Fix a test that has no checks.

X86 doesn't have fneg, so check for xor.

Differential Revision: http://reviews.llvm.org/D4812

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214992 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/CodeGen/X86/vec_fneg.ll b/test/CodeGen/X86/vec_fneg.ll
index d49c70e..00383be 100644 (file)
--- a/test/CodeGen/X86/vec_fneg.ll
+++ b/test/CodeGen/X86/vec_fneg.ll
@@ -1,11 +1,23 @@
-; RUN: llc < %s -march=x86 -mattr=+sse2
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=corei7 | FileCheck %s
 
+; FNEG is defined as subtraction from -0.0.
+
+; This test verifies that we use an xor with a constant to flip the sign bits; no subtraction needed.
 define <4 x float> @t1(<4 x float> %Q) {
-        %tmp15 = fsub <4 x float> < float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00 >, %Q
-       ret <4 x float> %tmp15
+; CHECK-LABEL: t1:
+; CHECK: xorps {{.*}}LCPI0_0{{.*}}, %xmm0
+; CHECK-NEXT: retq
+        %tmp = fsub <4 x float> < float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00 >, %Q
+       ret <4 x float> %tmp
 }
 
+; This test verifies that we generate an FP subtraction because "0.0 - x" is not an fneg.
 define <4 x float> @t2(<4 x float> %Q) {
-        %tmp15 = fsub <4 x float> zeroinitializer, %Q
-       ret <4 x float> %tmp15
+; CHECK-LABEL: t2:
+; CHECK: xorps %[[X:xmm[0-9]+]], %[[X]]
+; CHECK-NEXT: subps    %xmm0, %[[X]]
+; CHECK-NEXT: movaps   %[[X]], %xmm0
+; CHECK-NEXT: retq
+        %tmp = fsub <4 x float> zeroinitializer, %Q
+       ret <4 x float> %tmp
 }