Fix .comm and .lcomm on COFF.

These should not use COMDATs. GNU as uses .bss for .lcomm and section 0 for
.comm.

Given

static int a;
int b;

MSVC puts both in .bss. This patch then puts both .comm and .lcomm on .bss. With
this change we agree with gas on .lcomm, are much closer on .comm and clang-cl
matches msvc on the above example.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195654 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2013-11-25 16:06:04 +00:00
parent 68bef45439
commit c7daeb3098
2 changed files with 27 additions and 18 deletions

View File

@ -140,28 +140,12 @@ void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment, bool External) {
assert(!Symbol->isInSection() && "Symbol must not already have a section!");
std::string SectionName(".bss$linkonce");
SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
unsigned Characteristics =
COFF::IMAGE_SCN_LNK_COMDAT |
COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
const MCSection *Section = MCStreamer::getContext().getCOFFSection(
SectionName, Characteristics, SectionKind::getBSS(), Symbol->getName(),
Selection);
const MCSectionCOFF *Section = getSectionBSS();
MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
if (SectionData.getAlignment() < ByteAlignment)
SectionData.setAlignment(ByteAlignment);
MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
SymbolData.setExternal(External);
AssignSection(Symbol, Section);

25
test/MC/COFF/comm.s Normal file
View File

@ -0,0 +1,25 @@
// RUN: llvm-mc -filetype=obj -triple i686-pc-win32 %s | llvm-readobj -t | FileCheck %s
.lcomm _a,4,4
.comm _b, 4, 2
// CHECK: Symbol {
// CHECK: Name: _a
// CHECK-NEXT: Value:
// CHECK-NEXT: Section: .bss
// CHECK-NEXT: BaseType: Null
// CHECK-NEXT: ComplexType: Null
// CHECK-NEXT: StorageClass: Static
// CHECK-NEXT: AuxSymbolCount: 0
// CHECK-NEXT: }
// CHECK: Symbol {
// CHECK: Name: _b
// CHECK-NEXT: Value: 4
// CHECK-NEXT: Section: .bss
// CHECK-NEXT: BaseType: Null
// CHECK-NEXT: ComplexType: Null
// CHECK-NEXT: StorageClass: External
// CHECK-NEXT: AuxSymbolCount: 0
// CHECK-NEXT: }