Implement cfi_restore. Patch by Brian Anderson!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147356 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 80 insertions, 2 deletions

diff --git a/include/llvm/MC/MCDwarf.h b/include/llvm/MC/MCDwarf.h
index 56d732c497..bca50b21dc 100644
--- a/include/llvm/MC/MCDwarf.h
+++ b/include/llvm/MC/MCDwarf.h
@@ -271,7 +271,8 @@ namespace llvm {
 
   class MCCFIInstruction {
   public:
-    enum OpType { SameValue, RememberState, RestoreState, Move, RelMove, Escape };
+    enum OpType { SameValue, RememberState, RestoreState, Move, RelMove, Escape,
+                  Restore};
   private:
     OpType Operation;
     MCSymbol *Label;
@@ -286,7 +287,7 @@ namespace llvm {
     }
     MCCFIInstruction(OpType Op, MCSymbol *L, unsigned Register)
       : Operation(Op), Label(L), Destination(Register) {
-      assert(Op == SameValue);
+      assert(Op == SameValue || Op == Restore);
     }
     MCCFIInstruction(MCSymbol *L, const MachineLocation &D,
                      const MachineLocation &S)
diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index 5483fb07f1..e550dfa3ef 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -547,6 +547,7 @@ namespace llvm {
     virtual void EmitCFIRememberState();
     virtual void EmitCFIRestoreState();
     virtual void EmitCFISameValue(int64_t Register);
+    virtual void EmitCFIRestore(int64_t Register);
     virtual void EmitCFIRelOffset(int64_t Register, int64_t Offset);
     virtual void EmitCFIAdjustCfaOffset(int64_t Adjustment);
     virtual void EmitCFIEscape(StringRef Values);
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 881fed4690..986b8b67df 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -987,6 +987,15 @@ void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
     Streamer.EmitULEB128IntValue(Reg);
     return;
   }
+  case MCCFIInstruction::Restore: {
+    unsigned Reg = Instr.getDestination().getReg();
+    if (VerboseAsm) {
+      Streamer.AddComment("DW_CFA_restore");
+      Streamer.AddComment(Twine("Reg ") + Twine(Reg));
+    }
+    Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
+    return;
+  }
   case MCCFIInstruction::Escape:
     if (VerboseAsm) Streamer.AddComment("Escape bytes");
     Streamer.EmitBytes(Instr.getValues(), 0);
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 2ccea786c7..5a69bea2fe 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -302,6 +302,8 @@ public:
     AddDirectiveHandler<
       &GenericAsmParser::ParseDirectiveCFISameValue>(".cfi_same_value");
     AddDirectiveHandler<
+      &GenericAsmParser::ParseDirectiveCFIRestore>(".cfi_restore");
+    AddDirectiveHandler<
       &GenericAsmParser::ParseDirectiveCFIEscape>(".cfi_escape");
 
     // Macro directives.
@@ -336,6 +338,7 @@ public:
   bool ParseDirectiveCFIRememberState(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFIRestoreState(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFISameValue(StringRef, SMLoc DirectiveLoc);
+  bool ParseDirectiveCFIRestore(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveCFIEscape(StringRef, SMLoc DirectiveLoc);
 
   bool ParseDirectiveMacrosOnOff(StringRef, SMLoc DirectiveLoc);
@@ -2815,6 +2818,19 @@ bool GenericAsmParser::ParseDirectiveCFISameValue(StringRef IDVal,
   return false;
 }
 
+/// ParseDirectiveCFIRestore
+/// ::= .cfi_restore register
+bool GenericAsmParser::ParseDirectiveCFIRestore(StringRef IDVal,
+						SMLoc DirectiveLoc) {
+  int64_t Register = 0;
+  if (ParseRegisterOrRegisterNumber(Register, DirectiveLoc))
+    return true;
+
+  getStreamer().EmitCFIRestore(Register);
+
+  return false;
+}
+
 /// ParseDirectiveCFIEscape
 /// ::= .cfi_escape expression[,...]
 bool GenericAsmParser::ParseDirectiveCFIEscape(StringRef IDVal,
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 4169188cbb..8567941c45 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -408,6 +408,15 @@ void MCStreamer::EmitCFISameValue(int64_t Register) {
   CurFrame->Instructions.push_back(Instruction);
 }
 
+void MCStreamer::EmitCFIRestore(int64_t Register) {
+  EnsureValidFrame();
+  MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
+  MCSymbol *Label = getContext().CreateTempSymbol();
+  EmitLabel(Label);
+  MCCFIInstruction Instruction(MCCFIInstruction::Restore, Label, Register);
+  CurFrame->Instructions.push_back(Instruction);
+}
+
 void MCStreamer::EmitCFIEscape(StringRef Values) {
   EnsureValidFrame();
   MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
diff --git a/test/MC/ELF/cfi-restore.s b/test/MC/ELF/cfi-restore.s
new file mode 100644
index 0000000000..0fc3129c71
--- /dev/null
+++ b/test/MC/ELF/cfi-restore.s
@@ -0,0 +1,42 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck %s
+
+f:
+	.cfi_startproc
+        nop
+	.cfi_restore %rbp
+        nop
+	.cfi_endproc
+
+// CHECK:       # Section 4
+// CHECK-NEXT:  (('sh_name', 0x00000011) # '.eh_frame'
+// CHECK-NEXT:   ('sh_type', 0x00000001)
+// CHECK-NEXT:   ('sh_flags', 0x0000000000000002)
+// CHECK-NEXT:   ('sh_addr', 0x0000000000000000)
+// CHECK-NEXT:   ('sh_offset', 0x0000000000000048)
+// CHECK-NEXT:   ('sh_size', 0x0000000000000030)
+// CHECK-NEXT:   ('sh_link', 0x00000000)
+// CHECK-NEXT:   ('sh_info', 0x00000000)
+// CHECK-NEXT:   ('sh_addralign', 0x0000000000000008)
+// CHECK-NEXT:   ('sh_entsize', 0x0000000000000000)
+// CHECK-NEXT:   ('_section_data', '14000000 00000000 017a5200 01781001 1b0c0708 90010000 14000000 1c000000 00000000 02000000 0041c600 00000000')
+// CHECK-NEXT:  ),
+// CHECK-NEXT:  # Section 5
+// CHECK-NEXT:  (('sh_name', 0x0000000c) # '.rela.eh_frame'
+// CHECK-NEXT:   ('sh_type', 0x00000004)
+// CHECK-NEXT:   ('sh_flags', 0x0000000000000000)
+// CHECK-NEXT:   ('sh_addr', 0x0000000000000000)
+// CHECK-NEXT:   ('sh_offset', 0x0000000000000390)
+// CHECK-NEXT:   ('sh_size', 0x0000000000000018)
+// CHECK-NEXT:   ('sh_link', 0x00000007)
+// CHECK-NEXT:   ('sh_info', 0x00000004)
+// CHECK-NEXT:   ('sh_addralign', 0x0000000000000008)
+// CHECK-NEXT:   ('sh_entsize', 0x0000000000000018)
+// CHECK-NEXT:   ('_relocations', [
+// CHECK-NEXT:    # Relocation 0
+// CHECK-NEXT:    (('r_offset', 0x0000000000000020)
+// CHECK-NEXT:     ('r_sym', 0x00000002)
+// CHECK-NEXT:     ('r_type', 0x00000002)
+// CHECK-NEXT:     ('r_addend', 0x0000000000000000)
+// CHECK-NEXT:    ),
+// CHECK-NEXT:   ])
+// CHECK-NEXT:  ),