LLVM  7.0.0svn
MCExpr.cpp
Go to the documentation of this file.
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_TYPEINDEX: return "TYPEINDEX";
308  case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo";
309  case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi";
310  case VK_AMDGPU_REL32_LO: return "rel32@lo";
311  case VK_AMDGPU_REL32_HI: return "rel32@hi";
312  case VK_AMDGPU_REL64: return "rel64";
313  }
314  llvm_unreachable("Invalid variant kind");
315 }
316 
317 MCSymbolRefExpr::VariantKind
318 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
319  return StringSwitch<VariantKind>(Name.lower())
320  .Case("dtprel", VK_DTPREL)
321  .Case("dtpoff", VK_DTPOFF)
322  .Case("got", VK_GOT)
323  .Case("gotoff", VK_GOTOFF)
324  .Case("gotrel", VK_GOTREL)
325  .Case("gotpcrel", VK_GOTPCREL)
326  .Case("gottpoff", VK_GOTTPOFF)
327  .Case("indntpoff", VK_INDNTPOFF)
328  .Case("ntpoff", VK_NTPOFF)
329  .Case("gotntpoff", VK_GOTNTPOFF)
330  .Case("plt", VK_PLT)
331  .Case("tlscall", VK_TLSCALL)
332  .Case("tlsdesc", VK_TLSDESC)
333  .Case("tlsgd", VK_TLSGD)
334  .Case("tlsld", VK_TLSLD)
335  .Case("tlsldm", VK_TLSLDM)
336  .Case("tpoff", VK_TPOFF)
337  .Case("tprel", VK_TPREL)
338  .Case("tlvp", VK_TLVP)
339  .Case("tlvppage", VK_TLVPPAGE)
340  .Case("tlvppageoff", VK_TLVPPAGEOFF)
341  .Case("page", VK_PAGE)
342  .Case("pageoff", VK_PAGEOFF)
343  .Case("gotpage", VK_GOTPAGE)
344  .Case("gotpageoff", VK_GOTPAGEOFF)
345  .Case("imgrel", VK_COFF_IMGREL32)
346  .Case("secrel32", VK_SECREL)
347  .Case("size", VK_SIZE)
348  .Case("abs8", VK_X86_ABS8)
349  .Case("l", VK_PPC_LO)
350  .Case("h", VK_PPC_HI)
351  .Case("ha", VK_PPC_HA)
352  .Case("high", VK_PPC_HIGH)
353  .Case("higha", VK_PPC_HIGHA)
354  .Case("higher", VK_PPC_HIGHER)
355  .Case("highera", VK_PPC_HIGHERA)
356  .Case("highest", VK_PPC_HIGHEST)
357  .Case("highesta", VK_PPC_HIGHESTA)
358  .Case("got@l", VK_PPC_GOT_LO)
359  .Case("got@h", VK_PPC_GOT_HI)
360  .Case("got@ha", VK_PPC_GOT_HA)
361  .Case("local", VK_PPC_LOCAL)
362  .Case("tocbase", VK_PPC_TOCBASE)
363  .Case("toc", VK_PPC_TOC)
364  .Case("toc@l", VK_PPC_TOC_LO)
365  .Case("toc@h", VK_PPC_TOC_HI)
366  .Case("toc@ha", VK_PPC_TOC_HA)
367  .Case("tls", VK_PPC_TLS)
368  .Case("dtpmod", VK_PPC_DTPMOD)
369  .Case("tprel@l", VK_PPC_TPREL_LO)
370  .Case("tprel@h", VK_PPC_TPREL_HI)
371  .Case("tprel@ha", VK_PPC_TPREL_HA)
372  .Case("tprel@high", VK_PPC_TPREL_HIGH)
373  .Case("tprel@higha", VK_PPC_TPREL_HIGHA)
374  .Case("tprel@higher", VK_PPC_TPREL_HIGHER)
375  .Case("tprel@highera", VK_PPC_TPREL_HIGHERA)
376  .Case("tprel@highest", VK_PPC_TPREL_HIGHEST)
377  .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA)
378  .Case("dtprel@l", VK_PPC_DTPREL_LO)
379  .Case("dtprel@h", VK_PPC_DTPREL_HI)
380  .Case("dtprel@ha", VK_PPC_DTPREL_HA)
381  .Case("dtprel@high", VK_PPC_DTPREL_HIGH)
382  .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA)
383  .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER)
384  .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA)
385  .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST)
386  .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA)
387  .Case("got@tprel", VK_PPC_GOT_TPREL)
388  .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO)
389  .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI)
390  .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA)
391  .Case("got@dtprel", VK_PPC_GOT_DTPREL)
392  .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO)
393  .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI)
394  .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA)
395  .Case("got@tlsgd", VK_PPC_GOT_TLSGD)
396  .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO)
397  .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI)
398  .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA)
399  .Case("got@tlsld", VK_PPC_GOT_TLSLD)
400  .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO)
401  .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI)
402  .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA)
403  .Case("gdgot", VK_Hexagon_GD_GOT)
404  .Case("gdplt", VK_Hexagon_GD_PLT)
405  .Case("iegot", VK_Hexagon_IE_GOT)
406  .Case("ie", VK_Hexagon_IE)
407  .Case("ldgot", VK_Hexagon_LD_GOT)
408  .Case("ldplt", VK_Hexagon_LD_PLT)
409  .Case("pcrel", VK_Hexagon_PCREL)
410  .Case("none", VK_ARM_NONE)
411  .Case("got_prel", VK_ARM_GOT_PREL)
412  .Case("target1", VK_ARM_TARGET1)
413  .Case("target2", VK_ARM_TARGET2)
414  .Case("prel31", VK_ARM_PREL31)
415  .Case("sbrel", VK_ARM_SBREL)
416  .Case("tlsldo", VK_ARM_TLSLDO)
417  .Case("lo8", VK_AVR_LO8)
418  .Case("hi8", VK_AVR_HI8)
419  .Case("hlo8", VK_AVR_HLO8)
420  .Case("function", VK_WebAssembly_FUNCTION)
421  .Case("typeindex", VK_WebAssembly_TYPEINDEX)
422  .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO)
423  .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI)
424  .Case("rel32@lo", VK_AMDGPU_REL32_LO)
425  .Case("rel32@hi", VK_AMDGPU_REL32_HI)
426  .Case("rel64", VK_AMDGPU_REL64)
427  .Default(VK_Invalid);
428 }
429 
430 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {
431  if (UseParensForSymbolVariant)
432  OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';
433  else
434  OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());
435 }
436 
437 /* *** */
438 
439 void MCTargetExpr::anchor() {}
440 
441 /* *** */
442 
443 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const {
444  return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr);
445 }
446 
447 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
448  const MCAsmLayout &Layout) const {
449  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr);
450 }
451 
452 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
453  const MCAsmLayout &Layout,
454  const SectionAddrMap &Addrs) const {
455  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
456 }
457 
458 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
459  return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr);
460 }
461 
462 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const {
463  return evaluateAsAbsolute(Res, Asm, nullptr, nullptr);
464 }
465 
466 bool MCExpr::evaluateKnownAbsolute(int64_t &Res,
467  const MCAsmLayout &Layout) const {
468  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr,
469  true);
470 }
471 
472 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
473  const MCAsmLayout *Layout,
474  const SectionAddrMap *Addrs) const {
475  // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
476  // absolutize differences across sections and that is what the MachO writer
477  // uses Addrs for.
478  return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs);
479 }
480 
481 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
482  const MCAsmLayout *Layout,
483  const SectionAddrMap *Addrs, bool InSet) const {
484  MCValue Value;
485 
486  // Fast path constants.
487  if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
488  Res = CE->getValue();
489  return true;
490  }
491 
492  bool IsRelocatable =
493  evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet);
494 
495  // Record the current value.
496  Res = Value.getConstant();
497 
498  return IsRelocatable && Value.isAbsolute();
499 }
500 
501 /// Helper method for \see EvaluateSymbolAdd().
502 static void AttemptToFoldSymbolOffsetDifference(
503  const MCAssembler *Asm, const MCAsmLayout *Layout,
504  const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A,
505  const MCSymbolRefExpr *&B, int64_t &Addend) {
506  if (!A || !B)
507  return;
508 
509  const MCSymbol &SA = A->getSymbol();
510  const MCSymbol &SB = B->getSymbol();
511 
512  if (SA.isUndefined() || SB.isUndefined())
513  return;
514 
515  if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
516  return;
517 
518  if (SA.getFragment() == SB.getFragment() && !SA.isVariable() &&
519  !SA.isUnset() && !SB.isVariable() && !SB.isUnset()) {
520  Addend += (SA.getOffset() - SB.getOffset());
521 
522  // Pointers to Thumb symbols need to have their low-bit set to allow
523  // for interworking.
524  if (Asm->isThumbFunc(&SA))
525  Addend |= 1;
526 
527  // Clear the symbol expr pointers to indicate we have folded these
528  // operands.
529  A = B = nullptr;
530  return;
531  }
532 
533  if (!Layout)
534  return;
535 
536  const MCSection &SecA = *SA.getFragment()->getParent();
537  const MCSection &SecB = *SB.getFragment()->getParent();
538 
539  if ((&SecA != &SecB) && !Addrs)
540  return;
541 
542  // Eagerly evaluate.
543  Addend += Layout->getSymbolOffset(A->getSymbol()) -
544  Layout->getSymbolOffset(B->getSymbol());
545  if (Addrs && (&SecA != &SecB))
546  Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
547 
548  // Pointers to Thumb symbols need to have their low-bit set to allow
549  // for interworking.
550  if (Asm->isThumbFunc(&SA))
551  Addend |= 1;
552 
553  // Clear the symbol expr pointers to indicate we have folded these
554  // operands.
555  A = B = nullptr;
556 }
557 
558 /// Evaluate the result of an add between (conceptually) two MCValues.
559 ///
560 /// This routine conceptually attempts to construct an MCValue:
561 /// Result = (Result_A - Result_B + Result_Cst)
562 /// from two MCValue's LHS and RHS where
563 /// Result = LHS + RHS
564 /// and
565 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
566 ///
567 /// This routine attempts to aggresively fold the operands such that the result
568 /// is representable in an MCValue, but may not always succeed.
569 ///
570 /// \returns True on success, false if the result is not representable in an
571 /// MCValue.
572 
573 /// NOTE: It is really important to have both the Asm and Layout arguments.
574 /// They might look redundant, but this function can be used before layout
575 /// is done (see the object streamer for example) and having the Asm argument
576 /// lets us avoid relaxations early.
577 static bool
578 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout,
579  const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS,
580  const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B,
581  int64_t RHS_Cst, MCValue &Res) {
582  // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
583  // about dealing with modifiers. This will ultimately bite us, one day.
584  const MCSymbolRefExpr *LHS_A = LHS.getSymA();
585  const MCSymbolRefExpr *LHS_B = LHS.getSymB();
586  int64_t LHS_Cst = LHS.getConstant();
587 
588  // Fold the result constant immediately.
589  int64_t Result_Cst = LHS_Cst + RHS_Cst;
590 
591  assert((!Layout || Asm) &&
592  "Must have an assembler object if layout is given!");
593 
594  // If we have a layout, we can fold resolved differences. Do not do this if
595  // the backend requires this to be emitted as individual relocations, unless
596  // the InSet flag is set to get the current difference anyway (used for
597  // example to calculate symbol sizes).
598  if (Asm &&
599  (InSet || !Asm->getBackend().requiresDiffExpressionRelocations())) {
600  // First, fold out any differences which are fully resolved. By
601  // reassociating terms in
602  // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
603  // we have the four possible differences:
604  // (LHS_A - LHS_B),
605  // (LHS_A - RHS_B),
606  // (RHS_A - LHS_B),
607  // (RHS_A - RHS_B).
608  // Since we are attempting to be as aggressive as possible about folding, we
609  // attempt to evaluate each possible alternative.
610  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
611  Result_Cst);
612  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
613  Result_Cst);
614  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
615  Result_Cst);
616  AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
617  Result_Cst);
618  }
619 
620  // We can't represent the addition or subtraction of two symbols.
621  if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
622  return false;
623 
624  // At this point, we have at most one additive symbol and one subtractive
625  // symbol -- find them.
626  const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
627  const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
628 
629  Res = MCValue::get(A, B, Result_Cst);
630  return true;
631 }
632 
634  const MCAsmLayout *Layout,
635  const MCFixup *Fixup) const {
636  MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr;
637  return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr,
638  false);
639 }
640 
641 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const {
642  MCAssembler *Assembler = &Layout.getAssembler();
643  return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr,
644  true);
645 }
646 
647 static bool canExpand(const MCSymbol &Sym, bool InSet) {
648  const MCExpr *Expr = Sym.getVariableValue();
649  const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
650  if (Inner) {
651  if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
652  return false;
653  }
654 
655  if (InSet)
656  return true;
657  return !Sym.isInSection();
658 }
659 
661  const MCAsmLayout *Layout,
662  const MCFixup *Fixup,
663  const SectionAddrMap *Addrs,
664  bool InSet) const {
665  ++stats::MCExprEvaluate;
666 
667  switch (getKind()) {
668  case Target:
669  return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout,
670  Fixup);
671 
672  case Constant:
673  Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
674  return true;
675 
676  case SymbolRef: {
677  const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
678  const MCSymbol &Sym = SRE->getSymbol();
679 
680  // Evaluate recursively if this is a variable.
681  if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None &&
682  canExpand(Sym, InSet)) {
683  bool IsMachO = SRE->hasSubsectionsViaSymbols();
684  if (Sym.getVariableValue()->evaluateAsRelocatableImpl(
685  Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) {
686  if (!IsMachO)
687  return true;
688 
689  const MCSymbolRefExpr *A = Res.getSymA();
690  const MCSymbolRefExpr *B = Res.getSymB();
691  // FIXME: This is small hack. Given
692  // a = b + 4
693  // .long a
694  // the OS X assembler will completely drop the 4. We should probably
695  // include it in the relocation or produce an error if that is not
696  // possible.
697  // Allow constant expressions.
698  if (!A && !B)
699  return true;
700  // Allows aliases with zero offset.
701  if (Res.getConstant() == 0 && (!A || !B))
702  return true;
703  }
704  }
705 
706  Res = MCValue::get(SRE, nullptr, 0);
707  return true;
708  }
709 
710  case Unary: {
711  const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
712  MCValue Value;
713 
714  if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup,
715  Addrs, InSet))
716  return false;
717 
718  switch (AUE->getOpcode()) {
719  case MCUnaryExpr::LNot:
720  if (!Value.isAbsolute())
721  return false;
722  Res = MCValue::get(!Value.getConstant());
723  break;
724  case MCUnaryExpr::Minus:
725  /// -(a - b + const) ==> (b - a - const)
726  if (Value.getSymA() && !Value.getSymB())
727  return false;
728 
729  // The cast avoids undefined behavior if the constant is INT64_MIN.
730  Res = MCValue::get(Value.getSymB(), Value.getSymA(),
731  -(uint64_t)Value.getConstant());
732  break;
733  case MCUnaryExpr::Not:
734  if (!Value.isAbsolute())
735  return false;
736  Res = MCValue::get(~Value.getConstant());
737  break;
738  case MCUnaryExpr::Plus:
739  Res = Value;
740  break;
741  }
742 
743  return true;
744  }
745 
746  case Binary: {
747  const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
748  MCValue LHSValue, RHSValue;
749 
750  if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup,
751  Addrs, InSet) ||
752  !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup,
753  Addrs, InSet))
754  return false;
755 
756  // We only support a few operations on non-constant expressions, handle
757  // those first.
758  if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
759  switch (ABE->getOpcode()) {
760  default:
761  return false;
762  case MCBinaryExpr::Sub:
763  // Negate RHS and add.
764  // The cast avoids undefined behavior if the constant is INT64_MIN.
765  return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
766  RHSValue.getSymB(), RHSValue.getSymA(),
767  -(uint64_t)RHSValue.getConstant(), Res);
768 
769  case MCBinaryExpr::Add:
770  return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
771  RHSValue.getSymA(), RHSValue.getSymB(),
772  RHSValue.getConstant(), Res);
773  }
774  }
775 
776  // FIXME: We need target hooks for the evaluation. It may be limited in
777  // width, and gas defines the result of comparisons differently from
778  // Apple as.
779  int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
780  int64_t Result = 0;
781  auto Op = ABE->getOpcode();
782  switch (Op) {
783  case MCBinaryExpr::AShr: Result = LHS >> RHS; break;
784  case MCBinaryExpr::Add: Result = LHS + RHS; break;
785  case MCBinaryExpr::And: Result = LHS & RHS; break;
786  case MCBinaryExpr::Div:
787  case MCBinaryExpr::Mod:
788  // Handle division by zero. gas just emits a warning and keeps going,
789  // we try to be stricter.
790  // FIXME: Currently the caller of this function has no way to understand
791  // we're bailing out because of 'division by zero'. Therefore, it will
792  // emit a 'expected relocatable expression' error. It would be nice to
793  // change this code to emit a better diagnostic.
794  if (RHS == 0)
795  return false;
796  if (ABE->getOpcode() == MCBinaryExpr::Div)
797  Result = LHS / RHS;
798  else
799  Result = LHS % RHS;
800  break;
801  case MCBinaryExpr::EQ: Result = LHS == RHS; break;
802  case MCBinaryExpr::GT: Result = LHS > RHS; break;
803  case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
804  case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
805  case MCBinaryExpr::LOr: Result = LHS || RHS; break;
806  case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break;
807  case MCBinaryExpr::LT: Result = LHS < RHS; break;
808  case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
809  case MCBinaryExpr::Mul: Result = LHS * RHS; break;
810  case MCBinaryExpr::NE: Result = LHS != RHS; break;
811  case MCBinaryExpr::Or: Result = LHS | RHS; break;
812  case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break;
813  case MCBinaryExpr::Sub: Result = LHS - RHS; break;
814  case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
815  }
816 
817  switch (Op) {
818  default:
819  Res = MCValue::get(Result);
820  break;
821  case MCBinaryExpr::EQ:
822  case MCBinaryExpr::GT:
823  case MCBinaryExpr::GTE:
824  case MCBinaryExpr::LT:
825  case MCBinaryExpr::LTE:
826  case MCBinaryExpr::NE:
827  // A comparison operator returns a -1 if true and 0 if false.
828  Res = MCValue::get(Result ? -1 : 0);
829  break;
830  }
831 
832  return true;
833  }
834  }
835 
836  llvm_unreachable("Invalid assembly expression kind!");
837 }
838 
840  switch (getKind()) {
841  case Target:
842  // We never look through target specific expressions.
843  return cast<MCTargetExpr>(this)->findAssociatedFragment();
844 
845  case Constant:
847 
848  case SymbolRef: {
849  const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
850  const MCSymbol &Sym = SRE->getSymbol();
851  return Sym.getFragment();
852  }
853 
854  case Unary:
855  return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment();
856 
857  case Binary: {
858  const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
859  MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment();
860  MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment();
861 
862  // If either is absolute, return the other.
864  return RHS_F;
866  return LHS_F;
867 
868  // Not always correct, but probably the best we can do without more context.
869  if (BE->getOpcode() == MCBinaryExpr::Sub)
871 
872  // Otherwise, return the first non-null fragment.
873  return LHS_F ? LHS_F : RHS_F;
874  }
875  }
876 
877  llvm_unreachable("Invalid assembly expression kind!");
878 }
Signed less than comparison (result is either 0 or some target-specific non-zero value).
Definition: MCExpr.h:428
Bitwise negation.
Definition: MCExpr.h:363
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:430
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:336
Bitwise and.
Definition: MCExpr.h:419
Multiplication.
Definition: MCExpr.h:433
Opcode getOpcode() const
Get the kind of this unary expression.
Definition: MCExpr.h:402
const MCExpr * getLHS() const
Get the left-hand side expression of the binary operator.
Definition: MCExpr.h:562
Unary plus.
Definition: MCExpr.h:364
STATISTIC(NumFunctions, "Total number of functions")
Equality comparison.
Definition: MCExpr.h:421
Bitwise or.
Definition: MCExpr.h:435
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
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:437
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:633
const MCExpr * getRHS() const
Get the right-hand side expression of the binary operator.
Definition: MCExpr.h:565
Logical or.
Definition: MCExpr.h:427
Signed remainder.
Definition: MCExpr.h:432
Unary assembler expressions.
Definition: MCExpr.h:358
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:647
Signed division.
Definition: MCExpr.h:420
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:436
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:578
const MCSymbolRefExpr * getSymA() const
Definition: MCValue.h:48
Logical negation.
Definition: MCExpr.h:361
Logical and.
Definition: MCExpr.h:426
Binary assembler expressions.
Definition: MCExpr.h:415
bool hasSubsectionsViaSymbols() const
Definition: MCExpr.h:340
#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:430
const MCSymbol & getSymbol() const
Definition: MCExpr.h:334
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:660
Inequality comparison.
Definition: MCExpr.h:434
Signed greater than comparison (result is either 0 or some target-specific non-zero value) ...
Definition: MCExpr.h:422
MCFragment * findAssociatedFragment() const
Find the "associated section" for this expression, which is currently defined as the absolute section...
Definition: MCExpr.cpp:839
Signed greater than or equal comparison (result is either 0 or some target-specific non-zero value)...
Definition: MCExpr.h:424
Target - Wrapper for Target specific information.
Bitwise exclusive or.
Definition: MCExpr.h:440
Logical shift right.
Definition: MCExpr.h:438
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:362
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:641
Opcode getOpcode() const
Get the kind of this binary expression.
Definition: MCExpr.h:559
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:405
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:439
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