mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-28 04:33:05 +00:00
9615d702ad
This patch allows a vector fneg of a bitcasted integer value to be optimized in the same way that we already optimize a scalar fneg. If the integer variable is a constant, we can precompute the result and not require any logic ops. This patch is very similar to a fabs patch committed at r214892. Differential Revision: http://reviews.llvm.org/D4852 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215646 91177308-0d34-0410-b5e6-96231b3b80d8
46 lines
1.6 KiB
LLVM
46 lines
1.6 KiB
LLVM
; 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) {
|
|
; 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
|
|
}
|