| ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=sse | 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) { |
| ; 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) { |
| ; 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 |
| } |
| |
| ; If we're bitcasting an integer to an FP vector, we should avoid the FPU/vector unit entirely. |
| ; Make sure that we're flipping the sign bit and only the sign bit of each float. |
| ; So instead of something like this: |
| ; movd %rdi, %xmm0 |
| ; xorps .LCPI2_0(%rip), %xmm0 |
| ; |
| ; We should generate: |
| ; movabsq (put sign bit mask in integer register)) |
| ; xorq (flip sign bits) |
| ; movd (move to xmm return register) |
| |
| define <2 x float> @fneg_bitcast(i64 %i) { |
| ; CHECK-LABEL: fneg_bitcast: |
| ; CHECK: movabsq $-9223372034707292160, %rax # imm = 0x8000000080000000 |
| ; CHECK-NEXT: xorq %rdi, %rax |
| ; CHECK-NEXT: movd %rax, %xmm0 |
| ; CHECK-NEXT: retq |
| %bitcast = bitcast i64 %i to <2 x float> |
| %fneg = fsub <2 x float> <float -0.0, float -0.0>, %bitcast |
| ret <2 x float> %fneg |
| } |