llvm/lib/MC/MCSectionCOFF.cpp
Reid Kleckner 65c4329181 MC COFF: Emit the 'b' section flag for .bss sections in GNU assembly
Without this, assembling clang's disassembly would produce an object
file with the IMAGE_SCN_CNT_INITIALIZED_DATA section characteristic
rather than the uninitialized one.  link.exe would warn when merging
comdats with different flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197529 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-17 22:12:40 +00:00

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3.2 KiB
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//===- lib/MC/MCSectionCOFF.cpp - COFF Code Section Representation --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
MCSectionCOFF::~MCSectionCOFF() {} // anchor.
// ShouldOmitSectionDirective - Decides whether a '.section' directive
// should be printed before the section name
bool MCSectionCOFF::ShouldOmitSectionDirective(StringRef Name,
const MCAsmInfo &MAI) const {
if (COMDATSymbol)
return false;
// FIXME: Does .section .bss/.data/.text work everywhere??
if (Name == ".text" || Name == ".data" || Name == ".bss")
return true;
return false;
}
void MCSectionCOFF::setSelection(int Selection,
const MCSectionCOFF *Assoc) const {
assert(Selection != 0 && "invalid COMDAT selection type");
assert((Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) ==
(Assoc != 0) &&
"associative COMDAT section must have an associated section");
this->Selection = Selection;
this->Assoc = Assoc;
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
}
void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
raw_ostream &OS,
const MCExpr *Subsection) const {
// standard sections don't require the '.section'
if (ShouldOmitSectionDirective(SectionName, MAI)) {
OS << '\t' << getSectionName() << '\n';
return;
}
OS << "\t.section\t" << getSectionName() << ",\"";
if (getKind().isText())
OS << 'x';
else if (getKind().isBSS())
OS << 'b';
if (getKind().isWriteable())
OS << 'w';
else
OS << 'r';
if (getCharacteristics() & COFF::IMAGE_SCN_MEM_DISCARDABLE)
OS << 'n';
OS << '"';
if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
OS << ",";
switch (Selection) {
case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
OS << "one_only,";
break;
case COFF::IMAGE_COMDAT_SELECT_ANY:
OS << "discard,";
break;
case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
OS << "same_size,";
break;
case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
OS << "same_contents,";
break;
case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
OS << "associative " << Assoc->getSectionName() << ",";
break;
case COFF::IMAGE_COMDAT_SELECT_LARGEST:
OS << "largest,";
break;
case COFF::IMAGE_COMDAT_SELECT_NEWEST:
OS << "newest,";
break;
default:
assert (0 && "unsupported COFF selection type");
break;
}
assert(COMDATSymbol);
OS << *COMDATSymbol;
}
OS << '\n';
}
bool MCSectionCOFF::UseCodeAlign() const {
return getKind().isText();
}
bool MCSectionCOFF::isVirtualSection() const {
return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
}