Change MCExpr::EvaluateAsRelocatableImpl of variables to return the original

variable if recursing fails to simplify it.

Factor AliasedSymbol to be a method of MCSymbol.

Update MCAssembler::EvaluateFixup to match the change in
EvaluateAsRelocatableImpl.

Remove the WeakRefExpr hack, as the object writer now sees the weakref with
no extra effort needed.

Nothing else is using MCTargetExpr, but keep it for now.

Now that the ELF writer sees relocations with aliases, handle

    .weak    foo2
foo2:
    .weak    bar2
    .set    bar2,foo2
    .quad    bar2

the same way gas does and produce a relocation with bar2.

llvm-svn: 119152

1 files changed, 33 insertions, 56 deletions

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index e11d68e8d8d..18d8e74216b 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -504,31 +504,6 @@ static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout) {
   return 0;
 }
 
-static const MCSymbol &AliasedSymbol(const MCSymbol &Symbol) {
-  const MCSymbol *S = &Symbol;
-  while (S->isVariable()) {
-    const MCExpr *Value = S->getVariableValue();
-    MCExpr::ExprKind Kind = Value->getKind();
-    switch (Kind) {
-    case MCExpr::SymbolRef: {
-      const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
-      S = &Ref->getSymbol();
-      break;
-    }
-    case MCExpr::Target: {
-      const MCTargetExpr *TExp = static_cast<const MCTargetExpr*>(Value);
-      MCValue Res;
-      TExp->EvaluateAsRelocatableImpl(Res, NULL);
-      S = &Res.getSymA()->getSymbol();
-      break;
-    }
-    default:
-      return *S;
-    }
-  }
-  return *S;
-}
-
 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
   // The presence of symbol versions causes undefined symbols and
   // versions declared with @@@ to be renamed.
@@ -536,7 +511,7 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
   for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
          ie = Asm.symbol_end(); it != ie; ++it) {
     const MCSymbol &Alias = it->getSymbol();
-    const MCSymbol &Symbol = AliasedSymbol(Alias);
+    const MCSymbol &Symbol = Alias.AliasedSymbol();
     MCSymbolData &SD = Asm.getSymbolData(Symbol);
 
     // Not an alias.
@@ -572,7 +547,7 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
                                   const MCAsmLayout &Layout) {
   MCSymbolData &OrigData = *MSD.SymbolData;
   MCSymbolData &Data =
-    Layout.getAssembler().getSymbolData(AliasedSymbol(OrigData.getSymbol()));
+    Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
 
   bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
     Data.getSymbol().isVariable();
@@ -673,28 +648,24 @@ const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
                                                const MCValue &Target,
                                                const MCFragment &F) const {
   const MCSymbol &Symbol = Target.getSymA()->getSymbol();
-  const MCSymbol &ASymbol = AliasedSymbol(Symbol);
-  const MCSymbol *RenamedP = Renames.lookup(&Symbol);
-
-  if (!RenamedP) {
-    if (Target.getSymA()->getKind() == MCSymbolRefExpr::VK_None ||
-        Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
-      RenamedP = &ASymbol;
-    else
-      RenamedP = &Symbol;
+  const MCSymbol &ASymbol = Symbol.AliasedSymbol();
+  const MCSymbol *Renamed = Renames.lookup(&Symbol);
+  const MCSymbolData &SD = Asm.getSymbolData(Symbol);
+
+  if (ASymbol.isUndefined()) {
+    if (Renamed)
+      return Renamed;
+    return &ASymbol;
   }
-  const MCSymbol &Renamed = *RenamedP;
-
-  MCSymbolData &SD = Asm.getSymbolData(Symbol);
-
-  if (Symbol.isUndefined())
-    return &Renamed;
 
-  if (SD.isExternal())
-    return &Renamed;
+  if (SD.isExternal()) {
+    if (Renamed)
+      return Renamed;
+    return &Symbol;
+  }
 
   const MCSectionELF &Section =
-    static_cast<const MCSectionELF&>(Symbol.getSection());
+    static_cast<const MCSectionELF&>(ASymbol.getSection());
 
   if (Section.getKind().isBSS())
     return NULL;
@@ -706,13 +677,18 @@ const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
   if (&Sec2 != &Section &&
       (Kind == MCSymbolRefExpr::VK_PLT ||
        Kind == MCSymbolRefExpr::VK_GOTPCREL ||
-       Kind == MCSymbolRefExpr::VK_GOTOFF))
-    return &Renamed;
+       Kind == MCSymbolRefExpr::VK_GOTOFF)) {
+    if (Renamed)
+      return Renamed;
+    return &Symbol;
+  }
 
   if (Section.getFlags() & MCSectionELF::SHF_MERGE) {
-    if (Target.getConstant() != 0)
-      return &Renamed;
-    return NULL;
+    if (Target.getConstant() == 0)
+      return NULL;
+    if (Renamed)
+      return Renamed;
+    return &Symbol;
   }
 
   return NULL;
@@ -742,7 +718,7 @@ static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
   if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
     return true;
 
-  const MCSymbol &A = AliasedSymbol(Symbol);
+  const MCSymbol &A = Symbol.AliasedSymbol();
   if (!A.isVariable() && A.isUndefined() && !Data.isCommon())
     return false;
 
@@ -761,7 +737,7 @@ static bool isLocal(const MCSymbolData &Data, bool isSignature,
     return false;
 
   const MCSymbol &Symbol = Data.getSymbol();
-  const MCSymbol &RefSymbol = AliasedSymbol(Symbol);
+  const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
 
   if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
     if (isSignature && !isUsedInReloc)
@@ -830,7 +806,7 @@ void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
 
     ELFSymbolData MSD;
     MSD.SymbolData = it;
-    const MCSymbol &RefSymbol = AliasedSymbol(Symbol);
+    const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
 
     // Undefined symbols are global, but this is the first place we
     // are able to set it.
@@ -1104,13 +1080,13 @@ bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
   const MCSection *SectionA = 0;
   const MCSymbol *SymbolA = 0;
   if (const MCSymbolRefExpr *A = Target.getSymA()) {
-    SymbolA = &A->getSymbol();
+    SymbolA = &A->getSymbol().AliasedSymbol();
     SectionA = &SymbolA->getSection();
   }
 
   const MCSection *SectionB = 0;
   if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    SectionB = &B->getSymbol().getSection();
+    SectionB = &B->getSymbol().AliasedSymbol().getSection();
   }
 
   if (!BaseSection)
@@ -1413,6 +1389,7 @@ void X86ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
   int Index = 0;
   int64_t Value = Target.getConstant();
   const MCSymbol &Symbol = Target.getSymA()->getSymbol();
+  const MCSymbol &ASymbol = Symbol.AliasedSymbol();
   const MCSymbol *RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
 
   bool IsPCRel = isFixupKindX86PCRel(Fixup.getKind());
@@ -1432,7 +1409,7 @@ void X86ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
     }
 
     if (!RelocSymbol) {
-      MCSymbolData &SD = Asm.getSymbolData(Symbol);
+      MCSymbolData &SD = Asm.getSymbolData(ASymbol);
       MCFragment *F = SD.getFragment();
 
       Index = F->getParent()->getOrdinal();