Add back r203962, r204028 and r204059.

This reverts commit r204137.

This includes a fix for handling aliases of aliases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204178 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 150 insertions, 39 deletions

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 909ea80083..dd06304b71 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -271,6 +271,7 @@ 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);
@@ -462,33 +463,47 @@ void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
   }
 }
 
-uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
+uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &OrigData,
                                       const MCAsmLayout &Layout) {
-  if (Data.isCommon() && Data.isExternal())
-    return Data.getCommonAlignment();
-
-  const MCSymbol &Symbol = Data.getSymbol();
-
-  if (Symbol.isAbsolute() && Symbol.isVariable()) {
-    if (const MCExpr *Value = Symbol.getVariableValue()) {
-      int64_t IntValue;
-      if (Value->EvaluateAsAbsolute(IntValue, Layout))
-        return (uint64_t)IntValue;
-    }
+  MCSymbolData *Data = &OrigData;
+  if (Data->isCommon() && Data->isExternal())
+    return Data->getCommonAlignment();
+
+  const MCSymbol *Symbol = &Data->getSymbol();
+  const bool IsThumbFunc = OrigData.getFlags() & ELF_Other_ThumbFunc;
+
+  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.isInSection())
+  if (!Symbol->isInSection())
     return 0;
 
+  if (!Data->getFragment())
+    return 0;
 
-  if (Data.getFragment()) {
-    if (Data.getFlags() & ELF_Other_ThumbFunc)
-      return Layout.getSymbolOffset(&Data)+1;
-    else
-      return Layout.getSymbolOffset(&Data);
-  }
+  Res += Layout.getSymbolOffset(Data);
+  if (IsThumbFunc || Data->getFlags() & ELF_Other_ThumbFunc)
+    Res |= 1;
 
-  return 0;
+  return Res;
 }
 
 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
@@ -569,8 +584,9 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
                                   ELFSymbolData &MSD,
                                   const MCAsmLayout &Layout) {
   MCSymbolData &OrigData = *MSD.SymbolData;
-  MCSymbolData &Data =
-    Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
+  const MCSymbol *Base = OrigData.getSymbol().getBaseSymbol(Layout);
+  const MCSymbolData &Data =
+      Base ? Layout.getAssembler().getSymbolData(*Base) : OrigData;
 
   bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
     Data.getSymbol().isVariable();
@@ -578,6 +594,8 @@ 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
@@ -586,7 +604,7 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
   uint8_t Other = MCELF::getOther(OrigData) << (ELF_STO_Shift - ELF_STV_Shift);
   Other |= Visibility;
 
-  uint64_t Value = SymbolValue(Data, Layout);
+  uint64_t Value = SymbolValue(OrigData, Layout);
   uint64_t Size = 0;
 
   assert(!(Data.isCommon() && !Data.isExternal()));
@@ -897,10 +915,11 @@ void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
   }
 }
 
-void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
-                                      const SectionIndexMapTy &SectionIndexMap,
-                                         RevGroupMapTy RevGroupMap,
-                                         unsigned NumRegularSections) {
+void
+ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
+                                    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) {
@@ -948,33 +967,33 @@ void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
 
     ELFSymbolData MSD;
     MSD.SymbolData = it;
-    const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
+    const MCSymbol *BaseSymbol = Symbol.getBaseSymbol(Layout);
 
     // 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) {
-      MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
+      assert(BaseSymbol);
+      MCSymbolData &SD = Asm.getSymbolData(*BaseSymbol);
       MCELF::SetBinding(*it, ELF::STB_GLOBAL);
       MCELF::SetBinding(SD, ELF::STB_GLOBAL);
     }
 
-    if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
-      MCELF::SetBinding(*it, ELF::STB_WEAK);
-
-    if (it->isCommon()) {
+    if (!BaseSymbol) {
+      MSD.SectionIndex = ELF::SHN_ABS;
+    } else if (it->isCommon()) {
       assert(!Local);
       MSD.SectionIndex = ELF::SHN_COMMON;
-    } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
-      MSD.SectionIndex = ELF::SHN_ABS;
-    } else if (RefSymbol.isUndefined()) {
+    } else if (BaseSymbol->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&>(RefSymbol.getSection());
+        static_cast<const MCSectionELF&>(BaseSymbol->getSection());
       MSD.SectionIndex = SectionIndexMap.lookup(&Section);
       if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
         NeedsSymtabShndx = true;
@@ -1560,8 +1579,8 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
   unsigned NumRegularSections = NumUserSections + NumIndexedSections;
 
   // Compute symbol table information.
-  ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections);
-
+  ComputeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap,
+                     NumRegularSections);
 
   WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
 
diff --git a/lib/MC/MCSymbol.cpp b/lib/MC/MCSymbol.cpp
index 24165254e5..6876cb165d 100644
--- a/lib/MC/MCSymbol.cpp
+++ b/lib/MC/MCSymbol.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
@@ -51,6 +52,27 @@ const MCSymbol &MCSymbol::AliasedSymbol() const {
   return *S;
 }
 
+const MCSymbol *MCSymbol::getBaseSymbol(const MCAsmLayout &Layout) const {
+  // FIXME: shouldn't EvaluateAsRelocatable be responsible for following as many
+  // variables as possible?
+
+  const MCSymbol *S = this;
+  while (S->isVariable()) {
+    const MCExpr *Expr = S->getVariableValue();
+    MCValue Value;
+    if (!Expr->EvaluateAsRelocatable(Value, &Layout))
+      return nullptr;
+
+    if (Value.getSymB())
+      return nullptr;
+    const MCSymbolRefExpr *A = Value.getSymA();
+    if (!A)
+      return nullptr;
+    S = &A->getSymbol();
+  }
+  return S;
+}
+
 void MCSymbol::setVariableValue(const MCExpr *Value) {
   assert(!IsUsed && "Cannot set a variable that has already been used.");
   assert(Value && "Invalid variable value!");
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index b581ef2541..ccb1c641ef 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -30,6 +30,7 @@
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstrDesc.h"
 #include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCParser/MCAsmLexer.h"
 #include "llvm/MC/MCParser/MCAsmParser.h"
 #include "llvm/MC/MCParser/MCParsedAsmOperand.h"
@@ -41,6 +42,7 @@
 #include "llvm/MC/MCTargetAsmParser.h"
 #include "llvm/Support/ARMBuildAttributes.h"
 #include "llvm/Support/ARMEHABI.h"
+#include "llvm/Support/COFF.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ELF.h"
 #include "llvm/Support/MathExtras.h"
@@ -229,6 +231,7 @@ class ARMAsmParser : public MCTargetAsmParser {
   bool parseDirectiveObjectArch(SMLoc L);
   bool parseDirectiveArchExtension(SMLoc L);
   bool parseDirectiveAlign(SMLoc L);
+  bool parseDirectiveThumbSet(SMLoc L);
 
   StringRef splitMnemonic(StringRef Mnemonic, unsigned &PredicationCode,
                           bool &CarrySetting, unsigned &ProcessorIMod,
@@ -8030,6 +8033,8 @@ bool ARMAsmParser::ParseDirective(AsmToken DirectiveID) {
     return parseDirectiveArchExtension(DirectiveID.getLoc());
   else if (IDVal == ".align")
     return parseDirectiveAlign(DirectiveID.getLoc());
+  else if (IDVal == ".thumb_set")
+    return parseDirectiveThumbSet(DirectiveID.getLoc());
   return true;
 }
 
@@ -9087,6 +9092,71 @@ bool ARMAsmParser::parseDirectiveAlign(SMLoc L) {
   return false;
 }
 
+/// parseDirectiveThumbSet
+///  ::= .thumb_set name, value
+bool ARMAsmParser::parseDirectiveThumbSet(SMLoc L) {
+  StringRef Name;
+  if (Parser.parseIdentifier(Name)) {
+    TokError("expected identifier after '.thumb_set'");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+
+  if (getLexer().isNot(AsmToken::Comma)) {
+    TokError("expected comma after name '" + Name + "'");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+  Lex();
+
+  const MCExpr *Value;
+  if (Parser.parseExpression(Value)) {
+    TokError("missing expression");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+
+  if (getLexer().isNot(AsmToken::EndOfStatement)) {
+    TokError("unexpected token");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+  Lex();
+
+  MCSymbol *Alias = getContext().GetOrCreateSymbol(Name);
+  if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
+    MCSymbol *Sym = getContext().LookupSymbol(SRE->getSymbol().getName());
+    if (!Sym->isDefined()) {
+      getStreamer().EmitSymbolAttribute(Sym, MCSA_Global);
+      getStreamer().EmitAssignment(Alias, Value);
+      return false;
+    }
+
+    const MCObjectFileInfo::Environment Format =
+      getContext().getObjectFileInfo()->getObjectFileType();
+    switch (Format) {
+    case MCObjectFileInfo::IsCOFF: {
+      char Type = COFF::IMAGE_SYM_DTYPE_FUNCTION << COFF::SCT_COMPLEX_TYPE_SHIFT;
+      getStreamer().EmitCOFFSymbolType(Type);
+      // .set values are always local in COFF
+      getStreamer().EmitSymbolAttribute(Alias, MCSA_Local);
+      break;
+    }
+    case MCObjectFileInfo::IsELF:
+      getStreamer().EmitSymbolAttribute(Alias, MCSA_ELF_TypeFunction);
+      break;
+    case MCObjectFileInfo::IsMachO:
+      break;
+    }
+  }
+
+  // FIXME: set the function as being a thumb function via the assembler
+  getStreamer().EmitThumbFunc(Alias);
+  getStreamer().EmitAssignment(Alias, Value);
+
+  return false;
+}
+
 /// Force static initialization.
 extern "C" void LLVMInitializeARMAsmParser() {
   RegisterMCAsmParser<ARMAsmParser> X(TheARMTarget);