1; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=sse | FileCheck %s 2 3; FNEG is defined as subtraction from -0.0. 4 5; This test verifies that we use an xor with a constant to flip the sign bits; no subtraction needed. 6define <4 x float> @t1(<4 x float> %Q) { 7; CHECK-LABEL: t1: 8; CHECK: xorps {{.*}}LCPI0_0{{.*}}, %xmm0 9; CHECK-NEXT: retq 10 %tmp = fsub <4 x float> < float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00 >, %Q 11 ret <4 x float> %tmp 12} 13 14; This test verifies that we generate an FP subtraction because "0.0 - x" is not an fneg. 15define <4 x float> @t2(<4 x float> %Q) { 16; CHECK-LABEL: t2: 17; CHECK: xorps %[[X:xmm[0-9]+]], %[[X]] 18; CHECK-NEXT: subps %xmm0, %[[X]] 19; CHECK-NEXT: movaps %[[X]], %xmm0 20; CHECK-NEXT: retq 21 %tmp = fsub <4 x float> zeroinitializer, %Q 22 ret <4 x float> %tmp 23} 24 25; If we're bitcasting an integer to an FP vector, we should avoid the FPU/vector unit entirely. 26; Make sure that we're flipping the sign bit and only the sign bit of each float. 27; So instead of something like this: 28; movd %rdi, %xmm0 29; xorps .LCPI2_0(%rip), %xmm0 30; 31; We should generate: 32; movabsq (put sign bit mask in integer register)) 33; xorq (flip sign bits) 34; movd (move to xmm return register) 35 36define <2 x float> @fneg_bitcast(i64 %i) { 37; CHECK-LABEL: fneg_bitcast: 38; CHECK: movabsq $-9223372034707292160, %rax # imm = 0x8000000080000000 39; CHECK-NEXT: xorq %rdi, %rax 40; CHECK-NEXT: movd %rax, %xmm0 41; CHECK-NEXT: retq 42 %bitcast = bitcast i64 %i to <2 x float> 43 %fneg = fsub <2 x float> <float -0.0, float -0.0>, %bitcast 44 ret <2 x float> %fneg 45} 46