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Revert r203962 and two revisions depending on it: r204028 and r204059.

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The revision I'm reverting breaks handling of transitive aliases. This blocks us
and breaks sanitizer bootstrap:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/2651
(and checked locally by Alexey).

This revision is the result of:

  svn merge -r204059:204058 -r204028:204027 -r203962:203961 .

+ the regression test added to test/MC/ELF/alias.s

Another way to reproduce the regression with clang:
  $ cat q.c
  void a1();
  void a2() __attribute__((alias("a1")));
  void a3() __attribute__((alias("a2")));
  void a1() {}

  $ ~/work/llvm-build/bin/clang-3.5-good -c q.c && mv q.o good.o && \
      ~/work/llvm-build/bin/clang-3.5-bad -c q.c && mv q.o bad.o && \
      objdump -t good.o bad.o

    good.o:     file format elf64-x86-64

    SYMBOL TABLE:
    0000000000000000 l    df *ABS*  0000000000000000 q.c
    0000000000000000 l    d  .text  0000000000000000 .text
    0000000000000000 l    d  .data  0000000000000000 .data
    0000000000000000 l    d  .bss   0000000000000000 .bss
    0000000000000000 l    d  .comment       0000000000000000 .comment
    0000000000000000 l    d  .note.GNU-stack        0000000000000000 .note.GNU-stack
    0000000000000000 l    d  .eh_frame      0000000000000000 .eh_frame
    0000000000000000 g     F .text  0000000000000006 a1
    0000000000000000 g     F .text  0000000000000006 a2
    0000000000000000 g     F .text  0000000000000006 a3



    bad.o:     file format elf64-x86-64

    SYMBOL TABLE:
    0000000000000000 l    df *ABS*  0000000000000000 q.c
    0000000000000000 l    d  .text  0000000000000000 .text
    0000000000000000 l    d  .data  0000000000000000 .data
    0000000000000000 l    d  .bss   0000000000000000 .bss
    0000000000000000 l    d  .comment       0000000000000000 .comment
    0000000000000000 l    d  .note.GNU-stack        0000000000000000 .note.GNU-stack
    0000000000000000 l    d  .eh_frame      0000000000000000 .eh_frame
    0000000000000000 g     F .text  0000000000000006 a1
    0000000000000000 g     F .text  0000000000000006 a2
    0000000000000000 g       .text  0000000000000000 a3




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204137 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexander Kornienko
2014-03-18 10:36:11 +00:00
parent f48cfddd26
commit 8a99824c5a
8 changed files with 49 additions and 404 deletions
Download Patch File Download Diff File Expand all files Collapse all files

93
lib/MC/ELFObjectWriter.cpp
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@@ -271,7 +271,6 @@ class ELFObjectWriter : public MCObjectWriter {
/// \param RevGroupMap - Maps a signature symbol to the group section.
/// \param NumRegularSections - Number of non-relocation sections.
void ComputeSymbolTable(MCAssembler &Asm,
const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap,
RevGroupMapTy RevGroupMap,
unsigned NumRegularSections);
@@ -463,47 +462,33 @@ void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
}
}
uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &OrigData,
uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
const MCAsmLayout &Layout) {
MCSymbolData *Data = &OrigData;
if (Data->isCommon() && Data->isExternal())
return Data->getCommonAlignment();
if (Data.isCommon() && Data.isExternal())
return Data.getCommonAlignment();
const MCSymbol *Symbol = &Data->getSymbol();
const bool IsThumbFunc = OrigData.getFlags() & ELF_Other_ThumbFunc;
const MCSymbol &Symbol = Data.getSymbol();
uint64_t Res = 0;
if (Symbol->isVariable()) {
const MCExpr *Expr = Symbol->getVariableValue();
MCValue Value;
if (!Expr->EvaluateAsRelocatable(Value, &Layout))
return 0;
if (Value.getSymB())
return 0;
Res = Value.getConstant();
if (IsThumbFunc)
Res |= 1;
const MCSymbolRefExpr *A = Value.getSymA();
if (!A)
return Res;
Symbol = &A->getSymbol();
Data = &Layout.getAssembler().getSymbolData(*Symbol);
if (Symbol.isAbsolute() && Symbol.isVariable()) {
if (const MCExpr *Value = Symbol.getVariableValue()) {
int64_t IntValue;
if (Value->EvaluateAsAbsolute(IntValue, Layout))
return (uint64_t)IntValue;
}
}
if (!Symbol->isInSection())
if (!Symbol.isInSection())
return 0;
if (!Data->getFragment())
return 0;
Res += Layout.getSymbolOffset(Data);
if (IsThumbFunc || Data->getFlags() & ELF_Other_ThumbFunc)
Res |= 1;
if (Data.getFragment()) {
if (Data.getFlags() & ELF_Other_ThumbFunc)
return Layout.getSymbolOffset(&Data)+1;
else
return Layout.getSymbolOffset(&Data);
}
return Res;
return 0;
}
void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
@@ -584,9 +569,8 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
ELFSymbolData &MSD,
const MCAsmLayout &Layout) {
MCSymbolData &OrigData = *MSD.SymbolData;
const MCSymbol *Base = OrigData.getSymbol().getBaseSymbol(Layout);
const MCSymbolData &Data =
Base ? Layout.getAssembler().getSymbolData(*Base) : OrigData;
MCSymbolData &Data =
Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
Data.getSymbol().isVariable();
@@ -594,8 +578,6 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
// Binding and Type share the same byte as upper and lower nibbles
uint8_t Binding = MCELF::GetBinding(OrigData);
uint8_t Type = mergeTypeForSet(MCELF::GetType(OrigData), MCELF::GetType(Data));
if (OrigData.getFlags() & ELF_Other_ThumbFunc)
Type = ELF::STT_FUNC;
uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
// Other and Visibility share the same byte with Visibility using the lower
@@ -604,7 +586,7 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
uint8_t Other = MCELF::getOther(OrigData) << (ELF_STO_Shift - ELF_STV_Shift);
Other |= Visibility;
uint64_t Value = SymbolValue(OrigData, Layout);
uint64_t Value = SymbolValue(Data, Layout);
uint64_t Size = 0;
assert(!(Data.isCommon() && !Data.isExternal()));
@@ -915,11 +897,10 @@ void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
}
}
void
ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap,
RevGroupMapTy RevGroupMap,
unsigned NumRegularSections) {
void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
RevGroupMapTy RevGroupMap,
unsigned NumRegularSections) {
// FIXME: Is this the correct place to do this?
// FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed?
if (NeedsGOT) {
@@ -967,33 +948,33 @@ ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
ELFSymbolData MSD;
MSD.SymbolData = it;
const MCSymbol *BaseSymbol = Symbol.getBaseSymbol(Layout);
const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
// Undefined symbols are global, but this is the first place we
// are able to set it.
bool Local = isLocal(*it, isSignature, Used);
if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) {
assert(BaseSymbol);
MCSymbolData &SD = Asm.getSymbolData(*BaseSymbol);
MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
MCELF::SetBinding(*it, ELF::STB_GLOBAL);
MCELF::SetBinding(SD, ELF::STB_GLOBAL);
}
if (!BaseSymbol) {
MSD.SectionIndex = ELF::SHN_ABS;
} else if (it->isCommon()) {
if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
MCELF::SetBinding(*it, ELF::STB_WEAK);
if (it->isCommon()) {
assert(!Local);
MSD.SectionIndex = ELF::SHN_COMMON;
} else if (BaseSymbol->isUndefined()) {
} else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
MSD.SectionIndex = ELF::SHN_ABS;
} else if (RefSymbol.isUndefined()) {
if (isSignature && !Used)
MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
else
MSD.SectionIndex = ELF::SHN_UNDEF;
if (!Used && WeakrefUsed)
MCELF::SetBinding(*it, ELF::STB_WEAK);
} else {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(BaseSymbol->getSection());
static_cast<const MCSectionELF&>(RefSymbol.getSection());
MSD.SectionIndex = SectionIndexMap.lookup(&Section);
if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
NeedsSymtabShndx = true;
@@ -1579,8 +1560,8 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
unsigned NumRegularSections = NumUserSections + NumIndexedSections;
// Compute symbol table information.
ComputeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap,
NumRegularSections);
ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections);
WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);