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[AMDGPU] Remove s_delay_alu for VALU->SGPR->SALU #127212

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Mar 12, 2025
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[AMDGPU] Remove s_delay_alu for VALU->SGPR->SALU #127212

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38 changes: 38 additions & 0 deletions llvm/lib/Target/AMDGPU/AMDGPUInsertDelayAlu.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,13 @@ class AMDGPUInsertDelayAlu {
return false;
}

static bool instructionWaitsForSGPRWrites(const MachineInstr &MI) {
// These instruction types wait for VA_SDST==0 before issuing.
const uint64_t VA_SDST_0 = SIInstrFlags::SALU | SIInstrFlags::SMRD;
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other instructions are already covered by instructionWaitsForVALU function


return MI.getDesc().TSFlags & VA_SDST_0;
}

// Types of delay that can be encoded in an s_delay_alu instruction.
enum DelayType { VALU, TRANS, SALU, OTHER };

Expand Down Expand Up @@ -227,6 +234,16 @@ class AMDGPUInsertDelayAlu {
}
}

void advanceByVALUNum(unsigned VALUNum) {
iterator Next;
for (auto I = begin(), E = end(); I != E; I = Next) {
Next = std::next(I);
if (I->second.VALUNum >= VALUNum && I->second.VALUCycles > 0) {
erase(I);
}
}
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void dump(const TargetRegisterInfo *TRI) const {
if (empty()) {
Expand Down Expand Up @@ -331,6 +348,7 @@ class AMDGPUInsertDelayAlu {
bool Changed = false;
MachineInstr *LastDelayAlu = nullptr;

MCRegUnit LastSGPRFromVALU = 0;
// Iterate over the contents of bundles, but don't emit any instructions
// inside a bundle.
for (auto &MI : MBB.instrs()) {
Expand All @@ -345,6 +363,15 @@ class AMDGPUInsertDelayAlu {

DelayType Type = getDelayType(MI.getDesc().TSFlags);

if (instructionWaitsForSGPRWrites(MI)) {
auto It = State.find(LastSGPRFromVALU);
if (It != State.end()) {
DelayInfo Info = It->getSecond();
State.advanceByVALUNum(Info.VALUNum);
LastSGPRFromVALU = 0;
}
}

if (instructionWaitsForVALU(MI)) {
// Forget about all outstanding VALU delays.
// TODO: This is overkill since it also forgets about SALU delays.
Expand All @@ -368,6 +395,17 @@ class AMDGPUInsertDelayAlu {
}
}
}

if (SII->isVALU(MI.getOpcode())) {
for (const auto &Op : MI.defs()) {
Register Reg = Op.getReg();
if (AMDGPU::isSGPR(Reg, TRI)) {
LastSGPRFromVALU = *TRI->regunits(Reg).begin();
break;
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eliminating the outer loop by only taking the first unit of the SGPR operand

}
}
}

if (Emit && !MI.isBundledWithPred()) {
// TODO: For VALU->SALU delays should we use s_delay_alu or s_nop or
// just ignore them?
Expand Down
2 changes: 0 additions & 2 deletions llvm/test/CodeGen/AMDGPU/GlobalISel/atomicrmw_uinc_wrap.ll
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Expand Up @@ -2854,7 +2854,6 @@ define amdgpu_kernel void @flat_atomic_inc_ret_i32_offset_addr64(ptr %out, ptr %
; GFX12-NEXT: v_dual_mov_b32 v0, s0 :: v_dual_mov_b32 v1, s1
; GFX12-NEXT: v_add_co_u32 v0, vcc_lo, v0, v2
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_2)
; GFX12-NEXT: v_add_co_ci_u32_e32 v1, vcc_lo, 0, v1, vcc_lo
; GFX12-NEXT: flat_store_b32 v[0:1], v3
; GFX12-NEXT: s_endpgm
Expand Down Expand Up @@ -3842,7 +3841,6 @@ define amdgpu_kernel void @flat_atomic_inc_ret_i64_offset_addr64(ptr %out, ptr %
; GFX12-NEXT: v_dual_mov_b32 v3, s1 :: v_dual_mov_b32 v2, s0
; GFX12-NEXT: v_add_co_u32 v2, vcc_lo, v2, v4
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_2)
; GFX12-NEXT: v_add_co_ci_u32_e32 v3, vcc_lo, 0, v3, vcc_lo
; GFX12-NEXT: flat_store_b64 v[2:3], v[0:1]
; GFX12-NEXT: s_endpgm
Expand Down
96 changes: 48 additions & 48 deletions llvm/test/CodeGen/AMDGPU/GlobalISel/fdiv.f32.ll
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8 changes: 4 additions & 4 deletions llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.intersect_ray.ll
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Expand Up @@ -234,8 +234,8 @@ define amdgpu_ps <4 x float> @image_bvh_intersect_ray_vgpr_descr(i32 %node_ptr,
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_2)
; GFX11-NEXT: v_cmp_eq_u64_e32 vcc_lo, s[4:5], v[18:19]
; GFX11-NEXT: v_cmp_eq_u64_e64 s0, s[6:7], v[13:14]
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(SALU_CYCLE_1)
; GFX11-NEXT: s_and_b32 s0, vcc_lo, s0
; GFX11-NEXT: s_delay_alu instid0(SALU_CYCLE_1)
; GFX11-NEXT: s_and_saveexec_b32 s0, s0
; GFX11-NEXT: image_bvh_intersect_ray v[0:3], [v20, v21, v[15:17], v[5:7], v[8:10]], s[4:7]
; GFX11-NEXT: ; implicit-def: $vgpr18
Expand Down Expand Up @@ -360,8 +360,8 @@ define amdgpu_ps <4 x float> @image_bvh_intersect_ray_a16_vgpr_descr(i32 %node_p
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_2)
; GFX11-NEXT: v_cmp_eq_u64_e32 vcc_lo, s[4:5], v[18:19]
; GFX11-NEXT: v_cmp_eq_u64_e64 s0, s[6:7], v[11:12]
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(SALU_CYCLE_1)
; GFX11-NEXT: s_and_b32 s0, vcc_lo, s0
; GFX11-NEXT: s_delay_alu instid0(SALU_CYCLE_1)
; GFX11-NEXT: s_and_saveexec_b32 s0, s0
; GFX11-NEXT: image_bvh_intersect_ray v[0:3], [v16, v17, v[13:15], v[4:6]], s[4:7] a16
; GFX11-NEXT: ; implicit-def: $vgpr18
Expand Down Expand Up @@ -476,8 +476,8 @@ define amdgpu_ps <4 x float> @image_bvh64_intersect_ray_vgpr_descr(i64 %node_ptr
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_2)
; GFX11-NEXT: v_cmp_eq_u64_e32 vcc_lo, s[4:5], v[4:5]
; GFX11-NEXT: v_cmp_eq_u64_e64 s0, s[6:7], v[14:15]
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(SALU_CYCLE_1)
; GFX11-NEXT: s_and_b32 s0, vcc_lo, s0
; GFX11-NEXT: s_delay_alu instid0(SALU_CYCLE_1)
; GFX11-NEXT: s_and_saveexec_b32 s0, s0
; GFX11-NEXT: image_bvh64_intersect_ray v[0:3], [v[19:20], v21, v[16:18], v[6:8], v[9:11]], s[4:7]
; GFX11-NEXT: ; implicit-def: $vgpr4
Expand Down Expand Up @@ -604,8 +604,8 @@ define amdgpu_ps <4 x float> @image_bvh64_intersect_ray_a16_vgpr_descr(i64 %node
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_2)
; GFX11-NEXT: v_cmp_eq_u64_e32 vcc_lo, s[4:5], v[4:5]
; GFX11-NEXT: v_cmp_eq_u64_e64 s0, s[6:7], v[12:13]
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(SALU_CYCLE_1)
; GFX11-NEXT: s_and_b32 s0, vcc_lo, s0
; GFX11-NEXT: s_delay_alu instid0(SALU_CYCLE_1)
; GFX11-NEXT: s_and_saveexec_b32 s0, s0
; GFX11-NEXT: image_bvh64_intersect_ray v[0:3], [v[17:18], v19, v[14:16], v[20:22]], s[4:7] a16
; GFX11-NEXT: ; implicit-def: $vgpr4
Expand Down
1 change: 0 additions & 1 deletion llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.s.setreg.ll
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Expand Up @@ -1468,7 +1468,6 @@ define void @test_setreg_roundingmode_var_vgpr(i32 %var.mode) {
; GFX11-NEXT: v_readfirstlane_b32 s0, v0 ; encoding: [0x00,0x05,0x00,0x7e]
; GFX11-NEXT: ;;#ASMSTART
; GFX11-NEXT: ;;#ASMEND
; GFX11-NEXT: s_delay_alu instid0(VALU_DEP_1) ; encoding: [0x01,0x00,0x87,0xbf]
; GFX11-NEXT: s_setreg_b32 hwreg(HW_REG_MODE, 0, 3), s0 ; encoding: [0x01,0x10,0x00,0xb9]
; GFX11-NEXT: s_setpc_b64 s[30:31] ; encoding: [0x1e,0x48,0x80,0xbe]
call void @llvm.amdgcn.s.setreg(i32 4097, i32 %var.mode)
Expand Down
18 changes: 4 additions & 14 deletions llvm/test/CodeGen/AMDGPU/GlobalISel/mul.ll
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Expand Up @@ -1072,12 +1072,11 @@ define i128 @v_mul_i128(i128 %num, i128 %den) {
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(VALU_DEP_1)
; GFX12-NEXT: v_mov_b32_e32 v2, v11
; GFX12-NEXT: v_mad_co_u64_u32 v[1:2], vcc_lo, v8, v5, v[1:2]
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(SKIP_1) | instid1(VALU_DEP_4)
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(SKIP_4) | instid1(VALU_DEP_1)
; GFX12-NEXT: v_mad_co_u64_u32 v[1:2], s0, v9, v4, v[1:2]
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: v_add_co_ci_u32_e64 v7, s0, v12, v7, s0
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(VALU_DEP_1)
; GFX12-NEXT: v_add_co_ci_u32_e32 v6, vcc_lo, v7, v6, vcc_lo
; GFX12-NEXT: v_mad_co_u64_u32 v[5:6], null, v10, v5, v[6:7]
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1)
Expand Down Expand Up @@ -2436,39 +2435,33 @@ define i256 @v_mul_i256(i256 %num, i256 %den) {
; GFX12-NEXT: v_mad_co_u64_u32 v[18:19], null, v16, v12, 0
; GFX12-NEXT: v_mul_lo_u32 v30, v17, v14
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], null, v17, v13, v[0:1]
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(SKIP_2) | instid1(VALU_DEP_3)
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3)
; GFX12-NEXT: v_mad_co_u64_u32 v[18:19], s0, v17, v11, v[18:19]
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: v_cndmask_b32_e64 v20, 0, 1, s0
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], null, v2, v12, v[0:1]
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(SKIP_1) | instid1(VALU_DEP_3)
; GFX12-NEXT: v_mad_co_u64_u32 v[18:19], vcc_lo, v2, v10, v[18:19]
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: v_add_co_ci_u32_e32 v22, vcc_lo, 0, v20, vcc_lo
; GFX12-NEXT: v_mad_co_u64_u32 v[20:21], null, v16, v10, 0
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_4) | instskip(NEXT) | instid1(VALU_DEP_4)
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], null, v3, v11, v[0:1]
; GFX12-NEXT: v_mad_co_u64_u32 v[18:19], vcc_lo, v3, v9, v[18:19]
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: v_add_co_ci_u32_e32 v24, vcc_lo, 0, v22, vcc_lo
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_3)
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], null, v4, v10, v[0:1]
; GFX12-NEXT: v_mad_co_u64_u32 v[18:19], vcc_lo, v4, v8, v[18:19]
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_3)
; GFX12-NEXT: v_add_co_ci_u32_e32 v26, vcc_lo, 0, v24, vcc_lo
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], null, v5, v9, v[0:1]
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(SKIP_3) | instid1(VALU_DEP_3)
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1)
; GFX12-NEXT: v_mad_co_u64_u32 v[22:23], null, v6, v8, v[0:1]
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], s0, v17, v9, v[20:21]
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: v_cndmask_b32_e64 v25, 0, 1, s0
; GFX12-NEXT: v_mov_b32_e32 v20, v22
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(SKIP_1) | instid1(VALU_DEP_3)
; GFX12-NEXT: v_mad_co_u64_u32 v[21:22], vcc_lo, v2, v8, v[0:1]
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: v_add_co_ci_u32_e32 v29, vcc_lo, 0, v25, vcc_lo
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_3) | instskip(NEXT) | instid1(VALU_DEP_3)
; GFX12-NEXT: v_mad_co_u64_u32 v[0:1], s0, v16, v13, v[19:20]
; GFX12-NEXT: v_mov_b32_e32 v19, v22
; GFX12-NEXT: v_mul_lo_u32 v22, v16, v15
Expand All @@ -2490,7 +2483,6 @@ define i256 @v_mul_i256(i256 %num, i256 %den) {
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: v_add_co_ci_u32_e64 v6, s2, 0, v6, s2
; GFX12-NEXT: v_mov_b32_e32 v14, v21
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_4) | instskip(SKIP_1) | instid1(VALU_DEP_3)
; GFX12-NEXT: v_mad_co_u64_u32 v[1:2], s2, v2, v9, v[11:12]
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: v_add_co_ci_u32_e64 v6, s2, 0, v6, s2
Expand All @@ -2504,7 +2496,6 @@ define i256 @v_mul_i256(i256 %num, i256 %den) {
; GFX12-NEXT: v_mad_co_u64_u32 v[5:6], s4, v5, v8, v[10:11]
; GFX12-NEXT: v_mad_co_u64_u32 v[1:2], s5, v17, v8, v[12:13]
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_4) | instskip(SKIP_3) | instid1(VALU_DEP_4)
; GFX12-NEXT: v_add_co_ci_u32_e64 v3, s5, v9, v3, s5
; GFX12-NEXT: s_wait_alu 0xf1ff
; GFX12-NEXT: v_add_co_ci_u32_e64 v4, s5, v29, v4, s5
Expand All @@ -2521,10 +2512,9 @@ define i256 @v_mul_i256(i256 %num, i256 %den) {
; GFX12-NEXT: v_add_co_ci_u32_e64 v9, s2, v9, v25, s3
; GFX12-NEXT: v_add_co_ci_u32_e64 v9, s1, v9, v20, s1
; GFX12-NEXT: s_wait_alu 0xfffd
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(VALU_DEP_1)
; GFX12-NEXT: v_add_co_ci_u32_e32 v9, vcc_lo, v9, v28, vcc_lo
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1) | instskip(NEXT) | instid1(VALU_DEP_1)
; GFX12-NEXT: v_add_co_ci_u32_e64 v9, vcc_lo, v9, v27, s0
; GFX12-NEXT: s_delay_alu instid0(VALU_DEP_1)
; GFX12-NEXT: v_mad_co_u64_u32 v[7:8], null, v7, v8, v[9:10]
; GFX12-NEXT: s_wait_alu 0xf1fd
; GFX12-NEXT: s_setpc_b64 s[30:31]
Expand Down
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