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AMDGPU/SI: Use the hazard recognizer to break SMEM soft clauses

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Summary:
Add support for detecting hazards in SMEM soft clauses, so that we only
break the clauses when necessary, either by adding s_nop or re-ordering
other alu instructions.

Reviewers: arsenm

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D18870

llvm-svn: 268260
This commit is contained in:
Tom Stellard 2016-05-02 17:39:06 +00:00
parent 634941ba37
commit 179b86b996
6 changed files with 109 additions and 43 deletions
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72
lib/Target/AMDGPU/GCNHazardRecognizer.cpp
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@ -132,18 +132,86 @@ int GCNHazardRecognizer::getWaitStatesSinceDef(unsigned Reg,
// No-op Hazard Detection
//===----------------------------------------------------------------------===//
static void addRegsToSet(iterator_range<MachineInstr::const_mop_iterator> Ops,
std::set<unsigned> &Set) {
for (const MachineOperand &Op : Ops) {
if (Op.isReg())
Set.insert(Op.getReg());
}
}
int GCNHazardRecognizer::checkSMEMSoftClauseHazards(MachineInstr *SMEM) {
const AMDGPUSubtarget &ST = MF.getSubtarget<AMDGPUSubtarget>();
// SMEM soft clause are only present on VI+
if (ST.getGeneration() < AMDGPUSubtarget::VOLCANIC_ISLANDS)
return 0;
// A soft-clause is any group of consecutive SMEM instructions. The
// instructions in this group may return out of order and/or may be
// replayed (i.e. the same instruction issued more than once).
//
// In order to handle these situations correctly we need to make sure
// that when a clause has more than one instruction, no instruction in the
// clause writes to a register that is read another instruction in the clause
// (including itself). If we encounter this situaion, we need to break the
// clause by inserting a non SMEM instruction.
const SIInstrInfo *TII = static_cast<const SIInstrInfo*>(ST.getInstrInfo());
std::set<unsigned> ClauseDefs;
std::set<unsigned> ClauseUses;
for (MachineInstr *MI : EmittedInstrs) {
// When we hit a non-SMEM instruction then we have passed the start of the
// clause and we can stop.
if (!MI || !TII->isSMRD(*MI))
break;
addRegsToSet(MI->defs(), ClauseDefs);
addRegsToSet(MI->uses(), ClauseUses);
}
if (ClauseDefs.empty())
return 0;
// FIXME: When we support stores, we need to make sure not to put loads and
// stores in the same clause if they use the same address. For now, just
// start a new clause whenever we see a store.
if (SMEM->mayStore())
return 1;
addRegsToSet(SMEM->defs(), ClauseDefs);
addRegsToSet(SMEM->uses(), ClauseUses);
std::vector<unsigned> Result(std::max(ClauseDefs.size(), ClauseUses.size()));
std::vector<unsigned>::iterator End;
End = std::set_intersection(ClauseDefs.begin(), ClauseDefs.end(),
ClauseUses.begin(), ClauseUses.end(), Result.begin());
// If the set of defs and uses intersect then we cannot add this instruction
// to the clause, so we have a hazard.
if (End != Result.begin())
return 1;
return 0;
}
int GCNHazardRecognizer::checkSMRDHazards(MachineInstr *SMRD) {
const AMDGPUSubtarget &ST = MF.getSubtarget<AMDGPUSubtarget>();
const SIInstrInfo *TII = static_cast<const SIInstrInfo*>(ST.getInstrInfo());
int WaitStatesNeeded = 0;
WaitStatesNeeded = checkSMEMSoftClauseHazards(SMRD);
// This SMRD hazard only affects SI.
if (ST.getGeneration() != AMDGPUSubtarget::SOUTHERN_ISLANDS)
return 0;
return WaitStatesNeeded;
// A read of an SGPR by SMRD instruction requires 4 wait states when the
// SGPR was written by a VALU instruction.
int SmrdSgprWaitStates = 4;
int WaitStatesNeeded = 0;
auto IsHazardDefFn = [TII] (MachineInstr *MI) { return TII->isVALU(*MI); };
for (const MachineOperand &Use : SMRD->uses()) {

1
lib/Target/AMDGPU/GCNHazardRecognizer.h
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@ -38,6 +38,7 @@ class GCNHazardRecognizer final : public ScheduleHazardRecognizer {
std::function<bool(MachineInstr*)> IsHazardDef =
[](MachineInstr*) {return true;});
int checkSMEMSoftClauseHazards(MachineInstr *SMEM);
int checkSMRDHazards(MachineInstr *SMRD);
int checkVMEMHazards(MachineInstr* VMEM);
int checkDPPHazards(MachineInstr *DPP);

3
lib/Target/AMDGPU/SIInsertWaits.cpp
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@ -314,8 +314,7 @@ void SIInsertWaits::pushInstruction(MachineBasicBlock &MBB,
// and destination registers don't overlap, e.g. this is illegal:
// r0 = load r2
// r2 = load r0
if ((LastOpcodeType == SMEM && TII->isSMRD(*I)) ||
(LastOpcodeType == VMEM && Increment.Named.VM)) {
if (LastOpcodeType == VMEM && Increment.Named.VM) {
// Insert a NOP to break the clause.
BuildMI(MBB, I, DebugLoc(), TII->get(AMDGPU::S_NOP))
.addImm(0);

8
test/CodeGen/AMDGPU/atomic_cmp_swap_local.ll
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@ -23,8 +23,8 @@ define void @lds_atomic_cmpxchg_ret_i32_offset(i32 addrspace(1)* %out, i32 addrs
; FUNC-LABEL: {{^}}lds_atomic_cmpxchg_ret_i64_offset:
; SICI: s_load_dword [[PTR:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0xb
; SICI: s_load_dwordx2 s{{\[}}[[LOSWAP:[0-9]+]]:[[HISWAP:[0-9]+]]{{\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0xd
; VI: s_load_dword [[PTR:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0x2c
; VI: s_load_dwordx2 s{{\[}}[[LOSWAP:[0-9]+]]:[[HISWAP:[0-9]+]]{{\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x34
; VI-DAG: s_load_dword [[PTR:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0x2c
; VI-DAG: s_load_dwordx2 s{{\[}}[[LOSWAP:[0-9]+]]:[[HISWAP:[0-9]+]]{{\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x34
; GCN-DAG: v_mov_b32_e32 v[[LOVCMP:[0-9]+]], 7
; GCN-DAG: v_mov_b32_e32 v[[HIVCMP:[0-9]+]], 0
; GCN-DAG: v_mov_b32_e32 [[VPTR:v[0-9]+]], [[PTR]]
@ -75,8 +75,8 @@ define void @lds_atomic_cmpxchg_noret_i32_offset(i32 addrspace(3)* %ptr, i32 %sw
; FUNC-LABEL: {{^}}lds_atomic_cmpxchg_noret_i64_offset:
; SICI: s_load_dword [[PTR:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0x9
; SICI: s_load_dwordx2 s{{\[}}[[LOSWAP:[0-9]+]]:[[HISWAP:[0-9]+]]{{\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0xb
; VI: s_load_dword [[PTR:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0x24
; VI: s_load_dwordx2 s{{\[}}[[LOSWAP:[0-9]+]]:[[HISWAP:[0-9]+]]{{\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x2c
; VI-DAG: s_load_dword [[PTR:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0x24
; VI-DAG: s_load_dwordx2 s{{\[}}[[LOSWAP:[0-9]+]]:[[HISWAP:[0-9]+]]{{\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x2c
; GCN-DAG: v_mov_b32_e32 v[[LOVCMP:[0-9]+]], 7
; GCN-DAG: v_mov_b32_e32 v[[HIVCMP:[0-9]+]], 0
; GCN-DAG: v_mov_b32_e32 [[VPTR:v[0-9]+]], [[PTR]]

59
test/CodeGen/AMDGPU/fneg-fabs.f64.ll
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@ -1,11 +1,11 @@
; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=GCN %s
; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=VI -check-prefix=GCN %s
; FIXME: Check something here. Currently it seems fabs + fneg aren't
; into 2 modifiers, although theoretically that should work.
; FUNC-LABEL: {{^}}fneg_fabs_fadd_f64:
; SI: v_add_f64 {{v\[[0-9]+:[0-9]+\]}}, {{s\[[0-9]+:[0-9]+\]}}, -|v{{\[[0-9]+:[0-9]+\]}}|
; GCN-LABEL: {{^}}fneg_fabs_fadd_f64:
; GCN: v_add_f64 {{v\[[0-9]+:[0-9]+\]}}, {{s\[[0-9]+:[0-9]+\]}}, -|v{{\[[0-9]+:[0-9]+\]}}|
define void @fneg_fabs_fadd_f64(double addrspace(1)* %out, double %x, double %y) {
%fabs = call double @llvm.fabs.f64(double %x)
%fsub = fsub double -0.000000e+00, %fabs
@ -24,8 +24,8 @@ define void @v_fneg_fabs_fadd_f64(double addrspace(1)* %out, double addrspace(1)
ret void
}
; FUNC-LABEL: {{^}}fneg_fabs_fmul_f64:
; SI: v_mul_f64 {{v\[[0-9]+:[0-9]+\]}}, {{s\[[0-9]+:[0-9]+\]}}, -|{{v\[[0-9]+:[0-9]+\]}}|
; GCN-LABEL: {{^}}fneg_fabs_fmul_f64:
; GCN: v_mul_f64 {{v\[[0-9]+:[0-9]+\]}}, {{s\[[0-9]+:[0-9]+\]}}, -|{{v\[[0-9]+:[0-9]+\]}}|
define void @fneg_fabs_fmul_f64(double addrspace(1)* %out, double %x, double %y) {
%fabs = call double @llvm.fabs.f64(double %x)
%fsub = fsub double -0.000000e+00, %fabs
@ -34,7 +34,7 @@ define void @fneg_fabs_fmul_f64(double addrspace(1)* %out, double %x, double %y)
ret void
}
; FUNC-LABEL: {{^}}fneg_fabs_free_f64:
; GCN-LABEL: {{^}}fneg_fabs_free_f64:
define void @fneg_fabs_free_f64(double addrspace(1)* %out, i64 %in) {
%bc = bitcast i64 %in to double
%fabs = call double @llvm.fabs.f64(double %bc)
@ -43,9 +43,9 @@ define void @fneg_fabs_free_f64(double addrspace(1)* %out, i64 %in) {
ret void
}
; FUNC-LABEL: {{^}}fneg_fabs_fn_free_f64:
; SI: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN-LABEL: {{^}}fneg_fabs_fn_free_f64:
; GCN: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
define void @fneg_fabs_fn_free_f64(double addrspace(1)* %out, i64 %in) {
%bc = bitcast i64 %in to double
%fabs = call double @fabs(double %bc)
@ -54,13 +54,14 @@ define void @fneg_fabs_fn_free_f64(double addrspace(1)* %out, i64 %in) {
ret void
}
; FUNC-LABEL: {{^}}fneg_fabs_f64:
; SI: s_load_dwordx2
; SI: s_load_dwordx2 s{{\[}}[[LO_X:[0-9]+]]:[[HI_X:[0-9]+]]{{\]}}
; SI: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; SI-DAG: v_or_b32_e32 v[[HI_V:[0-9]+]], s[[HI_X]], [[IMMREG]]
; SI-DAG: v_mov_b32_e32 v[[LO_V:[0-9]+]], s[[LO_X]]
; SI: buffer_store_dwordx2 v{{\[}}[[LO_V]]:[[HI_V]]{{\]}}
; GCN-LABEL: {{^}}fneg_fabs_f64:
; GCN: s_load_dwordx2
; GCN-DAG: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; SI-DAG: s_load_dwordx2 s{{\[}}[[LO_X:[0-9]+]]:[[HI_X:[0-9]+]]{{\]}}, s[{{[0-9]+:[0-9]+}}], 0xb
; VI-DAG: s_load_dwordx2 s{{\[}}[[LO_X:[0-9]+]]:[[HI_X:[0-9]+]]{{\]}}, s[{{[0-9]+:[0-9]+}}], 0x2c
; GCN-DAG: v_or_b32_e32 v[[HI_V:[0-9]+]], s[[HI_X]], [[IMMREG]]
; GCN-DAG: v_mov_b32_e32 v[[LO_V:[0-9]+]], s[[LO_X]]
; GCN: buffer_store_dwordx2 v{{\[}}[[LO_V]]:[[HI_V]]{{\]}}
define void @fneg_fabs_f64(double addrspace(1)* %out, double %in) {
%fabs = call double @llvm.fabs.f64(double %in)
%fsub = fsub double -0.000000e+00, %fabs
@ -68,11 +69,11 @@ define void @fneg_fabs_f64(double addrspace(1)* %out, double %in) {
ret void
}
; FUNC-LABEL: {{^}}fneg_fabs_v2f64:
; SI: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; SI-NOT: 0x80000000
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN-LABEL: {{^}}fneg_fabs_v2f64:
; GCN: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; GCN-NOT: 0x80000000
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
define void @fneg_fabs_v2f64(<2 x double> addrspace(1)* %out, <2 x double> %in) {
%fabs = call <2 x double> @llvm.fabs.v2f64(<2 x double> %in)
%fsub = fsub <2 x double> <double -0.000000e+00, double -0.000000e+00>, %fabs
@ -80,13 +81,13 @@ define void @fneg_fabs_v2f64(<2 x double> addrspace(1)* %out, <2 x double> %in)
ret void
}
; FUNC-LABEL: {{^}}fneg_fabs_v4f64:
; SI: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; SI-NOT: 0x80000000
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; SI: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN-LABEL: {{^}}fneg_fabs_v4f64:
; GCN: v_bfrev_b32_e32 [[IMMREG:v[0-9]+]], 1{{$}}
; GCN-NOT: 0x80000000
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
; GCN: v_or_b32_e32 v{{[0-9]+}}, s{{[0-9]+}}, [[IMMREG]]
define void @fneg_fabs_v4f64(<4 x double> addrspace(1)* %out, <4 x double> %in) {
%fabs = call <4 x double> @llvm.fabs.v4f64(<4 x double> %in)
%fsub = fsub <4 x double> <double -0.000000e+00, double -0.000000e+00, double -0.000000e+00, double -0.000000e+00>, %fabs

9
test/CodeGen/AMDGPU/schedule-kernel-arg-loads.ll
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@ -2,18 +2,15 @@
; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=FUNC -check-prefix=VI --check-prefix=GCN %s
; FUNC-LABEL: {{^}}cluster_arg_loads:
; FIXME: Due to changes in the load clustering heuristics. We now longer
; cluster all argument loads together.
; FIXME: Due to changes in the load clustering heuristics. We no longer
; cluster all argument loads together on SI.
; SI: s_load_dword s{{[0-9]+}}, s{{\[[0-9]+:[0-9]+\]}}, 0xd
; SI-NEXT: s_load_dword s{{[0-9]+}}, s{{\[[0-9]+:[0-9]+\]}}, 0xe
; SI: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x9
; SI-NEXT: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0xb
; VI: s_load_dword s{{[0-9]+}}, s{{\[[0-9]+:[0-9]+\]}}, 0x34
; VI-NEXT: s_nop 0
; VI-NEXT: s_load_dword s{{[0-9]+}}, s{{\[[0-9]+:[0-9]+\]}}, 0x38
; VI-NEXT: s_nop 0
; VI: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x24
; VI-NEXT: s_nop 0
; VI-NEXT: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x24
; VI-NEXT: s_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, 0x2c
define void @cluster_arg_loads(i32 addrspace(1)* %out0, i32 addrspace(1)* %out1, i32 %x, i32 %y) nounwind {
store i32 %x, i32 addrspace(1)* %out0, align 4