1 files changed, 40 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/fold-buildvector-bug.ll b/llvm/test/CodeGen/X86/fold-buildvector-bug.ll
new file mode 100644
index 00000000000..76deab7edae
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fold-buildvector-bug.ll
@@ -0,0 +1,40 @@
+; RUN: llc -mtriple=x86_64-unknown-unknown -mattr=+sse4.1 < %s | FileCheck %s
+
+; Verify that the DAGCombiner doesn't wrongly fold a build_vector into a
+; blend with a zero vector if the build_vector contains negative zero.
+;
+; TODO: the codegen for function 'test_negative_zero_1' is sub-optimal.
+; Ideally, we should generate a single shuffle blend operation.
+
+define <4 x float> @test_negative_zero_1(<4 x float> %A) {
+; CHECK-LABEL: test_negative_zero_1:
+; CHECK:       # BB#0: # %entry
+; CHECK-NEXT:    movapd %xmm0, %xmm1
+; CHECK-NEXT:    shufpd {{.*#+}} xmm1 = xmm1[1,0]
+; CHECK-NEXT:    xorps %xmm2, %xmm2
+; CHECK-NEXT:    blendps {{.*#+}} xmm2 = xmm1[0],xmm2[1,2,3]
+; CHECK-NEXT:    movss {{.*#+}} xmm1 = mem[0],zero,zero,zero
+; CHECK-NEXT:    unpcklps {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]
+; CHECK-NEXT:    unpcklpd {{.*#+}} xmm0 = xmm0[0],xmm2[0]
+; CHECK-NEXT:    retq
+entry:
+  %0 = extractelement <4 x float> %A, i32 0
+  %1 = insertelement <4 x float> undef, float %0, i32 0
+  %2 = insertelement <4 x float> %1, float -0.0, i32 1
+  %3 = extractelement <4 x float> %A, i32 2
+  %4 = insertelement <4 x float> %2, float %3, i32 2
+  %5 = insertelement <4 x float> %4, float 0.0, i32 3
+  ret <4 x float> %5
+}
+
+define <2 x double> @test_negative_zero_2(<2 x double> %A) {
+; CHECK-LABEL: test_negative_zero_2:
+; CHECK:       # BB#0: # %entry
+; CHECK-NEXT:    movhpd {{.*}}(%rip), %xmm0
+; CHECK-NEXT:    retq
+entry:
+  %0 = extractelement <2 x double> %A, i32 0
+  %1 = insertelement <2 x double> undef, double %0, i32 0
+  %2 = insertelement <2 x double> %1, double -0.0, i32 1
+  ret <2 x double> %2
+}