[RISCV] Fix a crash in RISCVGatherScatterLowering

We were assuming that the constant must always be fixed length when this is not required. Such code is unlikely after optimization, which is why we didn't see this previously.
llvm · Apr 16, 2023 · d4773c6 · d4773c6
1 parent 8308e81
commit d4773c6
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 0 deletions.
diff --git a/llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp b/llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
@@ -107,6 +107,9 @@ bool RISCVGatherScatterLowering::isLegalTypeAndAlignment(Type *DataType,
 
 // TODO: Should we consider the mask when looking for a stride?
 static std::pair<Value *, Value *> matchStridedConstant(Constant *StartC) {
+  if (!isa<FixedVectorType>(StartC->getType()))
+    return std::make_pair(nullptr, nullptr);
+
   unsigned NumElts = cast<FixedVectorType>(StartC->getType())->getNumElements();
 
   // Check that the start value is a strided constant.

diff --git a/llvm/test/CodeGen/RISCV/rvv/strided-load-store.ll b/llvm/test/CodeGen/RISCV/rvv/strided-load-store.ll
@@ -135,6 +135,23 @@ define void @scatter_loopless(<vscale x 1 x i64> %x, ptr %p, i64 %stride) {
   ret void
 }
 
+; We previously crashed expecting a constant to be fixed length.
+define void @constant_stride(<vscale x 1 x i64> %x, ptr %p, i64 %stride) {
+; CHECK-LABEL: @constant_stride(
+; CHECK-NEXT:    [[PTRS:%.*]] = getelementptr i32, ptr [[P:%.*]], <vscale x 1 x i64> zeroinitializer
+; CHECK-NEXT:    call void @llvm.masked.scatter.nxv1i64.nxv1p0(<vscale x 1 x i64> [[X:%.*]], <vscale x 1 x ptr> [[PTRS]], i32 8, <vscale x 1 x i1> shufflevector (<vscale x 1 x i1> insertelement (<vscale x 1 x i1> poison, i1 true, i64 0), <vscale x 1 x i1> poison, <vscale x 1 x i32> zeroinitializer))
+; CHECK-NEXT:    ret void
+;
+  %ptrs = getelementptr i32, ptr %p, <vscale x 1 x i64> zeroinitializer
+  call void @llvm.masked.scatter.nxv1i64.nxv1p0(
+  <vscale x 1 x i64> %x,
+  <vscale x 1 x ptr> %ptrs,
+  i32 8,
+  <vscale x 1 x i1> shufflevector (<vscale x 1 x i1> insertelement (<vscale x 1 x i1> poison, i1 1, i64 0), <vscale x 1 x i1> poison, <vscale x 1 x i32> zeroinitializer)
+  )
+  ret void
+}
+
 declare i64 @llvm.vscale.i64()
 declare void @llvm.masked.scatter.nxv1i64.nxv1p0(<vscale x 1 x i64>, <vscale x 1 x ptr>, i32, <vscale x 1 x i1>)
 declare <vscale x 1 x i64> @llvm.masked.gather.nxv1i64.nxv1p0(<vscale x 1 x ptr>, i32, <vscale x 1 x i1>, <vscale x 1 x i64>)