[X86] Standardize floating point assembly comments

Consistently try to use APFloat::toString for floating point constant comments to get rid of differences between Constant / ConstantDataSequential values - it should help stop some of the linux-windows buildbot failures matching NaN/INF etc. as well.

Differential Revision: https://reviews.llvm.org/D52702

llvm-svn: 343562
diff --git a/llvm/test/CodeGen/X86/pow.ll b/llvm/test/CodeGen/X86/pow.ll
index 639f7dd..f170488 100644
--- a/llvm/test/CodeGen/X86/pow.ll
+++ b/llvm/test/CodeGen/X86/pow.ll
@@ -56,11 +56,11 @@
 ; CHECK-NEXT:    rsqrtps %xmm0, %xmm1
 ; CHECK-NEXT:    movaps %xmm0, %xmm2
 ; CHECK-NEXT:    mulps %xmm1, %xmm2
-; CHECK-NEXT:    movaps {{.*#+}} xmm3 = [-5.000000e-01,-5.000000e-01,-5.000000e-01,-5.000000e-01]
+; CHECK-NEXT:    movaps {{.*#+}} xmm3 = [-0.5,-0.5,-0.5,-0.5]
 ; CHECK-NEXT:    movaps %xmm2, %xmm4
 ; CHECK-NEXT:    mulps %xmm3, %xmm4
 ; CHECK-NEXT:    mulps %xmm1, %xmm2
-; CHECK-NEXT:    movaps {{.*#+}} xmm1 = [-3.000000e+00,-3.000000e+00,-3.000000e+00,-3.000000e+00]
+; CHECK-NEXT:    movaps {{.*#+}} xmm1 = [-3,-3,-3,-3]
 ; CHECK-NEXT:    addps %xmm1, %xmm2
 ; CHECK-NEXT:    mulps %xmm4, %xmm2
 ; CHECK-NEXT:    xorps %xmm4, %xmm4