mirror of
https://github.com/llvm/llvm-project.git
synced 2025-05-02 07:36:07 +00:00

When LLVM emits DWARF call frame information, it currently creates a local, section-relative symbol in the code section, which is pointed to by a relocation on the .eh_frame section. However, for C++ we emit some functions in section groups, and the SysV ABI has some rules to make it easier to remove these sections (http://www.sco.com/developers/gabi/latest/ch4.sheader.html#section_group_rules): A symbol table entry with STB_LOCAL binding that is defined relative to one of a group's sections, and that is contained in a symbol table section that is not part of the group, must be discarded if the group members are discarded. References to this symbol table entry from outside the group are not allowed. This means that we need to use the function symbol for the relocation, not a temporary symbol. There was a comment in the code claiming that the local symbol was used to avoid creating a relocation, but a relocation must be created anyway as the code and CFI are in different sections. llvm-svn: 221150
155 lines
5.2 KiB
C++
155 lines
5.2 KiB
C++
//===-- 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;
|
|
|
|
DwarfCFIException::DwarfCFIException(AsmPrinter *A)
|
|
: EHStreamer(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);
|
|
|
|
if (!Asm->MAI->isExceptionHandlingDwarf())
|
|
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);
|
|
}
|
|
}
|
|
|
|
/// beginFunction - Gather pre-function exception information. Assumes it's
|
|
/// being emitted immediately after the function entry point.
|
|
void DwarfCFIException::beginFunction(const MachineFunction *MF) {
|
|
shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
|
|
|
|
// 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 = MMI->getPersonalities()[MMI->getPersonalityIndex()];
|
|
|
|
shouldEmitPersonality = hasLandingPads &&
|
|
PerEncoding != dwarf::DW_EH_PE_omit && Per;
|
|
|
|
unsigned LSDAEncoding = TLOF.getLSDAEncoding();
|
|
shouldEmitLSDA = shouldEmitPersonality &&
|
|
LSDAEncoding != dwarf::DW_EH_PE_omit;
|
|
|
|
if (!shouldEmitPersonality && !shouldEmitMoves)
|
|
return;
|
|
|
|
Asm->OutStreamer.EmitCFIStartProc(/*IsSimple=*/false, Asm->CurrentFnSym);
|
|
|
|
// Indicate personality routine, if any.
|
|
if (!shouldEmitPersonality)
|
|
return;
|
|
|
|
const MCSymbol *Sym =
|
|
TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
|
|
Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
|
|
|
|
MCSymbol *EHBegin =
|
|
Asm->GetTempSymbol("eh_func_begin", Asm->getFunctionNumber());
|
|
if (Asm->MAI->useAssignmentForEHBegin()) {
|
|
MCContext &Ctx = Asm->OutContext;
|
|
MCSymbol *CurPos = Ctx.CreateTempSymbol();
|
|
Asm->OutStreamer.EmitLabel(CurPos);
|
|
Asm->OutStreamer.EmitAssignment(EHBegin,
|
|
MCSymbolRefExpr::Create(CurPos, Ctx));
|
|
} else {
|
|
Asm->OutStreamer.EmitLabel(EHBegin);
|
|
}
|
|
|
|
// Provide LSDA information.
|
|
if (!shouldEmitLSDA)
|
|
return;
|
|
|
|
Asm->OutStreamer.EmitCFILsda(Asm->GetTempSymbol("exception",
|
|
Asm->getFunctionNumber()),
|
|
LSDAEncoding);
|
|
}
|
|
|
|
/// endFunction - Gather and emit post-function exception information.
|
|
///
|
|
void DwarfCFIException::endFunction(const MachineFunction *) {
|
|
if (!shouldEmitPersonality && !shouldEmitMoves)
|
|
return;
|
|
|
|
Asm->OutStreamer.EmitCFIEndProc();
|
|
|
|
if (!shouldEmitPersonality)
|
|
return;
|
|
|
|
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
|
|
Asm->getFunctionNumber()));
|
|
|
|
// Map all labels and get rid of any dead landing pads.
|
|
MMI->TidyLandingPads();
|
|
|
|
emitExceptionTable();
|
|
}
|