From ebf46143eaf7fa3ad956baf8cc876cbe2c6ae306 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Tue, 18 Sep 2018 02:34:54 +0000
Subject: [PATCH] AMDGPU: Don't form fmed3 if it will require materialization

If there is a single use constant, it can be folded into the
min/max, but not into med3.

llvm-svn: 342443
---
 llvm/lib/Target/AMDGPU/SIISelLowering.cpp | 11 +++++-
 llvm/test/CodeGen/AMDGPU/clamp.ll         |  4 +-
 llvm/test/CodeGen/AMDGPU/fmed3.ll         | 62 +++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 47217a0..3de6a54 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -7733,8 +7733,15 @@ SDValue SITargetLowering::performFPMed3ImmCombine(SelectionDAG &DAG,
     if (!DAG.isKnownNeverSNaN(Var))
       return SDValue();
 
-    return DAG.getNode(AMDGPUISD::FMED3, SL, K0->getValueType(0),
-                       Var, SDValue(K0, 0), SDValue(K1, 0));
+    const SIInstrInfo *TII = getSubtarget()->getInstrInfo();
+
+    if ((!K0->hasOneUse() ||
+         TII->isInlineConstant(K0->getValueAPF().bitcastToAPInt())) &&
+        (!K1->hasOneUse() ||
+         TII->isInlineConstant(K1->getValueAPF().bitcastToAPInt()))) {
+      return DAG.getNode(AMDGPUISD::FMED3, SL, K0->getValueType(0),
+                         Var, SDValue(K0, 0), SDValue(K1, 0));
+    }
   }
 
   return SDValue();
diff --git a/llvm/test/CodeGen/AMDGPU/clamp.ll b/llvm/test/CodeGen/AMDGPU/clamp.ll
index ec9ec10..e73f286 100644
--- a/llvm/test/CodeGen/AMDGPU/clamp.ll
+++ b/llvm/test/CodeGen/AMDGPU/clamp.ll
@@ -54,8 +54,8 @@ define amdgpu_kernel void @v_clamp_negabs_f32(float addrspace(1)* %out, float ad
 ; GCN-LABEL: {{^}}v_clamp_negzero_f32:
 ; GCN-DAG: {{buffer|flat|global}}_load_dword [[A:v[0-9]+]]
 ; GCN-DAG: v_add_f32_e32 [[ADD:v[0-9]+]], 0.5, [[A]]
-; GCN-DAG: s_brev_b32 [[SIGNBIT:s[0-9]+]], 1
-; GCN: v_med3_f32 v{{[0-9]+}}, [[ADD]], [[SIGNBIT]], 1.0
+; GCN: v_max_f32_e32 [[MAX:v[0-9]+]], 0x80000000, [[ADD]]
+; GCN: v_min_f32_e32 v{{[0-9]+}}, 1.0, [[MAX]]
 define amdgpu_kernel void @v_clamp_negzero_f32(float addrspace(1)* %out, float addrspace(1)* %aptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
diff --git a/llvm/test/CodeGen/AMDGPU/fmed3.ll b/llvm/test/CodeGen/AMDGPU/fmed3.ll
index e27f430..8b88167 100644
--- a/llvm/test/CodeGen/AMDGPU/fmed3.ll
+++ b/llvm/test/CodeGen/AMDGPU/fmed3.ll
@@ -951,6 +951,68 @@ define amdgpu_kernel void @v_nnan_inputs_med3_f16_pat0(half addrspace(1)* %out,
   ret void
 }
 
+; GCN-LABEL: {{^}}two_non_inline_constant:
+; GCN: v_add_f32_e32 [[ADD:v[0-9]+]], 0.5,
+; GCN: v_max_f32_e32 [[MAX:v[0-9]+]], 0x41000000, [[ADD]]
+; GCN: v_min_f32_e32 v{{[0-9]+}}, 0x41800000, [[MAX]]
+define amdgpu_kernel void @two_non_inline_constant(float addrspace(1)* %out, float addrspace(1)* %aptr) #1 {
+  %tid = call i32 @llvm.amdgcn.workitem.id.x()
+  %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
+  %out.gep = getelementptr float, float addrspace(1)* %out, i32 %tid
+  %a = load float, float addrspace(1)* %gep0
+  %add = fadd nnan float %a, 0.5
+  %max = call float @llvm.maxnum.f32(float %add, float 8.0)
+  %med = call float @llvm.minnum.f32(float %max, float 16.0)
+
+  store float %med, float addrspace(1)* %out.gep
+  ret void
+}
+
+; FIXME: Simple stores do not work as a multiple use because they are bitcasted to integer constants.
+; GCN-LABEL: {{^}}one_non_inline_constant:
+; GCN-DAG: s_mov_b32 [[K1:s[0-9]+]], 0x41800000
+; GCN-DAG: v_add_f32_e32 [[ADD:v[0-9]+]], 0.5,
+; GCN: v_med3_f32 v{{[0-9]+}}, [[ADD]], 1.0, [[K1]]
+define amdgpu_kernel void @one_non_inline_constant(float addrspace(1)* %out, float addrspace(1)* %aptr) #1 {
+  %tid = call i32 @llvm.amdgcn.workitem.id.x()
+  %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
+  %out.gep = getelementptr float, float addrspace(1)* %out, i32 %tid
+  %a = load float, float addrspace(1)* %gep0
+  %add = fadd nnan float %a, 0.5
+  %max = call float @llvm.maxnum.f32(float %add, float 1.0)
+  %med = call float @llvm.minnum.f32(float %max, float 16.0)
+
+  store float %med, float addrspace(1)* %out.gep
+
+  %extra.use = fadd float %a, 16.0
+  store volatile float %extra.use, float addrspace(1)* undef
+  ret void
+}
+
+; GCN-LABEL: {{^}}two_non_inline_constant_multi_use:
+; GCN-DAG: s_mov_b32 [[K1:s[0-9]+]], 0x41800000
+; GCN-DAG: s_mov_b32 [[K0:s[0-9]+]], 0x41000000
+; GCN-DAG: v_mov_b32_e32 [[VK1:v[0-9]+]], [[K1]]
+; GCN-DAG: v_add_f32_e32 [[ADD:v[0-9]+]], 0.5,
+; GCN: v_med3_f32 v{{[0-9]+}}, [[ADD]], [[K0]], [[VK1]]
+define amdgpu_kernel void @two_non_inline_constant_multi_use(float addrspace(1)* %out, float addrspace(1)* %aptr) #1 {
+  %tid = call i32 @llvm.amdgcn.workitem.id.x()
+  %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
+  %out.gep = getelementptr float, float addrspace(1)* %out, i32 %tid
+  %a = load float, float addrspace(1)* %gep0
+  %add = fadd nnan float %a, 0.5
+  %max = call float @llvm.maxnum.f32(float %add, float 8.0)
+  %med = call float @llvm.minnum.f32(float %max, float 16.0)
+
+  store float %med, float addrspace(1)* %out.gep
+
+  %extra.use0 = fadd float %a, 16.0
+  store volatile float %extra.use0, float addrspace(1)* undef
+  %extra.use1 = fadd float %a, 8.0
+  store volatile float %extra.use1, float addrspace(1)* undef
+  ret void
+}
+
 declare i32 @llvm.amdgcn.workitem.id.x() #0
 declare float @llvm.fabs.f32(float) #0
 declare float @llvm.minnum.f32(float, float) #0
-- 
2.7.4