[PATCH] R600/SI: Add fmin and fmax intrinsics

[Tom Stellard]

On Thu, Nov 20, 2014 at 07:05:27PM +0100, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
> 
> For some reason, clamp isn't moved into the instruction. I always get this:
>    v_min_f32     v0, -abs(v5), -abs(v1)
>    v_add_f32     v0, 0, v0 clamp
> 

Clamp folding has not been implemented yet, which is why there is an
extra instruction.

Mesa should be using llvm.minnum.f32 and llvm.maxnum.f32 intrinsics
for LLVM >=3.6, because these are lowered directly to V_MIN_F32 and
V_MAX_F32.

I can accept this patch for the 3.5 branch, with one change mentioned
below:

> v2: add tests
> ---
>  lib/Target/R600/AMDGPUIntrinsics.td   |  2 ++
>  lib/Target/R600/SIInstructions.td     |  9 +++++++++
>  test/CodeGen/R600/llvm.AMDGPU.fmax.ll | 21 +++++++++++++++++++++
>  test/CodeGen/R600/llvm.AMDGPU.fmin.ll | 21 +++++++++++++++++++++
>  4 files changed, 53 insertions(+)
>  create mode 100644 test/CodeGen/R600/llvm.AMDGPU.fmax.ll
>  create mode 100644 test/CodeGen/R600/llvm.AMDGPU.fmin.ll
> 
> diff --git a/lib/Target/R600/AMDGPUIntrinsics.td b/lib/Target/R600/AMDGPUIntrinsics.td
> index eee9c29..3ee4023 100644
> --- a/lib/Target/R600/AMDGPUIntrinsics.td
> +++ b/lib/Target/R600/AMDGPUIntrinsics.td
> @@ -50,6 +50,8 @@ let TargetPrefix = "AMDGPU", isTarget = 1 in {
>    def int_AMDGPU_trunc : Intrinsic<[llvm_float_ty], [llvm_float_ty], [IntrNoMem]>;
>    def int_AMDGPU_ddx : Intrinsic<[llvm_v4f32_ty], [llvm_v4f32_ty, llvm_i32_ty, llvm_i32_ty, llvm_i32_ty], [IntrNoMem]>;
>    def int_AMDGPU_ddy : Intrinsic<[llvm_v4f32_ty], [llvm_v4f32_ty, llvm_i32_ty, llvm_i32_ty, llvm_i32_ty], [IntrNoMem]>;
> +  def int_AMDGPU_fmax : Intrinsic<[llvm_float_ty], [llvm_float_ty, llvm_float_ty], [IntrNoMem]>;
> +  def int_AMDGPU_fmin : Intrinsic<[llvm_float_ty], [llvm_float_ty, llvm_float_ty], [IntrNoMem]>;
>    def int_AMDGPU_imax : Intrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty], [IntrNoMem]>;
>    def int_AMDGPU_imin : Intrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty], [IntrNoMem]>;
>    def int_AMDGPU_umax : Intrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty], [IntrNoMem]>;
> diff --git a/lib/Target/R600/SIInstructions.td b/lib/Target/R600/SIInstructions.td
> index 90da7a9..27fdff9 100644
> --- a/lib/Target/R600/SIInstructions.td
> +++ b/lib/Target/R600/SIInstructions.td
> @@ -2517,6 +2517,15 @@ def : Pat <
>  /* llvm.AMDGPU.pow */
>  def : POW_Common <V_LOG_F32_e32, V_EXP_F32_e32, V_MUL_LEGACY_F32_e32>;
>  
> +class VOP2Pat <SDPatternOperator pattern, InstSI inst> : Pat <
> +  (pattern (VOP3Mods0 f32:$src0, i32:$src0_modifiers, i1:$clamp, i32:$omod),
> +           (VOP3Mods f32:$src1, i32:$src1_modifiers)),
> +  (inst $src0_modifiers, $src0, $src1_modifiers, $src1, $clamp, $omod)
> +>;
> +
> +def : VOP2Pat <int_AMDGPU_fmin, V_MIN_F32_e64>;
> +def : VOP2Pat <int_AMDGPU_fmax, V_MAX_F32_e64>;
> +

For 3.5, we don't need to add stand-alone patterns, we
can add the pattern to the instruction definition.

-Tom

>  def : Pat <
>    (int_AMDGPU_div f32:$src0, f32:$src1),
>    (V_MUL_LEGACY_F32_e32 $src0, (V_RCP_LEGACY_F32_e32 $src1))
> diff --git a/test/CodeGen/R600/llvm.AMDGPU.fmax.ll b/test/CodeGen/R600/llvm.AMDGPU.fmax.ll
> new file mode 100644
> index 0000000..e01143e
> --- /dev/null
> +++ b/test/CodeGen/R600/llvm.AMDGPU.fmax.ll
> @@ -0,0 +1,21 @@
> +; RUN: llc < %s -march=r600 -mcpu=verde -verify-machineinstrs | FileCheck -check-prefix=SI %s
> +
> +; SI-LABEL: {{^}}vector_fmax:
> +; SI: v_max_f32_e32
> +define void @vector_fmax(float %p0, float addrspace(1)* %in) #0 {
> +main_body:
> +  %load = load float addrspace(1)* %in, align 4
> +  %max = call float @llvm.AMDGPU.fmax(float %p0, float %load)
> +  call void @llvm.SI.export(i32 15, i32 1, i32 1, i32 0, i32 0, float %max, float %max, float %max, float %max)
> +  ret void
> +}
> +
> +; Function Attrs: readnone
> +declare float @llvm.AMDGPU.fmax(float, float) #1
> +
> +declare void @llvm.SI.export(i32, i32, i32, i32, i32, float, float, float, float)
> +
> +attributes #0 = { nounwind }
> +attributes #1 = { nounwind readnone }
> +
> +!0 = metadata !{metadata !"const", null, i32 1}
> diff --git a/test/CodeGen/R600/llvm.AMDGPU.fmin.ll b/test/CodeGen/R600/llvm.AMDGPU.fmin.ll
> new file mode 100644
> index 0000000..b8b40ca
> --- /dev/null
> +++ b/test/CodeGen/R600/llvm.AMDGPU.fmin.ll
> @@ -0,0 +1,21 @@
> +; RUN: llc < %s -march=r600 -mcpu=verde -verify-machineinstrs | FileCheck -check-prefix=SI %s
> +
> +; SI-LABEL: {{^}}vector_fmin:
> +; SI: v_min_f32_e32
> +define void @vector_fmin(float %p0, float addrspace(1)* %in) #0 {
> +main_body:
> +  %load = load float addrspace(1)* %in, align 4
> +  %min = call float @llvm.AMDGPU.fmin(float %p0, float %load)
> +  call void @llvm.SI.export(i32 15, i32 1, i32 1, i32 0, i32 0, float %min, float %min, float %min, float %min)
> +  ret void
> +}
> +
> +; Function Attrs: readnone
> +declare float @llvm.AMDGPU.fmin(float, float) #1
> +
> +declare void @llvm.SI.export(i32, i32, i32, i32, i32, float, float, float, float)
> +
> +attributes #0 = { nounwind }
> +attributes #1 = { nounwind readnone }
> +
> +!0 = metadata !{metadata !"const", null, i32 1}
> -- 
> 2.1.0
> 
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