[AVX-512] Fix lowering for mask register concatenation with undef in the lower half.

Previously this test case fired an assertion in getNode because we tried to create an insert_subvector with both input types the same size and the index pointing to half the vector width.

llvm-svn: 293446

2 files changed, 13 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 88b3c2ee267..e5ff4dc8828 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -7791,7 +7791,7 @@ static SDValue LowerCONCAT_VECTORSvXi1(SDValue Op,
 
   SDValue IdxVal = DAG.getIntPtrConstant(NumElems/2, dl);
   if (V1.isUndef())
-    V2 = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResVT, Undef, V2, IdxVal);
+    return DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResVT, Undef, V2, IdxVal);
 
   if (IsZeroV1)
     return DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResVT, ZeroVec, V2, IdxVal);
diff --git a/llvm/test/CodeGen/X86/avx512-skx-insert-subvec.ll b/llvm/test/CodeGen/X86/avx512-skx-insert-subvec.ll
index 2200f115988..3a93b544b95 100644
--- a/llvm/test/CodeGen/X86/avx512-skx-insert-subvec.ll
+++ b/llvm/test/CodeGen/X86/avx512-skx-insert-subvec.ll
@@ -167,3 +167,15 @@ define <2 x i1> @test10(<4 x i1> %a, <4 x i1> %b) {
   %res = shufflevector <4 x i1> %a, <4 x i1> %b, <2 x i32> <i32 2, i32 3>
   ret <2 x i1> %res
 }
+
+define <8 x i1> @test11(<4 x i1> %a, <4 x i1>%b) {
+; CHECK-LABEL: test11:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    vpslld $31, %xmm0, %xmm0
+; CHECK-NEXT:    vptestmd %xmm0, %xmm0, %k0
+; CHECK-NEXT:    kshiftlb $4, %k0, %k0
+; CHECK-NEXT:    vpmovm2w %k0, %xmm0
+; CHECK-NEXT:    retq
+  %res = shufflevector <4 x i1> %a, <4 x i1> undef, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 undef, i32 0, i32 1, i32 2, i32 3>
+  ret <8 x i1> %res
+}