[llvm-commits] [llvm] r119026 - in /llvm/trunk: lib/MC/ELFObjectWriter.cpp lib/MC/MCELFStreamer.cpp test/MC/ELF/comdat.s
Rafael Espindola
rafael.espindola at gmail.com
Sat Nov 13 20:17:37 PST 2010
Author: rafael
Date: Sat Nov 13 22:17:37 2010
New Revision: 119026
URL: http://llvm.org/viewvc/llvm-project?rev=119026&view=rev
Log:
Handle a peculiar comdat case: Creating a section with an undefined
signature symbol causes a local symbol to be created unless there is
some other use of the symbol.
Modified:
llvm/trunk/lib/MC/ELFObjectWriter.cpp
llvm/trunk/lib/MC/MCELFStreamer.cpp
llvm/trunk/test/MC/ELF/comdat.s
Modified: llvm/trunk/lib/MC/ELFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/ELFObjectWriter.cpp?rev=119026&r1=119025&r2=119026&view=diff
==============================================================================
--- llvm/trunk/lib/MC/ELFObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/ELFObjectWriter.cpp Sat Nov 13 22:17:37 2010
@@ -285,13 +285,19 @@
uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
const MCSymbol *S);
+ // Map from a group section to the signature symbol
+ typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
+ // Map from a signature symbol to the group section
+ typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
+
/// ComputeSymbolTable - Compute the symbol table data
///
/// \param StringTable [out] - The string table data.
/// \param StringIndexMap [out] - Map from symbol names to offsets in the
/// string table.
void ComputeSymbolTable(MCAssembler &Asm,
- const SectionIndexMapTy &SectionIndexMap);
+ const SectionIndexMapTy &SectionIndexMap,
+ RevGroupMapTy RevGroupMap);
void ComputeIndexMap(MCAssembler &Asm,
SectionIndexMapTy &SectionIndexMap);
@@ -309,10 +315,8 @@
void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap);
- // Map from a group section to the signature symbol
- typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
void CreateGroupSections(MCAssembler &Asm, MCAsmLayout &Layout,
- GroupMapTy &GroupMap);
+ GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap);
void ExecutePostLayoutBinding(MCAssembler &Asm);
@@ -490,15 +494,6 @@
const MCSymbol &Symbol = AliasedSymbol(Alias);
MCSymbolData &SD = Asm.getSymbolData(Symbol);
- // Undefined symbols are global, but this is the first place we
- // are able to set it.
- if (Symbol.isUndefined() && !Symbol.isVariable()) {
- if (GetBinding(SD) == ELF::STB_LOCAL) {
- SetBinding(SD, ELF::STB_GLOBAL);
- SetBinding(*it, ELF::STB_GLOBAL);
- }
- }
-
// Not an alias.
if (&Symbol == &Alias)
continue;
@@ -904,13 +899,20 @@
return true;
}
-static bool isLocal(const MCSymbolData &Data) {
+static bool isLocal(const MCSymbolData &Data, bool isSignature,
+ bool isUsedInReloc) {
if (Data.isExternal())
return false;
const MCSymbol &Symbol = Data.getSymbol();
- if (Symbol.isUndefined() && !Symbol.isVariable())
+ const MCSymbol &RefSymbol = AliasedSymbol(Symbol);
+
+ if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
+ if (isSignature && !isUsedInReloc)
+ return true;
+
return false;
+ }
return true;
}
@@ -938,7 +940,8 @@
}
void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
- const SectionIndexMapTy &SectionIndexMap) {
+ const SectionIndexMapTy &SectionIndexMap,
+ RevGroupMapTy RevGroupMap) {
// FIXME: Is this the correct place to do this?
if (NeedsGOT) {
llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
@@ -962,15 +965,26 @@
bool Used = UsedInReloc.count(&Symbol);
bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
- if (!isInSymtab(Asm, *it, Used || WeakrefUsed,
+ bool isSignature = RevGroupMap.count(&Symbol);
+
+ if (!isInSymtab(Asm, *it,
+ Used || WeakrefUsed || isSignature,
Renames.count(&Symbol)))
continue;
ELFSymbolData MSD;
MSD.SymbolData = it;
- bool Local = isLocal(*it);
const MCSymbol &RefSymbol = AliasedSymbol(Symbol);
+ // Undefined symbols are global, but this is the first place we
+ // are able to set it.
+ bool Local = isLocal(*it, isSignature, Used);
+ if (!Local && GetBinding(*it) == ELF::STB_LOCAL) {
+ MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
+ SetBinding(*it, ELF::STB_GLOBAL);
+ SetBinding(SD, ELF::STB_GLOBAL);
+ }
+
if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
SetBinding(*it, ELF::STB_WEAK);
@@ -980,7 +994,10 @@
} else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
MSD.SectionIndex = ELF::SHN_ABS;
} else if (RefSymbol.isUndefined()) {
- MSD.SectionIndex = ELF::SHN_UNDEF;
+ if (isSignature && !Used)
+ MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
+ else
+ MSD.SectionIndex = ELF::SHN_UNDEF;
} else {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(RefSymbol.getSection());
@@ -1252,10 +1269,9 @@
void ELFObjectWriter::CreateGroupSections(MCAssembler &Asm,
MCAsmLayout &Layout,
- GroupMapTy &GroupMap) {
- typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
+ GroupMapTy &GroupMap,
+ RevGroupMapTy &RevGroupMap) {
// Build the groups
- RevGroupMapTy Groups;
for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
it != ie; ++it) {
const MCSectionELF &Section =
@@ -1265,7 +1281,7 @@
const MCSymbol *SignatureSymbol = Section.getGroup();
Asm.getOrCreateSymbolData(*SignatureSymbol);
- const MCSectionELF *&Group = Groups[SignatureSymbol];
+ const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
if (!Group) {
Group = Asm.getContext().CreateELFGroupSection();
MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
@@ -1278,22 +1294,22 @@
// Add sections to the groups
unsigned Index = 1;
- unsigned NumGroups = Groups.size();
+ unsigned NumGroups = RevGroupMap.size();
for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
it != ie; ++it, ++Index) {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(it->getSection());
if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
continue;
- const MCSectionELF *Group = Groups[Section.getGroup()];
+ const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
// FIXME: we could use the previous fragment
MCDataFragment *F = new MCDataFragment(&Data);
String32(*F, NumGroups + Index);
}
- for (RevGroupMapTy::const_iterator i = Groups.begin(), e = Groups.end();
- i != e; ++i) {
+ for (RevGroupMapTy::const_iterator i = RevGroupMap.begin(),
+ e = RevGroupMap.end(); i != e; ++i) {
const MCSectionELF *Group = i->second;
MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
Asm.AddSectionToTheEnd(*this, Data, Layout);
@@ -1373,14 +1389,16 @@
void ELFObjectWriter::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
GroupMapTy GroupMap;
- CreateGroupSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap);
+ RevGroupMapTy RevGroupMap;
+ CreateGroupSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
+ RevGroupMap);
SectionIndexMapTy SectionIndexMap;
ComputeIndexMap(Asm, SectionIndexMap);
// Compute symbol table information.
- ComputeSymbolTable(Asm, SectionIndexMap);
+ ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap);
CreateMetadataSections(const_cast<MCAssembler&>(Asm),
const_cast<MCAsmLayout&>(Layout),
Modified: llvm/trunk/lib/MC/MCELFStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCELFStreamer.cpp?rev=119026&r1=119025&r2=119026&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCELFStreamer.cpp (original)
+++ llvm/trunk/lib/MC/MCELFStreamer.cpp Sat Nov 13 22:17:37 2010
@@ -84,6 +84,7 @@
virtual void EmitThumbFunc(MCSymbol *Func);
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
+ virtual void SwitchSection(const MCSection *Section);
virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
assert(0 && "ELF doesn't support this directive");
@@ -282,6 +283,13 @@
};
} // end anonymous namespace
+void MCELFStreamer::SwitchSection(const MCSection *Section) {
+ const MCSymbol *Grp = static_cast<const MCSectionELF *>(Section)->getGroup();
+ if (Grp)
+ getAssembler().getOrCreateSymbolData(*Grp);
+ this->MCObjectStreamer::SwitchSection(Section);
+}
+
void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
getAssembler().getOrCreateSymbolData(*Symbol);
MCSymbolData &AliasSD = getAssembler().getOrCreateSymbolData(*Alias);
Modified: llvm/trunk/test/MC/ELF/comdat.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/comdat.s?rev=119026&r1=119025&r2=119026&view=diff
==============================================================================
--- llvm/trunk/test/MC/ELF/comdat.s (original)
+++ llvm/trunk/test/MC/ELF/comdat.s Sat Nov 13 22:17:37 2010
@@ -1,31 +1,76 @@
// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump | FileCheck %s
-// Test that we produce the two group sections and that they are a the beginning
+// Test that we produce the group sections and that they are a the beginning
// of the file.
// CHECK: # Section 0x00000001
-// CHECK-NEXT: (('sh_name', 0x00000021) # '.group'
+// CHECK-NEXT: (('sh_name', 0x00000026) # '.group'
// CHECK-NEXT: ('sh_type', 0x00000011)
// CHECK-NEXT: ('sh_flags', 0x00000000)
// CHECK-NEXT: ('sh_addr', 0x00000000)
// CHECK-NEXT: ('sh_offset', 0x00000040)
// CHECK-NEXT: ('sh_size', 0x0000000c)
-// CHECK-NEXT: ('sh_link', 0x0000000a)
+// CHECK-NEXT: ('sh_link', 0x0000000c)
// CHECK-NEXT: ('sh_info', 0x00000001)
// CHECK-NEXT: ('sh_addralign', 0x00000004)
// CHECK-NEXT: ('sh_entsize', 0x00000004)
// CHECK-NEXT: ),
// CHECK-NEXT: # Section 0x00000002
-// CHECK-NEXT: (('sh_name', 0x00000021) # '.group'
+// CHECK-NEXT: (('sh_name', 0x00000026) # '.group'
// CHECK-NEXT: ('sh_type', 0x00000011)
// CHECK-NEXT: ('sh_flags', 0x00000000)
// CHECK-NEXT: ('sh_addr', 0x00000000)
// CHECK-NEXT: ('sh_offset', 0x0000004c)
// CHECK-NEXT: ('sh_size', 0x00000008)
-// CHECK-NEXT: ('sh_link', 0x0000000a)
+// CHECK-NEXT: ('sh_link', 0x0000000c)
// CHECK-NEXT: ('sh_info', 0x00000002)
// CHECK-NEXT: ('sh_addralign', 0x00000004)
// CHECK-NEXT: ('sh_entsize', 0x00000004)
+// CHECK-NEXT: ),
+// CHECK-NEXT: # Section 0x00000003
+// CHECK-NEXT: (('sh_name', 0x00000026) # '.group'
+// CHECK-NEXT: ('sh_type', 0x00000011)
+// CHECK-NEXT: ('sh_flags', 0x00000000)
+// CHECK-NEXT: ('sh_addr', 0x00000000)
+// CHECK-NEXT: ('sh_offset', 0x00000054)
+// CHECK-NEXT: ('sh_size', 0x00000008)
+// CHECK-NEXT: ('sh_link', 0x0000000c)
+// CHECK-NEXT: ('sh_info', 0x0000000d)
+// CHECK-NEXT: ('sh_addralign', 0x00000004)
+// CHECK-NEXT: ('sh_entsize', 0x00000004)
+// CHECK-NEXT: ),
+
+// Test that g1 and g2 are local, but g3 is an undefined global.
+
+// CHECK: # Symbol 0x00000001
+// CHECK-NEXT: (('st_name', 0x00000001) # 'g1'
+// CHECK-NEXT: ('st_bind', 0x00000000)
+// CHECK-NEXT: ('st_type', 0x00000000)
+// CHECK-NEXT: ('st_other', 0x00000000)
+// CHECK-NEXT: ('st_shndx', 0x00000007)
+// CHECK-NEXT: ('st_value', 0x00000000)
+// CHECK-NEXT: ('st_size', 0x00000000)
+// CHECK-NEXT: ),
+// CHECK-NEXT: # Symbol 0x00000002
+// CHECK-NEXT: (('st_name', 0x00000004) # 'g2'
+// CHECK-NEXT: ('st_bind', 0x00000000)
+// CHECK-NEXT: ('st_type', 0x00000000)
+// CHECK-NEXT: ('st_other', 0x00000000)
+// CHECK-NEXT: ('st_shndx', 0x00000002)
+// CHECK-NEXT: ('st_value', 0x00000000)
+// CHECK-NEXT: ('st_size', 0x00000000)
+// CHECK-NEXT: ),
+
+// CHECK: # Symbol 0x0000000d
+// CHECK-NEXT: (('st_name', 0x00000007) # 'g3'
+// CHECK-NEXT: ('st_bind', 0x00000001)
+// CHECK-NEXT: ('st_type', 0x00000000)
+// CHECK-NEXT: ('st_other', 0x00000000)
+// CHECK-NEXT: ('st_shndx', 0x00000000)
+// CHECK-NEXT: ('st_value', 0x00000000)
+// CHECK-NEXT: ('st_size', 0x00000000)
+// CHECK-NEXT: ),
+
.section .foo,"axG", at progbits,g1,comdat
g1:
@@ -35,5 +80,7 @@
nop
.section .zed,"axG", at progbits,g2,comdat
-g2:
nop
+
+ .section .baz,"axG", at progbits,g3,comdat
+ .long g3
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