1//===-- llvm/MC/WinCOFFStreamer.cpp -----------------------------*- C++ -*-===// 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// This file contains an implementation of a Windows COFF object file streamer. 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/MC/MCAsmBackend.h" 15#include "llvm/MC/MCAsmLayout.h" 16#include "llvm/MC/MCAssembler.h" 17#include "llvm/MC/MCCodeEmitter.h" 18#include "llvm/MC/MCContext.h" 19#include "llvm/MC/MCExpr.h" 20#include "llvm/MC/MCObjectFileInfo.h" 21#include "llvm/MC/MCObjectStreamer.h" 22#include "llvm/MC/MCSection.h" 23#include "llvm/MC/MCSectionCOFF.h" 24#include "llvm/MC/MCStreamer.h" 25#include "llvm/MC/MCSymbolCOFF.h" 26#include "llvm/MC/MCValue.h" 27#include "llvm/MC/MCWinCOFFStreamer.h" 28#include "llvm/Support/COFF.h" 29#include "llvm/Support/Debug.h" 30#include "llvm/Support/ErrorHandling.h" 31#include "llvm/Support/MathExtras.h" 32#include "llvm/Support/TargetRegistry.h" 33#include "llvm/Support/raw_ostream.h" 34 35using namespace llvm; 36 37#define DEBUG_TYPE "WinCOFFStreamer" 38 39namespace llvm { 40MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB, 41 MCCodeEmitter &CE, raw_pwrite_stream &OS) 42 : MCObjectStreamer(Context, MAB, OS, &CE), CurSymbol(nullptr) {} 43 44void MCWinCOFFStreamer::EmitInstToData(const MCInst &Inst, 45 const MCSubtargetInfo &STI) { 46 MCDataFragment *DF = getOrCreateDataFragment(); 47 48 SmallVector<MCFixup, 4> Fixups; 49 SmallString<256> Code; 50 raw_svector_ostream VecOS(Code); 51 getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI); 52 53 // Add the fixups and data. 54 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) { 55 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size()); 56 DF->getFixups().push_back(Fixups[i]); 57 } 58 59 DF->getContents().append(Code.begin(), Code.end()); 60} 61 62void MCWinCOFFStreamer::InitSections(bool NoExecStack) { 63 // FIXME: this is identical to the ELF one. 64 // This emulates the same behavior of GNU as. This makes it easier 65 // to compare the output as the major sections are in the same order. 66 SwitchSection(getContext().getObjectFileInfo()->getTextSection()); 67 EmitCodeAlignment(4); 68 69 SwitchSection(getContext().getObjectFileInfo()->getDataSection()); 70 EmitCodeAlignment(4); 71 72 SwitchSection(getContext().getObjectFileInfo()->getBSSSection()); 73 EmitCodeAlignment(4); 74 75 SwitchSection(getContext().getObjectFileInfo()->getTextSection()); 76} 77 78void MCWinCOFFStreamer::EmitLabel(MCSymbol *Symbol) { 79 assert(Symbol->isUndefined() && "Cannot define a symbol twice!"); 80 MCObjectStreamer::EmitLabel(Symbol); 81} 82 83void MCWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) { 84 llvm_unreachable("not implemented"); 85} 86 87void MCWinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) { 88 llvm_unreachable("not implemented"); 89} 90 91bool MCWinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol, 92 MCSymbolAttr Attribute) { 93 assert(Symbol && "Symbol must be non-null!"); 94 assert((!Symbol->isInSection() || 95 Symbol->getSection().getVariant() == MCSection::SV_COFF) && 96 "Got non-COFF section in the COFF backend!"); 97 98 getAssembler().registerSymbol(*Symbol); 99 100 switch (Attribute) { 101 default: return false; 102 case MCSA_WeakReference: 103 case MCSA_Weak: 104 cast<MCSymbolCOFF>(Symbol)->setIsWeakExternal(); 105 Symbol->setExternal(true); 106 break; 107 case MCSA_Global: 108 Symbol->setExternal(true); 109 break; 110 } 111 112 return true; 113} 114 115void MCWinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) { 116 llvm_unreachable("not implemented"); 117} 118 119void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) { 120 assert((!Symbol->isInSection() || 121 Symbol->getSection().getVariant() == MCSection::SV_COFF) && 122 "Got non-COFF section in the COFF backend!"); 123 124 if (CurSymbol) 125 Error("starting a new symbol definition without completing the " 126 "previous one"); 127 CurSymbol = Symbol; 128} 129 130void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) { 131 if (!CurSymbol) { 132 Error("storage class specified outside of symbol definition"); 133 return; 134 } 135 136 if (StorageClass & ~COFF::SSC_Invalid) { 137 Error("storage class value '" + Twine(StorageClass) + 138 "' out of range"); 139 return; 140 } 141 142 getAssembler().registerSymbol(*CurSymbol); 143 cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass); 144} 145 146void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) { 147 if (!CurSymbol) { 148 Error("symbol type specified outside of a symbol definition"); 149 return; 150 } 151 152 if (Type & ~0xffff) { 153 Error("type value '" + Twine(Type) + "' out of range"); 154 return; 155 } 156 157 getAssembler().registerSymbol(*CurSymbol); 158 cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type); 159} 160 161void MCWinCOFFStreamer::EndCOFFSymbolDef() { 162 if (!CurSymbol) 163 Error("ending symbol definition without starting one"); 164 CurSymbol = nullptr; 165} 166 167void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) { 168 // SafeSEH is a feature specific to 32-bit x86. It does not exist (and is 169 // unnecessary) on all platforms which use table-based exception dispatch. 170 if (getContext().getObjectFileInfo()->getTargetTriple().getArch() != 171 Triple::x86) 172 return; 173 174 const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol); 175 if (CSymbol->isSafeSEH()) 176 return; 177 178 MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection(); 179 getAssembler().registerSection(*SXData); 180 if (SXData->getAlignment() < 4) 181 SXData->setAlignment(4); 182 183 new MCSafeSEHFragment(Symbol, SXData); 184 185 getAssembler().registerSymbol(*Symbol); 186 CSymbol->setIsSafeSEH(); 187 188 // The Microsoft linker requires that the symbol type of a handler be 189 // function. Go ahead and oblige it here. 190 CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION 191 << COFF::SCT_COMPLEX_TYPE_SHIFT); 192} 193 194void MCWinCOFFStreamer::EmitCOFFSectionIndex(MCSymbol const *Symbol) { 195 MCDataFragment *DF = getOrCreateDataFragment(); 196 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext()); 197 MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2); 198 DF->getFixups().push_back(Fixup); 199 DF->getContents().resize(DF->getContents().size() + 2, 0); 200} 201 202void MCWinCOFFStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol) { 203 MCDataFragment *DF = getOrCreateDataFragment(); 204 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext()); 205 MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_4); 206 DF->getFixups().push_back(Fixup); 207 DF->getContents().resize(DF->getContents().size() + 4, 0); 208} 209 210void MCWinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size, 211 unsigned ByteAlignment) { 212 assert((!Symbol->isInSection() || 213 Symbol->getSection().getVariant() == MCSection::SV_COFF) && 214 "Got non-COFF section in the COFF backend!"); 215 216 const Triple &T = getContext().getObjectFileInfo()->getTargetTriple(); 217 if (T.isKnownWindowsMSVCEnvironment()) { 218 if (ByteAlignment > 32) 219 report_fatal_error("alignment is limited to 32-bytes"); 220 221 // Round size up to alignment so that we will honor the alignment request. 222 Size = std::max(Size, static_cast<uint64_t>(ByteAlignment)); 223 } 224 225 getAssembler().registerSymbol(*Symbol); 226 Symbol->setExternal(true); 227 Symbol->setCommon(Size, ByteAlignment); 228 229 if (!T.isKnownWindowsMSVCEnvironment() && ByteAlignment > 1) { 230 SmallString<128> Directive; 231 raw_svector_ostream OS(Directive); 232 const MCObjectFileInfo *MFI = getContext().getObjectFileInfo(); 233 234 OS << " -aligncomm:\"" << Symbol->getName() << "\"," 235 << Log2_32_Ceil(ByteAlignment); 236 237 PushSection(); 238 SwitchSection(MFI->getDrectveSection()); 239 EmitBytes(Directive); 240 PopSection(); 241 } 242} 243 244void MCWinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size, 245 unsigned ByteAlignment) { 246 assert(!Symbol->isInSection() && "Symbol must not already have a section!"); 247 248 MCSection *Section = getContext().getObjectFileInfo()->getBSSSection(); 249 getAssembler().registerSection(*Section); 250 if (Section->getAlignment() < ByteAlignment) 251 Section->setAlignment(ByteAlignment); 252 253 getAssembler().registerSymbol(*Symbol); 254 Symbol->setExternal(false); 255 256 if (ByteAlignment != 1) 257 new MCAlignFragment(ByteAlignment, /*Value=*/0, /*ValueSize=*/0, 258 ByteAlignment, Section); 259 260 MCFillFragment *Fragment = new MCFillFragment( 261 /*Value=*/0, /*ValueSize=*/0, Size, Section); 262 Symbol->setFragment(Fragment); 263} 264 265void MCWinCOFFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol, 266 uint64_t Size, unsigned ByteAlignment) { 267 llvm_unreachable("not implemented"); 268} 269 270void MCWinCOFFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol, 271 uint64_t Size, unsigned ByteAlignment) { 272 llvm_unreachable("not implemented"); 273} 274 275void MCWinCOFFStreamer::EmitFileDirective(StringRef Filename) { 276 getAssembler().addFileName(Filename); 277} 278 279// TODO: Implement this if you want to emit .comment section in COFF obj files. 280void MCWinCOFFStreamer::EmitIdent(StringRef IdentString) { 281 llvm_unreachable("not implemented"); 282} 283 284void MCWinCOFFStreamer::EmitWinEHHandlerData() { 285 llvm_unreachable("not implemented"); 286} 287 288void MCWinCOFFStreamer::FinishImpl() { 289 MCObjectStreamer::FinishImpl(); 290} 291 292void MCWinCOFFStreamer::Error(const Twine &Msg) const { 293 getContext().reportError(SMLoc(), Msg); 294} 295} 296 297