[X86] Add a one use check to the setcc inversion code in combineVSelectWithAllOnesOrZeros

If we're going to generate a new inverted setcc, we should make sure we will be able to remove the old setcc.

Differential Revision: https://reviews.llvm.org/D56765

llvm-svn: 351378

2 files changed, 13 insertions, 16 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 9e17f4c455a..ece273302e6 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -33923,8 +33923,8 @@ combineVSelectWithAllOnesOrZeros(SDNode *N, SelectionDAG &DAG,
   bool FValIsAllZeros = ISD::isBuildVectorAllZeros(RHS.getNode());
 
   // Try to invert the condition if true value is not all 1s and false value is
-  // not all 0s.
-  if (!TValIsAllOnes && !FValIsAllZeros &&
+  // not all 0s. Only do this if the condition has one use.
+  if (!TValIsAllOnes && !FValIsAllZeros && Cond.hasOneUse() &&
       // Check if the selector will be produced by CMPP*/PCMP*.
       Cond.getOpcode() == ISD::SETCC &&
       // Check if SETCC has already been promoted.
diff --git a/llvm/test/CodeGen/X86/vselect.ll b/llvm/test/CodeGen/X86/vselect.ll
index 81baca29fc0..f29e53d0143 100644
--- a/llvm/test/CodeGen/X86/vselect.ll
+++ b/llvm/test/CodeGen/X86/vselect.ll
@@ -617,26 +617,23 @@ define void @vselect_allzeros_LHS_multiple_use_setcc(<4 x i32> %x, <4 x i32> %y,
 ; SSE:       # %bb.0:
 ; SSE-NEXT:    movdqa {{.*#+}} xmm3 = [1,2,4,8]
 ; SSE-NEXT:    pand %xmm3, %xmm0
-; SSE-NEXT:    pcmpeqd %xmm0, %xmm3
-; SSE-NEXT:    pxor %xmm4, %xmm4
-; SSE-NEXT:    pcmpeqd %xmm0, %xmm4
-; SSE-NEXT:    pand %xmm1, %xmm4
-; SSE-NEXT:    pand %xmm2, %xmm3
-; SSE-NEXT:    movdqa %xmm4, (%rdi)
-; SSE-NEXT:    movdqa %xmm3, (%rsi)
+; SSE-NEXT:    pcmpeqd %xmm3, %xmm0
+; SSE-NEXT:    movdqa %xmm0, %xmm3
+; SSE-NEXT:    pandn %xmm1, %xmm3
+; SSE-NEXT:    pand %xmm2, %xmm0
+; SSE-NEXT:    movdqa %xmm3, (%rdi)
+; SSE-NEXT:    movdqa %xmm0, (%rsi)
 ; SSE-NEXT:    retq
 ;
 ; AVX-LABEL: vselect_allzeros_LHS_multiple_use_setcc:
 ; AVX:       # %bb.0:
 ; AVX-NEXT:    vmovdqa {{.*#+}} xmm3 = [1,2,4,8]
 ; AVX-NEXT:    vpand %xmm3, %xmm0, %xmm0
-; AVX-NEXT:    vpcmpeqd %xmm3, %xmm0, %xmm3
-; AVX-NEXT:    vpxor %xmm4, %xmm4, %xmm4
-; AVX-NEXT:    vpcmpeqd %xmm4, %xmm0, %xmm0
-; AVX-NEXT:    vpand %xmm1, %xmm0, %xmm0
-; AVX-NEXT:    vpand %xmm2, %xmm3, %xmm1
-; AVX-NEXT:    vmovdqa %xmm0, (%rdi)
-; AVX-NEXT:    vmovdqa %xmm1, (%rsi)
+; AVX-NEXT:    vpcmpeqd %xmm3, %xmm0, %xmm0
+; AVX-NEXT:    vpandn %xmm1, %xmm0, %xmm1
+; AVX-NEXT:    vpand %xmm2, %xmm0, %xmm0
+; AVX-NEXT:    vmovdqa %xmm1, (%rdi)
+; AVX-NEXT:    vmovdqa %xmm0, (%rsi)
 ; AVX-NEXT:    retq
   %and = and <4 x i32> %x, <i32 1, i32 2, i32 4, i32 8>
   %cond = icmp ne <4 x i32> %and, zeroinitializer