[WinEH] Fix eh.exceptionpointer intrinsic lowering

[JosephTremoulet]

Summary

Some shared code for handling eh.exceptionpointer and eh.exceptioncode
needs to not share the part that truncates to 32 bits, which is intended
just for exception codes.

[rnk]

lgtm

lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
   case Intrinsic::eh_exceptioncode: {
     // Get the exception pointer vreg, copy from it, and resize it to fit.
     const auto *CPI = cast<CatchPadInst>(I.getArgOperand(0));
     MVT PtrVT = TLI.getPointerTy(DAG.getDataLayout());
     const TargetRegisterClass *PtrRC = TLI.getRegClassFor(PtrVT);
     unsigned VReg = FuncInfo.getCatchPadExceptionPointerVReg(CPI, PtrRC);
     SDValue N =
         DAG.getCopyFromReg(DAG.getEntryNode(), getCurSDLoc(), VReg, PtrVT);
+    if (Intrinsic == Intrinsic::eh_exceptioncode)
       N = DAG.getZExtOrTrunc(N, getCurSDLoc(), MVT::i32);
     setValue(&I, N);
     return nullptr;
   }
   }
 }
 
 std::pair<SDValue, SDValue>
 SelectionDAGBuilder::lowerInvokable(TargetLowering::CallLoweringInfo &CLI,

test/CodeGen/WinEH/wineh-exceptionpointer.ll

+; RUN: llc -mtriple=x86_64-pc-windows-coreclr < %s | FileCheck %s
+
+declare void @ProcessCLRException()
+declare i8 addrspace(1)* @llvm.eh.exceptionpointer.p1i8(token)
+declare void @f()
+declare void @g(i32 addrspace(1)*)
+
+; CHECK-LABEL: test1: # @test1
+define void @test1() personality i8* bitcast (void ()* @ProcessCLRException to i8*) {
+entry:
+  invoke void @f()
+    to label %exit unwind label %catch.pad
+catch.pad:
+; CHECK: {{^[^: ]+}}: # %catch.pad
+  %catch = catchpad [i32 5]
+    to label %catch.body unwind label %catch.end
+catch.body:
+  %exn = call i8 addrspace(1)* @llvm.eh.exceptionpointer.p1i8(token %catch)
+  %cast_exn = bitcast i8 addrspace(1)* %exn to i32 addrspace(1)*
+  ; CHECK: movq %rax, %rcx
+  ; CHECK-NEXT: callq g
+  call void @g(i32 addrspace(1)* %cast_exn)
+  catchret %catch to label %exit
+catch.end:
+  catchendpad unwind to caller
+exit:
+  ret void
+}