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Correctly set the comdat symbol on COFF. 

We extended the .section syntax to allow multiple sections with the
same name but different comdats, but currently we don't make sure that
the output section has that comdat symbol.

That happens to work with the code llc produces currently because it looks like

.section secName, "dr", one_only, "COMDATSym"
.globl COMDATSym
COMDATSym:
....

but that is not very friendly to anyone coding in assembly or even to
llc once we get comdat support in the IR.

This patch changes the coff object writer to make sure the comdat symbol is
output just after the section symbol, as required by the coff spec.

llvm-svn: 210298
This commit is contained in:
Rafael Espindola 2014-06-05 23:09:25 +00:00
parent 72dfa16aa9
commit 942f4bc488
4 changed files with 71 additions and 26 deletions
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1
llvm/include/llvm/MC/MCSectionCOFF.h
View File

@ -76,6 +76,7 @@ class MCSymbol;
return SectionName.str() + "_end";
}
unsigned getCharacteristics() const { return Characteristics; }
const MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
int getSelection() const { return Selection; }
const MCSectionCOFF *getAssocSection() const { return Assoc; }

15
llvm/lib/MC/WinCOFFObjectWriter.cpp
View File

@ -347,6 +347,11 @@ void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
COFFSection *coff_section = createSection(Sec.getSectionName());
COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
if (const MCSymbol *S = Sec.getCOMDATSymbol()) {
COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
assert(!COMDATSymbol->Section);
COMDATSymbol->Section = coff_section;
}
coff_section->Symbol = coff_symbol;
coff_symbol->Section = coff_section;
@ -458,9 +463,15 @@ void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
} else {
const MCSymbolData &BaseData = Assembler.getSymbolData(*Base);
if (BaseData.Fragment)
coff_symbol->Section =
if (BaseData.Fragment) {
COFFSection *Sec =
SectionMap[&BaseData.Fragment->getParent()->getSection()];
if (coff_symbol->Section && coff_symbol->Section != Sec)
report_fatal_error("conflicting sections for symbol");
coff_symbol->Section = Sec;
}
}
coff_symbol->MCData = &ResSymData;

13
llvm/test/MC/COFF/section-comdat-conflict.s Normal file
View File

@ -0,0 +1,13 @@
// RUN: not llvm-mc -triple i386-pc-win32 -filetype=obj < %s 2>&1 | FileCheck %s
// CHECK: conflicting sections for symbol
.section .xyz
.global bar
bar:
.long 42
.section .abcd,"xr",discard,bar
.global foo
foo:
.long 42

68
llvm/test/MC/COFF/section-comdat.s
View File

@ -40,6 +40,11 @@ Symbol6:
Symbol7:
.long 1
.section SecName, "dr", newest, "Symbol8"
.globl AnotherSymbol
AnotherSymbol:
.long 1
// CHECK: Sections [
// CHECK: Section {
// CHECK: Number: 1
@ -114,6 +119,10 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol1
// CHECK: Section: secName (2)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: secName
// CHECK: Section: secName (3)
// CHECK: AuxSectionDef {
@ -121,6 +130,10 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol2
// CHECK: Section: secName (3)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: SecName
// CHECK: Section: SecName (4)
// CHECK: AuxSectionDef {
@ -128,6 +141,10 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol3
// CHECK: Section: SecName (4)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: SecName
// CHECK: Section: SecName (5)
// CHECK: AuxSymbolCount: 1
@ -136,6 +153,10 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol4
// CHECK: Section: SecName (5)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: SecName
// CHECK: Section: SecName (6)
// CHECK: AuxSectionDef {
@ -144,6 +165,10 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol5
// CHECK: Section: SecName (6)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: SecName
// CHECK: Section: SecName (7)
// CHECK: AuxSectionDef {
@ -151,6 +176,10 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol6
// CHECK: Section: SecName (7)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: SecName
// CHECK: Section: SecName (8)
// CHECK: AuxSectionDef {
@ -158,31 +187,22 @@ Symbol7:
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol1
// CHECK: Section: secName (2)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol2
// CHECK: Section: secName (3)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol3
// CHECK: Section: SecName (4)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol4
// CHECK: Section: SecName (5)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol5
// CHECK: Section: SecName (6)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol6
// CHECK: Section: SecName (7)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol7
// CHECK: Section: SecName (8)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: SecName
// CHECK: Section: SecName (9)
// CHECK: AuxSectionDef {
// CHECK: Selection: Newest (0x7)
// CHECK: }
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: Symbol8
// CHECK: Section: SecName (9)
// CHECK: }
// CHECK: Symbol {
// CHECK: Name: AnotherSymbol
// CHECK: Section: SecName (9)
// CHECK: }
// CHECK: ]