[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.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 6e6324a..9befd02 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -2608,3 +2608,13 @@
     Result = Builder.CreateTrunc(Result, Builder.getInt32Ty());
   return Result;
 }
+
+unsigned RISCVTargetLowering::getExceptionPointerRegister(
+    const Constant *PersonalityFn) const {
+  return RISCV::X10;
+}
+
+unsigned RISCVTargetLowering::getExceptionSelectorRegister(
+    const Constant *PersonalityFn) const {
+  return RISCV::X11;
+}