| //===- lib/MC/MCWin64EH.cpp - MCWin64EH implementation --------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/MC/MCWin64EH.h" |
| #include "llvm/MC/MCStreamer.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCObjectFileInfo.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/MC/MCSectionCOFF.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/ADT/Twine.h" |
| |
| namespace llvm { |
| |
| // NOTE: All relocations generated here are 4-byte image-relative. |
| |
| static uint8_t CountOfUnwindCodes(std::vector<MCWin64EHInstruction> &instArray){ |
| uint8_t count = 0; |
| for (std::vector<MCWin64EHInstruction>::const_iterator I = instArray.begin(), |
| E = instArray.end(); I != E; ++I) { |
| switch (I->getOperation()) { |
| case Win64EH::UOP_PushNonVol: |
| case Win64EH::UOP_AllocSmall: |
| case Win64EH::UOP_SetFPReg: |
| case Win64EH::UOP_PushMachFrame: |
| count += 1; |
| break; |
| case Win64EH::UOP_SaveNonVol: |
| case Win64EH::UOP_SaveXMM128: |
| count += 2; |
| break; |
| case Win64EH::UOP_SaveNonVolBig: |
| case Win64EH::UOP_SaveXMM128Big: |
| count += 3; |
| break; |
| case Win64EH::UOP_AllocLarge: |
| if (I->getSize() > 512*1024-8) |
| count += 3; |
| else |
| count += 2; |
| break; |
| } |
| } |
| return count; |
| } |
| |
| static void EmitAbsDifference(MCStreamer &streamer, MCSymbol *lhs, |
| MCSymbol *rhs) { |
| MCContext &context = streamer.getContext(); |
| const MCExpr *diff = MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create( |
| lhs, context), |
| MCSymbolRefExpr::Create( |
| rhs, context), |
| context); |
| streamer.EmitAbsValue(diff, 1); |
| |
| } |
| |
| static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin, |
| MCWin64EHInstruction &inst) { |
| uint8_t b1, b2; |
| uint16_t w; |
| b2 = (inst.getOperation() & 0x0F); |
| switch (inst.getOperation()) { |
| case Win64EH::UOP_PushNonVol: |
| EmitAbsDifference(streamer, inst.getLabel(), begin); |
| b2 |= (inst.getRegister() & 0x0F) << 4; |
| streamer.EmitIntValue(b2, 1); |
| break; |
| case Win64EH::UOP_AllocLarge: |
| EmitAbsDifference(streamer, inst.getLabel(), begin); |
| if (inst.getSize() > 512*1024-8) { |
| b2 |= 0x10; |
| streamer.EmitIntValue(b2, 1); |
| w = inst.getSize() & 0xFFF8; |
| streamer.EmitIntValue(w, 2); |
| w = inst.getSize() >> 16; |
| } else { |
| streamer.EmitIntValue(b2, 1); |
| w = inst.getSize() >> 3; |
| } |
| streamer.EmitIntValue(w, 2); |
| break; |
| case Win64EH::UOP_AllocSmall: |
| b2 |= (((inst.getSize()-8) >> 3) & 0x0F) << 4; |
| EmitAbsDifference(streamer, inst.getLabel(), begin); |
| streamer.EmitIntValue(b2, 1); |
| break; |
| case Win64EH::UOP_SetFPReg: |
| b1 = inst.getOffset() & 0xF0; |
| streamer.EmitIntValue(b1, 1); |
| streamer.EmitIntValue(b2, 1); |
| break; |
| case Win64EH::UOP_SaveNonVol: |
| case Win64EH::UOP_SaveXMM128: |
| b2 |= (inst.getRegister() & 0x0F) << 4; |
| EmitAbsDifference(streamer, inst.getLabel(), begin); |
| streamer.EmitIntValue(b2, 1); |
| w = inst.getOffset() >> 3; |
| if (inst.getOperation() == Win64EH::UOP_SaveXMM128) |
| w >>= 1; |
| streamer.EmitIntValue(w, 2); |
| break; |
| case Win64EH::UOP_SaveNonVolBig: |
| case Win64EH::UOP_SaveXMM128Big: |
| b2 |= (inst.getRegister() & 0x0F) << 4; |
| EmitAbsDifference(streamer, inst.getLabel(), begin); |
| streamer.EmitIntValue(b2, 1); |
| if (inst.getOperation() == Win64EH::UOP_SaveXMM128Big) |
| w = inst.getOffset() & 0xFFF0; |
| else |
| w = inst.getOffset() & 0xFFF8; |
| streamer.EmitIntValue(w, 2); |
| w = inst.getOffset() >> 16; |
| streamer.EmitIntValue(w, 2); |
| break; |
| case Win64EH::UOP_PushMachFrame: |
| if (inst.isPushCodeFrame()) |
| b2 |= 0x10; |
| EmitAbsDifference(streamer, inst.getLabel(), begin); |
| streamer.EmitIntValue(b2, 1); |
| break; |
| } |
| } |
| |
| static void EmitRuntimeFunction(MCStreamer &streamer, |
| const MCWin64EHUnwindInfo *info) { |
| MCContext &context = streamer.getContext(); |
| |
| streamer.EmitValueToAlignment(4); |
| streamer.EmitValue(MCSymbolRefExpr::Create(info->Begin, context), 4); |
| streamer.EmitValue(MCSymbolRefExpr::Create(info->End, context), 4); |
| streamer.EmitValue(MCSymbolRefExpr::Create(info->Symbol, context), 4); |
| } |
| |
| static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) { |
| // If this UNWIND_INFO already has a symbol, it's already been emitted. |
| if (info->Symbol) return; |
| |
| MCContext &context = streamer.getContext(); |
| streamer.EmitValueToAlignment(4); |
| // Upper 3 bits are the version number (currently 1). |
| uint8_t flags = 0x01; |
| info->Symbol = context.CreateTempSymbol(); |
| streamer.EmitLabel(info->Symbol); |
| |
| if (info->ChainedParent) |
| flags |= Win64EH::UNW_ChainInfo << 3; |
| else { |
| if (info->HandlesUnwind) |
| flags |= Win64EH::UNW_TerminateHandler << 3; |
| if (info->HandlesExceptions) |
| flags |= Win64EH::UNW_ExceptionHandler << 3; |
| } |
| streamer.EmitIntValue(flags, 1); |
| |
| if (info->PrologEnd) |
| EmitAbsDifference(streamer, info->PrologEnd, info->Begin); |
| else |
| streamer.EmitIntValue(0, 1); |
| |
| uint8_t numCodes = CountOfUnwindCodes(info->Instructions); |
| streamer.EmitIntValue(numCodes, 1); |
| |
| uint8_t frame = 0; |
| if (info->LastFrameInst >= 0) { |
| MCWin64EHInstruction &frameInst = info->Instructions[info->LastFrameInst]; |
| assert(frameInst.getOperation() == Win64EH::UOP_SetFPReg); |
| frame = (frameInst.getRegister() & 0x0F) | |
| (frameInst.getOffset() & 0xF0); |
| } |
| streamer.EmitIntValue(frame, 1); |
| |
| // Emit unwind instructions (in reverse order). |
| uint8_t numInst = info->Instructions.size(); |
| for (uint8_t c = 0; c < numInst; ++c) { |
| MCWin64EHInstruction inst = info->Instructions.back(); |
| info->Instructions.pop_back(); |
| EmitUnwindCode(streamer, info->Begin, inst); |
| } |
| |
| if (flags & (Win64EH::UNW_ChainInfo << 3)) |
| EmitRuntimeFunction(streamer, info->ChainedParent); |
| else if (flags & |
| ((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3)) |
| streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler, context), |
| 4); |
| else if (numCodes < 2) { |
| // The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not |
| // a chained unwind info, if there is no handler, and if there are fewer |
| // than 2 slots used in the unwind code array, we have to pad to 8 bytes. |
| if (numCodes == 1) |
| streamer.EmitIntValue(0, 2); |
| else |
| streamer.EmitIntValue(0, 4); |
| } |
| } |
| |
| StringRef MCWin64EHUnwindEmitter::GetSectionSuffix(const MCSymbol *func) { |
| if (!func || !func->isInSection()) return ""; |
| const MCSection *section = &func->getSection(); |
| const MCSectionCOFF *COFFSection; |
| if ((COFFSection = dyn_cast<MCSectionCOFF>(section))) { |
| StringRef name = COFFSection->getSectionName(); |
| size_t dollar = name.find('$'); |
| size_t dot = name.find('.', 1); |
| if (dollar == StringRef::npos && dot == StringRef::npos) |
| return ""; |
| if (dot == StringRef::npos) |
| return name.substr(dollar); |
| if (dollar == StringRef::npos || dot < dollar) |
| return name.substr(dot); |
| return name.substr(dollar); |
| } |
| return ""; |
| } |
| |
| static const MCSection *getWin64EHTableSection(StringRef suffix, |
| MCContext &context) { |
| if (suffix == "") |
| return context.getObjectFileInfo()->getXDataSection(); |
| |
| return context.getCOFFSection((".xdata"+suffix).str(), |
| COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | |
| COFF::IMAGE_SCN_MEM_READ | |
| COFF::IMAGE_SCN_MEM_WRITE, |
| SectionKind::getDataRel()); |
| } |
| |
| static const MCSection *getWin64EHFuncTableSection(StringRef suffix, |
| MCContext &context) { |
| if (suffix == "") |
| return context.getObjectFileInfo()->getPDataSection(); |
| return context.getCOFFSection((".pdata"+suffix).str(), |
| COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | |
| COFF::IMAGE_SCN_MEM_READ | |
| COFF::IMAGE_SCN_MEM_WRITE, |
| SectionKind::getDataRel()); |
| } |
| |
| void MCWin64EHUnwindEmitter::EmitUnwindInfo(MCStreamer &streamer, |
| MCWin64EHUnwindInfo *info) { |
| // Switch sections (the static function above is meant to be called from |
| // here and from Emit(). |
| MCContext &context = streamer.getContext(); |
| const MCSection *xdataSect = |
| getWin64EHTableSection(GetSectionSuffix(info->Function), context); |
| streamer.SwitchSection(xdataSect); |
| |
| llvm::EmitUnwindInfo(streamer, info); |
| } |
| |
| void MCWin64EHUnwindEmitter::Emit(MCStreamer &streamer) { |
| MCContext &context = streamer.getContext(); |
| // Emit the unwind info structs first. |
| for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) { |
| MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i); |
| const MCSection *xdataSect = |
| getWin64EHTableSection(GetSectionSuffix(info.Function), context); |
| streamer.SwitchSection(xdataSect); |
| llvm::EmitUnwindInfo(streamer, &info); |
| } |
| // Now emit RUNTIME_FUNCTION entries. |
| for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) { |
| MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i); |
| const MCSection *pdataSect = |
| getWin64EHFuncTableSection(GetSectionSuffix(info.Function), context); |
| streamer.SwitchSection(pdataSect); |
| EmitRuntimeFunction(streamer, &info); |
| } |
| } |
| |
| } // End of namespace llvm |
| |
