[PATCH] D80164: [WebAssembly] Fix bug in custom shuffle combine

[Thomas Lively via Phabricator via llvm-commits]

tlively created this revision.
tlively added a reviewer: aheejin.
Herald added subscribers: llvm-commits, sunfish, hiraditya, jgravelle-google, sbc100, dschuff.
Herald added a project: LLVM.

The code previously assumed the source of the bitcast in the combined
pattern was a vector type, but this is not always true. This patch
adds a check to avoid an assertion failure in that case.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80164

Files:
  llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
  llvm/test/CodeGen/WebAssembly/simd-shuffle-bitcast.ll


Index: llvm/test/CodeGen/WebAssembly/simd-shuffle-bitcast.ll
===================================================================
--- llvm/test/CodeGen/WebAssembly/simd-shuffle-bitcast.ll
+++ llvm/test/CodeGen/WebAssembly/simd-shuffle-bitcast.ll
@@ -17,3 +17,14 @@
   %b = shufflevector <4 x i32> %a, <4 x i32> undef, <4 x i32> zeroinitializer
   ret <4 x i32> %b
 }
+
+; CHECK-LABEL: not_a_vec:
+; CHECK-NEXT: .functype not_a_vec (i64, i64) -> (v128){{$}}
+; CHECK-NEXT: i64x2.splat $push[[L1:[0-9]+]]=, $0{{$}}
+; CHECK-NEXT: v8x16.shuffle $push[[R:[0-9]+]]=, $pop[[L1]], $2, 0, 1, 2, 3
+; CHECK-NEXT: return $pop[[R]]
+define <4 x i32> @not_a_vec(i128 %x) {
+  %a = bitcast i128 %x to <4 x i32>
+  %b = shufflevector <4 x i32> %a, <4 x i32> undef, <4 x i32> zeroinitializer
+  ret <4 x i32> %b
+}
Index: llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -1725,7 +1725,8 @@
   SDValue CastOp = Bitcast.getOperand(0);
   MVT SrcType = CastOp.getSimpleValueType();
   MVT DstType = Bitcast.getSimpleValueType();
-  if (SrcType.getVectorNumElements() != DstType.getVectorNumElements())
+  if (!SrcType.is128BitVector() ||
+      SrcType.getVectorNumElements() != DstType.getVectorNumElements())
     return SDValue();
   SDValue NewShuffle = DAG.getVectorShuffle(
       SrcType, SDLoc(N), CastOp, DAG.getUNDEF(SrcType), Shuffle->getMask());


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