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/StringSwitch.h"
12 #include "llvm/MC/MCAsmInfo.h"
13 #include "llvm/MC/MCAsmLayout.h"
14 #include "llvm/MC/MCAssembler.h"
15 #include "llvm/MC/MCContext.h"
16 #include "llvm/MC/MCObjectWriter.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MCValue.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/raw_ostream.h"
22 using namespace llvm;
23
24 #define DEBUG_TYPE "mcexpr"
25
26
print(raw_ostream & OS,const MCAsmInfo * MAI) const27 void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI) const {
28 switch (getKind()) {
29 case MCExpr::Target:
30 return cast<MCTargetExpr>(this)->printImpl(OS, MAI);
31 case MCExpr::Constant:
32 OS << cast<MCConstantExpr>(*this).getValue();
33 return;
34
35 case MCExpr::SymbolRef: {
36 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
37 const MCSymbol &Sym = SRE.getSymbol();
38 // Parenthesize names that start with $ so that they don't look like
39 // absolute names.
40 bool UseParens = Sym.getName().size() && Sym.getName()[0] == '$';
41 if (UseParens) {
42 OS << '(';
43 Sym.print(OS, MAI);
44 OS << ')';
45 } else
46 Sym.print(OS, MAI);
47
48 if (SRE.getKind() != MCSymbolRefExpr::VK_None)
49 SRE.printVariantKind(OS);
50
51 return;
52 }
53
54 case MCExpr::Unary: {
55 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
56 switch (UE.getOpcode()) {
57 case MCUnaryExpr::LNot: OS << '!'; break;
58 case MCUnaryExpr::Minus: OS << '-'; break;
59 case MCUnaryExpr::Not: OS << '~'; break;
60 case MCUnaryExpr::Plus: OS << '+'; break;
61 }
62 UE.getSubExpr()->print(OS, MAI);
63 return;
64 }
65
66 case MCExpr::Binary: {
67 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
68
69 // Only print parens around the LHS if it is non-trivial.
70 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
71 BE.getLHS()->print(OS, MAI);
72 } else {
73 OS << '(';
74 BE.getLHS()->print(OS, MAI);
75 OS << ')';
76 }
77
78 switch (BE.getOpcode()) {
79 case MCBinaryExpr::Add:
80 // Print "X-42" instead of "X+-42".
81 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
82 if (RHSC->getValue() < 0) {
83 OS << RHSC->getValue();
84 return;
85 }
86 }
87
88 OS << '+';
89 break;
90 case MCBinaryExpr::AShr: OS << ">>"; break;
91 case MCBinaryExpr::And: OS << '&'; break;
92 case MCBinaryExpr::Div: OS << '/'; break;
93 case MCBinaryExpr::EQ: OS << "=="; break;
94 case MCBinaryExpr::GT: OS << '>'; break;
95 case MCBinaryExpr::GTE: OS << ">="; break;
96 case MCBinaryExpr::LAnd: OS << "&&"; break;
97 case MCBinaryExpr::LOr: OS << "||"; break;
98 case MCBinaryExpr::LShr: OS << ">>"; break;
99 case MCBinaryExpr::LT: OS << '<'; break;
100 case MCBinaryExpr::LTE: OS << "<="; break;
101 case MCBinaryExpr::Mod: OS << '%'; break;
102 case MCBinaryExpr::Mul: OS << '*'; break;
103 case MCBinaryExpr::NE: OS << "!="; break;
104 case MCBinaryExpr::Or: OS << '|'; break;
105 case MCBinaryExpr::Shl: OS << "<<"; break;
106 case MCBinaryExpr::Sub: OS << '-'; break;
107 case MCBinaryExpr::Xor: OS << '^'; break;
108 }
109
110 // Only print parens around the LHS if it is non-trivial.
111 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
112 BE.getRHS()->print(OS, MAI);
113 } else {
114 OS << '(';
115 BE.getRHS()->print(OS, MAI);
116 OS << ')';
117 }
118 return;
119 }
120 }
121
122 llvm_unreachable("Invalid expression kind!");
123 }
124
125 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
dump() const126 LLVM_DUMP_METHOD void MCExpr::dump() const {
127 }
128 #endif
129
130 /* *** */
131
create(Opcode Opc,const MCExpr * LHS,const MCExpr * RHS,MCContext & Ctx)132 const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS,
133 const MCExpr *RHS, MCContext &Ctx) {
134 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
135 }
136
create(Opcode Opc,const MCExpr * Expr,MCContext & Ctx)137 const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr,
138 MCContext &Ctx) {
139 return new (Ctx) MCUnaryExpr(Opc, Expr);
140 }
141
create(int64_t Value,MCContext & Ctx)142 const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx) {
143 return new (Ctx) MCConstantExpr(Value);
144 }
145
146 /* *** */
147
MCSymbolRefExpr(const MCSymbol * Symbol,VariantKind Kind,const MCAsmInfo * MAI)148 MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,
149 const MCAsmInfo *MAI)
150 : MCExpr(MCExpr::SymbolRef), Kind(Kind),
151 UseParensForSymbolVariant(MAI->useParensForSymbolVariant()),
152 HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()),
153 Symbol(Symbol) {
154 assert(Symbol);
155 }
156
create(const MCSymbol * Sym,VariantKind Kind,MCContext & Ctx)157 const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym,
158 VariantKind Kind,
159 MCContext &Ctx) {
160 return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo());
161 }
162
create(StringRef Name,VariantKind Kind,MCContext & Ctx)163 const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind,
164 MCContext &Ctx) {
165 return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx);
166 }
167
getVariantKindName(VariantKind Kind)168 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
169 switch (Kind) {
170 case VK_Invalid: return "<<invalid>>";
171 case VK_None: return "<<none>>";
172
173 case VK_GOT: return "GOT";
174 case VK_GOTOFF: return "GOTOFF";
175 case VK_GOTPCREL: return "GOTPCREL";
176 case VK_GOTTPOFF: return "GOTTPOFF";
177 case VK_INDNTPOFF: return "INDNTPOFF";
178 case VK_NTPOFF: return "NTPOFF";
179 case VK_GOTNTPOFF: return "GOTNTPOFF";
180 case VK_PLT: return "PLT";
181 case VK_TLSGD: return "TLSGD";
182 case VK_TLSLD: return "TLSLD";
183 case VK_TLSLDM: return "TLSLDM";
184 case VK_TPOFF: return "TPOFF";
185 case VK_DTPOFF: return "DTPOFF";
186 case VK_TLVP: return "TLVP";
187 case VK_TLVPPAGE: return "TLVPPAGE";
188 case VK_TLVPPAGEOFF: return "TLVPPAGEOFF";
189 case VK_PAGE: return "PAGE";
190 case VK_PAGEOFF: return "PAGEOFF";
191 case VK_GOTPAGE: return "GOTPAGE";
192 case VK_GOTPAGEOFF: return "GOTPAGEOFF";
193 case VK_SECREL: return "SECREL32";
194 case VK_SIZE: return "SIZE";
195 case VK_WEAKREF: return "WEAKREF";
196 case VK_ARM_NONE: return "none";
197 case VK_ARM_GOT_PREL: return "GOT_PREL";
198 case VK_ARM_TARGET1: return "target1";
199 case VK_ARM_TARGET2: return "target2";
200 case VK_ARM_PREL31: return "prel31";
201 case VK_ARM_SBREL: return "sbrel";
202 case VK_ARM_TLSLDO: return "tlsldo";
203 case VK_ARM_TLSCALL: return "tlscall";
204 case VK_ARM_TLSDESC: return "tlsdesc";
205 case VK_ARM_TLSDESCSEQ: return "tlsdescseq";
206 case VK_PPC_LO: return "l";
207 case VK_PPC_HI: return "h";
208 case VK_PPC_HA: return "ha";
209 case VK_PPC_HIGHER: return "higher";
210 case VK_PPC_HIGHERA: return "highera";
211 case VK_PPC_HIGHEST: return "highest";
212 case VK_PPC_HIGHESTA: return "highesta";
213 case VK_PPC_GOT_LO: return "got@l";
214 case VK_PPC_GOT_HI: return "got@h";
215 case VK_PPC_GOT_HA: return "got@ha";
216 case VK_PPC_TOCBASE: return "tocbase";
217 case VK_PPC_TOC: return "toc";
218 case VK_PPC_TOC_LO: return "toc@l";
219 case VK_PPC_TOC_HI: return "toc@h";
220 case VK_PPC_TOC_HA: return "toc@ha";
221 case VK_PPC_DTPMOD: return "dtpmod";
222 case VK_PPC_TPREL: return "tprel";
223 case VK_PPC_TPREL_LO: return "tprel@l";
224 case VK_PPC_TPREL_HI: return "tprel@h";
225 case VK_PPC_TPREL_HA: return "tprel@ha";
226 case VK_PPC_TPREL_HIGHER: return "tprel@higher";
227 case VK_PPC_TPREL_HIGHERA: return "tprel@highera";
228 case VK_PPC_TPREL_HIGHEST: return "tprel@highest";
229 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta";
230 case VK_PPC_DTPREL: return "dtprel";
231 case VK_PPC_DTPREL_LO: return "dtprel@l";
232 case VK_PPC_DTPREL_HI: return "dtprel@h";
233 case VK_PPC_DTPREL_HA: return "dtprel@ha";
234 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher";
235 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera";
236 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest";
237 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta";
238 case VK_PPC_GOT_TPREL: return "got@tprel";
239 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l";
240 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h";
241 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha";
242 case VK_PPC_GOT_DTPREL: return "got@dtprel";
243 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l";
244 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h";
245 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha";
246 case VK_PPC_TLS: return "tls";
247 case VK_PPC_GOT_TLSGD: return "got@tlsgd";
248 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l";
249 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h";
250 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha";
251 case VK_PPC_TLSGD: return "tlsgd";
252 case VK_PPC_GOT_TLSLD: return "got@tlsld";
253 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";
254 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";
255 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha";
256 case VK_PPC_TLSLD: return "tlsld";
257 case VK_PPC_LOCAL: return "local";
258 case VK_Mips_GPREL: return "GPREL";
259 case VK_Mips_GOT_CALL: return "GOT_CALL";
260 case VK_Mips_GOT16: return "GOT16";
261 case VK_Mips_GOT: return "GOT";
262 case VK_Mips_ABS_HI: return "ABS_HI";
263 case VK_Mips_ABS_LO: return "ABS_LO";
264 case VK_Mips_TLSGD: return "TLSGD";
265 case VK_Mips_TLSLDM: return "TLSLDM";
266 case VK_Mips_DTPREL_HI: return "DTPREL_HI";
267 case VK_Mips_DTPREL_LO: return "DTPREL_LO";
268 case VK_Mips_GOTTPREL: return "GOTTPREL";
269 case VK_Mips_TPREL_HI: return "TPREL_HI";
270 case VK_Mips_TPREL_LO: return "TPREL_LO";
271 case VK_Mips_GPOFF_HI: return "GPOFF_HI";
272 case VK_Mips_GPOFF_LO: return "GPOFF_LO";
273 case VK_Mips_GOT_DISP: return "GOT_DISP";
274 case VK_Mips_GOT_PAGE: return "GOT_PAGE";
275 case VK_Mips_GOT_OFST: return "GOT_OFST";
276 case VK_Mips_HIGHER: return "HIGHER";
277 case VK_Mips_HIGHEST: return "HIGHEST";
278 case VK_Mips_GOT_HI16: return "GOT_HI16";
279 case VK_Mips_GOT_LO16: return "GOT_LO16";
280 case VK_Mips_CALL_HI16: return "CALL_HI16";
281 case VK_Mips_CALL_LO16: return "CALL_LO16";
282 case VK_Mips_PCREL_HI16: return "PCREL_HI16";
283 case VK_Mips_PCREL_LO16: return "PCREL_LO16";
284 case VK_COFF_IMGREL32: return "IMGREL";
285 case VK_Hexagon_PCREL: return "PCREL";
286 case VK_Hexagon_LO16: return "LO16";
287 case VK_Hexagon_HI16: return "HI16";
288 case VK_Hexagon_GPREL: return "GPREL";
289 case VK_Hexagon_GD_GOT: return "GDGOT";
290 case VK_Hexagon_LD_GOT: return "LDGOT";
291 case VK_Hexagon_GD_PLT: return "GDPLT";
292 case VK_Hexagon_LD_PLT: return "LDPLT";
293 case VK_Hexagon_IE: return "IE";
294 case VK_Hexagon_IE_GOT: return "IEGOT";
295 case VK_WebAssembly_FUNCTION: return "FUNCTION";
296 case VK_TPREL: return "tprel";
297 case VK_DTPREL: return "dtprel";
298 }
299 llvm_unreachable("Invalid variant kind");
300 }
301
302 MCSymbolRefExpr::VariantKind
getVariantKindForName(StringRef Name)303 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
304 return StringSwitch<VariantKind>(Name.lower())
305 .Case("got", VK_GOT)
306 .Case("gotoff", VK_GOTOFF)
307 .Case("gotpcrel", VK_GOTPCREL)
308 .Case("gottpoff", VK_GOTTPOFF)
309 .Case("indntpoff", VK_INDNTPOFF)
310 .Case("ntpoff", VK_NTPOFF)
311 .Case("gotntpoff", VK_GOTNTPOFF)
312 .Case("plt", VK_PLT)
313 .Case("tlsgd", VK_TLSGD)
314 .Case("tlsld", VK_TLSLD)
315 .Case("tlsldm", VK_TLSLDM)
316 .Case("tpoff", VK_TPOFF)
317 .Case("dtpoff", VK_DTPOFF)
318 .Case("tlvp", VK_TLVP)
319 .Case("tlvppage", VK_TLVPPAGE)
320 .Case("tlvppageoff", VK_TLVPPAGEOFF)
321 .Case("page", VK_PAGE)
322 .Case("pageoff", VK_PAGEOFF)
323 .Case("gotpage", VK_GOTPAGE)
324 .Case("gotpageoff", VK_GOTPAGEOFF)
325 .Case("imgrel", VK_COFF_IMGREL32)
326 .Case("secrel32", VK_SECREL)
327 .Case("size", VK_SIZE)
328 .Case("l", VK_PPC_LO)
329 .Case("h", VK_PPC_HI)
330 .Case("ha", VK_PPC_HA)
331 .Case("higher", VK_PPC_HIGHER)
332 .Case("highera", VK_PPC_HIGHERA)
333 .Case("highest", VK_PPC_HIGHEST)
334 .Case("highesta", VK_PPC_HIGHESTA)
335 .Case("got@l", VK_PPC_GOT_LO)
336 .Case("got@h", VK_PPC_GOT_HI)
337 .Case("got@ha", VK_PPC_GOT_HA)
338 .Case("local", VK_PPC_LOCAL)
339 .Case("tocbase", VK_PPC_TOCBASE)
340 .Case("toc", VK_PPC_TOC)
341 .Case("toc@l", VK_PPC_TOC_LO)
342 .Case("toc@h", VK_PPC_TOC_HI)
343 .Case("toc@ha", VK_PPC_TOC_HA)
344 .Case("tls", VK_PPC_TLS)
345 .Case("dtpmod", VK_PPC_DTPMOD)
346 .Case("tprel", VK_PPC_TPREL)
347 .Case("tprel@l", VK_PPC_TPREL_LO)
348 .Case("tprel@h", VK_PPC_TPREL_HI)
349 .Case("tprel@ha", VK_PPC_TPREL_HA)
350 .Case("tprel@higher", VK_PPC_TPREL_HIGHER)
351 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA)
352 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST)
353 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA)
354 .Case("dtprel", VK_PPC_DTPREL)
355 .Case("dtprel@l", VK_PPC_DTPREL_LO)
356 .Case("dtprel@h", VK_PPC_DTPREL_HI)
357 .Case("dtprel@ha", VK_PPC_DTPREL_HA)
358 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER)
359 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA)
360 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST)
361 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA)
362 .Case("got@tprel", VK_PPC_GOT_TPREL)
363 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO)
364 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI)
365 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA)
366 .Case("got@dtprel", VK_PPC_GOT_DTPREL)
367 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO)
368 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI)
369 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA)
370 .Case("got@tlsgd", VK_PPC_GOT_TLSGD)
371 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO)
372 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI)
373 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA)
374 .Case("got@tlsld", VK_PPC_GOT_TLSLD)
375 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO)
376 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI)
377 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA)
378 .Case("gdgot", VK_Hexagon_GD_GOT)
379 .Case("gdplt", VK_Hexagon_GD_PLT)
380 .Case("iegot", VK_Hexagon_IE_GOT)
381 .Case("ie", VK_Hexagon_IE)
382 .Case("ldgot", VK_Hexagon_LD_GOT)
383 .Case("ldplt", VK_Hexagon_LD_PLT)
384 .Case("pcrel", VK_Hexagon_PCREL)
385 .Case("none", VK_ARM_NONE)
386 .Case("got_prel", VK_ARM_GOT_PREL)
387 .Case("target1", VK_ARM_TARGET1)
388 .Case("target2", VK_ARM_TARGET2)
389 .Case("prel31", VK_ARM_PREL31)
390 .Case("sbrel", VK_ARM_SBREL)
391 .Case("tlsldo", VK_ARM_TLSLDO)
392 .Case("tlscall", VK_ARM_TLSCALL)
393 .Case("tlsdesc", VK_ARM_TLSDESC)
394 .Default(VK_Invalid);
395 }
396
printVariantKind(raw_ostream & OS) const397 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {
398 if (UseParensForSymbolVariant)
399 OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';
400 else
401 OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());
402 }
403
404 /* *** */
405
evaluateAsAbsolute(int64_t & Res) const406 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const {
407 return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr);
408 }
409
evaluateAsAbsolute(int64_t & Res,const MCAsmLayout & Layout) const410 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
411 const MCAsmLayout &Layout) const {
412 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr);
413 }
414
evaluateAsAbsolute(int64_t & Res,const MCAsmLayout & Layout,const SectionAddrMap & Addrs) const415 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
416 const MCAsmLayout &Layout,
417 const SectionAddrMap &Addrs) const {
418 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
419 }
420
evaluateAsAbsolute(int64_t & Res,const MCAssembler & Asm) const421 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
422 return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr);
423 }
424
evaluateKnownAbsolute(int64_t & Res,const MCAsmLayout & Layout) const425 bool MCExpr::evaluateKnownAbsolute(int64_t &Res,
426 const MCAsmLayout &Layout) const {
427 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr,
428 true);
429 }
430
evaluateAsAbsolute(int64_t & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs) const431 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
432 const MCAsmLayout *Layout,
433 const SectionAddrMap *Addrs) const {
434 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
435 // absolutize differences across sections and that is what the MachO writer
436 // uses Addrs for.
437 return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs);
438 }
439
evaluateAsAbsolute(int64_t & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const SectionAddrMap * Addrs,bool InSet) const440 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
441 const MCAsmLayout *Layout,
442 const SectionAddrMap *Addrs, bool InSet) const
443 {
444 MCValue Value;
445
446 // Fast path constants.
447 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
448 Res = CE->getValue();
449 return true;
450 }
451
452 bool valid;
453 bool IsRelocatable =
454 evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet, valid);
455
456 // Record the current value.
457 Res = Value.getConstant();
458
459 return IsRelocatable && Value.isAbsolute();
460 }
461
462 /// \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,bool & valid)463 static void AttemptToFoldSymbolOffsetDifference(
464 const MCAssembler *Asm, const MCAsmLayout *Layout,
465 const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A,
466 const MCSymbolRefExpr *&B, int64_t &Addend, bool &valid) {
467 valid = true;
468 if (!A || !B)
469 return;
470
471 const MCSymbol &SA = A->getSymbol();
472 const MCSymbol &SB = B->getSymbol();
473
474 if (SA.isUndefined() || SB.isUndefined())
475 return;
476
477 if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet, valid))
478 return;
479 if (!valid)
480 return;
481
482 if (SA.getFragment() == SB.getFragment() && !SA.isVariable() &&
483 !SB.isVariable()) {
484 Addend += (SA.getOffset() - SB.getOffset());
485
486 // Pointers to Thumb symbols need to have their low-bit set to allow
487 // for interworking.
488 if (Asm->isThumbFunc(&SA))
489 Addend |= 1;
490
491 // Clear the symbol expr pointers to indicate we have folded these
492 // operands.
493 A = B = nullptr;
494 return;
495 }
496
497 if (!Layout)
498 return;
499
500 const MCSection &SecA = *SA.getFragment()->getParent();
501 const MCSection &SecB = *SB.getFragment()->getParent();
502
503 if ((&SecA != &SecB) && !Addrs)
504 return;
505
506 // Eagerly evaluate.
507 bool valid1, valid2;
508 Addend += Layout->getSymbolOffset(A->getSymbol(), valid1) -
509 Layout->getSymbolOffset(B->getSymbol(), valid2);
510 if (Addrs && (&SecA != &SecB))
511 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
512
513 // Pointers to Thumb symbols need to have their low-bit set to allow
514 // for interworking.
515 if (Asm->isThumbFunc(&SA))
516 Addend |= 1;
517
518 // Clear the symbol expr pointers to indicate we have folded these
519 // operands.
520 A = B = nullptr;
521 }
522
523 /// \brief Evaluate the result of an add between (conceptually) two MCValues.
524 ///
525 /// This routine conceptually attempts to construct an MCValue:
526 /// Result = (Result_A - Result_B + Result_Cst)
527 /// from two MCValue's LHS and RHS where
528 /// Result = LHS + RHS
529 /// and
530 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
531 ///
532 /// This routine attempts to aggresively fold the operands such that the result
533 /// is representable in an MCValue, but may not always succeed.
534 ///
535 /// \returns True on success, false if the result is not representable in an
536 /// MCValue.
537
538 /// NOTE: It is really important to have both the Asm and Layout arguments.
539 /// They might look redundant, but this function can be used before layout
540 /// is done (see the object streamer for example) and having the Asm argument
541 /// lets us avoid relaxations early.
542 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,bool & valid)543 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout,
544 const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS,
545 const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B,
546 int64_t RHS_Cst, MCValue &Res, bool &valid)
547 {
548 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
549 // about dealing with modifiers. This will ultimately bite us, one day.
550 const MCSymbolRefExpr *LHS_A = LHS.getSymA();
551 const MCSymbolRefExpr *LHS_B = LHS.getSymB();
552 int64_t LHS_Cst = LHS.getConstant();
553
554 // Fold the result constant immediately.
555 int64_t Result_Cst = LHS_Cst + RHS_Cst;
556
557 assert((!Layout || Asm) &&
558 "Must have an assembler object if layout is given!");
559
560 // If we have a layout, we can fold resolved differences.
561 if (Asm) {
562 // First, fold out any differences which are fully resolved. By
563 // reassociating terms in
564 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
565 // we have the four possible differences:
566 // (LHS_A - LHS_B),
567 // (LHS_A - RHS_B),
568 // (RHS_A - LHS_B),
569 // (RHS_A - RHS_B).
570 // Since we are attempting to be as aggressive as possible about folding, we
571 // attempt to evaluate each possible alternative.
572 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
573 Result_Cst, valid);
574 if (!valid)
575 return false;
576 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
577 Result_Cst, valid);
578 if (!valid)
579 return false;
580 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
581 Result_Cst, valid);
582 if (!valid)
583 return false;
584 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
585 Result_Cst, valid);
586 if (!valid)
587 return false;
588 }
589
590 // We can't represent the addition or subtraction of two symbols.
591 if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
592 return false;
593
594 // At this point, we have at most one additive symbol and one subtractive
595 // symbol -- find them.
596 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
597 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
598
599 Res = MCValue::get(A, B, Result_Cst);
600 return true;
601 }
602
evaluateAsRelocatable(MCValue & Res,const MCAsmLayout * Layout,const MCFixup * Fixup) const603 bool MCExpr::evaluateAsRelocatable(MCValue &Res,
604 const MCAsmLayout *Layout,
605 const MCFixup *Fixup) const
606 {
607 MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr;
608 bool valid;
609 return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr,
610 false, valid);
611 }
612
evaluateAsValue(MCValue & Res,const MCAsmLayout & Layout) const613 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const
614 {
615 MCAssembler *Assembler = &Layout.getAssembler();
616 bool valid;
617 return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr,
618 true, valid);
619 }
620
canExpand(const MCSymbol & Sym,bool InSet)621 static bool canExpand(const MCSymbol &Sym, bool InSet) {
622 const MCExpr *Expr = Sym.getVariableValue();
623 const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
624 if (Inner) {
625 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
626 return false;
627 }
628
629 if (InSet)
630 return true;
631 return !Sym.isInSection();
632 }
633
evaluateAsRelocatableImpl(MCValue & Res,const MCAssembler * Asm,const MCAsmLayout * Layout,const MCFixup * Fixup,const SectionAddrMap * Addrs,bool InSet,bool & valid) const634 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
635 const MCAsmLayout *Layout,
636 const MCFixup *Fixup,
637 const SectionAddrMap *Addrs,
638 bool InSet, bool &valid) const
639 {
640 switch (getKind()) {
641 case Target:
642 return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout,
643 Fixup);
644
645 case Constant:
646 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
647 return true;
648
649 case SymbolRef: {
650 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
651 const MCSymbol &Sym = SRE->getSymbol();
652
653 // Evaluate recursively if this is a variable.
654 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None &&
655 canExpand(Sym, InSet)) {
656 bool IsMachO = SRE->hasSubsectionsViaSymbols();
657 bool valid;
658 if (Sym.getVariableValue()->evaluateAsRelocatableImpl(
659 Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO, valid)) {
660 if (!IsMachO)
661 return true;
662
663 const MCSymbolRefExpr *A = Res.getSymA();
664 const MCSymbolRefExpr *B = Res.getSymB();
665 // FIXME: This is small hack. Given
666 // a = b + 4
667 // .long a
668 // the OS X assembler will completely drop the 4. We should probably
669 // include it in the relocation or produce an error if that is not
670 // possible.
671 if (!A && !B)
672 return true;
673 }
674 }
675
676 Res = MCValue::get(SRE, nullptr, 0);
677 return true;
678 }
679
680 case Unary: {
681 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
682 MCValue Value;
683
684 bool valid;
685 if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup,
686 Addrs, InSet, valid))
687 return false;
688
689 switch (AUE->getOpcode()) {
690 case MCUnaryExpr::LNot:
691 if (!Value.isAbsolute())
692 return false;
693 Res = MCValue::get(!Value.getConstant());
694 break;
695 case MCUnaryExpr::Minus:
696 /// -(a - b + const) ==> (b - a - const)
697 if (Value.getSymA() && !Value.getSymB())
698 return false;
699 Res = MCValue::get(Value.getSymB(), Value.getSymA(),
700 -Value.getConstant());
701 break;
702 case MCUnaryExpr::Not:
703 if (!Value.isAbsolute())
704 return false;
705 Res = MCValue::get(~Value.getConstant());
706 break;
707 case MCUnaryExpr::Plus:
708 Res = Value;
709 break;
710 }
711
712 return true;
713 }
714
715 case Binary: {
716 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
717 MCValue LHSValue, RHSValue;
718 bool valid;
719
720 if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup,
721 Addrs, InSet, valid) ||
722 !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup,
723 Addrs, InSet, valid))
724 return false;
725
726 // We only support a few operations on non-constant expressions, handle
727 // those first.
728 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
729 switch (ABE->getOpcode()) {
730 default:
731 return false;
732 case MCBinaryExpr::Sub:
733 // Negate RHS and add.
734 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
735 RHSValue.getSymB(), RHSValue.getSymA(),
736 -RHSValue.getConstant(), Res, valid);
737
738 case MCBinaryExpr::Add:
739 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
740 RHSValue.getSymA(), RHSValue.getSymB(),
741 RHSValue.getConstant(), Res, valid);
742 }
743 }
744
745 // FIXME: We need target hooks for the evaluation. It may be limited in
746 // width, and gas defines the result of comparisons differently from
747 // Apple as.
748 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
749 int64_t Result = 0;
750 switch (ABE->getOpcode()) {
751 case MCBinaryExpr::AShr: Result = LHS >> RHS; break;
752 case MCBinaryExpr::Add: Result = LHS + RHS; break;
753 case MCBinaryExpr::And: Result = LHS & RHS; break;
754 case MCBinaryExpr::Div:
755 // Handle division by zero. gas just emits a warning and keeps going,
756 // we try to be stricter.
757 // FIXME: Currently the caller of this function has no way to understand
758 // we're bailing out because of 'division by zero'. Therefore, it will
759 // emit a 'expected relocatable expression' error. It would be nice to
760 // change this code to emit a better diagnostic.
761 if (RHS == 0)
762 return false;
763 Result = LHS / RHS;
764 break;
765 case MCBinaryExpr::EQ: Result = LHS == RHS; break;
766 case MCBinaryExpr::GT: Result = LHS > RHS; break;
767 case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
768 case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
769 case MCBinaryExpr::LOr: Result = LHS || RHS; break;
770 case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break;
771 case MCBinaryExpr::LT: Result = LHS < RHS; break;
772 case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
773 case MCBinaryExpr::Mod:
774 // Handle division by zero. gas just emits a warning and keeps going,
775 // we try to be stricter.
776 // FIXME: Currently the caller of this function has no way to understand
777 // we're bailing out because of 'division by zero'. Therefore, it will
778 // emit a 'expected relocatable expression' error. It would be nice to
779 // change this code to emit a better diagnostic.
780 if (RHS == 0)
781 return false;
782 Result = LHS % RHS;
783 break;
784 case MCBinaryExpr::Mul: Result = LHS * RHS; break;
785 case MCBinaryExpr::NE: Result = LHS != RHS; break;
786 case MCBinaryExpr::Or: Result = LHS | RHS; break;
787 case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break;
788 case MCBinaryExpr::Sub: Result = LHS - RHS; break;
789 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
790 }
791
792 Res = MCValue::get(Result);
793 return true;
794 }
795 }
796
797 llvm_unreachable("Invalid assembly expression kind!");
798 }
799
findAssociatedFragment() const800 MCFragment *MCExpr::findAssociatedFragment() const {
801 switch (getKind()) {
802 case Target:
803 // We never look through target specific expressions.
804 return cast<MCTargetExpr>(this)->findAssociatedFragment();
805
806 case Constant:
807 return MCSymbol::AbsolutePseudoFragment;
808
809 case SymbolRef: {
810 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
811 const MCSymbol &Sym = SRE->getSymbol();
812 return Sym.getFragment();
813 }
814
815 case Unary:
816 return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment();
817
818 case Binary: {
819 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
820 MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment();
821 MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment();
822
823 // If either is absolute, return the other.
824 if (LHS_F == MCSymbol::AbsolutePseudoFragment)
825 return RHS_F;
826 if (RHS_F == MCSymbol::AbsolutePseudoFragment)
827 return LHS_F;
828
829 // Not always correct, but probably the best we can do without more context.
830 if (BE->getOpcode() == MCBinaryExpr::Sub)
831 return MCSymbol::AbsolutePseudoFragment;
832
833 // Otherwise, return the first non-null fragment.
834 return LHS_F ? LHS_F : RHS_F;
835 }
836 }
837
838 llvm_unreachable("Invalid assembly expression kind!");
839 }
840