Fix a few issues with comdat handling on COFF.
* Section association cannot use just the section name as many
sections can have the same name. With this patch, the comdat symbol in
an assoc section is interpreted to mean a symbol in the associated
section and the mapping is discovered from it.
* Comdat symbols were not being set correctly. Instead we were getting
whatever was output first for that section.
A consequence is that associative sections now must use .section to
set the association. Using .linkonce would not work since it is not
possible to change a sections comdat symbol (it is used to decide if
we should create a new section or reuse an existing one).
This includes r210298, which was reverted because it was asserting
on an associated section having the same comdat as the associated
section.
llvm-svn: 210367
diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index c163268..130bb99 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -277,10 +277,11 @@
return Result;
}
-const MCSectionCOFF *
-MCContext::getCOFFSection(StringRef Section, unsigned Characteristics,
- SectionKind Kind, StringRef COMDATSymName,
- int Selection, const MCSectionCOFF *Assoc) {
+const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
+ unsigned Characteristics,
+ SectionKind Kind,
+ StringRef COMDATSymName,
+ int Selection) {
// Do the lookup, if we have a hit, return it.
SectionGroupPair P(Section, COMDATSymName);
@@ -294,8 +295,8 @@
COMDATSymbol = GetOrCreateSymbol(COMDATSymName);
StringRef CachedName = Iter->first.first;
- MCSectionCOFF *Result = new (*this) MCSectionCOFF(
- CachedName, Characteristics, COMDATSymbol, Selection, Assoc, Kind);
+ MCSectionCOFF *Result = new (*this)
+ MCSectionCOFF(CachedName, Characteristics, COMDATSymbol, Selection, Kind);
Iter->second = Result;
return Result;
diff --git a/llvm/lib/MC/MCParser/COFFAsmParser.cpp b/llvm/lib/MC/MCParser/COFFAsmParser.cpp
index decf01c..8e8447f 100644
--- a/llvm/lib/MC/MCParser/COFFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/COFFAsmParser.cpp
@@ -37,7 +37,7 @@
bool ParseSectionSwitch(StringRef Section, unsigned Characteristics,
SectionKind Kind, StringRef COMDATSymName,
- COFF::COMDATType Type, const MCSectionCOFF *Assoc);
+ COFF::COMDATType Type);
bool ParseSectionName(StringRef &SectionName);
bool ParseSectionFlags(StringRef FlagsString, unsigned* Flags);
@@ -117,8 +117,7 @@
bool ParseDirectiveEndef(StringRef, SMLoc);
bool ParseDirectiveSecRel32(StringRef, SMLoc);
bool ParseDirectiveSecIdx(StringRef, SMLoc);
- bool parseCOMDATTypeAndAssoc(COFF::COMDATType &Type,
- const MCSectionCOFF *&Assoc);
+ bool parseCOMDATType(COFF::COMDATType &Type);
bool ParseDirectiveLinkOnce(StringRef, SMLoc);
// Win64 EH directives.
@@ -293,21 +292,20 @@
unsigned Characteristics,
SectionKind Kind) {
return ParseSectionSwitch(Section, Characteristics, Kind, "",
- COFF::IMAGE_COMDAT_SELECT_ANY, nullptr);
+ COFF::IMAGE_COMDAT_SELECT_ANY);
}
bool COFFAsmParser::ParseSectionSwitch(StringRef Section,
unsigned Characteristics,
SectionKind Kind,
StringRef COMDATSymName,
- COFF::COMDATType Type,
- const MCSectionCOFF *Assoc) {
+ COFF::COMDATType Type) {
if (getLexer().isNot(AsmToken::EndOfStatement))
return TokError("unexpected token in section switching directive");
Lex();
getStreamer().SwitchSection(getContext().getCOFFSection(
- Section, Characteristics, Kind, COMDATSymName, Type, Assoc));
+ Section, Characteristics, Kind, COMDATSymName, Type));
return false;
}
@@ -359,14 +357,13 @@
}
COFF::COMDATType Type = COFF::IMAGE_COMDAT_SELECT_ANY;
- const MCSectionCOFF *Assoc = nullptr;
StringRef COMDATSymName;
if (getLexer().is(AsmToken::Comma)) {
Lex();
Flags |= COFF::IMAGE_SCN_LNK_COMDAT;
- if (parseCOMDATTypeAndAssoc(Type, Assoc))
+ if (parseCOMDATType(Type))
return true;
if (getLexer().isNot(AsmToken::Comma))
@@ -381,7 +378,7 @@
return TokError("unexpected token in directive");
SectionKind Kind = computeSectionKind(Flags);
- ParseSectionSwitch(SectionName, Flags, Kind, COMDATSymName, Type, Assoc);
+ ParseSectionSwitch(SectionName, Flags, Kind, COMDATSymName, Type);
return false;
}
@@ -461,9 +458,8 @@
return false;
}
-/// ::= [ identifier [ identifier ] ]
-bool COFFAsmParser::parseCOMDATTypeAndAssoc(COFF::COMDATType &Type,
- const MCSectionCOFF *&Assoc) {
+/// ::= [ identifier ]
+bool COFFAsmParser::parseCOMDATType(COFF::COMDATType &Type) {
StringRef TypeId = getTok().getIdentifier();
Type = StringSwitch<COFF::COMDATType>(TypeId)
@@ -481,48 +477,28 @@
Lex();
- if (Type == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
- SMLoc Loc = getTok().getLoc();
- StringRef AssocName;
- if (ParseSectionName(AssocName))
- return TokError("expected associated section name");
-
- Assoc = static_cast<const MCSectionCOFF*>(
- getContext().getCOFFSection(AssocName));
- if (!Assoc)
- return Error(Loc, "cannot associate unknown section '" + AssocName + "'");
- if (!(Assoc->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT))
- return Error(Loc, "associated section must be a COMDAT section");
- if (Assoc->getSelection() == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
- return Error(Loc, "associated section cannot be itself associative");
- }
-
return false;
}
/// ParseDirectiveLinkOnce
-/// ::= .linkonce [ identifier [ identifier ] ]
+/// ::= .linkonce [ identifier ]
bool COFFAsmParser::ParseDirectiveLinkOnce(StringRef, SMLoc Loc) {
COFF::COMDATType Type = COFF::IMAGE_COMDAT_SELECT_ANY;
- const MCSectionCOFF *Assoc = nullptr;
if (getLexer().is(AsmToken::Identifier))
- if (parseCOMDATTypeAndAssoc(Type, Assoc))
+ if (parseCOMDATType(Type))
return true;
const MCSectionCOFF *Current = static_cast<const MCSectionCOFF*>(
getStreamer().getCurrentSection().first);
-
- if (Type == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
- if (Assoc == Current)
- return Error(Loc, "cannot associate a section with itself");
- }
+ if (Type == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
+ return Error(Loc, "cannot make section associative with .linkonce");
if (Current->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT)
return Error(Loc, Twine("section '") + Current->getSectionName() +
"' is already linkonce");
- Current->setSelection(Type, Assoc);
+ Current->setSelection(Type);
if (getLexer().isNot(AsmToken::EndOfStatement))
return TokError("unexpected token in directive");
diff --git a/llvm/lib/MC/MCSectionCOFF.cpp b/llvm/lib/MC/MCSectionCOFF.cpp
index 335b8cd..fc2bd36 100644
--- a/llvm/lib/MC/MCSectionCOFF.cpp
+++ b/llvm/lib/MC/MCSectionCOFF.cpp
@@ -30,14 +30,9 @@
return false;
}
-void MCSectionCOFF::setSelection(int Selection,
- const MCSectionCOFF *Assoc) const {
+void MCSectionCOFF::setSelection(int Selection) const {
assert(Selection != 0 && "invalid COMDAT selection type");
- assert((Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) ==
- (Assoc != nullptr) &&
- "associative COMDAT section must have an associated section");
this->Selection = Selection;
- this->Assoc = Assoc;
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
}
@@ -82,7 +77,7 @@
OS << "same_contents,";
break;
case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
- OS << "associative " << Assoc->getSectionName() << ",";
+ OS << "associative,";
break;
case COFF::IMAGE_COMDAT_SELECT_LARGEST:
OS << "largest,";
diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
index 961cbc6..6f9c73b 100644
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -347,6 +347,14 @@
COFFSection *coff_section = createSection(Sec.getSectionName());
COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
+ if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
+ if (const MCSymbol *S = Sec.getCOMDATSymbol()) {
+ COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
+ if (COMDATSymbol->Section)
+ report_fatal_error("two sections have the same comdat");
+ COMDATSymbol->Section = coff_section;
+ }
+ }
coff_section->Symbol = coff_symbol;
coff_symbol->Section = coff_section;
@@ -458,9 +466,15 @@
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;
@@ -865,11 +879,15 @@
const MCSectionCOFF &MCSec =
static_cast<const MCSectionCOFF &>(Section->MCData->getSection());
- COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
+ const MCSymbol *COMDAT = MCSec.getCOMDATSymbol();
+ assert(COMDAT);
+ COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT);
+ assert(COMDATSymbol);
+ COFFSection *Assoc = COMDATSymbol->Section;
if (!Assoc)
- report_fatal_error(Twine("Missing associated COMDAT section ") +
- MCSec.getAssocSection()->getSectionName() +
- " for section " + MCSec.getSectionName());
+ report_fatal_error(
+ Twine("Missing associated COMDAT section for section ") +
+ MCSec.getSectionName());
// Skip this section if the associated section is unused.
if (Assoc->Number == -1)