From 9de0a3da6a76030f96a2d6793ca4f094fa538db5 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Mon, 7 Sep 2020 16:11:40 +0100
Subject: [PATCH] [X86][SSE] Don't use LowerVSETCCWithSUBUS for unsigned
 compare with +ve operands (PR47448)

We already simplify the unsigned comparisons if we've found the operands are non-negative, but we were still calling LowerVSETCCWithSUBUS which resulted in the PR47448 regressions.
---
 llvm/lib/Target/X86/X86ISelLowering.cpp      |  6 +++--
 llvm/test/CodeGen/X86/vector-unsigned-cmp.ll | 33 ++++++++++------------------
 2 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index a8a41d9..1395db5 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -22731,8 +22731,10 @@ static SDValue LowerVSETCC(SDValue Op, const X86Subtarget &Subtarget,
   }
 
   // Try to use SUBUS and PCMPEQ.
-  if (SDValue V = LowerVSETCCWithSUBUS(Op0, Op1, VT, Cond, dl, Subtarget, DAG))
-    return V;
+  if (FlipSigns)
+    if (SDValue V =
+            LowerVSETCCWithSUBUS(Op0, Op1, VT, Cond, dl, Subtarget, DAG))
+      return V;
 
   // We are handling one of the integer comparisons here. Since SSE only has
   // GT and EQ comparisons for integer, swapping operands and multiple
diff --git a/llvm/test/CodeGen/X86/vector-unsigned-cmp.ll b/llvm/test/CodeGen/X86/vector-unsigned-cmp.ll
index c770729..d6849a9 100644
--- a/llvm/test/CodeGen/X86/vector-unsigned-cmp.ll
+++ b/llvm/test/CodeGen/X86/vector-unsigned-cmp.ll
@@ -285,9 +285,9 @@ define <8 x i1> @uge_v8i16(<8 x i16> %x, <8 x i16> %y) {
 ; SSE2:       # %bb.0:
 ; SSE2-NEXT:    psrlw $1, %xmm0
 ; SSE2-NEXT:    psrlw $1, %xmm1
-; SSE2-NEXT:    psubusw %xmm0, %xmm1
-; SSE2-NEXT:    pxor %xmm0, %xmm0
-; SSE2-NEXT:    pcmpeqw %xmm1, %xmm0
+; SSE2-NEXT:    pcmpgtw %xmm0, %xmm1
+; SSE2-NEXT:    pcmpeqd %xmm0, %xmm0
+; SSE2-NEXT:    pxor %xmm1, %xmm0
 ; SSE2-NEXT:    retq
 ;
 ; SSE41-LABEL: uge_v8i16:
@@ -316,9 +316,9 @@ define <8 x i1> @ule_v8i16(<8 x i16> %x, <8 x i16> %y) {
 ; SSE2:       # %bb.0:
 ; SSE2-NEXT:    psrlw $1, %xmm0
 ; SSE2-NEXT:    psrlw $1, %xmm1
-; SSE2-NEXT:    psubusw %xmm1, %xmm0
-; SSE2-NEXT:    pxor %xmm1, %xmm1
-; SSE2-NEXT:    pcmpeqw %xmm1, %xmm0
+; SSE2-NEXT:    pcmpgtw %xmm1, %xmm0
+; SSE2-NEXT:    pcmpeqd %xmm1, %xmm1
+; SSE2-NEXT:    pxor %xmm1, %xmm0
 ; SSE2-NEXT:    retq
 ;
 ; SSE41-LABEL: ule_v8i16:
@@ -459,9 +459,9 @@ define <8 x i16> @PR47448_uge(i16 signext %0) {
 ; SSE2-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,0,0,0,4,5,6,7]
 ; SSE2-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; SSE2-NEXT:    movdqa {{.*#+}} xmm1 = [0,1,2,3,4,5,6,7]
-; SSE2-NEXT:    psubusw %xmm0, %xmm1
-; SSE2-NEXT:    pxor %xmm0, %xmm0
-; SSE2-NEXT:    pcmpeqw %xmm1, %xmm0
+; SSE2-NEXT:    pcmpgtw %xmm0, %xmm1
+; SSE2-NEXT:    pcmpeqd %xmm0, %xmm0
+; SSE2-NEXT:    pxor %xmm1, %xmm0
 ; SSE2-NEXT:    retq
 ;
 ; SSE41-LABEL: PR47448_uge:
@@ -508,10 +508,7 @@ define <8 x i16> @PR47448_ugt(i16 signext %0) {
 ; SSE-NEXT:    movd %edi, %xmm0
 ; SSE-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,0,0,0,4,5,6,7]
 ; SSE-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
-; SSE-NEXT:    movdqa {{.*#+}} xmm1 = [1,2,3,4,5,6,7,8]
-; SSE-NEXT:    psubusw %xmm0, %xmm1
-; SSE-NEXT:    pxor %xmm0, %xmm0
-; SSE-NEXT:    pcmpeqw %xmm1, %xmm0
+; SSE-NEXT:    pcmpgtw {{.*}}(%rip), %xmm0
 ; SSE-NEXT:    retq
 ;
 ; AVX1-LABEL: PR47448_ugt:
@@ -520,10 +517,7 @@ define <8 x i16> @PR47448_ugt(i16 signext %0) {
 ; AVX1-NEXT:    vmovd %edi, %xmm0
 ; AVX1-NEXT:    vpshuflw {{.*#+}} xmm0 = xmm0[0,0,0,0,4,5,6,7]
 ; AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
-; AVX1-NEXT:    vmovdqa {{.*#+}} xmm1 = [1,2,3,4,5,6,7,8]
-; AVX1-NEXT:    vpsubusw %xmm0, %xmm1, %xmm0
-; AVX1-NEXT:    vpxor %xmm1, %xmm1, %xmm1
-; AVX1-NEXT:    vpcmpeqw %xmm1, %xmm0, %xmm0
+; AVX1-NEXT:    vpcmpgtw {{.*}}(%rip), %xmm0, %xmm0
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: PR47448_ugt:
@@ -531,10 +525,7 @@ define <8 x i16> @PR47448_ugt(i16 signext %0) {
 ; AVX2-NEXT:    andl $7, %edi
 ; AVX2-NEXT:    vmovd %edi, %xmm0
 ; AVX2-NEXT:    vpbroadcastw %xmm0, %xmm0
-; AVX2-NEXT:    vmovdqa {{.*#+}} xmm1 = [1,2,3,4,5,6,7,8]
-; AVX2-NEXT:    vpsubusw %xmm0, %xmm1, %xmm0
-; AVX2-NEXT:    vpxor %xmm1, %xmm1, %xmm1
-; AVX2-NEXT:    vpcmpeqw %xmm1, %xmm0, %xmm0
+; AVX2-NEXT:    vpcmpgtw {{.*}}(%rip), %xmm0, %xmm0
 ; AVX2-NEXT:    retq
   %2 = and i16 %0, 7
   %3 = insertelement <8 x i16> undef, i16 %2, i32 0
-- 
2.7.4