[RISCV] Fix a codegen crash in getSetCCResultType

This patch fixes some crashes coming from
`RISCVISelLowering::getSetCCResultType`, which would occasionally return
an EVT constructed from an invalid MVT, which has a null Type pointer.

The attached test shows this happening currently for some fixed-length
vectors, which hit this issue when the V extension was enabled, even
though they're not legal types under the V extension. The fix was also
pre-emptively extended to scalable vectors which can't be represented as
an MVT, even though a test case couldn't be found for them.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D95434

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 97f46d9..9bf1d70 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -481,12 +481,13 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
   }
 }
 
-EVT RISCVTargetLowering::getSetCCResultType(const DataLayout &DL, LLVMContext &,
+EVT RISCVTargetLowering::getSetCCResultType(const DataLayout &DL,
+                                            LLVMContext &Context,
                                             EVT VT) const {
   if (!VT.isVector())
     return getPointerTy(DL);
-  if (Subtarget.hasStdExtV())
-    return MVT::getVectorVT(MVT::i1, VT.getVectorElementCount());
+  if (Subtarget.hasStdExtV() && VT.isScalableVector())
+    return EVT::getVectorVT(Context, MVT::i1, VT.getVectorElementCount());
   return VT.changeVectorElementTypeToInteger();
 }