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[AMDGPU] Enable load clustering in the post-RA scheduler
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This has a couple of benefits:
1. It can sometimes fix clusters that got broken apart when the register
   allocator inserted a copy.
2. Post-RA scheduling does not have to worry about increasing register
   pressure, which in some cases gives it more freedom to reorder
   instructions.

Testing on a collection of 10,000 graphics shaders compiled for gfx1010
showed:
- The average length of each run of one or more load instructions
  increased by about 1%.
- The number of runs of two or more load instructions increased by
  about 4%.

Differential Revision: https://reviews.llvm.org/D111646
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@jayfoad
jayfoad committed Oct 13, 2021
1 parent 08c8016 commit c885857
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Showing 10 changed files with 16 additions and 15 deletions.
1 change: 1 addition & 0 deletions llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
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Expand Up @@ -851,6 +851,7 @@ class GCNPassConfig final : public AMDGPUPassConfig {
createPostMachineScheduler(MachineSchedContext *C) const override {
ScheduleDAGMI *DAG = createGenericSchedPostRA(C);
const GCNSubtarget &ST = C->MF->getSubtarget<GCNSubtarget>();
DAG->addMutation(createLoadClusterDAGMutation(DAG->TII, DAG->TRI));
DAG->addMutation(ST.createFillMFMAShadowMutation(DAG->TII));
return DAG;
}
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5 changes: 2 additions & 3 deletions llvm/test/CodeGen/AMDGPU/GlobalISel/extractelement.i128.ll
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Expand Up @@ -185,21 +185,20 @@ define i128 @extractelement_vgpr_v4i128_vgpr_idx(<4 x i128> addrspace(1)* %ptr,
; GFX8-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
; GFX8-NEXT: v_add_u32_e32 v3, vcc, 16, v0
; GFX8-NEXT: v_addc_u32_e32 v4, vcc, 0, v1, vcc
; GFX8-NEXT: flat_load_dwordx4 v[8:11], v[0:1]
; GFX8-NEXT: flat_load_dwordx4 v[4:7], v[3:4]
; GFX8-NEXT: flat_load_dwordx4 v[8:11], v[0:1]
; GFX8-NEXT: v_lshlrev_b32_e32 v16, 1, v2
; GFX8-NEXT: v_add_u32_e32 v17, vcc, 1, v16
; GFX8-NEXT: v_cmp_eq_u32_e32 vcc, 1, v17
; GFX8-NEXT: v_cmp_eq_u32_e64 s[4:5], 1, v16
; GFX8-NEXT: v_cmp_eq_u32_e64 s[6:7], 6, v16
; GFX8-NEXT: v_cmp_eq_u32_e64 s[8:9], 7, v16
; GFX8-NEXT: s_waitcnt vmcnt(1)
; GFX8-NEXT: s_waitcnt vmcnt(0)
; GFX8-NEXT: v_cndmask_b32_e64 v2, v8, v10, s[4:5]
; GFX8-NEXT: v_cndmask_b32_e64 v3, v9, v11, s[4:5]
; GFX8-NEXT: v_cndmask_b32_e32 v8, v8, v10, vcc
; GFX8-NEXT: v_cndmask_b32_e32 v9, v9, v11, vcc
; GFX8-NEXT: v_cmp_eq_u32_e32 vcc, 2, v16
; GFX8-NEXT: s_waitcnt vmcnt(0)
; GFX8-NEXT: v_cndmask_b32_e32 v2, v2, v4, vcc
; GFX8-NEXT: v_cndmask_b32_e32 v3, v3, v5, vcc
; GFX8-NEXT: v_cmp_eq_u32_e32 vcc, 2, v17
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5 changes: 3 additions & 2 deletions llvm/test/CodeGen/AMDGPU/GlobalISel/udivrem.ll
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Expand Up @@ -830,8 +830,8 @@ define amdgpu_kernel void @udivrem_v4i32(<4 x i32> addrspace(1)* %out0, <4 x i32
; GFX9-LABEL: udivrem_v4i32:
; GFX9: ; %bb.0:
; GFX9-NEXT: s_load_dwordx4 s[0:3], s[4:5], 0x20
; GFX9-NEXT: v_mov_b32_e32 v2, 0x4f7ffffe
; GFX9-NEXT: s_load_dwordx4 s[8:11], s[4:5], 0x10
; GFX9-NEXT: v_mov_b32_e32 v2, 0x4f7ffffe
; GFX9-NEXT: s_waitcnt lgkmcnt(0)
; GFX9-NEXT: v_cvt_f32_u32_e32 v0, s0
; GFX9-NEXT: v_cvt_f32_u32_e32 v1, s1
Expand Down Expand Up @@ -926,9 +926,10 @@ define amdgpu_kernel void @udivrem_v4i32(<4 x i32> addrspace(1)* %out0, <4 x i32
;
; GFX10-LABEL: udivrem_v4i32:
; GFX10: ; %bb.0:
; GFX10-NEXT: s_clause 0x1
; GFX10-NEXT: s_load_dwordx4 s[8:11], s[4:5], 0x20
; GFX10-NEXT: v_mov_b32_e32 v4, 0x4f7ffffe
; GFX10-NEXT: s_load_dwordx4 s[0:3], s[4:5], 0x10
; GFX10-NEXT: v_mov_b32_e32 v4, 0x4f7ffffe
; GFX10-NEXT: v_mov_b32_e32 v8, 0
; GFX10-NEXT: s_waitcnt lgkmcnt(0)
; GFX10-NEXT: v_cvt_f32_u32_e32 v0, s8
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4 changes: 2 additions & 2 deletions llvm/test/CodeGen/AMDGPU/amdgpu-codegenprepare-idiv.ll
View file
Expand Up @@ -11236,8 +11236,8 @@ define amdgpu_kernel void @sdiv_i64_pow2_shl_denom(i64 addrspace(1)* %out, i64 %
; GFX6-LABEL: sdiv_i64_pow2_shl_denom:
; GFX6: ; %bb.0:
; GFX6-NEXT: s_load_dword s4, s[0:1], 0xd
; GFX6-NEXT: s_mov_b64 s[2:3], 0x1000
; GFX6-NEXT: s_load_dwordx4 s[8:11], s[0:1], 0x9
; GFX6-NEXT: s_mov_b64 s[2:3], 0x1000
; GFX6-NEXT: s_mov_b32 s7, 0xf000
; GFX6-NEXT: s_mov_b32 s6, -1
; GFX6-NEXT: s_waitcnt lgkmcnt(0)
Expand Down Expand Up @@ -13358,8 +13358,8 @@ define amdgpu_kernel void @srem_i64_pow2_shl_denom(i64 addrspace(1)* %out, i64 %
; GFX6-LABEL: srem_i64_pow2_shl_denom:
; GFX6: ; %bb.0:
; GFX6-NEXT: s_load_dword s4, s[0:1], 0xd
; GFX6-NEXT: s_mov_b64 s[2:3], 0x1000
; GFX6-NEXT: s_load_dwordx4 s[8:11], s[0:1], 0x9
; GFX6-NEXT: s_mov_b64 s[2:3], 0x1000
; GFX6-NEXT: s_mov_b32 s7, 0xf000
; GFX6-NEXT: s_mov_b32 s6, -1
; GFX6-NEXT: s_waitcnt lgkmcnt(0)
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/idiv-licm.ll
View file
Expand Up @@ -491,8 +491,8 @@ define amdgpu_kernel void @urem16_invariant_denom(i16 addrspace(1)* nocapture %a
; GFX9-LABEL: urem16_invariant_denom:
; GFX9: ; %bb.0: ; %bb
; GFX9-NEXT: s_load_dword s2, s[0:1], 0x2c
; GFX9-NEXT: s_mov_b32 s6, 0xffff
; GFX9-NEXT: s_load_dwordx2 s[4:5], s[0:1], 0x24
; GFX9-NEXT: s_mov_b32 s6, 0xffff
; GFX9-NEXT: v_mov_b32_e32 v1, 0
; GFX9-NEXT: s_movk_i32 s8, 0x400
; GFX9-NEXT: s_waitcnt lgkmcnt(0)
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6 changes: 3 additions & 3 deletions llvm/test/CodeGen/AMDGPU/promote-constOffset-to-imm.ll
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Expand Up @@ -100,14 +100,14 @@ define hidden amdgpu_kernel void @clmem_read(i8 addrspace(1)* %buffer) {
; GFX900: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
;
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off offset:-2048
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off offset:-2048
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off offset:-2048
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off offset:-2048
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off offset:-2048
; GFX10: global_load_dwordx2 v[{{[0-9]+:[0-9]+}}], v[{{[0-9]+:[0-9]+}}], off{{$}}

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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/sdiv64.ll
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Expand Up @@ -6,8 +6,8 @@ define amdgpu_kernel void @s_test_sdiv(i64 addrspace(1)* %out, i64 %x, i64 %y) {
; GCN-LABEL: s_test_sdiv:
; GCN: ; %bb.0:
; GCN-NEXT: s_load_dwordx2 s[4:5], s[0:1], 0xd
; GCN-NEXT: v_mov_b32_e32 v7, 0
; GCN-NEXT: s_load_dwordx4 s[8:11], s[0:1], 0x9
; GCN-NEXT: v_mov_b32_e32 v7, 0
; GCN-NEXT: s_mov_b32 s7, 0xf000
; GCN-NEXT: s_mov_b32 s6, -1
; GCN-NEXT: s_waitcnt lgkmcnt(0)
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/srem64.ll
View file
Expand Up @@ -6,8 +6,8 @@ define amdgpu_kernel void @s_test_srem(i64 addrspace(1)* %out, i64 %x, i64 %y) {
; GCN-LABEL: s_test_srem:
; GCN: ; %bb.0:
; GCN-NEXT: s_load_dwordx2 s[12:13], s[0:1], 0xd
; GCN-NEXT: v_mov_b32_e32 v2, 0
; GCN-NEXT: s_load_dwordx4 s[8:11], s[0:1], 0x9
; GCN-NEXT: v_mov_b32_e32 v2, 0
; GCN-NEXT: s_mov_b32 s7, 0xf000
; GCN-NEXT: s_mov_b32 s6, -1
; GCN-NEXT: s_waitcnt lgkmcnt(0)
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/udiv64.ll
View file
Expand Up @@ -6,8 +6,8 @@ define amdgpu_kernel void @s_test_udiv_i64(i64 addrspace(1)* %out, i64 %x, i64 %
; GCN-LABEL: s_test_udiv_i64:
; GCN: ; %bb.0:
; GCN-NEXT: s_load_dwordx2 s[2:3], s[0:1], 0xd
; GCN-NEXT: v_mov_b32_e32 v2, 0
; GCN-NEXT: s_load_dwordx4 s[8:11], s[0:1], 0x9
; GCN-NEXT: v_mov_b32_e32 v2, 0
; GCN-NEXT: s_mov_b32 s7, 0xf000
; GCN-NEXT: s_mov_b32 s6, -1
; GCN-NEXT: s_waitcnt lgkmcnt(0)
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/urem64.ll
View file
Expand Up @@ -6,8 +6,8 @@ define amdgpu_kernel void @s_test_urem_i64(i64 addrspace(1)* %out, i64 %x, i64 %
; GCN-LABEL: s_test_urem_i64:
; GCN: ; %bb.0:
; GCN-NEXT: s_load_dwordx2 s[12:13], s[0:1], 0xd
; GCN-NEXT: v_mov_b32_e32 v2, 0
; GCN-NEXT: s_load_dwordx4 s[8:11], s[0:1], 0x9
; GCN-NEXT: v_mov_b32_e32 v2, 0
; GCN-NEXT: s_mov_b32 s7, 0xf000
; GCN-NEXT: s_mov_b32 s6, -1
; GCN-NEXT: s_waitcnt lgkmcnt(0)
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