[PATCH] D42379: [DAGCombiner] Bail out if vector size is not a multiple

[Sven van Haastregt via Phabricator via llvm-commits]

svenvh created this revision.
svenvh added reviewers: arsenm, RKSimon.
Herald added subscribers: nhaehnle, wdng.

For the included test case, visitCONCAT_VECTORS would attempt to
create a v2i32 vector for a v9i8 concat_vector.  Bail out to avoid
creating a bitcast with mismatching sizes later on.


https://reviews.llvm.org/D42379

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/AMDGPU/concat_vectors.ll


Index: test/CodeGen/AMDGPU/concat_vectors.ll
===================================================================
--- test/CodeGen/AMDGPU/concat_vectors.ll
+++ test/CodeGen/AMDGPU/concat_vectors.ll
@@ -294,3 +294,15 @@
   store <8 x float> %tmp2, <8 x float> addrspace(1)* %out, align 32
   ret void
 }
+
+; FUNC-LABEL: {{^}}concat_vector_crash2:
+; SI: s_endpgm
+define amdgpu_kernel void @concat_vector_crash2(<8 x i8> addrspace(1)* %out, i32 addrspace(1)* %in) {
+  %tmp = load i32, i32 addrspace(1)* %in, align 1
+  %tmp1 = trunc i32 %tmp to i24
+  %tmp2 = bitcast i24 %tmp1 to <3 x i8>
+  %tmp3 = shufflevector <3 x i8> %tmp2, <3 x i8> undef, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 1, i32 undef, i32 undef>
+  %tmp4 = shufflevector <8 x i8> %tmp3, <8 x i8> <i8 undef, i8 undef, i8 undef, i8 undef, i8 undef, i8 undef, i8 7, i8 8>, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 14, i32 15>
+  store <8 x i8> %tmp4, <8 x i8> addrspace(1)* %out, align 8
+  ret void
+}
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -15188,6 +15188,10 @@
       if (!SclTy.isFloatingPoint() && !SclTy.isInteger())
         return SDValue();
 
+      // Bail out if the vector size is not a multiple of the scalar size.
+      if (VT.getSizeInBits() % SclTy.getSizeInBits())
+        return SDValue();
+
       unsigned VNTNumElms = VT.getSizeInBits() / SclTy.getSizeInBits();
       if (VNTNumElms < 2)
         return SDValue();


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