[MC][COFF] Delay handling symbol aliases when writing

Fixes PR14447 and PR9034. Patch by Nico Rieck!

llvm-svn: 173839

llvm/lib/MC/WinCOFFObjectWriter.cpp

@@ -147,7 +147,9 @@ public:
   object_t *createCOFFEntity(StringRef Name, list_t &List);
 
   void DefineSection(MCSectionData const &SectionData);
-  void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler);
+  void DefineSymbol(MCSymbol const &Symbol,
+                    MCSymbolData const &SymbolData,
+                    MCAssembler &Assembler);
 
   void MakeSymbolReal(COFFSymbol &S, size_t Index);
   void MakeSectionReal(COFFSection &S, size_t Number);
@@ -408,9 +410,10 @@ void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
 
 /// This function takes a section data object from the assembler
 /// and creates the associated COFF symbol staging object.
-void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
+void WinCOFFObjectWriter::DefineSymbol(MCSymbol const &Symbol,
+                                       MCSymbolData const &SymbolData,
                                        MCAssembler &Assembler) {
-  COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&SymbolData.getSymbol());
+  COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
 
   coff_symbol->Data.Type         = (SymbolData.getFlags() & 0x0000FFFF) >>  0;
   coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
@@ -418,9 +421,9 @@ void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
   if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
     coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
 
-    if (SymbolData.getSymbol().isVariable()) {
+    if (Symbol.isVariable()) {
       coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
-      const MCExpr *Value = SymbolData.getSymbol().getVariableValue();
+      const MCExpr *Value = Symbol.getVariableValue();
 
       // FIXME: This assert message isn't very good.
       assert(Value->getKind() == MCExpr::SymbolRef &&
@@ -428,10 +431,10 @@ void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
 
       const MCSymbolRefExpr *SymbolRef =
         static_cast<const MCSymbolRefExpr *>(Value);
-      coff_symbol->Other = GetOrCreateCOFFSymbol(&SymbolRef->getSymbol());
+      coff_symbol->Other = GetOrCreateCOFFSymbol(&Symbol);
     } else {
       std::string WeakName = std::string(".weak.")
-                           +  SymbolData.getSymbol().getName().str()
+                           +  Symbol.getName().str()
                            + ".default";
       COFFSymbol *WeakDefault = createSymbol(WeakName);
       WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
@@ -464,7 +467,7 @@ void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
 
   // Bind internal COFF symbol to MC symbol.
   coff_symbol->MCData = &SymbolData;
-  SymbolMap[&SymbolData.getSymbol()] = coff_symbol;
+  SymbolMap[&Symbol] = coff_symbol;
 }
 
 /// making a section real involves assigned it a number and putting
@@ -619,8 +622,11 @@ void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
 
   for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
                                           e = Asm.symbol_end(); i != e; i++) {
-    if (ExportSymbol(*i, Asm))
-      DefineSymbol(*i, Asm);
+    if (ExportSymbol(*i, Asm)) {
+      const MCSymbol &Alias = i->getSymbol();
+      const MCSymbol &Symbol = Alias.AliasedSymbol();
+      DefineSymbol(Alias, Asm.getSymbolData(Symbol), Asm);
+    }
   }
 }
 

llvm/lib/MC/WinCOFFStreamer.cpp

@@ -55,7 +55,6 @@ public:
   virtual void EmitDebugLabel(MCSymbol *Symbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
   virtual void EmitThumbFunc(MCSymbol *Func);
-  virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
   virtual void BeginCOFFSymbolDef(MCSymbol const *Symbol);
@@ -201,44 +200,6 @@ void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
   llvm_unreachable("not implemented");
 }
 
-void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
-  assert((Symbol->isInSection()
-         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
-         : true) && "Got non COFF section in the COFF backend!");
-  // FIXME: This is all very ugly and depressing. What needs to happen here
-  // depends on quite a few things that are all part of relaxation, which we
-  // don't really even do.
-
-  if (Value->getKind() != MCExpr::SymbolRef) {
-    MCObjectStreamer::EmitAssignment(Symbol, Value);
-  } else {
-    // FIXME: This is a horrible way to do this :(. This should really be
-    // handled after we are done with the MC* objects and immediately before
-    // writing out the object file when we know exactly what the symbol should
-    // look like in the coff symbol table. I'm not doing that now because the
-    // COFF object writer doesn't have a clearly defined separation between MC
-    // data structures, the object writers data structures, and the raw, POD,
-    // data structures that get written to disk.
-
-    // Copy over the aliased data.
-    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
-    const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
-      dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
-
-    // FIXME: This is particularly nasty because it breaks as soon as any data
-    // members of MCSymbolData change.
-    SD.CommonAlign     = RealSD.CommonAlign;
-    SD.CommonSize      = RealSD.CommonSize;
-    SD.Flags           = RealSD.Flags;
-    SD.Fragment        = RealSD.Fragment;
-    SD.Index           = RealSD.Index;
-    SD.IsExternal      = RealSD.IsExternal;
-    SD.IsPrivateExtern = RealSD.IsPrivateExtern;
-    SD.Offset          = RealSD.Offset;
-    SD.SymbolSize      = RealSD.SymbolSize;
-  }
-}
-
 void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
                                           MCSymbolAttr Attribute) {
   assert(Symbol && "Symbol must be non-null!");

llvm/test/MC/COFF/symbol-alias.s

@@ -23,8 +23,11 @@ _bar:
 	.long	0                       # 0x0
 
 
+# Order is important here. Assign _bar_alias_alias before _bar_alias.
 	.globl	_foo_alias
 _foo_alias = _foo
+	.globl	_bar_alias_alias
+_bar_alias_alias = _bar_alias
 	.globl	_bar_alias
 _bar_alias = _bar
 
@@ -52,6 +55,14 @@ _bar_alias = _bar
 // CHECK-NEXT: StorageClass       = [[FOO_STORAGE_CLASS]]
 // CHECK-NEXT: NumberOfAuxSymbols = [[FOO_NUMBER_OF_AUX_SYMBOLS]]
 
+// CHECK:      Name               = {{_?}}bar_alias_alias
+// CHECK-NEXT: Value              = [[BAR_VALUE]]
+// CHECK-NEXT: SectionNumber      = [[BAR_SECTION_NUMBER]]
+// CHECK-NEXT: SimpleType         = [[BAR_SIMPLE_TYPE]]
+// CHECK-NEXT: ComplexType        = [[BAR_COMPLEX_TYPE]]
+// CHECK-NEXT: StorageClass       = [[BAR_STORAGE_CLASS]]
+// CHECK-NEXT: NumberOfAuxSymbols = [[BAR_NUMBER_OF_AUX_SYMBOLS]]
+
 // CHECK:      Name               = {{_?}}bar_alias
 // CHECK-NEXT: Value              = [[BAR_VALUE]]
 // CHECK-NEXT: SectionNumber      = [[BAR_SECTION_NUMBER]]