[RISCV] Add CFI directives for RISCV prologue/epilog.

In order to generate correct debug frame information, it needs to
generate CFI information in prologue and epilog.

Differential Revision: https://reviews.llvm.org/D61773

llvm-svn: 363120

2 files changed, 8 insertions, 1 deletions

diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCAsmInfo.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCAsmInfo.cpp
index 51106cd4e64..98362969288 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCAsmInfo.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCAsmInfo.cpp
@@ -21,6 +21,7 @@ RISCVMCAsmInfo::RISCVMCAsmInfo(const Triple &TT) {
   CommentString = "#";
   AlignmentIsInBytes = false;
   SupportsDebugInformation = true;
+  ExceptionsType = ExceptionHandling::DwarfCFI;
   Data16bitsDirective = "\t.half\t";
   Data32bitsDirective = "\t.word\t";
 }
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
index d920fd203d8..bc45262ab2d 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
@@ -50,7 +50,13 @@ static MCRegisterInfo *createRISCVMCRegisterInfo(const Triple &TT) {
 
 static MCAsmInfo *createRISCVMCAsmInfo(const MCRegisterInfo &MRI,
                                        const Triple &TT) {
-  return new RISCVMCAsmInfo(TT);
+  MCAsmInfo *MAI = new RISCVMCAsmInfo(TT);
+
+  unsigned SP = MRI.getDwarfRegNum(RISCV::X2, true);
+  MCCFIInstruction Inst = MCCFIInstruction::createDefCfa(nullptr, SP, 0);
+  MAI->addInitialFrameState(Inst);
+
+  return MAI;
 }
 
 static MCSubtargetInfo *createRISCVMCSubtargetInfo(const Triple &TT,