Add support for .cfi_register now that it is easy to extent the representation
to support it. Original patch with the parsing and plumbing by the PaX team and
Roman Divacky. I added the bits in MCDwarf.cpp and the test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168565 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index e53bc7b..32dee5e 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -227,6 +227,7 @@
   virtual void EmitCFIAdjustCfaOffset(int64_t Adjustment);
   virtual void EmitCFISignalFrame();
   virtual void EmitCFIUndefined(int64_t Register);
+  virtual void EmitCFIRegister(int64_t Register1, int64_t Register2);
 
   virtual void EmitWin64EHStartProc(const MCSymbol *Symbol);
   virtual void EmitWin64EHEndProc();
@@ -1047,6 +1048,16 @@
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitCFIRegister(int64_t Register1, int64_t Register2) {
+  MCStreamer::EmitCFIRegister(Register1, Register2);
+
+  if (!UseCFI)
+    return;
+
+  OS << "\t.cfi_register " << Register1 << ", " << Register2;
+  EmitEOL();
+}
+
 void MCAsmStreamer::EmitWin64EHStartProc(const MCSymbol *Symbol) {
   MCStreamer::EmitWin64EHStartProc(Symbol);
 
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 4a07537..92ed6cc 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -938,6 +938,19 @@
   bool VerboseAsm = Streamer.isVerboseAsm();
 
   switch (Instr.getOperation()) {
+  case MCCFIInstruction::OpRegister: {
+    unsigned Reg1 = Instr.getRegister();
+    unsigned Reg2 = Instr.getRegister2();
+    if (VerboseAsm) {
+      Streamer.AddComment("DW_CFA_register");
+      Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
+      Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
+    }
+    Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
+    Streamer.EmitULEB128IntValue(Reg1);
+    Streamer.EmitULEB128IntValue(Reg2);
+    return;
+  }
   case MCCFIInstruction::OpUndefined: {
     unsigned Reg = Instr.getRegister();
     if (VerboseAsm) {
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 34ebe3b..106dd53 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -398,6 +398,8 @@
       &GenericAsmParser::ParseDirectiveCFISignalFrame>(".cfi_signal_frame");
     AddDirectiveHandler<
       &GenericAsmParser::ParseDirectiveCFIUndefined>(".cfi_undefined");
+    AddDirectiveHandler<
+      &GenericAsmParser::ParseDirectiveCFIRegister>(".cfi_register");
 
     // Macro directives.
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveMacrosOnOff>(
@@ -436,6 +438,7 @@
   bool ParseDirectiveCFIEscape(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFISignalFrame(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFIUndefined(StringRef, SMLoc DirectiveLoc);
+  bool ParseDirectiveCFIRegister(StringRef, SMLoc DirectiveLoc);
 
   bool ParseDirectiveMacrosOnOff(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveMacro(StringRef, SMLoc DirectiveLoc);
@@ -3263,6 +3266,29 @@
   return false;
 }
 
+/// ParseDirectiveCFIRegister
+/// ::= .cfi_register register, register
+bool GenericAsmParser::ParseDirectiveCFIRegister(StringRef Directive,
+                                                 SMLoc DirectiveLoc) {
+  int64_t Register1 = 0;
+
+  if (ParseRegisterOrRegisterNumber(Register1, DirectiveLoc))
+    return true;
+
+  if (getLexer().isNot(AsmToken::Comma))
+    return TokError("unexpected token in directive");
+  Lex();
+
+  int64_t Register2 = 0;
+
+  if (ParseRegisterOrRegisterNumber(Register2, DirectiveLoc))
+    return true;
+
+  getStreamer().EmitCFIRegister(Register1, Register2);
+
+  return false;
+}
+
 /// ParseDirectiveMacrosOnOff
 /// ::= .macros_on
 /// ::= .macros_off
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 4f6b623..cdfd524 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -356,6 +356,14 @@
   CurFrame->Instructions.push_back(Instruction);
 }
 
+void MCStreamer::EmitCFIRegister(int64_t Register1, int64_t Register2) {
+  MCSymbol *Label = EmitCFICommon();
+  MCCFIInstruction Instruction =
+    MCCFIInstruction::createRegister(Label, Register1, Register2);
+  MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
+  CurFrame->Instructions.push_back(Instruction);
+}
+
 void MCStreamer::setCurrentW64UnwindInfo(MCWin64EHUnwindInfo *Frame) {
   W64UnwindInfos.push_back(Frame);
   CurrentW64UnwindInfo = W64UnwindInfos.back();