Implement .cfi_undefined. Based on a patch from PaX team, updated by

Roman Divacky. I just added the testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168520 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 47 insertions, 0 deletions

diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 17a6323d0e..e53bc7b4ea 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -226,6 +226,7 @@ public:
   virtual void EmitCFIRelOffset(int64_t Register, int64_t Offset);
   virtual void EmitCFIAdjustCfaOffset(int64_t Adjustment);
   virtual void EmitCFISignalFrame();
+  virtual void EmitCFIUndefined(int64_t Register);
 
   virtual void EmitWin64EHStartProc(const MCSymbol *Symbol);
   virtual void EmitWin64EHEndProc();
@@ -1036,6 +1037,16 @@ void MCAsmStreamer::EmitCFISignalFrame() {
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitCFIUndefined(int64_t Register) {
+  MCStreamer::EmitCFIUndefined(Register);
+
+  if (!UseCFI)
+    return;
+
+  OS << "\t.cfi_undefined " << Register;
+  EmitEOL();
+}
+
 void MCAsmStreamer::EmitWin64EHStartProc(const MCSymbol *Symbol) {
   MCStreamer::EmitWin64EHStartProc(Symbol);
 
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index bb9ed4952e..85b47fe437 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -938,6 +938,16 @@ void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
   bool VerboseAsm = Streamer.isVerboseAsm();
 
   switch (Instr.getOperation()) {
+  case MCCFIInstruction::Undefined: {
+    unsigned Reg = Instr.getDestination().getReg();
+    if (VerboseAsm) {
+      Streamer.AddComment("DW_CFA_undefined");
+      Streamer.AddComment(Twine("Reg ") + Twine(Reg));
+    }
+    Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
+    Streamer.EmitULEB128IntValue(Reg);
+    return;
+  }
   case MCCFIInstruction::Move:
   case MCCFIInstruction::RelMove: {
     const MachineLocation &Dst = Instr.getDestination();
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 6f2e85e553..34ebe3b859 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -396,6 +396,8 @@ public:
       &GenericAsmParser::ParseDirectiveCFIEscape>(".cfi_escape");
     AddDirectiveHandler<
       &GenericAsmParser::ParseDirectiveCFISignalFrame>(".cfi_signal_frame");
+    AddDirectiveHandler<
+      &GenericAsmParser::ParseDirectiveCFIUndefined>(".cfi_undefined");
 
     // Macro directives.
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveMacrosOnOff>(
@@ -433,6 +435,7 @@ public:
   bool ParseDirectiveCFIRestore(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFIEscape(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFISignalFrame(StringRef, SMLoc DirectiveLoc);
+  bool ParseDirectiveCFIUndefined(StringRef, SMLoc DirectiveLoc);
 
   bool ParseDirectiveMacrosOnOff(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveMacro(StringRef, SMLoc DirectiveLoc);
@@ -3246,6 +3249,20 @@ bool GenericAsmParser::ParseDirectiveCFISignalFrame(StringRef Directive,
   return false;
 }
 
+/// ParseDirectiveCFIUndefined
+/// ::= .cfi_undefined register
+bool GenericAsmParser::ParseDirectiveCFIUndefined(StringRef Directive,
+                                                  SMLoc DirectiveLoc) {
+  int64_t Register = 0;
+
+  if (ParseRegisterOrRegisterNumber(Register, DirectiveLoc))
+    return true;
+
+  getStreamer().EmitCFIUndefined(Register);
+
+  return false;
+}
+
 /// ParseDirectiveMacrosOnOff
 /// ::= .macros_on
 /// ::= .macros_off
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index afece0ba55..02e1028ada 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -367,6 +367,15 @@ void MCStreamer::EmitCFISignalFrame() {
   CurFrame->IsSignalFrame = true;
 }
 
+void MCStreamer::EmitCFIUndefined(int64_t Register) {
+  EnsureValidFrame();
+  MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
+  MCSymbol *Label = getContext().CreateTempSymbol();
+  EmitLabel(Label);
+  MCCFIInstruction Instruction(MCCFIInstruction::Undefined, Label, Register);
+  CurFrame->Instructions.push_back(Instruction);
+}
+
 void MCStreamer::setCurrentW64UnwindInfo(MCWin64EHUnwindInfo *Frame) {
   W64UnwindInfos.push_back(Frame);
   CurrentW64UnwindInfo = W64UnwindInfos.back();