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[AMDGPU] Fix to prevent sinking of PERMLANE_SWAP instruction #144423

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Merged
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Jun 20, 2025
Merged

[AMDGPU] Fix to prevent sinking of PERMLANE_SWAP instruction #144423

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[AMDGPU] Fix to prevent sinking of PERMLANE_SWAP instruction
VigneshwarJ Jun 16, 2025
6913acf
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VigneshwarJ Jun 17, 2025
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6 changes: 5 additions & 1 deletion llvm/lib/Target/AMDGPU/VOP1Instructions.td
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Original file line number Diff line number Diff line change
Expand Up @@ -775,7 +775,8 @@ defm V_PRNG_B32 : VOP1Inst <"v_prng_b32", VOP_I32_I32, int_amdgcn_prng_b32>;

let Constraints = "$vdst = $vdst_in, $src0_out = $src0",
DisableEncoding="$vdst_in,$src0_out",
SchedRW = [Write32Bit, Write32Bit] in {
SchedRW = [Write32Bit, Write32Bit],
isConvergent = 1 in {
let SubtargetPredicate = HasPermlane16Swap in {
defm V_PERMLANE16_SWAP_B32 : VOP1Inst<"v_permlane16_swap_b32", VOP_PERMLANE_SWAP>;
}
Expand Down Expand Up @@ -1550,8 +1551,11 @@ defm V_CVT_PK_F32_FP8 : VOP1_Real_NoDstSel_SDWA_gfx9<0x56>;
defm V_CVT_PK_F32_BF8 : VOP1_Real_NoDstSel_SDWA_gfx9<0x57>;

defm V_PRNG_B32 : VOP1_Real_gfx9 <0x58>;

let isConvergent = 1 in {
defm V_PERMLANE16_SWAP_B32 : VOP1_OpSel_Real_e32e64_gfx9<0x059>;
defm V_PERMLANE32_SWAP_B32 : VOP1_OpSel_Real_e32e64_gfx9<0x05a>;
}

class MovDPP8Pattern<Predicate Pred, Instruction Inst, ValueType vt> : GCNPat <
(vt (int_amdgcn_mov_dpp8 vt:$src, timm:$dpp8)),
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1 change: 1 addition & 0 deletions llvm/lib/Target/AMDGPU/VOPInstructions.td
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Expand Up @@ -15,6 +15,7 @@ class LetDummies {
bit isConvertibleToThreeAddress;
bit isMoveImm;
bit isReMaterializable;
bit isConvergent;
bit isAsCheapAsAMove;
bit FPDPRounding;
Predicate SubtargetPredicate;
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61 changes: 61 additions & 0 deletions llvm/test/CodeGen/AMDGPU/machine-sink-ignorable-exec-use.mir
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Expand Up @@ -733,3 +733,64 @@ body: |
liveins: $vgpr0, $vgpr1, $vgpr2_vgpr3, $vcc
S_ENDPGM 0
...
---
name: test_no_sink_permlane_swap
tracksRegLiveness: true
machineFunctionInfo:
isEntryFunction: true
body: |
; GFX9-LABEL: name: test_no_sink_permlane_swap
; GFX9: bb.0:
; GFX9-NEXT: successors: %bb.2(0x40000000), %bb.1(0x40000000)
; GFX9-NEXT: liveins: $vgpr0
; GFX9-NEXT: {{ $}}
; GFX9-NEXT: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
; GFX9-NEXT: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
; GFX9-NEXT: [[S_MOV_B64_:%[0-9]+]]:sreg_64 = S_MOV_B64 0
; GFX9-NEXT: [[COPY1:%[0-9]+]]:vreg_64 = COPY [[S_MOV_B64_]]
; GFX9-NEXT: [[GLOBAL_LOAD_DWORD:%[0-9]+]]:vgpr_32 = GLOBAL_LOAD_DWORD killed [[COPY1]], 0, 0, implicit $exec :: (load (s32), addrspace 1)
; GFX9-NEXT: [[V_PERMLANE32_SWAP_B32_e64_:%[0-9]+]]:vgpr_32, [[V_PERMLANE32_SWAP_B32_e64_1:%[0-9]+]]:vgpr_32 = V_PERMLANE32_SWAP_B32_e64 [[GLOBAL_LOAD_DWORD]], [[GLOBAL_LOAD_DWORD]], 0, 0, implicit $exec
; GFX9-NEXT: [[COPY2:%[0-9]+]]:vgpr_32(s32) = COPY $vgpr0
; GFX9-NEXT: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 1
; GFX9-NEXT: [[V_CMP_LT_I32_e64_:%[0-9]+]]:sreg_64 = V_CMP_LT_I32_e64 [[COPY2]](s32), [[S_MOV_B32_]], implicit $exec
; GFX9-NEXT: [[SI_IF:%[0-9]+]]:sreg_64 = SI_IF [[V_CMP_LT_I32_e64_]], %bb.2, implicit-def dead $exec, implicit-def dead $scc, implicit $exec
; GFX9-NEXT: S_BRANCH %bb.1
; GFX9-NEXT: {{ $}}
; GFX9-NEXT: bb.1:
; GFX9-NEXT: successors: %bb.2(0x80000000)
; GFX9-NEXT: {{ $}}
; GFX9-NEXT: [[V_MAX_I32_e64_:%[0-9]+]]:vgpr_32 = V_MAX_I32_e64 [[V_PERMLANE32_SWAP_B32_e64_]], [[V_PERMLANE32_SWAP_B32_e64_1]], implicit $exec
; GFX9-NEXT: {{ $}}
; GFX9-NEXT: bb.2:
; GFX9-NEXT: successors: %bb.3(0x80000000)
; GFX9-NEXT: {{ $}}
; GFX9-NEXT: [[PHI:%[0-9]+]]:vgpr_32 = PHI [[V_MOV_B32_e32_]], %bb.0, [[V_MAX_I32_e64_]], %bb.1
; GFX9-NEXT: SI_END_CF [[SI_IF]], implicit-def dead $exec, implicit-def dead $scc, implicit $exec
; GFX9-NEXT: {{ $}}
; GFX9-NEXT: bb.3:
; GFX9-NEXT: S_ENDPGM 0, implicit [[PHI]]
bb.0:
liveins: $vgpr0
%1:vgpr_32 = COPY $vgpr0
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@arsenm arsenm Jun 17, 2025

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Should run -run-pass=none to compact the register numbers

%3:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
%5:sreg_64 = S_MOV_B64 0
%7:vreg_64 = COPY %5
%9:vgpr_32 = GLOBAL_LOAD_DWORD killed %7, 0, 0, implicit $exec :: (load (s32), addrspace 1)
%10:vgpr_32, %11:vgpr_32 = V_PERMLANE32_SWAP_B32_e64 %9:vgpr_32, %9:vgpr_32, 0, 0, implicit $exec
%15:vgpr_32(s32) = COPY $vgpr0
%16:sreg_32 = S_MOV_B32 1
%17:sreg_64 = V_CMP_LT_I32_e64 %15(s32), %16, implicit $exec
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@arsenm arsenm Jun 17, 2025

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Suggested change
%17:sreg_64 = V_CMP_LT_I32_e64 %15(s32), %16, implicit $exec
%17:sreg_64 = V_CMP_LT_I32_e64 %15, %16, implicit $exec

Drop the accidental LLTs

%18:sreg_64 = COPY %17
%19:sreg_64 = SI_IF %18, %bb.2, implicit-def dead $exec, implicit-def dead $scc, implicit $exec
S_BRANCH %bb.1

bb.1:
%20:vgpr_32 = V_MAX_I32_e64 %10:vgpr_32, %11:vgpr_32, implicit $exec

bb.2:
%22:vgpr_32 = PHI %3, %bb.0, %20, %bb.1
SI_END_CF %19, implicit-def dead $exec, implicit-def dead $scc, implicit $exec

bb.3:
S_ENDPGM 0, implicit %22
...
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