| //===- 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/ADT/Twine.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCStreamer.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/Support/Win64EH.h" |
| |
| using namespace llvm; |
| |
| // NOTE: All relocations generated here are 4-byte image-relative. |
| |
| static uint8_t CountOfUnwindCodes(std::vector<WinEH::Instruction> &Insns) { |
| uint8_t Count = 0; |
| for (const auto &I : Insns) { |
| switch (static_cast<Win64EH::UnwindOpcodes>(I.Operation)) { |
| 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: |
| Count += (I.Offset > 512 * 1024 - 8) ? 3 : 2; |
| break; |
| } |
| } |
| return Count; |
| } |
| |
| static void EmitAbsDifference(MCStreamer &Streamer, const MCSymbol *LHS, |
| const MCSymbol *RHS) { |
| MCContext &Context = Streamer.getContext(); |
| const MCExpr *Diff = |
| MCBinaryExpr::createSub(MCSymbolRefExpr::create(LHS, Context), |
| MCSymbolRefExpr::create(RHS, Context), Context); |
| Streamer.EmitValue(Diff, 1); |
| } |
| |
| static void EmitUnwindCode(MCStreamer &streamer, const MCSymbol *begin, |
| WinEH::Instruction &inst) { |
| uint8_t b2; |
| uint16_t w; |
| b2 = (inst.Operation & 0x0F); |
| switch (static_cast<Win64EH::UnwindOpcodes>(inst.Operation)) { |
| case Win64EH::UOP_PushNonVol: |
| EmitAbsDifference(streamer, inst.Label, begin); |
| b2 |= (inst.Register & 0x0F) << 4; |
| streamer.EmitIntValue(b2, 1); |
| break; |
| case Win64EH::UOP_AllocLarge: |
| EmitAbsDifference(streamer, inst.Label, begin); |
| if (inst.Offset > 512 * 1024 - 8) { |
| b2 |= 0x10; |
| streamer.EmitIntValue(b2, 1); |
| w = inst.Offset & 0xFFF8; |
| streamer.EmitIntValue(w, 2); |
| w = inst.Offset >> 16; |
| } else { |
| streamer.EmitIntValue(b2, 1); |
| w = inst.Offset >> 3; |
| } |
| streamer.EmitIntValue(w, 2); |
| break; |
| case Win64EH::UOP_AllocSmall: |
| b2 |= (((inst.Offset - 8) >> 3) & 0x0F) << 4; |
| EmitAbsDifference(streamer, inst.Label, begin); |
| streamer.EmitIntValue(b2, 1); |
| break; |
| case Win64EH::UOP_SetFPReg: |
| EmitAbsDifference(streamer, inst.Label, begin); |
| streamer.EmitIntValue(b2, 1); |
| break; |
| case Win64EH::UOP_SaveNonVol: |
| case Win64EH::UOP_SaveXMM128: |
| b2 |= (inst.Register & 0x0F) << 4; |
| EmitAbsDifference(streamer, inst.Label, begin); |
| streamer.EmitIntValue(b2, 1); |
| w = inst.Offset >> 3; |
| if (inst.Operation == Win64EH::UOP_SaveXMM128) |
| w >>= 1; |
| streamer.EmitIntValue(w, 2); |
| break; |
| case Win64EH::UOP_SaveNonVolBig: |
| case Win64EH::UOP_SaveXMM128Big: |
| b2 |= (inst.Register & 0x0F) << 4; |
| EmitAbsDifference(streamer, inst.Label, begin); |
| streamer.EmitIntValue(b2, 1); |
| if (inst.Operation == Win64EH::UOP_SaveXMM128Big) |
| w = inst.Offset & 0xFFF0; |
| else |
| w = inst.Offset & 0xFFF8; |
| streamer.EmitIntValue(w, 2); |
| w = inst.Offset >> 16; |
| streamer.EmitIntValue(w, 2); |
| break; |
| case Win64EH::UOP_PushMachFrame: |
| if (inst.Offset == 1) |
| b2 |= 0x10; |
| EmitAbsDifference(streamer, inst.Label, begin); |
| streamer.EmitIntValue(b2, 1); |
| break; |
| } |
| } |
| |
| static void EmitSymbolRefWithOfs(MCStreamer &streamer, |
| const MCSymbol *Base, |
| const MCSymbol *Other) { |
| MCContext &Context = streamer.getContext(); |
| const MCSymbolRefExpr *BaseRef = MCSymbolRefExpr::create(Base, Context); |
| const MCSymbolRefExpr *OtherRef = MCSymbolRefExpr::create(Other, Context); |
| const MCExpr *Ofs = MCBinaryExpr::createSub(OtherRef, BaseRef, Context); |
| const MCSymbolRefExpr *BaseRefRel = MCSymbolRefExpr::create(Base, |
| MCSymbolRefExpr::VK_COFF_IMGREL32, |
| Context); |
| streamer.EmitValue(MCBinaryExpr::createAdd(BaseRefRel, Ofs, Context), 4); |
| } |
| |
| static void EmitRuntimeFunction(MCStreamer &streamer, |
| const WinEH::FrameInfo *info) { |
| MCContext &context = streamer.getContext(); |
| |
| streamer.EmitValueToAlignment(4); |
| EmitSymbolRefWithOfs(streamer, info->Function, info->Begin); |
| EmitSymbolRefWithOfs(streamer, info->Function, info->End); |
| streamer.EmitValue(MCSymbolRefExpr::create(info->Symbol, |
| MCSymbolRefExpr::VK_COFF_IMGREL32, |
| context), 4); |
| } |
| |
| static void EmitUnwindInfo(MCStreamer &streamer, WinEH::FrameInfo *info) { |
| // If this UNWIND_INFO already has a symbol, it's already been emitted. |
| if (info->Symbol) |
| return; |
| |
| MCContext &context = streamer.getContext(); |
| MCSymbol *Label = context.createTempSymbol(); |
| |
| streamer.EmitValueToAlignment(4); |
| streamer.EmitLabel(Label); |
| info->Symbol = Label; |
| |
| // Upper 3 bits are the version number (currently 1). |
| uint8_t flags = 0x01; |
| 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) { |
| WinEH::Instruction &frameInst = info->Instructions[info->LastFrameInst]; |
| assert(frameInst.Operation == Win64EH::UOP_SetFPReg); |
| frame = (frameInst.Register & 0x0F) | (frameInst.Offset & 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) { |
| WinEH::Instruction inst = info->Instructions.back(); |
| info->Instructions.pop_back(); |
| EmitUnwindCode(streamer, info->Begin, inst); |
| } |
| |
| // For alignment purposes, the instruction array will always have an even |
| // number of entries, with the final entry potentially unused (in which case |
| // the array will be one longer than indicated by the count of unwind codes |
| // field). |
| if (numCodes & 1) { |
| streamer.EmitIntValue(0, 2); |
| } |
| |
| 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, |
| MCSymbolRefExpr::VK_COFF_IMGREL32, |
| context), 4); |
| else if (numCodes == 0) { |
| // 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. |
| streamer.EmitIntValue(0, 4); |
| } |
| } |
| |
| void llvm::Win64EH::UnwindEmitter::Emit(MCStreamer &Streamer) const { |
| // Emit the unwind info structs first. |
| for (const auto &CFI : Streamer.getWinFrameInfos()) { |
| MCSection *XData = Streamer.getAssociatedXDataSection(CFI->TextSection); |
| Streamer.SwitchSection(XData); |
| ::EmitUnwindInfo(Streamer, CFI.get()); |
| } |
| |
| // Now emit RUNTIME_FUNCTION entries. |
| for (const auto &CFI : Streamer.getWinFrameInfos()) { |
| MCSection *PData = Streamer.getAssociatedPDataSection(CFI->TextSection); |
| Streamer.SwitchSection(PData); |
| EmitRuntimeFunction(Streamer, CFI.get()); |
| } |
| } |
| |
| void llvm::Win64EH::UnwindEmitter::EmitUnwindInfo( |
| MCStreamer &Streamer, WinEH::FrameInfo *info) const { |
| // Switch sections (the static function above is meant to be called from |
| // here and from Emit(). |
| MCSection *XData = Streamer.getAssociatedXDataSection(info->TextSection); |
| Streamer.SwitchSection(XData); |
| |
| ::EmitUnwindInfo(Streamer, info); |
| } |
| |
