) {
591 case Target:
592 // We never look through target specific expressions.
593 return cast<MCTargetExpr>(this)->FindAssociatedSection();
594
595 case Constant:
596 return MCSymbol::AbsolutePseudoSection;
597
598 case SymbolRef: {
599 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
600 const MCSymbol &Sym = SRE->getSymbol();
601
602 if (Sym.isDefined())
603 return &Sym.getSection();
604
605 return 0;
606 }
607
608 case Unary:
609 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection();
610
611 case Binary: {
612 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
613 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection();
614 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection();
615
616 // If either section is absolute, return the other.
617 if (LHS_S == MCSymbol::AbsolutePseudoSection)
618 return RHS_S;
619 if (RHS_S == MCSymbol::AbsolutePseudoSection)
620 return LHS_S;
621
622 // Otherwise, return the first non-null section.
623 return LHS_S ? LHS_S : RHS_S;
624 }
625 }
626
627 llvm_unreachable("Invalid assembly expression kind!");
628 }
629