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llvm-mirror/test/CodeGen/AMDGPU/amdgpu-codegenprepare-fdiv.ll
Stanislav Mekhanoshin c39b2b753b [AMDGPU] Always use rcp + mul with fast math 
Regardless of relaxation options such as -cl-fast-relaxed-math
we are producing rather long code for fdiv via amdgcn_fdiv_fast
intrinsic. This intrinsic is used to replace fdiv with 2.5ulp
metadata and does not handle denormals, thus believed to be fast.

An fdiv instruction can also have fast math flag either by itself
or together with fpmath metadata. Clang used with a relaxation flag
always produces both metadata and fast flag:

%div = fdiv fast float %v, %0, !fpmath !12
!12 = !{float 2.500000e+00}

Current implementation ignores fast flag and favors metadata. An
instruction with just fast flag would be lowered to a fastest rcp +
mul, but that never happen on practice because of described mutual
clang and BE behavior.

This change allows an "fdiv fast" to be always lowered as rcp + mul.

Differential Revision: https://reviews.llvm.org/D34844

llvm-svn: 307308
2017-07-06 20:34:21 +00:00

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; RUN: opt -S -mtriple=amdgcn-- -amdgpu-codegenprepare %s | FileCheck %s
; RUN: opt -S -amdgpu-codegenprepare %s | FileCheck -check-prefix=NOOP %s
; Make sure this doesn't crash with no triple
; NOOP-LABEL: @noop_fdiv_fpmath(
; NOOP: %md.25ulp = fdiv float %a, %b, !fpmath !0
define amdgpu_kernel void @noop_fdiv_fpmath(float addrspace(1)* %out, float %a, float %b) #3 {
%md.25ulp = fdiv float %a, %b, !fpmath !0
store volatile float %md.25ulp, float addrspace(1)* %out
ret void
}
; CHECK-LABEL: @fdiv_fpmath(
; CHECK: %no.md = fdiv float %a, %b{{$}}
; CHECK: %md.half.ulp = fdiv float %a, %b, !fpmath !1
; CHECK: %md.1ulp = fdiv float %a, %b, !fpmath !2
; CHECK: %md.25ulp = call float @llvm.amdgcn.fdiv.fast(float %a, float %b), !fpmath !0
; CHECK: %md.3ulp = call float @llvm.amdgcn.fdiv.fast(float %a, float %b), !fpmath !3
; CHECK: %fast.md.25ulp = fdiv fast float %a, %b, !fpmath !0
; CHECK: arcp.md.25ulp = fdiv arcp float %a, %b, !fpmath !0
define amdgpu_kernel void @fdiv_fpmath(float addrspace(1)* %out, float %a, float %b) #1 {
%no.md = fdiv float %a, %b
store volatile float %no.md, float addrspace(1)* %out
%md.half.ulp = fdiv float %a, %b, !fpmath !1
store volatile float %md.half.ulp, float addrspace(1)* %out
%md.1ulp = fdiv float %a, %b, !fpmath !2
store volatile float %md.1ulp, float addrspace(1)* %out
%md.25ulp = fdiv float %a, %b, !fpmath !0
store volatile float %md.25ulp, float addrspace(1)* %out
%md.3ulp = fdiv float %a, %b, !fpmath !3
store volatile float %md.3ulp, float addrspace(1)* %out
%fast.md.25ulp = fdiv fast float %a, %b, !fpmath !0
store volatile float %fast.md.25ulp, float addrspace(1)* %out
%arcp.md.25ulp = fdiv arcp float %a, %b, !fpmath !0
store volatile float %arcp.md.25ulp, float addrspace(1)* %out
ret void
}
; CHECK-LABEL: @rcp_fdiv_fpmath(
; CHECK: %no.md = fdiv float 1.000000e+00, %x{{$}}
; CHECK: %md.25ulp = fdiv float 1.000000e+00, %x, !fpmath !0
; CHECK: %md.half.ulp = fdiv float 1.000000e+00, %x, !fpmath !1
; CHECK: %arcp.no.md = fdiv arcp float 1.000000e+00, %x{{$}}
; CHECK: %arcp.25ulp = fdiv arcp float 1.000000e+00, %x, !fpmath !0
; CHECK: %fast.no.md = fdiv fast float 1.000000e+00, %x{{$}}
; CHECK: %fast.25ulp = fdiv fast float 1.000000e+00, %x, !fpmath !0
define amdgpu_kernel void @rcp_fdiv_fpmath(float addrspace(1)* %out, float %x) #1 {
%no.md = fdiv float 1.0, %x
store volatile float %no.md, float addrspace(1)* %out
%md.25ulp = fdiv float 1.0, %x, !fpmath !0
store volatile float %md.25ulp, float addrspace(1)* %out
%md.half.ulp = fdiv float 1.0, %x, !fpmath !1
store volatile float %md.half.ulp, float addrspace(1)* %out
%arcp.no.md = fdiv arcp float 1.0, %x
store volatile float %arcp.no.md, float addrspace(1)* %out
%arcp.25ulp = fdiv arcp float 1.0, %x, !fpmath !0
store volatile float %arcp.25ulp, float addrspace(1)* %out
%fast.no.md = fdiv fast float 1.0, %x
store volatile float %fast.no.md, float addrspace(1)* %out
%fast.25ulp = fdiv fast float 1.0, %x, !fpmath !0
store volatile float %fast.25ulp, float addrspace(1)* %out
ret void
}
; CHECK-LABEL: @fdiv_fpmath_vector(
; CHECK: %no.md = fdiv <2 x float> %a, %b{{$}}
; CHECK: %md.half.ulp = fdiv <2 x float> %a, %b, !fpmath !1
; CHECK: %md.1ulp = fdiv <2 x float> %a, %b, !fpmath !2
; CHECK: %[[A0:[0-9]+]] = extractelement <2 x float> %a, i64 0
; CHECK: %[[B0:[0-9]+]] = extractelement <2 x float> %b, i64 0
; CHECK: %[[FDIV0:[0-9]+]] = call float @llvm.amdgcn.fdiv.fast(float %[[A0]], float %[[B0]]), !fpmath !0
; CHECK: %[[INS0:[0-9]+]] = insertelement <2 x float> undef, float %[[FDIV0]], i64 0
; CHECK: %[[A1:[0-9]+]] = extractelement <2 x float> %a, i64 1
; CHECK: %[[B1:[0-9]+]] = extractelement <2 x float> %b, i64 1
; CHECK: %[[FDIV1:[0-9]+]] = call float @llvm.amdgcn.fdiv.fast(float %[[A1]], float %[[B1]]), !fpmath !0
; CHECK: %md.25ulp = insertelement <2 x float> %[[INS0]], float %[[FDIV1]], i64 1
define amdgpu_kernel void @fdiv_fpmath_vector(<2 x float> addrspace(1)* %out, <2 x float> %a, <2 x float> %b) #1 {
%no.md = fdiv <2 x float> %a, %b
store volatile <2 x float> %no.md, <2 x float> addrspace(1)* %out
%md.half.ulp = fdiv <2 x float> %a, %b, !fpmath !1
store volatile <2 x float> %md.half.ulp, <2 x float> addrspace(1)* %out
%md.1ulp = fdiv <2 x float> %a, %b, !fpmath !2
store volatile <2 x float> %md.1ulp, <2 x float> addrspace(1)* %out
%md.25ulp = fdiv <2 x float> %a, %b, !fpmath !0
store volatile <2 x float> %md.25ulp, <2 x float> addrspace(1)* %out
ret void
}
; CHECK-LABEL: @rcp_fdiv_fpmath_vector(
; CHECK: %no.md = fdiv <2 x float> <float 1.000000e+00, float 1.000000e+00>, %x{{$}}
; CHECK: %md.half.ulp = fdiv <2 x float> <float 1.000000e+00, float 1.000000e+00>, %x, !fpmath !1
; CHECK: %arcp.no.md = fdiv arcp <2 x float> <float 1.000000e+00, float 1.000000e+00>, %x{{$}}
; CHECK: %fast.no.md = fdiv fast <2 x float> <float 1.000000e+00, float 1.000000e+00>, %x{{$}}
; CHECK: %arcp.25ulp = fdiv arcp <2 x float> <float 1.000000e+00, float 1.000000e+00>, %x, !fpmath !0
; CHECK: %fast.25ulp = fdiv fast <2 x float> <float 1.000000e+00, float 1.000000e+00>, %x, !fpmath !0
; CHECK: store volatile <2 x float> %fast.25ulp, <2 x float> addrspace(1)* %out
define amdgpu_kernel void @rcp_fdiv_fpmath_vector(<2 x float> addrspace(1)* %out, <2 x float> %x) #1 {
%no.md = fdiv <2 x float> <float 1.0, float 1.0>, %x
store volatile <2 x float> %no.md, <2 x float> addrspace(1)* %out
%md.half.ulp = fdiv <2 x float> <float 1.0, float 1.0>, %x, !fpmath !1
store volatile <2 x float> %md.half.ulp, <2 x float> addrspace(1)* %out
%arcp.no.md = fdiv arcp <2 x float> <float 1.0, float 1.0>, %x
store volatile <2 x float> %arcp.no.md, <2 x float> addrspace(1)* %out
%fast.no.md = fdiv fast <2 x float> <float 1.0, float 1.0>, %x
store volatile <2 x float> %fast.no.md, <2 x float> addrspace(1)* %out
%arcp.25ulp = fdiv arcp <2 x float> <float 1.0, float 1.0>, %x, !fpmath !0
store volatile <2 x float> %arcp.25ulp, <2 x float> addrspace(1)* %out
%fast.25ulp = fdiv fast <2 x float> <float 1.0, float 1.0>, %x, !fpmath !0
store volatile <2 x float> %fast.25ulp, <2 x float> addrspace(1)* %out
ret void
}
; CHECK-LABEL: @rcp_fdiv_fpmath_vector_nonsplat(
; CHECK: %no.md = fdiv <2 x float> <float 1.000000e+00, float 2.000000e+00>, %x
; CHECK: %arcp.no.md = fdiv arcp <2 x float> <float 1.000000e+00, float 2.000000e+00>, %x
; CHECK: %fast.no.md = fdiv fast <2 x float> <float 1.000000e+00, float 2.000000e+00>, %x{{$}}
; CHECK: %arcp.25ulp = fdiv arcp <2 x float> <float 1.000000e+00, float 2.000000e+00>, %x, !fpmath !0
; CHECK: %fast.25ulp = fdiv fast <2 x float> <float 1.000000e+00, float 2.000000e+00>, %x, !fpmath !0
; CHECK: store volatile <2 x float> %fast.25ulp
define amdgpu_kernel void @rcp_fdiv_fpmath_vector_nonsplat(<2 x float> addrspace(1)* %out, <2 x float> %x) #1 {
%no.md = fdiv <2 x float> <float 1.0, float 2.0>, %x
store volatile <2 x float> %no.md, <2 x float> addrspace(1)* %out
%arcp.no.md = fdiv arcp <2 x float> <float 1.0, float 2.0>, %x
store volatile <2 x float> %arcp.no.md, <2 x float> addrspace(1)* %out
%fast.no.md = fdiv fast <2 x float> <float 1.0, float 2.0>, %x
store volatile <2 x float> %fast.no.md, <2 x float> addrspace(1)* %out
%arcp.25ulp = fdiv arcp <2 x float> <float 1.0, float 2.0>, %x, !fpmath !0
store volatile <2 x float> %arcp.25ulp, <2 x float> addrspace(1)* %out
%fast.25ulp = fdiv fast <2 x float> <float 1.0, float 2.0>, %x, !fpmath !0
store volatile <2 x float> %fast.25ulp, <2 x float> addrspace(1)* %out
ret void
}
; FIXME: Should be able to get fdiv for 1.0 component
; CHECK-LABEL: @rcp_fdiv_fpmath_vector_partial_constant(
; CHECK: %arcp.25ulp = fdiv arcp <2 x float> %x.insert, %y, !fpmath !0
; CHECK: store volatile <2 x float> %arcp.25ulp
; CHECK: %fast.25ulp = fdiv fast <2 x float> %x.insert, %y, !fpmath !0
; CHECK: store volatile <2 x float> %fast.25ulp
define amdgpu_kernel void @rcp_fdiv_fpmath_vector_partial_constant(<2 x float> addrspace(1)* %out, <2 x float> %x, <2 x float> %y) #1 {
%x.insert = insertelement <2 x float> %x, float 1.0, i32 0
%arcp.25ulp = fdiv arcp <2 x float> %x.insert, %y, !fpmath !0
store volatile <2 x float> %arcp.25ulp, <2 x float> addrspace(1)* %out
%fast.25ulp = fdiv fast <2 x float> %x.insert, %y, !fpmath !0
store volatile <2 x float> %fast.25ulp, <2 x float> addrspace(1)* %out
ret void
}
; CHECK-LABEL: @fdiv_fpmath_f32_denormals(
; CHECK: %no.md = fdiv float %a, %b{{$}}
; CHECK: %md.half.ulp = fdiv float %a, %b, !fpmath !1
; CHECK: %md.1ulp = fdiv float %a, %b, !fpmath !2
; CHECK: %md.25ulp = fdiv float %a, %b, !fpmath !0
; CHECK: %md.3ulp = fdiv float %a, %b, !fpmath !3
; CHECK: %fast.md.25ulp = fdiv fast float %a, %b, !fpmath !0
; CHECK: %arcp.md.25ulp = fdiv arcp float %a, %b, !fpmath !0
define amdgpu_kernel void @fdiv_fpmath_f32_denormals(float addrspace(1)* %out, float %a, float %b) #2 {
%no.md = fdiv float %a, %b
store volatile float %no.md, float addrspace(1)* %out
%md.half.ulp = fdiv float %a, %b, !fpmath !1
store volatile float %md.half.ulp, float addrspace(1)* %out
%md.1ulp = fdiv float %a, %b, !fpmath !2
store volatile float %md.1ulp, float addrspace(1)* %out
%md.25ulp = fdiv float %a, %b, !fpmath !0
store volatile float %md.25ulp, float addrspace(1)* %out
%md.3ulp = fdiv float %a, %b, !fpmath !3
store volatile float %md.3ulp, float addrspace(1)* %out
%fast.md.25ulp = fdiv fast float %a, %b, !fpmath !0
store volatile float %fast.md.25ulp, float addrspace(1)* %out
%arcp.md.25ulp = fdiv arcp float %a, %b, !fpmath !0
store volatile float %arcp.md.25ulp, float addrspace(1)* %out
ret void
}
attributes #0 = { nounwind optnone noinline }
attributes #1 = { nounwind }
attributes #2 = { nounwind "target-features"="+fp32-denormals" }
; CHECK: !0 = !{float 2.500000e+00}
; CHECK: !1 = !{float 5.000000e-01}
; CHECK: !2 = !{float 1.000000e+00}
; CHECK: !3 = !{float 3.000000e+00}
!0 = !{float 2.500000e+00}
!1 = !{float 5.000000e-01}
!2 = !{float 1.000000e+00}
!3 = !{float 3.000000e+00}
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