Reapply 'ARM IAS: support .thumb_set'

Re-apply the change after it was reverted to do conflicts due to another change
being reverted.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204306 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 81 insertions, 4 deletions

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 1dae2f467d..9168fea53b 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -472,18 +472,21 @@ uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
   if (Symbol.isAbsolute() && Symbol.isVariable()) {
     if (const MCExpr *Value = Symbol.getVariableValue()) {
       int64_t IntValue;
-      if (Value->EvaluateAsAbsolute(IntValue, Layout))
-        return (uint64_t)IntValue;
+      if (Value->EvaluateAsAbsolute(IntValue, Layout)) {
+        if (Data.getFlags() & ELF_Other_ThumbFunc)
+          return static_cast<uint64_t>(IntValue | 1);
+        else
+          return static_cast<uint64_t>(IntValue);
+      }
     }
   }
 
   if (!Symbol.isInSection())
     return 0;
 
-
   if (Data.getFragment()) {
     if (Data.getFlags() & ELF_Other_ThumbFunc)
-      return Layout.getSymbolOffset(&Data)+1;
+      return Layout.getSymbolOffset(&Data) | 1;
     else
       return Layout.getSymbolOffset(&Data);
   }
@@ -578,6 +581,8 @@ 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
@@ -587,6 +592,8 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
   Other |= Visibility;
 
   uint64_t Value = SymbolValue(Data, Layout);
+  if (OrigData.getFlags() & ELF_Other_ThumbFunc)
+    Value |= 1;
   uint64_t Size = 0;
 
   assert(!(Data.isCommon() && !Data.isExternal()));
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);