ARM: suuport .tlsdescseq directive

This enhances the ARMAsmParser to handle .tlsdescseq directives.  This is a
slightly special relocation.  We must be able to generate them, but not consume
them in assembly.  The relocation is meant to assist the linker in generating a
TLS descriptor sequence.  The ELF target streamer is enhanced to append
additional fixups into the current segment and that is used to emit the new
R_ARM_TLS_DESCSEQ relocations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200448 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -296,6 +296,7 @@ class ARMAsmParser : public MCTargetAsmParser {
   bool parseDirectiveEven(SMLoc L);
   bool parseDirectivePersonalityIndex(SMLoc L);
   bool parseDirectiveUnwindRaw(SMLoc L);
+  bool parseDirectiveTLSDescSeq(SMLoc L);
 
   StringRef splitMnemonic(StringRef Mnemonic, unsigned &PredicationCode,
                           bool &CarrySetting, unsigned &ProcessorIMod,
@@ -8084,6 +8085,8 @@ bool ARMAsmParser::ParseDirective(AsmToken DirectiveID) {
     return parseDirectivePersonalityIndex(DirectiveID.getLoc());
   else if (IDVal == ".unwind_raw")
     return parseDirectiveUnwindRaw(DirectiveID.getLoc());
+  else if (IDVal == ".tlsdescseq")
+    return parseDirectiveTLSDescSeq(DirectiveID.getLoc());
   return true;
 }
 
@@ -9001,6 +9004,30 @@ bool ARMAsmParser::parseDirectiveUnwindRaw(SMLoc L) {
   return false;
 }
 
+/// parseDirectiveTLSDescSeq
+///   ::= .tlsdescseq tls-variable
+bool ARMAsmParser::parseDirectiveTLSDescSeq(SMLoc L) {
+  if (getLexer().isNot(AsmToken::Identifier)) {
+    TokError("expected variable after '.tlsdescseq' directive");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+
+  const MCSymbolRefExpr *SRE =
+    MCSymbolRefExpr::Create(Parser.getTok().getIdentifier(),
+                            MCSymbolRefExpr::VK_ARM_TLSDESCSEQ, getContext());
+  Lex();
+
+  if (getLexer().isNot(AsmToken::EndOfStatement)) {
+    Error(Parser.getTok().getLoc(), "unexpected token");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+
+  getTargetStreamer().AnnotateTLSDescriptorSequence(SRE);
+  return false;
+}
+
 /// Force static initialization.
 extern "C" void LLVMInitializeARMAsmParser() {
   RegisterMCAsmParser<ARMAsmParser> X(TheARMTarget);

lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp

@@ -269,6 +269,9 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
       case MCSymbolRefExpr::VK_ARM_TLSDESC:
         Type = ELF::R_ARM_TLS_GOTDESC;
         break;
+      case MCSymbolRefExpr::VK_ARM_TLSDESCSEQ:
+        Type = ELF::R_ARM_TLS_DESCSEQ;
+        break;
       }
       break;
     case ARM::fixup_arm_ldst_pcrel_12:

lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp

@@ -139,6 +139,8 @@ class ARMTargetAsmStreamer : public ARMTargetStreamer {
   virtual void emitInst(uint32_t Inst, char Suffix = '\0');
   virtual void finishAttributeSection();
 
+  virtual void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE);
+
 public:
   ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
                        MCInstPrinter &InstPrinter, bool VerboseAsm);
@@ -241,6 +243,10 @@ void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
 }
 void ARMTargetAsmStreamer::finishAttributeSection() {
 }
+void
+ARMTargetAsmStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
+  OS << "\t.tlsdescseq\t" << S->getSymbol().getName();
+}
 
 void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
   OS << "\t.inst";
@@ -397,6 +403,8 @@ private:
   virtual void emitInst(uint32_t Inst, char Suffix = '\0');
   virtual void finishAttributeSection();
 
+  virtual void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE);
+
   size_t calculateContentSize() const;
 
 public:
@@ -605,6 +613,8 @@ private:
   void SwitchToExTabSection(const MCSymbol &FnStart);
   void SwitchToExIdxSection(const MCSymbol &FnStart);
 
+  void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
+
   bool IsThumb;
   int64_t MappingSymbolCounter;
 
@@ -953,6 +963,10 @@ void ARMTargetELFStreamer::finishAttributeSection() {
   Contents.clear();
   FPU = ARM::INVALID_FPU;
 }
+void
+ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
+  getStreamer().EmitFixup(S, FK_Data_4);
+}
 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
   getStreamer().emitInst(Inst, Suffix);
 }
@@ -1011,6 +1025,11 @@ inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
                     SectionKind::getDataRel(),
                     FnStart);
 }
+void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
+  MCDataFragment *Frag = getOrCreateDataFragment();
+  Frag->getFixups().push_back(MCFixup::Create(Frag->getContents().size(), Expr,
+                                              Kind));
+}
 
 void ARMELFStreamer::Reset() {
   ExTab = NULL;