[RISCV] Specify registers used in DWARF exception handling

Defines RISCV registers for getExceptionPointerRegister() and
getExceptionSelectorRegister().

Differential Revision: https://reviews.llvm.org/D63411
Patch by Edward Jones.
Modified by Alex Bradbury to add CHECK lines to exception-pointer-register.ll.

llvm-svn: 365301
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.h b/llvm/lib/Target/RISCV/RISCVISelLowering.h
index db11ec8..17db03b 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.h
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.h
@@ -131,6 +131,16 @@
   bool isDesirableToCommuteWithShift(const SDNode *N,
                                      CombineLevel Level) const override;
 
+  /// If a physical register, this returns the register that receives the
+  /// exception address on entry to an EH pad.
+  unsigned
+  getExceptionPointerRegister(const Constant *PersonalityFn) const override;
+
+  /// If a physical register, this returns the register that receives the
+  /// exception typeid on entry to a landing pad.
+  unsigned
+  getExceptionSelectorRegister(const Constant *PersonalityFn) const override;
+
 private:
   void analyzeInputArgs(MachineFunction &MF, CCState &CCInfo,
                         const SmallVectorImpl<ISD::InputArg> &Ins,