[AMDGPU] Prefer fmac over fma when selecting FMA_W_CHAIN

FMA_W_CHAIN is used when lowering fdiv f32. Prefer to select it to fmac
if there are no source modifiers, just like we do for other mad/mac and
fma/fmac cases.

Differential Revision: https://reviews.llvm.org/D110074

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp b/llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
index c56fd0b..5aa89e9 100644 (file)
--- a/llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
@@ -1210,7 +1210,14 @@ void AMDGPUDAGToDAGISel::SelectFMA_W_CHAIN(SDNode *N) {
   Ops[8] = N->getOperand(0);
   Ops[9] = N->getOperand(4);
 
-  CurDAG->SelectNodeTo(N, AMDGPU::V_FMA_F32_e64, N->getVTList(), Ops);
+  // If there are no source modifiers, prefer fmac over fma because it can use
+  // the smaller VOP2 encoding.
+  bool UseFMAC = Subtarget->hasDLInsts() &&
+                 cast<ConstantSDNode>(Ops[0])->isZero() &&
+                 cast<ConstantSDNode>(Ops[2])->isZero() &&
+                 cast<ConstantSDNode>(Ops[4])->isZero();
+  unsigned Opcode = UseFMAC ? AMDGPU::V_FMAC_F32_e64 : AMDGPU::V_FMA_F32_e64;
+  CurDAG->SelectNodeTo(N, Opcode, N->getVTList(), Ops);
 }
 
 void AMDGPUDAGToDAGISel::SelectFMUL_W_CHAIN(SDNode *N) {

diff --git a/llvm/test/CodeGen/AMDGPU/fdiv.ll b/llvm/test/CodeGen/AMDGPU/fdiv.ll
index a11c864..a460099 100644 (file)
--- a/llvm/test/CodeGen/AMDGPU/fdiv.ll
+++ b/llvm/test/CodeGen/AMDGPU/fdiv.ll
@@ -21,10 +21,12 @@
 ; PREGFX10: s_setreg_imm32_b32 hwreg(HW_REG_MODE, 4, 2), 3
 ; GFX10: s_denorm_mode 15
 ; GCN: v_fma_f32 [[A:v[0-9]+]], -[[NUM_SCALE]], [[NUM_RCP]], 1.0
-; GCN: v_fma_f32 [[B:v[0-9]+]], [[A]], [[NUM_RCP]], [[NUM_RCP]]
+; PREGFX10: v_fma_f32 [[B:v[0-9]+]], [[A]], [[NUM_RCP]], [[NUM_RCP]]
+; GFX10: v_fmac_f32_e32 [[B:v[0-9]+]], [[A]], [[NUM_RCP]]
 ; GCN: v_mul_f32_e32 [[C:v[0-9]+]], [[DEN_SCALE]], [[B]]
 ; GCN: v_fma_f32 [[D:v[0-9]+]], -[[NUM_SCALE]], [[C]], [[DEN_SCALE]]
-; GCN: v_fma_f32 [[E:v[0-9]+]], [[D]], [[B]], [[C]]
+; PREGFX10: v_fma_f32 [[E:v[0-9]+]], [[D]], [[B]], [[C]]
+; GFX10: v_fmac_f32_e32 [[E:v[0-9]+]], [[D]], [[B]]
 ; GCN: v_fma_f32 [[F:v[0-9]+]], -[[NUM_SCALE]], [[E]], [[DEN_SCALE]]
 ; PREGFX10: s_setreg_imm32_b32 hwreg(HW_REG_MODE, 4, 2), 0
 ; GFX10: s_denorm_mode 12
@@ -293,10 +295,12 @@ define amdgpu_kernel void @fdiv_v4f32_arcp_math(<4 x float> addrspace(1)* %out,
 ; PREGFX10: s_setreg_imm32_b32 hwreg(HW_REG_MODE, 4, 2), 3
 ; GFX10: s_denorm_mode 15
 ; GCN: v_fma_f32 [[A:v[0-9]+]], -[[NUM_SCALE]], [[NUM_RCP]], 1.0
-; GCN: v_fma_f32 [[B:v[0-9]+]], [[A]], [[NUM_RCP]], [[NUM_RCP]]
+; PREGFX10: v_fma_f32 [[B:v[0-9]+]], [[A]], [[NUM_RCP]], [[NUM_RCP]]
+; GFX10: v_fmac_f32_e32 [[B:v[0-9]+]], [[A]], [[NUM_RCP]]
 ; GCN: v_mul_f32_e32 [[C:v[0-9]+]], [[DEN_SCALE]], [[B]]
 ; GCN: v_fma_f32 [[D:v[0-9]+]], -[[NUM_SCALE]], [[C]], [[DEN_SCALE]]
-; GCN: v_fma_f32 [[E:v[0-9]+]], [[D]], [[B]], [[C]]
+; PREGFX10: v_fma_f32 [[E:v[0-9]+]], [[D]], [[B]], [[C]]
+; GFX10: v_fmac_f32_e32 [[E:v[0-9]+]], [[D]], [[B]]
 ; GCN: v_fma_f32 [[F:v[0-9]+]], -[[NUM_SCALE]], [[E]], [[DEN_SCALE]]
 ; PREGFX10: s_setreg_imm32_b32 hwreg(HW_REG_MODE, 4, 2), 0
 ; GFX10: s_denorm_mode 12

diff --git a/llvm/test/CodeGen/AMDGPU/frem.ll b/llvm/test/CodeGen/AMDGPU/frem.ll
index 942f23e..239750e 100644 (file)
--- a/llvm/test/CodeGen/AMDGPU/frem.ll
+++ b/llvm/test/CodeGen/AMDGPU/frem.ll
@@ -566,10 +566,10 @@ define amdgpu_kernel void @frem_f32(float addrspace(1)* %out, float addrspace(1)
 ; GFX10-NEXT:    v_rcp_f32_e32 v5, v4
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v6, -v4, v5, 1.0
-; GFX10-NEXT:    v_fma_f32 v5, v6, v5, v5
+; GFX10-NEXT:    v_fmac_f32_e32 v5, v6, v5
 ; GFX10-NEXT:    v_mul_f32_e32 v6, v3, v5
 ; GFX10-NEXT:    v_fma_f32 v7, -v4, v6, v3
-; GFX10-NEXT:    v_fma_f32 v6, v7, v5, v6
+; GFX10-NEXT:    v_fmac_f32_e32 v6, v7, v5
 ; GFX10-NEXT:    v_fma_f32 v3, -v4, v6, v3
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v3, v3, v5, v6
@@ -2161,10 +2161,10 @@ define amdgpu_kernel void @frem_v2f32(<2 x float> addrspace(1)* %out, <2 x float
 ; GFX10-NEXT:    v_rcp_f32_e32 v7, v6
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v8, -v6, v7, 1.0
-; GFX10-NEXT:    v_fma_f32 v7, v8, v7, v7
+; GFX10-NEXT:    v_fmac_f32_e32 v7, v8, v7
 ; GFX10-NEXT:    v_mul_f32_e32 v8, v5, v7
 ; GFX10-NEXT:    v_fma_f32 v9, -v6, v8, v5
-; GFX10-NEXT:    v_fma_f32 v8, v9, v7, v8
+; GFX10-NEXT:    v_fmac_f32_e32 v8, v9, v7
 ; GFX10-NEXT:    v_fma_f32 v5, -v6, v8, v5
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v5, v5, v7, v8
@@ -2176,10 +2176,10 @@ define amdgpu_kernel void @frem_v2f32(<2 x float> addrspace(1)* %out, <2 x float
 ; GFX10-NEXT:    v_rcp_f32_e32 v6, v5
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v7, -v5, v6, 1.0
-; GFX10-NEXT:    v_fma_f32 v6, v7, v6, v6
+; GFX10-NEXT:    v_fmac_f32_e32 v6, v7, v6
 ; GFX10-NEXT:    v_mul_f32_e32 v7, v3, v6
 ; GFX10-NEXT:    v_fma_f32 v8, -v5, v7, v3
-; GFX10-NEXT:    v_fma_f32 v7, v8, v6, v7
+; GFX10-NEXT:    v_fmac_f32_e32 v7, v8, v6
 ; GFX10-NEXT:    v_fma_f32 v3, -v5, v7, v3
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v3, v3, v6, v7
@@ -2535,10 +2535,10 @@ define amdgpu_kernel void @frem_v4f32(<4 x float> addrspace(1)* %out, <4 x float
 ; GFX10-NEXT:    v_rcp_f32_e32 v11, v10
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v12, -v10, v11, 1.0
-; GFX10-NEXT:    v_fma_f32 v11, v12, v11, v11
+; GFX10-NEXT:    v_fmac_f32_e32 v11, v12, v11
 ; GFX10-NEXT:    v_mul_f32_e32 v12, v9, v11
 ; GFX10-NEXT:    v_fma_f32 v13, -v10, v12, v9
-; GFX10-NEXT:    v_fma_f32 v12, v13, v11, v12
+; GFX10-NEXT:    v_fmac_f32_e32 v12, v13, v11
 ; GFX10-NEXT:    v_fma_f32 v9, -v10, v12, v9
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v9, v9, v11, v12
@@ -2550,10 +2550,10 @@ define amdgpu_kernel void @frem_v4f32(<4 x float> addrspace(1)* %out, <4 x float
 ; GFX10-NEXT:    v_rcp_f32_e32 v10, v9
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v11, -v9, v10, 1.0
-; GFX10-NEXT:    v_fma_f32 v10, v11, v10, v10
+; GFX10-NEXT:    v_fmac_f32_e32 v10, v11, v10
 ; GFX10-NEXT:    v_mul_f32_e32 v11, v7, v10
 ; GFX10-NEXT:    v_fma_f32 v12, -v9, v11, v7
-; GFX10-NEXT:    v_fma_f32 v11, v12, v10, v11
+; GFX10-NEXT:    v_fmac_f32_e32 v11, v12, v10
 ; GFX10-NEXT:    v_fma_f32 v7, -v9, v11, v7
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v7, v7, v10, v11
@@ -2565,10 +2565,10 @@ define amdgpu_kernel void @frem_v4f32(<4 x float> addrspace(1)* %out, <4 x float
 ; GFX10-NEXT:    v_rcp_f32_e32 v9, v7
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v10, -v7, v9, 1.0
-; GFX10-NEXT:    v_fma_f32 v9, v10, v9, v9
+; GFX10-NEXT:    v_fmac_f32_e32 v9, v10, v9
 ; GFX10-NEXT:    v_mul_f32_e32 v10, v6, v9
 ; GFX10-NEXT:    v_fma_f32 v11, -v7, v10, v6
-; GFX10-NEXT:    v_fma_f32 v10, v11, v9, v10
+; GFX10-NEXT:    v_fmac_f32_e32 v10, v11, v9
 ; GFX10-NEXT:    v_fma_f32 v6, -v7, v10, v6
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v6, v6, v9, v10
@@ -2580,10 +2580,10 @@ define amdgpu_kernel void @frem_v4f32(<4 x float> addrspace(1)* %out, <4 x float
 ; GFX10-NEXT:    v_rcp_f32_e32 v7, v6
 ; GFX10-NEXT:    s_denorm_mode 15
 ; GFX10-NEXT:    v_fma_f32 v9, -v6, v7, 1.0
-; GFX10-NEXT:    v_fma_f32 v7, v9, v7, v7
+; GFX10-NEXT:    v_fmac_f32_e32 v7, v9, v7
 ; GFX10-NEXT:    v_mul_f32_e32 v9, v5, v7
 ; GFX10-NEXT:    v_fma_f32 v10, -v6, v9, v5
-; GFX10-NEXT:    v_fma_f32 v9, v10, v7, v9
+; GFX10-NEXT:    v_fmac_f32_e32 v9, v10, v7
 ; GFX10-NEXT:    v_fma_f32 v5, -v6, v9, v5
 ; GFX10-NEXT:    s_denorm_mode 12
 ; GFX10-NEXT:    v_div_fmas_f32 v5, v5, v7, v9