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