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//===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing DWARF exception info into asm files.
//
//===----------------------------------------------------------------------===//
#include "DwarfException.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
using namespace llvm;
DwarfCFIExceptionBase::DwarfCFIExceptionBase(AsmPrinter *A)
: EHStreamer(A), shouldEmitCFI(false) {}
void DwarfCFIExceptionBase::markFunctionEnd() {
if (shouldEmitCFI)
Asm->OutStreamer->EmitCFIEndProc();
if (MMI->getLandingPads().empty())
return;
// Map all labels and get rid of any dead landing pads.
MMI->TidyLandingPads();
}
DwarfCFIException::DwarfCFIException(AsmPrinter *A)
: DwarfCFIExceptionBase(A), shouldEmitPersonality(false),
shouldEmitLSDA(false), shouldEmitMoves(false),
moveTypeModule(AsmPrinter::CFI_M_None) {}
DwarfCFIException::~DwarfCFIException() {}
/// endModule - Emit all exception information that should come after the
/// content.
void DwarfCFIException::endModule() {
if (moveTypeModule == AsmPrinter::CFI_M_Debug)
Asm->OutStreamer->EmitCFISections(false, true);
// SjLj uses this pass and it doesn't need this info.
if (!Asm->MAI->usesCFIForEH())
return;
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
if ((PerEncoding & 0x80) != dwarf::DW_EH_PE_indirect)
return;
// Emit references to all used personality functions
const std::vector<const Function*> &Personalities = MMI->getPersonalities();
for (size_t i = 0, e = Personalities.size(); i != e; ++i) {
if (!Personalities[i])
continue;
MCSymbol *Sym = Asm->getSymbol(Personalities[i]);
TLOF.emitPersonalityValue(*Asm->OutStreamer, Asm->TM, Sym);
}
}
void DwarfCFIException::beginFunction(const MachineFunction *MF) {
shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
const Function *F = MF->getFunction();
// If any landing pads survive, we need an EH table.
bool hasLandingPads = !MMI->getLandingPads().empty();
// See if we need frame move info.
AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
if (MoveType == AsmPrinter::CFI_M_EH ||
(MoveType == AsmPrinter::CFI_M_Debug &&
moveTypeModule == AsmPrinter::CFI_M_None))
moveTypeModule = MoveType;
shouldEmitMoves = MoveType != AsmPrinter::CFI_M_None;
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
const Function *Per = nullptr;
if (F->hasPersonalityFn())
Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
assert(!MMI->getPersonality() || Per == MMI->getPersonality());
// Emit a personality function even when there are no landing pads
bool forceEmitPersonality =
// ...if a personality function is explicitly specified
F->hasPersonalityFn() &&
// ... and it's not known to be a noop in the absence of invokes
!isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
// ... and we're not explicitly asked not to emit it
F->needsUnwindTableEntry();
shouldEmitPersonality =
(forceEmitPersonality ||
(hasLandingPads && PerEncoding != dwarf::DW_EH_PE_omit)) &&
Per;
unsigned LSDAEncoding = TLOF.getLSDAEncoding();
shouldEmitLSDA = shouldEmitPersonality &&
LSDAEncoding != dwarf::DW_EH_PE_omit;
shouldEmitCFI = shouldEmitPersonality || shouldEmitMoves;
if (!shouldEmitCFI)
return;
Asm->OutStreamer->EmitCFIStartProc(/*IsSimple=*/false);
// Indicate personality routine, if any.
if (!shouldEmitPersonality)
return;
// If we are forced to emit this personality, make sure to record
// it because it might not appear in any landingpad
if (forceEmitPersonality)
MMI->addPersonality(Per);
const MCSymbol *Sym =
TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
Asm->OutStreamer->EmitCFIPersonality(Sym, PerEncoding);
// Provide LSDA information.
if (!shouldEmitLSDA)
return;
Asm->OutStreamer->EmitCFILsda(Asm->getCurExceptionSym(), LSDAEncoding);
}
/// endFunction - Gather and emit post-function exception information.
///
void DwarfCFIException::endFunction(const MachineFunction *) {
if (!shouldEmitPersonality)
return;
emitExceptionTable();
}
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