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9c411e649e
llvm/lib/MC/MCWin64EH.cpp
Kai Nacke 9c411e649e Revert: Fix alignment of unwind data. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185790 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-08 04:45:05 +00:00

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//===- 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/MCObjectFileInfo.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.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 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:
EmitAbsDifference(streamer, inst.getLabel(), begin);
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 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 MCWin64EHUnwindInfo *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, 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,
MCSymbolRefExpr::VK_COFF_IMGREL32,
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,
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,
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
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