1 //===- llvm/MC/MCWinCOFFStreamer.cpp --------------------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file contains an implementation of a Windows COFF object file streamer.
11 //===----------------------------------------------------------------------===//
13 #include "llvm/ADT/SmallString.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/ADT/Triple.h"
16 #include "llvm/ADT/Twine.h"
17 #include "llvm/BinaryFormat/COFF.h"
18 #include "llvm/MC/MCAsmBackend.h"
19 #include "llvm/MC/MCAssembler.h"
20 #include "llvm/MC/MCCodeEmitter.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCFixup.h"
24 #include "llvm/MC/MCFragment.h"
25 #include "llvm/MC/MCObjectFileInfo.h"
26 #include "llvm/MC/MCObjectStreamer.h"
27 #include "llvm/MC/MCObjectWriter.h"
28 #include "llvm/MC/MCSection.h"
29 #include "llvm/MC/MCSymbolCOFF.h"
30 #include "llvm/MC/MCWinCOFFStreamer.h"
31 #include "llvm/Support/Casting.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/MathExtras.h"
34 #include "llvm/Support/SMLoc.h"
35 #include "llvm/Support/raw_ostream.h"
42 #define DEBUG_TYPE "WinCOFFStreamer"
44 MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context,
45 std::unique_ptr<MCAsmBackend> MAB,
46 std::unique_ptr<MCCodeEmitter> CE,
47 std::unique_ptr<MCObjectWriter> OW)
48 : MCObjectStreamer(Context, std::move(MAB), std::move(OW), std::move(CE)),
51 void MCWinCOFFStreamer::emitInstToData(const MCInst &Inst,
52 const MCSubtargetInfo &STI) {
53 MCDataFragment *DF = getOrCreateDataFragment();
55 SmallVector<MCFixup, 4> Fixups;
56 SmallString<256> Code;
57 raw_svector_ostream VecOS(Code);
58 getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
60 // Add the fixups and data.
61 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
62 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
63 DF->getFixups().push_back(Fixups[i]);
65 DF->setHasInstructions(STI);
66 DF->getContents().append(Code.begin(), Code.end());
69 void MCWinCOFFStreamer::InitSections(bool NoExecStack) {
70 // FIXME: this is identical to the ELF one.
71 // This emulates the same behavior of GNU as. This makes it easier
72 // to compare the output as the major sections are in the same order.
73 SwitchSection(getContext().getObjectFileInfo()->getTextSection());
76 SwitchSection(getContext().getObjectFileInfo()->getDataSection());
79 SwitchSection(getContext().getObjectFileInfo()->getBSSSection());
82 SwitchSection(getContext().getObjectFileInfo()->getTextSection());
85 void MCWinCOFFStreamer::emitLabel(MCSymbol *S, SMLoc Loc) {
86 auto *Symbol = cast<MCSymbolCOFF>(S);
87 MCObjectStreamer::emitLabel(Symbol, Loc);
90 void MCWinCOFFStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {
91 // Let the target do whatever target specific stuff it needs to do.
92 getAssembler().getBackend().handleAssemblerFlag(Flag);
95 // None of these require COFF specific handling.
96 case MCAF_SyntaxUnified:
101 case MCAF_SubsectionsViaSymbols:
102 llvm_unreachable("COFF doesn't support .subsections_via_symbols");
106 void MCWinCOFFStreamer::emitThumbFunc(MCSymbol *Func) {
107 llvm_unreachable("not implemented");
110 bool MCWinCOFFStreamer::emitSymbolAttribute(MCSymbol *S,
111 MCSymbolAttr Attribute) {
112 auto *Symbol = cast<MCSymbolCOFF>(S);
113 getAssembler().registerSymbol(*Symbol);
116 default: return false;
117 case MCSA_WeakReference:
119 Symbol->setIsWeakExternal();
120 Symbol->setExternal(true);
123 Symbol->setExternal(true);
126 llvm_unreachable("COFF doesn't support the .alt_entry attribute");
132 void MCWinCOFFStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
133 llvm_unreachable("not implemented");
136 void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *S) {
137 auto *Symbol = cast<MCSymbolCOFF>(S);
139 Error("starting a new symbol definition without completing the "
144 void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
146 Error("storage class specified outside of symbol definition");
150 if (StorageClass & ~COFF::SSC_Invalid) {
151 Error("storage class value '" + Twine(StorageClass) +
156 getAssembler().registerSymbol(*CurSymbol);
157 cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass);
160 void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) {
162 Error("symbol type specified outside of a symbol definition");
166 if (Type & ~0xffff) {
167 Error("type value '" + Twine(Type) + "' out of range");
171 getAssembler().registerSymbol(*CurSymbol);
172 cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type);
175 void MCWinCOFFStreamer::EndCOFFSymbolDef() {
177 Error("ending symbol definition without starting one");
181 void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
182 // SafeSEH is a feature specific to 32-bit x86. It does not exist (and is
183 // unnecessary) on all platforms which use table-based exception dispatch.
184 if (getContext().getObjectFileInfo()->getTargetTriple().getArch() !=
188 const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol);
189 if (CSymbol->isSafeSEH())
192 MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
193 getAssembler().registerSection(*SXData);
194 if (SXData->getAlignment() < 4)
195 SXData->setAlignment(Align(4));
197 new MCSymbolIdFragment(Symbol, SXData);
199 getAssembler().registerSymbol(*Symbol);
200 CSymbol->setIsSafeSEH();
202 // The Microsoft linker requires that the symbol type of a handler be
203 // function. Go ahead and oblige it here.
204 CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
205 << COFF::SCT_COMPLEX_TYPE_SHIFT);
208 void MCWinCOFFStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {
209 MCSection *Sec = getCurrentSectionOnly();
210 getAssembler().registerSection(*Sec);
211 if (Sec->getAlignment() < 4)
212 Sec->setAlignment(Align(4));
214 new MCSymbolIdFragment(Symbol, getCurrentSectionOnly());
216 getAssembler().registerSymbol(*Symbol);
219 void MCWinCOFFStreamer::EmitCOFFSectionIndex(const MCSymbol *Symbol) {
220 visitUsedSymbol(*Symbol);
221 MCDataFragment *DF = getOrCreateDataFragment();
222 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
223 MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2);
224 DF->getFixups().push_back(Fixup);
225 DF->getContents().resize(DF->getContents().size() + 2, 0);
228 void MCWinCOFFStreamer::EmitCOFFSecRel32(const MCSymbol *Symbol,
230 visitUsedSymbol(*Symbol);
231 MCDataFragment *DF = getOrCreateDataFragment();
232 // Create Symbol A for the relocation relative reference.
233 const MCExpr *MCE = MCSymbolRefExpr::create(Symbol, getContext());
234 // Add the constant offset, if given.
236 MCE = MCBinaryExpr::createAdd(
237 MCE, MCConstantExpr::create(Offset, getContext()), getContext());
238 // Build the secrel32 relocation.
239 MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_SecRel_4);
240 // Record the relocation.
241 DF->getFixups().push_back(Fixup);
242 // Emit 4 bytes (zeros) to the object file.
243 DF->getContents().resize(DF->getContents().size() + 4, 0);
246 void MCWinCOFFStreamer::EmitCOFFImgRel32(const MCSymbol *Symbol,
248 visitUsedSymbol(*Symbol);
249 MCDataFragment *DF = getOrCreateDataFragment();
250 // Create Symbol A for the relocation relative reference.
251 const MCExpr *MCE = MCSymbolRefExpr::create(
252 Symbol, MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
253 // Add the constant offset, if given.
255 MCE = MCBinaryExpr::createAdd(
256 MCE, MCConstantExpr::create(Offset, getContext()), getContext());
257 // Build the imgrel relocation.
258 MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_Data_4);
259 // Record the relocation.
260 DF->getFixups().push_back(Fixup);
261 // Emit 4 bytes (zeros) to the object file.
262 DF->getContents().resize(DF->getContents().size() + 4, 0);
265 void MCWinCOFFStreamer::emitCommonSymbol(MCSymbol *S, uint64_t Size,
266 unsigned ByteAlignment) {
267 auto *Symbol = cast<MCSymbolCOFF>(S);
269 const Triple &T = getContext().getObjectFileInfo()->getTargetTriple();
270 if (T.isWindowsMSVCEnvironment()) {
271 if (ByteAlignment > 32)
272 report_fatal_error("alignment is limited to 32-bytes");
274 // Round size up to alignment so that we will honor the alignment request.
275 Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
278 getAssembler().registerSymbol(*Symbol);
279 Symbol->setExternal(true);
280 Symbol->setCommon(Size, ByteAlignment);
282 if (!T.isWindowsMSVCEnvironment() && ByteAlignment > 1) {
283 SmallString<128> Directive;
284 raw_svector_ostream OS(Directive);
285 const MCObjectFileInfo *MFI = getContext().getObjectFileInfo();
287 OS << " -aligncomm:\"" << Symbol->getName() << "\","
288 << Log2_32_Ceil(ByteAlignment);
291 SwitchSection(MFI->getDrectveSection());
292 emitBytes(Directive);
297 void MCWinCOFFStreamer::emitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
298 unsigned ByteAlignment) {
299 auto *Symbol = cast<MCSymbolCOFF>(S);
301 MCSection *Section = getContext().getObjectFileInfo()->getBSSSection();
303 SwitchSection(Section);
304 emitValueToAlignment(ByteAlignment, 0, 1, 0);
306 Symbol->setExternal(false);
311 void MCWinCOFFStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
312 uint64_t Size, unsigned ByteAlignment,
314 llvm_unreachable("not implemented");
317 void MCWinCOFFStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
318 uint64_t Size, unsigned ByteAlignment) {
319 llvm_unreachable("not implemented");
322 // TODO: Implement this if you want to emit .comment section in COFF obj files.
323 void MCWinCOFFStreamer::emitIdent(StringRef IdentString) {
324 llvm_unreachable("not implemented");
327 void MCWinCOFFStreamer::EmitWinEHHandlerData(SMLoc Loc) {
328 llvm_unreachable("not implemented");
331 void MCWinCOFFStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
332 const MCSymbolRefExpr *To,
334 // Ignore temporary symbols for now.
335 if (!From->getSymbol().isTemporary() && !To->getSymbol().isTemporary())
336 getAssembler().CGProfile.push_back({From, To, Count});
339 void MCWinCOFFStreamer::finalizeCGProfileEntry(const MCSymbolRefExpr *&SRE) {
340 const MCSymbol *S = &SRE->getSymbol();
342 getAssembler().registerSymbol(*S, &Created);
344 cast<MCSymbolCOFF>(S)->setIsWeakExternal();
345 cast<MCSymbolCOFF>(S)->setExternal(true);
349 void MCWinCOFFStreamer::finalizeCGProfile() {
350 for (MCAssembler::CGProfileEntry &E : getAssembler().CGProfile) {
351 finalizeCGProfileEntry(E.From);
352 finalizeCGProfileEntry(E.To);
356 void MCWinCOFFStreamer::finishImpl() {
359 MCObjectStreamer::finishImpl();
362 void MCWinCOFFStreamer::Error(const Twine &Msg) const {
363 getContext().reportError(SMLoc(), Msg);