LLVM  8.0.0svn
MCExpr.cpp
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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 #include "llvm/MC/MCExpr.h"
11 #include "llvm/ADT/Statistic.h"
12 #include "llvm/ADT/StringSwitch.h"
13 #include "llvm/Config/llvm-config.h"
14 #include "llvm/MC/MCAsmBackend.h"
15 #include "llvm/MC/MCAsmInfo.h"
16 #include "llvm/MC/MCAsmLayout.h"
17 #include "llvm/MC/MCAssembler.h"
18 #include "llvm/MC/MCContext.h"
19 #include "llvm/MC/MCObjectWriter.h"
20 #include "llvm/MC/MCSymbol.h"
21 #include "llvm/MC/MCValue.h"
22 #include "llvm/Support/Casting.h"
23 #include "llvm/Support/Compiler.h"
24 #include "llvm/Support/Debug.h"
27 #include <cassert>
28 #include <cstdint>
29 
30 using namespace llvm;
31 
32 #define DEBUG_TYPE "mcexpr"
33 
34 namespace {
35 namespace stats {
36 
37 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
38 
39 } // end namespace stats
40 } // end anonymous namespace
41 
42 void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens) const {
43  switch (getKind()) {
44  case MCExpr::Target:
45  return cast<MCTargetExpr>(this)->printImpl(OS, MAI);
46  case MCExpr::Constant:
47  OS << cast<MCConstantExpr>(*this).getValue();
48  return;
49 
50  case MCExpr::SymbolRef: {
51  const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
52  const MCSymbol &Sym = SRE.getSymbol();
53  // Parenthesize names that start with $ so that they don't look like
54  // absolute names.
55  bool UseParens =
56  !InParens && !Sym.getName().empty() && Sym.getName()[0] == '$';
57  if (UseParens) {
58  OS << '(';
59  Sym.print(OS, MAI);
60  OS << ')';
61  } else
62  Sym.print(OS, MAI);
63 
64  if (SRE.getKind() != MCSymbolRefExpr::VK_None)
65  SRE.printVariantKind(OS);
66 
67  return;
68  }
69 
70  case MCExpr::Unary: {
71  const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
72  switch (UE.getOpcode()) {
73  case MCUnaryExpr::LNot: OS << '!'; break;
74  case MCUnaryExpr::Minus: OS << '-'; break;
75  case MCUnaryExpr::Not: OS << '~'; break;
76  case MCUnaryExpr::Plus: OS << '+'; break;
77  }
78  bool Binary = UE.getSubExpr()->getKind() == MCExpr::Binary;
79  if (Binary) OS << "(";
80  UE.getSubExpr()->print(OS, MAI);
81  if (Binary) OS << ")";
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  BE.getLHS()->print(OS, MAI);
91  } else {
92  OS << '(';
93  BE.getLHS()->print(OS, MAI);
94  OS << ')';
95  }
96 
97  switch (BE.getOpcode()) {
98  case MCBinaryExpr::Add:
99  // Print "X-42" instead of "X+-42".
100  if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
101  if (RHSC->getValue() < 0) {
102  OS << RHSC->getValue();
103  return;
104  }
105  }
106 
107  OS << '+';
108  break;
109  case MCBinaryExpr::AShr: OS << ">>"; break;
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::LShr: OS << ">>"; break;
118  case MCBinaryExpr::LT: OS << '<'; break;
119  case MCBinaryExpr::LTE: OS << "<="; break;
120  case MCBinaryExpr::Mod: OS << '%'; break;
121  case MCBinaryExpr::Mul: OS << '*'; break;
122  case MCBinaryExpr::NE: OS << "!="; break;
123  case MCBinaryExpr::Or: OS << '|'; break;
124  case MCBinaryExpr::Shl: OS << "<<"; break;
125  case MCBinaryExpr::Sub: OS << '-'; break;
126  case MCBinaryExpr::Xor: OS << '^'; break;
127  }
128 
129  // Only print parens around the LHS if it is non-trivial.
130  if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
131  BE.getRHS()->print(OS, MAI);
132  } else {
133  OS << '(';
134  BE.getRHS()->print(OS, MAI);
135  OS << ')';
136  }
137  return;
138  }
139  }
140 
141  llvm_unreachable("Invalid expression kind!");
142 }
143 
144 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
145 LLVM_DUMP_METHOD void MCExpr::dump() const {
146  dbgs() << *this;
147  dbgs() << '\n';
148 }
149 #endif
150 
151 /* *** */
152 
153 const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS,
154  const MCExpr *RHS, MCContext &Ctx,
155  SMLoc Loc) {
156  return new (Ctx) MCBinaryExpr(Opc, LHS, RHS, Loc);
157 }
158 
159 const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr,
160  MCContext &Ctx, SMLoc Loc) {
161  return new (Ctx) MCUnaryExpr(Opc, Expr, Loc);
162 }
163 
164 const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx) {
165  return new (Ctx) MCConstantExpr(Value);
166 }
167 
168 /* *** */
169 
170 MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,
171  const MCAsmInfo *MAI, SMLoc Loc)
172  : MCExpr(MCExpr::SymbolRef, Loc), Kind(Kind),
173  UseParensForSymbolVariant(MAI->useParensForSymbolVariant()),
174  HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()),
175  Symbol(Symbol) {
176  assert(Symbol);
177 }
178 
179 const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym,
180  VariantKind Kind,
181  MCContext &Ctx, SMLoc Loc) {
182  return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo(), Loc);
183 }
184 
185 const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind,
186  MCContext &Ctx) {
187  return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx);
188 }
189 
190 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
191  switch (Kind) {
192  case VK_Invalid: return "<<invalid>>";
193  case VK_None: return "<<none>>";
194 
195  case VK_DTPOFF: return "DTPOFF";
196  case VK_DTPREL: return "DTPREL";
197  case VK_GOT: return "GOT";
198  case VK_GOTOFF: return "GOTOFF";
199  case VK_GOTREL: return "GOTREL";
200  case VK_GOTPCREL: return "GOTPCREL";
201  case VK_GOTTPOFF: return "GOTTPOFF";
202  case VK_INDNTPOFF: return "INDNTPOFF";
203  case VK_NTPOFF: return "NTPOFF";
204  case VK_GOTNTPOFF: return "GOTNTPOFF";
205  case VK_PLT: return "PLT";
206  case VK_TLSGD: return "TLSGD";
207  case VK_TLSLD: return "TLSLD";
208  case VK_TLSLDM: return "TLSLDM";
209  case VK_TPOFF: return "TPOFF";
210  case VK_TPREL: return "TPREL";
211  case VK_TLSCALL: return "tlscall";
212  case VK_TLSDESC: return "tlsdesc";
213  case VK_TLVP: return "TLVP";
214  case VK_TLVPPAGE: return "TLVPPAGE";
215  case VK_TLVPPAGEOFF: return "TLVPPAGEOFF";
216  case VK_PAGE: return "PAGE";
217  case VK_PAGEOFF: return "PAGEOFF";
218  case VK_GOTPAGE: return "GOTPAGE";
219  case VK_GOTPAGEOFF: return "GOTPAGEOFF";
220  case VK_SECREL: return "SECREL32";
221  case VK_SIZE: return "SIZE";
222  case VK_WEAKREF: return "WEAKREF";
223  case VK_X86_ABS8: return "ABS8";
224  case VK_ARM_NONE: return "none";
225  case VK_ARM_GOT_PREL: return "GOT_PREL";
226  case VK_ARM_TARGET1: return "target1";
227  case VK_ARM_TARGET2: return "target2";
228  case VK_ARM_PREL31: return "prel31";
229  case VK_ARM_SBREL: return "sbrel";
230  case VK_ARM_TLSLDO: return "tlsldo";
231  case VK_ARM_TLSDESCSEQ: return "tlsdescseq";
232  case VK_AVR_NONE: return "none";
233  case VK_AVR_LO8: return "lo8";
234  case VK_AVR_HI8: return "hi8";
235  case VK_AVR_HLO8: return "hlo8";
236  case VK_AVR_DIFF8: return "diff8";
237  case VK_AVR_DIFF16: return "diff16";
238  case VK_AVR_DIFF32: return "diff32";
239  case VK_PPC_LO: return "l";
240  case VK_PPC_HI: return "h";
241  case VK_PPC_HA: return "ha";
242  case VK_PPC_HIGH: return "high";
243  case VK_PPC_HIGHA: return "higha";
244  case VK_PPC_HIGHER: return "higher";
245  case VK_PPC_HIGHERA: return "highera";
246  case VK_PPC_HIGHEST: return "highest";
247  case VK_PPC_HIGHESTA: return "highesta";
248  case VK_PPC_GOT_LO: return "got@l";
249  case VK_PPC_GOT_HI: return "got@h";
250  case VK_PPC_GOT_HA: return "got@ha";
251  case VK_PPC_TOCBASE: return "tocbase";
252  case VK_PPC_TOC: return "toc";
253  case VK_PPC_TOC_LO: return "toc@l";
254  case VK_PPC_TOC_HI: return "toc@h";
255  case VK_PPC_TOC_HA: return "toc@ha";
256  case VK_PPC_DTPMOD: return "dtpmod";
257  case VK_PPC_TPREL_LO: return "tprel@l";
258  case VK_PPC_TPREL_HI: return "tprel@h";
259  case VK_PPC_TPREL_HA: return "tprel@ha";
260  case VK_PPC_TPREL_HIGH: return "tprel@high";
261  case VK_PPC_TPREL_HIGHA: return "tprel@higha";
262  case VK_PPC_TPREL_HIGHER: return "tprel@higher";
263  case VK_PPC_TPREL_HIGHERA: return "tprel@highera";
264  case VK_PPC_TPREL_HIGHEST: return "tprel@highest";
265  case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta";
266  case VK_PPC_DTPREL_LO: return "dtprel@l";
267  case VK_PPC_DTPREL_HI: return "dtprel@h";
268  case VK_PPC_DTPREL_HA: return "dtprel@ha";
269  case VK_PPC_DTPREL_HIGH: return "dtprel@high";
270  case VK_PPC_DTPREL_HIGHA: return "dtprel@higha";
271  case VK_PPC_DTPREL_HIGHER: return "dtprel@higher";
272  case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera";
273  case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest";
274  case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta";
275  case VK_PPC_GOT_TPREL: return "got@tprel";
276  case VK_PPC_GOT_TPREL_LO: return "got@tprel@l";
277  case VK_PPC_GOT_TPREL_HI: return "got@tprel@h";
278  case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha";
279  case VK_PPC_GOT_DTPREL: return "got@dtprel";
280  case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l";
281  case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h";
282  case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha";
283  case VK_PPC_TLS: return "tls";
284  case VK_PPC_GOT_TLSGD: return "got@tlsgd";
285  case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l";
286  case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h";
287  case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha";
288  case VK_PPC_TLSGD: return "tlsgd";
289  case VK_PPC_GOT_TLSLD: return "got@tlsld";
290  case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";
291  case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";
292  case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha";
293  case VK_PPC_TLSLD: return "tlsld";
294  case VK_PPC_LOCAL: return "local";
295  case VK_COFF_IMGREL32: return "IMGREL";
296  case VK_Hexagon_PCREL: return "PCREL";
297  case VK_Hexagon_LO16: return "LO16";
298  case VK_Hexagon_HI16: return "HI16";
299  case VK_Hexagon_GPREL: return "GPREL";
300  case VK_Hexagon_GD_GOT: return "GDGOT";
301  case VK_Hexagon_LD_GOT: return "LDGOT";
302  case VK_Hexagon_GD_PLT: return "GDPLT";
303  case VK_Hexagon_LD_PLT: return "LDPLT";
304  case VK_Hexagon_IE: return "IE";
305  case VK_Hexagon_IE_GOT: return "IEGOT";
306  case VK_WebAssembly_FUNCTION: return "FUNCTION";
307  case VK_WebAssembly_GLOBAL: return "GLOBAL";
308  case VK_WebAssembly_TYPEINDEX: return "TYPEINDEX";
309  case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo";
310  case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi";
311  case VK_AMDGPU_REL32_LO: return "rel32@lo";
312  case VK_AMDGPU_REL32_HI: return "rel32@hi";
313  case VK_AMDGPU_REL64: return "rel64";
314  }
315  llvm_unreachable("Invalid variant kind");
316 }
317 
318 MCSymbolRefExpr::VariantKind
319 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
320  return StringSwitch<VariantKind>(Name.lower())
321  .Case("dtprel", VK_DTPREL)
322  .Case("dtpoff", VK_DTPOFF)
323  .Case("got", VK_GOT)
324  .Case("gotoff", VK_GOTOFF)
325  .Case("gotrel", VK_GOTREL)
326  .Case("gotpcrel", VK_GOTPCREL)
327  .Case("gottpoff", VK_GOTTPOFF)
328  .Case("indntpoff", VK_INDNTPOFF)
329  .Case("ntpoff", VK_NTPOFF)
330  .Case("gotntpoff", VK_GOTNTPOFF)
331  .Case("plt", VK_PLT)
332  .Case("tlscall", VK_TLSCALL)
333  .Case("tlsdesc", VK_TLSDESC)
334  .Case("tlsgd", VK_TLSGD)
335  .Case("tlsld", VK_TLSLD)
336  .Case("tlsldm", VK_TLSLDM)
337  .Case("tpoff", VK_TPOFF)
338  .Case("tprel", VK_TPREL)
339  .Case("tlvp", VK_TLVP)
340  .Case("tlvppage", VK_TLVPPAGE)
341  .Case("tlvppageoff", VK_TLVPPAGEOFF)
342  .Case("page", VK_PAGE)
343  .Case("pageoff", VK_PAGEOFF)
344  .Case("gotpage", VK_GOTPAGE)
345  .Case("gotpageoff", VK_GOTPAGEOFF)
346  .Case("imgrel", VK_COFF_IMGREL32)
347  .Case("secrel32", VK_SECREL)
348  .Case("size", VK_SIZE)
349  .Case("abs8", VK_X86_ABS8)
350  .Case("l", VK_PPC_LO)
351  .Case("h", VK_PPC_HI)
352  .Case("ha", VK_PPC_HA)
353  .Case("high", VK_PPC_HIGH)
354  .Case("higha", VK_PPC_HIGHA)
355  .Case("higher", VK_PPC_HIGHER)
356  .Case("highera", VK_PPC_HIGHERA)
357  .Case("highest", VK_PPC_HIGHEST)
358  .Case("highesta", VK_PPC_HIGHESTA)
359  .Case("got@l", VK_PPC_GOT_LO)
360  .Case("got@h", VK_PPC_GOT_HI)
361  .Case("got@ha", VK_PPC_GOT_HA)
362  .Case("local", VK_PPC_LOCAL)
363  .Case("tocbase", VK_PPC_TOCBASE)
364  .Case("toc", VK_PPC_TOC)
365  .Case("toc@l", VK_PPC_TOC_LO)
366  .Case("toc@h", VK_PPC_TOC_HI)
367  .Case("toc@ha", VK_PPC_TOC_HA)
368  .Case("tls", VK_PPC_TLS)
369  .Case("dtpmod", VK_PPC_DTPMOD)
370  .Case("tprel@l", VK_PPC_TPREL_LO)
371  .Case("tprel@h", VK_PPC_TPREL_HI)
372  .Case("tprel@ha", VK_PPC_TPREL_HA)
373  .Case("tprel@high", VK_PPC_TPREL_HIGH)
374  .Case("tprel@higha", VK_PPC_TPREL_HIGHA)
375  .Case("tprel@higher", VK_PPC_TPREL_HIGHER)
376  .Case("tprel@highera", VK_PPC_TPREL_HIGHERA)
377  .Case("tprel@highest", VK_PPC_TPREL_HIGHEST)
378  .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA)
379  .Case("dtprel@l", VK_PPC_DTPREL_LO)
380  .Case("dtprel@h", VK_PPC_DTPREL_HI)
381  .Case("dtprel@ha", VK_PPC_DTPREL_HA)
382  .Case("dtprel@high", VK_PPC_DTPREL_HIGH)
383  .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA)
384  .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER)
385  .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA)
386  .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST)
387  .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA)
388  .Case("got@tprel", VK_PPC_GOT_TPREL)
389  .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO)
390  .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI)
391  .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA)
392  .Case("got@dtprel", VK_PPC_GOT_DTPREL)
393  .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO)
394  .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI)
395  .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA)
396  .Case("got@tlsgd", VK_PPC_GOT_TLSGD)
397  .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO)
398  .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI)
399  .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA)
400  .Case("got@tlsld", VK_PPC_GOT_TLSLD)
401  .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO)
402  .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI)
403  .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA)
404  .Case("gdgot", VK_Hexagon_GD_GOT)
405  .Case("gdplt", VK_Hexagon_GD_PLT)
406  .Case("iegot", VK_Hexagon_IE_GOT)
407  .Case("ie", VK_Hexagon_IE)
408  .Case("ldgot", VK_Hexagon_LD_GOT)
409  .Case("ldplt", VK_Hexagon_LD_PLT)
410  .Case("pcrel", VK_Hexagon_PCREL)
411  .Case("none", VK_ARM_NONE)
412  .Case("got_prel", VK_ARM_GOT_PREL)
413  .Case("target1", VK_ARM_TARGET1)
414  .Case("target2", VK_ARM_TARGET2)
415  .Case("prel31", VK_ARM_PREL31)
416  .Case("sbrel", VK_ARM_SBREL)
417  .Case("tlsldo", VK_ARM_TLSLDO)
418  .Case("lo8", VK_AVR_LO8)
419  .Case("hi8", VK_AVR_HI8)
420  .Case("hlo8", VK_AVR_HLO8)
421  .Case("function", VK_WebAssembly_FUNCTION)
422  .Case("typeindex", VK_WebAssembly_TYPEINDEX)
423  .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO)
424  .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI)
425  .Case("rel32@lo", VK_AMDGPU_REL32_LO)
426  .Case("rel32@hi", VK_AMDGPU_REL32_HI)
427  .Case("rel64", VK_AMDGPU_REL64)
428  .Default(VK_Invalid);
429 }
430 
431 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {
432  if (UseParensForSymbolVariant)
433  OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';
434  else
435  OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());
436 }
437 
438 /* *** */
439 
440 void MCTargetExpr::anchor() {}
441 
442 /* *** */
443 
444 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const {
445  return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr);
446 }
447 
448 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
449  const MCAsmLayout &Layout) const {
450  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr);
451 }
452 
453 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
454  const MCAsmLayout &Layout,
455  const SectionAddrMap &Addrs) const {
456  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
457 }
458 
459 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
460  return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr);
461 }
462 
463 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const {
464  return evaluateAsAbsolute(Res, Asm, nullptr, nullptr);
465 }
466 
467 bool MCExpr::evaluateKnownAbsolute(int64_t &Res,
468  const MCAsmLayout &Layout) const {
469  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr,
470  true);
471 }
472 
473 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
474  const MCAsmLayout *Layout,
475  const SectionAddrMap *Addrs) const {
476  // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
477  // absolutize differences across sections and that is what the MachO writer
478  // uses Addrs for.
479  return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs);
480 }
481 
482 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
483  const MCAsmLayout *Layout,
484  const SectionAddrMap *Addrs, bool InSet) const {
485  MCValue Value;
486 
487  // Fast path constants.
488  if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
489  Res = CE->getValue();
490  return true;
491  }
492 
493  bool IsRelocatable =
494  evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet);
495 
496  // Record the current value.
497  Res = Value.getConstant();
498 
499  return IsRelocatable && Value.isAbsolute();
500 }
501 
502 /// Helper method for \see EvaluateSymbolAdd().
503 static void AttemptToFoldSymbolOffsetDifference(
504  const MCAssembler *Asm, const MCAsmLayout *Layout,
505  const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A,
506  const MCSymbolRefExpr *&B, int64_t &Addend) {
507  if (!A || !B)
508  return;
509 
510  const MCSymbol &SA = A->getSymbol();
511  const MCSymbol &SB = B->getSymbol();
512 
513  if (SA.isUndefined() || SB.isUndefined())
514  return;
515 
516  if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
517  return;
518 
519  if (SA.getFragment() == SB.getFragment() && !SA.isVariable() &&
520  !SA.isUnset() && !SB.isVariable() && !SB.isUnset()) {
521  Addend += (SA.getOffset() - SB.getOffset());
522 
523  // Pointers to Thumb symbols need to have their low-bit set to allow
524  // for interworking.
525  if (Asm->isThumbFunc(&SA))
526  Addend |= 1;
527 
528  // Clear the symbol expr pointers to indicate we have folded these
529  // operands.
530  A = B = nullptr;
531  return;
532  }
533 
534  if (!Layout)
535  return;
536 
537  const MCSection &SecA = *SA.getFragment()->getParent();
538  const MCSection &SecB = *SB.getFragment()->getParent();
539 
540  if ((&SecA != &SecB) && !Addrs)
541  return;
542 
543  // Eagerly evaluate.
544  Addend += Layout->getSymbolOffset(A->getSymbol()) -
545  Layout->getSymbolOffset(B->getSymbol());
546  if (Addrs && (&SecA != &SecB))
547  Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
548 
549  // Pointers to Thumb symbols need to have their low-bit set to allow
550  // for interworking.
551  if (Asm->isThumbFunc(&SA))
552  Addend |= 1;
553 
554  // Clear the symbol expr pointers to indicate we have folded these
555  // operands.
556  A = B = nullptr;
557 }
558 
559 /// Evaluate the result of an add between (conceptually) two MCValues.
560 ///
561 /// This routine conceptually attempts to construct an MCValue:
562 /// Result = (Result_A - Result_B + Result_Cst)
563 /// from two MCValue's LHS and RHS where
564 /// Result = LHS + RHS
565 /// and
566 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
567 ///
568 /// This routine attempts to aggresively fold the operands such that the result
569 /// is representable in an MCValue, but may not always succeed.
570 ///
571 /// \returns True on success, false if the result is not representable in an
572 /// MCValue.
573 
574 /// NOTE: It is really important to have both the Asm and Layout arguments.
575 /// They might look redundant, but this function can be used before layout
576 /// is done (see the object streamer for example) and having the Asm argument
577 /// lets us avoid relaxations early.
578 static bool
579 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout,
580  const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS,
581  const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B,
582  int64_t RHS_Cst, MCValue &Res) {
583  // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
584  // about dealing with modifiers. This will ultimately bite us, one day.
585  const MCSymbolRefExpr *LHS_A = LHS.getSymA();
586  const MCSymbolRefExpr *LHS_B = LHS.getSymB();
587  int64_t LHS_Cst = LHS.getConstant();
588 
589  // Fold the result constant immediately.
590  int64_t Result_Cst = LHS_Cst + RHS_Cst;
591 
592  assert((!Layout || Asm) &&
593  "Must have an assembler object if layout is given!");
594 
595  // If we have a layout, we can fold resolved differences. Do not do this if
596  // the backend requires this to be emitted as individual relocations, unless
597  // the InSet flag is set to get the current difference anyway (used for
598  // example to calculate symbol sizes).
599  if (Asm &&
600  (InSet || !Asm->getBackend().requiresDiffExpressionRelocations())) {
601  // First, fold out any differences which are fully resolved. By
602  // reassociating terms in
603  // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
604  // we have the four possible differences:
605  // (LHS_A - LHS_B),
606  // (LHS_A - RHS_B),
607  // (RHS_A - LHS_B),
608  // (RHS_A - RHS_B).
609  // Since we are attempting to be as aggressive as possible about folding, we
610  // attempt to evaluate each possible alternative.
611  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
612  Result_Cst);
613  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
614  Result_Cst);
615  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
616  Result_Cst);
617  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
618  Result_Cst);
619  }
620 
621  // We can't represent the addition or subtraction of two symbols.
622  if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
623  return false;
624 
625  // At this point, we have at most one additive symbol and one subtractive
626  // symbol -- find them.
627  const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
628  const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
629 
630  Res = MCValue::get(A, B, Result_Cst);
631  return true;
632 }
633 
635  const MCAsmLayout *Layout,
636  const MCFixup *Fixup) const {
637  MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr;
638  return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr,
639  false);
640 }
641 
642 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const {
643  MCAssembler *Assembler = &Layout.getAssembler();
644  return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr,
645  true);
646 }
647 
648 static bool canExpand(const MCSymbol &Sym, bool InSet) {
649  const MCExpr *Expr = Sym.getVariableValue();
650  const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
651  if (Inner) {
652  if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
653  return false;
654  }
655 
656  if (InSet)
657  return true;
658  return !Sym.isInSection();
659 }
660 
662  const MCAsmLayout *Layout,
663  const MCFixup *Fixup,
664  const SectionAddrMap *Addrs,
665  bool InSet) const {
666  ++stats::MCExprEvaluate;
667 
668  switch (getKind()) {
669  case Target:
670  return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout,
671  Fixup);
672 
673  case Constant:
674  Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
675  return true;
676 
677  case SymbolRef: {
678  const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
679  const MCSymbol &Sym = SRE->getSymbol();
680 
681  // Evaluate recursively if this is a variable.
682  if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None &&
683  canExpand(Sym, InSet)) {
684  bool IsMachO = SRE->hasSubsectionsViaSymbols();
685  if (Sym.getVariableValue()->evaluateAsRelocatableImpl(
686  Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) {
687  if (!IsMachO)
688  return true;
689 
690  const MCSymbolRefExpr *A = Res.getSymA();
691  const MCSymbolRefExpr *B = Res.getSymB();
692  // FIXME: This is small hack. Given
693  // a = b + 4
694  // .long a
695  // the OS X assembler will completely drop the 4. We should probably
696  // include it in the relocation or produce an error if that is not
697  // possible.
698  // Allow constant expressions.
699  if (!A && !B)
700  return true;
701  // Allows aliases with zero offset.
702  if (Res.getConstant() == 0 && (!A || !B))
703  return true;
704  }
705  }
706 
707  Res = MCValue::get(SRE, nullptr, 0);
708  return true;
709  }
710 
711  case Unary: {
712  const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
713  MCValue Value;
714 
715  if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup,
716  Addrs, InSet))
717  return false;
718 
719  switch (AUE->getOpcode()) {
720  case MCUnaryExpr::LNot:
721  if (!Value.isAbsolute())
722  return false;
723  Res = MCValue::get(!Value.getConstant());
724  break;
725  case MCUnaryExpr::Minus:
726  /// -(a - b + const) ==> (b - a - const)
727  if (Value.getSymA() && !Value.getSymB())
728  return false;
729 
730  // The cast avoids undefined behavior if the constant is INT64_MIN.
731  Res = MCValue::get(Value.getSymB(), Value.getSymA(),
732  -(uint64_t)Value.getConstant());
733  break;
734  case MCUnaryExpr::Not:
735  if (!Value.isAbsolute())
736  return false;
737  Res = MCValue::get(~Value.getConstant());
738  break;
739  case MCUnaryExpr::Plus:
740  Res = Value;
741  break;
742  }
743 
744  return true;
745  }
746 
747  case Binary: {
748  const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
749  MCValue LHSValue, RHSValue;
750 
751  if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup,
752  Addrs, InSet) ||
753  !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup,
754  Addrs, InSet)) {
755  // Check if both are Target Expressions, see if we can compare them.
756  if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS()))
757  if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) {
758  switch (ABE->getOpcode()) {
759  case MCBinaryExpr::EQ:
760  Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0);
761  return true;
762  case MCBinaryExpr::NE:
763  Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1);
764  return true;
765  default: break;
766  }
767  }
768  return false;
769  }
770 
771  // We only support a few operations on non-constant expressions, handle
772  // those first.
773  if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
774  switch (ABE->getOpcode()) {
775  default:
776  return false;
777  case MCBinaryExpr::Sub:
778  // Negate RHS and add.
779  // The cast avoids undefined behavior if the constant is INT64_MIN.
780  return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
781  RHSValue.getSymB(), RHSValue.getSymA(),
782  -(uint64_t)RHSValue.getConstant(), Res);
783 
784  case MCBinaryExpr::Add:
785  return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
786  RHSValue.getSymA(), RHSValue.getSymB(),
787  RHSValue.getConstant(), Res);
788  }
789  }
790 
791  // FIXME: We need target hooks for the evaluation. It may be limited in
792  // width, and gas defines the result of comparisons differently from
793  // Apple as.
794  int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
795  int64_t Result = 0;
796  auto Op = ABE->getOpcode();
797  switch (Op) {
798  case MCBinaryExpr::AShr: Result = LHS >> RHS; break;
799  case MCBinaryExpr::Add: Result = LHS + RHS; break;
800  case MCBinaryExpr::And: Result = LHS & RHS; break;
801  case MCBinaryExpr::Div:
802  case MCBinaryExpr::Mod:
803  // Handle division by zero. gas just emits a warning and keeps going,
804  // we try to be stricter.
805  // FIXME: Currently the caller of this function has no way to understand
806  // we're bailing out because of 'division by zero'. Therefore, it will
807  // emit a 'expected relocatable expression' error. It would be nice to
808  // change this code to emit a better diagnostic.
809  if (RHS == 0)
810  return false;
811  if (ABE->getOpcode() == MCBinaryExpr::Div)
812  Result = LHS / RHS;
813  else
814  Result = LHS % RHS;
815  break;
816  case MCBinaryExpr::EQ: Result = LHS == RHS; break;
817  case MCBinaryExpr::GT: Result = LHS > RHS; break;
818  case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
819  case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
820  case MCBinaryExpr::LOr: Result = LHS || RHS; break;
821  case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break;
822  case MCBinaryExpr::LT: Result = LHS < RHS; break;
823  case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
824  case MCBinaryExpr::Mul: Result = LHS * RHS; break;
825  case MCBinaryExpr::NE: Result = LHS != RHS; break;
826  case MCBinaryExpr::Or: Result = LHS | RHS; break;
827  case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break;
828  case MCBinaryExpr::Sub: Result = LHS - RHS; break;
829  case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
830  }
831 
832  switch (Op) {
833  default:
834  Res = MCValue::get(Result);
835  break;
836  case MCBinaryExpr::EQ:
837  case MCBinaryExpr::GT:
838  case MCBinaryExpr::GTE:
839  case MCBinaryExpr::LT:
840  case MCBinaryExpr::LTE:
841  case MCBinaryExpr::NE:
842  // A comparison operator returns a -1 if true and 0 if false.
843  Res = MCValue::get(Result ? -1 : 0);
844  break;
845  }
846 
847  return true;
848  }
849  }
850 
851  llvm_unreachable("Invalid assembly expression kind!");
852 }
853 
855  switch (getKind()) {
856  case Target:
857  // We never look through target specific expressions.
858  return cast<MCTargetExpr>(this)->findAssociatedFragment();
859 
860  case Constant:
862 
863  case SymbolRef: {
864  const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
865  const MCSymbol &Sym = SRE->getSymbol();
866  return Sym.getFragment();
867  }
868 
869  case Unary:
870  return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment();
871 
872  case Binary: {
873  const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
874  MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment();
875  MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment();
876 
877  // If either is absolute, return the other.
879  return RHS_F;
881  return LHS_F;
882 
883  // Not always correct, but probably the best we can do without more context.
884  if (BE->getOpcode() == MCBinaryExpr::Sub)
886 
887  // Otherwise, return the first non-null fragment.
888  return LHS_F ? LHS_F : RHS_F;
889  }
890  }
891 
892  llvm_unreachable("Invalid assembly expression kind!");
893 }
Signed less than comparison (result is either 0 or some target-specific non-zero value).
Definition: MCExpr.h:429
Bitwise negation.
Definition: MCExpr.h:364
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
Signed less than or equal comparison (result is either 0 or some target-specific non-zero value)...
Definition: MCExpr.h:431
This represents an "assembler immediate".
Definition: MCValue.h:40
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:42
VariantKind getKind() const
Definition: MCExpr.h:337
Bitwise and.
Definition: MCExpr.h:420
Multiplication.
Definition: MCExpr.h:434
Opcode getOpcode() const
Get the kind of this unary expression.
Definition: MCExpr.h:403
const MCExpr * getLHS() const
Get the left-hand side expression of the binary operator.
Definition: MCExpr.h:563
Unary plus.
Definition: MCExpr.h:365
STATISTIC(NumFunctions, "Total number of functions")
Equality comparison.
Definition: MCExpr.h:422
Bitwise or.
Definition: MCExpr.h:436
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:74
int64_t getConstant() const
Definition: MCValue.h:47
const MCSymbolRefExpr * getSymB() const
Definition: MCValue.h:49
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:29
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:36
This is an extension point for target-specific MCExpr subclasses to implement.
Definition: MCExpr.h:580
bool isInSection() const
isInSection - Check if this symbol is defined in some section (i.e., it is defined but not absolute)...
Definition: MCSymbol.h:252
Represent a reference to a symbol from inside an expression.
Definition: MCExpr.h:166
Arithmetic shift right.
Definition: MCExpr.h:438
bool evaluateAsRelocatable(MCValue &Res, const MCAsmLayout *Layout, const MCFixup *Fixup) const
Try to evaluate the expression to a relocatable value, i.e.
Definition: MCExpr.cpp:634
const MCExpr * getRHS() const
Get the right-hand side expression of the binary operator.
Definition: MCExpr.h:566
Logical or.
Definition: MCExpr.h:428
Signed remainder.
Definition: MCExpr.h:433
Unary assembler expressions.
Definition: MCExpr.h:359
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:133
static bool canExpand(const MCSymbol &Sym, bool InSet)
Definition: MCExpr.cpp:648
Signed division.
Definition: MCExpr.h:421
MCAssembler & getAssembler() const
Get the assembler object this is a layout for.
Definition: MCAsmLayout.h:51
Unary expressions.
Definition: MCExpr.h:42
Shift left.
Definition: MCExpr.h:437
This class is intended to be used as a base class for asm properties and features specific to the tar...
Definition: MCAsmInfo.h:56
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
void print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens=false) const
Definition: MCExpr.cpp:42
This is an important base class in LLVM.
Definition: Constant.h:42
static bool 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)
Evaluate the result of an add between (conceptually) two MCValues.
Definition: MCExpr.cpp:579
const MCSymbolRefExpr * getSymA() const
Definition: MCValue.h:48
Logical negation.
Definition: MCExpr.h:362
Logical and.
Definition: MCExpr.h:427
Binary assembler expressions.
Definition: MCExpr.h:416
bool hasSubsectionsViaSymbols() const
Definition: MCExpr.h:341
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
static MCFragment * AbsolutePseudoFragment
Definition: MCSymbol.h:64
void printVariantKind(raw_ostream &OS) const
Definition: MCExpr.cpp:431
const MCSymbol & getSymbol() const
Definition: MCExpr.h:335
ExprKind getKind() const
Definition: MCExpr.h:73
MCFragment * getFragment(bool SetUsed=true) const
Definition: MCSymbol.h:384
bool evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, const MCAsmLayout *Layout, const MCFixup *Fixup, const SectionAddrMap *Addrs, bool InSet) const
Definition: MCExpr.cpp:661
Inequality comparison.
Definition: MCExpr.h:435
Signed greater than comparison (result is either 0 or some target-specific non-zero value) ...
Definition: MCExpr.h:423
MCFragment * findAssociatedFragment() const
Find the "associated section" for this expression, which is currently defined as the absolute section...
Definition: MCExpr.cpp:854
Signed greater than or equal comparison (result is either 0 or some target-specific non-zero value)...
Definition: MCExpr.h:425
Target - Wrapper for Target specific information.
Bitwise exclusive or.
Definition: MCExpr.h:441
Logical shift right.
Definition: MCExpr.h:439
static MCValue get(const MCSymbolRefExpr *SymA, const MCSymbolRefExpr *SymB=nullptr, int64_t Val=0, uint32_t RefKind=0)
Definition: MCValue.h:63
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
References to labels and assigned expressions.
Definition: MCExpr.h:41
Unary minus.
Definition: MCExpr.h:363
bool evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const
Try to evaluate the expression to the form (a - b + constant) where neither a nor b are variables...
Definition: MCExpr.cpp:642
Opcode getOpcode() const
Get the kind of this binary expression.
Definition: MCExpr.h:560
StringRef getName() const
getName - Get the symbol name.
Definition: MCSymbol.h:203
const MCExpr * getVariableValue(bool SetUsed=true) const
getVariableValue - Get the value for variable symbols.
Definition: MCSymbol.h:299
const MCExpr * getSubExpr() const
Get the child of this unary expression.
Definition: MCExpr.h:406
LLVM Value Representation.
Definition: Value.h:73
Constant expressions.
Definition: MCExpr.h:40
Binary expressions.
Definition: MCExpr.h:39
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:46
Subtraction.
Definition: MCExpr.h:440
Target specific expression.
Definition: MCExpr.h:43
void print(raw_ostream &OS, const MCAsmInfo *MAI) const
print - Print the value to the stream OS.
Definition: MCSymbol.cpp:60