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/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"
26 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
30 void MCExpr::print(raw_ostream &OS) const {
33 return cast<MCTargetExpr>(this)->PrintImpl(OS);
34 case MCExpr::Constant:
35 OS << cast<MCConstantExpr>(*this).getValue();
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
43 bool UseParens = Sym.getName()[0] == '$';
45 if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_HA16 ||
46 SRE.getKind() == MCSymbolRefExpr::VK_PPC_LO16) {
47 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
52 OS << '(' << Sym << ')';
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_HA16 &&
65 SRE.getKind() != MCSymbolRefExpr::VK_PPC_LO16)
66 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
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;
80 OS << *UE.getSubExpr();
84 case MCExpr::Binary: {
85 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
87 // Only print parens around the LHS if it is non-trivial.
88 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
91 OS << '(' << *BE.getLHS() << ')';
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();
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;
126 // Only print parens around the LHS if it is non-trivial.
127 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
130 OS << '(' << *BE.getRHS() << ')';
136 assert(0 && "Invalid expression kind!");
139 void MCExpr::dump() const {
146 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS,
147 const MCExpr *RHS, MCContext &Ctx) {
148 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
151 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
153 return new (Ctx) MCUnaryExpr(Opc, Expr);
156 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
157 return new (Ctx) MCConstantExpr(Value);
162 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
165 return new (Ctx) MCSymbolRefExpr(Sym, Kind);
168 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
170 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
173 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
176 case VK_Invalid: return "<<invalid>>";
177 case VK_None: return "<<none>>";
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_HA16: return "ha16";
201 case VK_PPC_LO16: return "lo16";
205 MCSymbolRefExpr::VariantKind
206 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
207 return StringSwitch<VariantKind>(Name)
210 .Case("GOTOFF", VK_GOTOFF)
211 .Case("gotoff", VK_GOTOFF)
212 .Case("GOTPCREL", VK_GOTPCREL)
213 .Case("gotpcrel", VK_GOTPCREL)
214 .Case("GOTTPOFF", VK_GOTTPOFF)
215 .Case("gottpoff", VK_GOTTPOFF)
216 .Case("INDNTPOFF", VK_INDNTPOFF)
217 .Case("indntpoff", VK_INDNTPOFF)
218 .Case("NTPOFF", VK_NTPOFF)
219 .Case("ntpoff", VK_NTPOFF)
220 .Case("GOTNTPOFF", VK_GOTNTPOFF)
221 .Case("gotntpoff", VK_GOTNTPOFF)
224 .Case("TLSGD", VK_TLSGD)
225 .Case("tlsgd", VK_TLSGD)
226 .Case("TLSLD", VK_TLSLD)
227 .Case("tlsld", VK_TLSLD)
228 .Case("TLSLDM", VK_TLSLDM)
229 .Case("tlsldm", VK_TLSLDM)
230 .Case("TPOFF", VK_TPOFF)
231 .Case("tpoff", VK_TPOFF)
232 .Case("DTPOFF", VK_DTPOFF)
233 .Case("dtpoff", VK_DTPOFF)
234 .Case("TLVP", VK_TLVP)
235 .Case("tlvp", VK_TLVP)
236 .Default(VK_Invalid);
241 void MCTargetExpr::Anchor() {}
245 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
246 return EvaluateAsAbsolute(Res, 0, 0, 0);
249 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
250 const MCAsmLayout &Layout) const {
251 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0);
254 bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
255 const MCAsmLayout &Layout,
256 const SectionAddrMap &Addrs) const {
257 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
260 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
261 return EvaluateAsAbsolute(Res, &Asm, 0, 0);
264 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
265 const MCAsmLayout *Layout,
266 const SectionAddrMap *Addrs) const {
269 // Fast path constants.
270 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
271 Res = CE->getValue();
275 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
276 // absolutize differences across sections and that is what the MachO writer
279 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs);
281 // Record the current value.
282 Res = Value.getConstant();
284 return IsRelocatable && Value.isAbsolute();
287 /// \brief Helper method for \see EvaluateSymbolAdd().
288 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm,
289 const MCAsmLayout *Layout,
290 const SectionAddrMap *Addrs,
292 const MCSymbolRefExpr *&A,
293 const MCSymbolRefExpr *&B,
298 const MCSymbol &SA = A->getSymbol();
299 const MCSymbol &SB = B->getSymbol();
301 if (SA.isUndefined() || SB.isUndefined())
304 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
307 MCSymbolData &AD = Asm->getSymbolData(SA);
308 MCSymbolData &BD = Asm->getSymbolData(SB);
310 if (AD.getFragment() == BD.getFragment()) {
311 Addend += (AD.getOffset() - BD.getOffset());
313 // Pointers to Thumb symbols need to have their low-bit set to allow
315 if (Asm->isThumbFunc(&SA))
318 // Clear the symbol expr pointers to indicate we have folded these
327 const MCSectionData &SecA = *AD.getFragment()->getParent();
328 const MCSectionData &SecB = *BD.getFragment()->getParent();
330 if ((&SecA != &SecB) && !Addrs)
334 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) -
335 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol())));
336 if (Addrs && (&SecA != &SecB))
337 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
339 // Clear the symbol expr pointers to indicate we have folded these
344 /// \brief Evaluate the result of an add between (conceptually) two MCValues.
346 /// This routine conceptually attempts to construct an MCValue:
347 /// Result = (Result_A - Result_B + Result_Cst)
348 /// from two MCValue's LHS and RHS where
349 /// Result = LHS + RHS
351 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
353 /// This routine attempts to aggresively fold the operands such that the result
354 /// is representable in an MCValue, but may not always succeed.
356 /// \returns True on success, false if the result is not representable in an
359 /// NOTE: It is really important to have both the Asm and Layout arguments.
360 /// They might look redundant, but this function can be used before layout
361 /// is done (see the object streamer for example) and having the Asm argument
362 /// lets us avoid relaxations early.
363 static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
364 const MCAsmLayout *Layout,
365 const SectionAddrMap *Addrs,
367 const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
368 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
370 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
371 // about dealing with modifiers. This will ultimately bite us, one day.
372 const MCSymbolRefExpr *LHS_A = LHS.getSymA();
373 const MCSymbolRefExpr *LHS_B = LHS.getSymB();
374 int64_t LHS_Cst = LHS.getConstant();
376 // Fold the result constant immediately.
377 int64_t Result_Cst = LHS_Cst + RHS_Cst;
379 assert((!Layout || Asm) &&
380 "Must have an assembler object if layout is given!");
382 // If we have a layout, we can fold resolved differences.
384 // First, fold out any differences which are fully resolved. By
385 // reassociating terms in
386 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
387 // we have the four possible differences:
392 // Since we are attempting to be as aggresive as possible about folding, we
393 // attempt to evaluate each possible alternative.
394 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
396 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
398 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
400 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
404 // We can't represent the addition or subtraction of two symbols.
405 if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
408 // At this point, we have at most one additive symbol and one subtractive
409 // symbol -- find them.
410 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
411 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
413 // If we have a negated symbol, then we must have also have a non-negated
414 // symbol in order to encode the expression.
418 Res = MCValue::get(A, B, Result_Cst);
422 bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
423 const MCAsmLayout &Layout) const {
424 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout,
428 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
429 const MCAssembler *Asm,
430 const MCAsmLayout *Layout,
431 const SectionAddrMap *Addrs,
433 ++stats::MCExprEvaluate;
437 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
440 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
444 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
445 const MCSymbol &Sym = SRE->getSymbol();
447 // Evaluate recursively if this is a variable.
448 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
449 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
453 // If we failed to simplify this to a constant, let the target
455 if (Ret && !Res.getSymA() && !Res.getSymB())
459 Res = MCValue::get(SRE, 0, 0);
464 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
467 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
471 switch (AUE->getOpcode()) {
472 case MCUnaryExpr::LNot:
473 if (!Value.isAbsolute())
475 Res = MCValue::get(!Value.getConstant());
477 case MCUnaryExpr::Minus:
478 /// -(a - b + const) ==> (b - a - const)
479 if (Value.getSymA() && !Value.getSymB())
481 Res = MCValue::get(Value.getSymB(), Value.getSymA(),
482 -Value.getConstant());
484 case MCUnaryExpr::Not:
485 if (!Value.isAbsolute())
487 Res = MCValue::get(~Value.getConstant());
489 case MCUnaryExpr::Plus:
498 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
499 MCValue LHSValue, RHSValue;
501 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
503 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
507 // We only support a few operations on non-constant expressions, handle
509 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
510 switch (ABE->getOpcode()) {
513 case MCBinaryExpr::Sub:
514 // Negate RHS and add.
515 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
516 RHSValue.getSymB(), RHSValue.getSymA(),
517 -RHSValue.getConstant(),
520 case MCBinaryExpr::Add:
521 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
522 RHSValue.getSymA(), RHSValue.getSymB(),
523 RHSValue.getConstant(),
528 // FIXME: We need target hooks for the evaluation. It may be limited in
529 // width, and gas defines the result of comparisons and right shifts
530 // differently from Apple as.
531 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
533 switch (ABE->getOpcode()) {
534 case MCBinaryExpr::Add: Result = LHS + RHS; break;
535 case MCBinaryExpr::And: Result = LHS & RHS; break;
536 case MCBinaryExpr::Div: Result = LHS / RHS; break;
537 case MCBinaryExpr::EQ: Result = LHS == RHS; break;
538 case MCBinaryExpr::GT: Result = LHS > RHS; break;
539 case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
540 case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
541 case MCBinaryExpr::LOr: Result = LHS || RHS; break;
542 case MCBinaryExpr::LT: Result = LHS < RHS; break;
543 case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
544 case MCBinaryExpr::Mod: Result = LHS % RHS; break;
545 case MCBinaryExpr::Mul: Result = LHS * RHS; break;
546 case MCBinaryExpr::NE: Result = LHS != RHS; break;
547 case MCBinaryExpr::Or: Result = LHS | RHS; break;
548 case MCBinaryExpr::Shl: Result = LHS << RHS; break;
549 case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
550 case MCBinaryExpr::Sub: Result = LHS - RHS; break;
551 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
554 Res = MCValue::get(Result);
559 assert(0 && "Invalid assembly expression kind!");