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llvm-mirror/test/CodeGen/AMDGPU/fold-fmul-to-neg-abs.ll
Stanislav Mekhanoshin 0b47718863 Fold fneg and fabs like multiplications
Given no NaNs and no signed zeroes it folds:

(fmul X, (select (fcmp X > 0.0), -1.0, 1.0)) -> (fneg (fabs X))
(fmul X, (select (fcmp X > 0.0), 1.0, -1.0)) -> (fabs X)

Differential Revision: https://reviews.llvm.org/D34579

llvm-svn: 306592
2017-06-28 20:25:50 +00:00

38 lines
1.4 KiB
LLVM

; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck -check-prefix=GCN %s
; GCN-LABEL: {{^}}fold_mul_neg:
; GCN: load_dword [[V:v[0-9]+]]
; GCN: v_or_b32_e32 [[NEG:v[0-9]]], 0x80000000, [[V]]
; GCN: store_dword [[NEG]]
define amdgpu_kernel void @fold_mul_neg(float addrspace(1)* %arg) {
%tid = tail call i32 @llvm.amdgcn.workitem.id.x()
%gep = getelementptr inbounds float, float addrspace(1)* %arg, i32 %tid
%v = load float, float addrspace(1)* %gep, align 4
%cmp = fcmp fast ogt float %v, 0.000000e+00
%sel = select i1 %cmp, float -1.000000e+00, float 1.000000e+00
%mul = fmul fast float %v, %sel
store float %mul, float addrspace(1)* %gep, align 4
ret void
}
; GCN-LABEL: {{^}}fold_mul_abs:
; GCN: load_dword [[V:v[0-9]+]]
; GCN: v_and_b32_e32 [[ABS:v[0-9]]], 0x7fffffff, [[V]]
; GCN: store_dword [[ABS]]
define amdgpu_kernel void @fold_mul_abs(float addrspace(1)* %arg) {
%tid = tail call i32 @llvm.amdgcn.workitem.id.x()
%gep = getelementptr inbounds float, float addrspace(1)* %arg, i32 %tid
%v = load float, float addrspace(1)* %gep, align 4
%cmp = fcmp fast olt float %v, 0.000000e+00
%sel = select i1 %cmp, float -1.000000e+00, float 1.000000e+00
%mul = fmul fast float %v, %sel
store float %mul, float addrspace(1)* %gep, align 4
ret void
}
declare i32 @llvm.amdgcn.workitem.id.x() #0
attributes #0 = { nounwind readnone speculatable }