llvm/lib/MC/MCWinEH.cpp
Reid Kleckner b9cb76d3f3 MC Win64: Put unwind info for COMDAT code into the same COMDAT group
Summary:
This fixes a long standing issue where we would emit many little .text
sections and only one .pdata and .xdata section. Now we generate one
.pdata / .xdata pair per .text section and associate them correctly.

Fixes PR19667.

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5181

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217176 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-04 17:42:03 +00:00

85 lines
2.9 KiB
C++

//===- lib/MC/MCWinEH.cpp - Windows EH implementation ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/StringRef.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCWinEH.h"
#include "llvm/Support/COFF.h"
namespace llvm {
namespace WinEH {
static StringRef getSectionSuffix(const MCSymbol *Function) {
if (!Function || !Function->isInSection())
return "";
const MCSection *FunctionSection = &Function->getSection();
if (const auto Section = dyn_cast<MCSectionCOFF>(FunctionSection)) {
StringRef Name = Section->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 *getUnwindInfoSection(
StringRef SecName, const MCSectionCOFF *UnwindSec, const MCSymbol *Function,
MCContext &Context) {
// If Function is in a COMDAT, get or create an unwind info section in that
// COMDAT group.
if (Function && Function->isInSection()) {
const MCSectionCOFF *FunctionSection =
cast<MCSectionCOFF>(&Function->getSection());
if (FunctionSection->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
return Context.getAssociativeCOFFSection(
UnwindSec, FunctionSection->getCOMDATSymbol());
}
}
// If Function is in a section other than .text, create a new .pdata section.
// Otherwise use the plain .pdata section.
StringRef Suffix = getSectionSuffix(Function);
if (Suffix.empty())
return UnwindSec;
return Context.getCOFFSection((SecName + Suffix).str(),
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getDataRel());
}
const MCSection *UnwindEmitter::getPDataSection(const MCSymbol *Function,
MCContext &Context) {
const MCSectionCOFF *PData =
cast<MCSectionCOFF>(Context.getObjectFileInfo()->getPDataSection());
return getUnwindInfoSection(".pdata", PData, Function, Context);
}
const MCSection *UnwindEmitter::getXDataSection(const MCSymbol *Function,
MCContext &Context) {
const MCSectionCOFF *XData =
cast<MCSectionCOFF>(Context.getObjectFileInfo()->getXDataSection());
return getUnwindInfoSection(".xdata", XData, Function, Context);
}
}
}