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llvm-project/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp

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//===-- GCNHazardRecognizers.cpp - GCN Hazard Recognizer Impls ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements hazard recognizers for scheduling on GCN processors.
//
//===----------------------------------------------------------------------===//
#include "GCNHazardRecognizer.h"
#include "AMDGPUSubtarget.h"
#include "SIDefines.h"
#include "SIInstrInfo.h"
#include "SIRegisterInfo.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Support/ErrorHandling.h"
#include <algorithm>
#include <cassert>
#include <limits>
#include <set>
#include <vector>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Hazard Recoginizer Implementation
//===----------------------------------------------------------------------===//
GCNHazardRecognizer::GCNHazardRecognizer(const MachineFunction &MF) :
IsHazardRecognizerMode(false),
CurrCycleInstr(nullptr),
MF(MF),
ST(MF.getSubtarget<GCNSubtarget>()),
TII(*ST.getInstrInfo()),
TRI(TII.getRegisterInfo()),
ClauseUses(TRI.getNumRegUnits()),
ClauseDefs(TRI.getNumRegUnits()) {
MaxLookAhead = MF.getRegInfo().isPhysRegUsed(AMDGPU::AGPR0) ? 18 : 5;
TSchedModel.init(&ST);
}
void GCNHazardRecognizer::EmitInstruction(SUnit *SU) {
EmitInstruction(SU->getInstr());
}
void GCNHazardRecognizer::EmitInstruction(MachineInstr *MI) {
CurrCycleInstr = MI;
}
static bool isDivFMas(unsigned Opcode) {
return Opcode == AMDGPU::V_DIV_FMAS_F32 || Opcode == AMDGPU::V_DIV_FMAS_F64;
}
static bool isSGetReg(unsigned Opcode) {
return Opcode == AMDGPU::S_GETREG_B32;
}
static bool isSSetReg(unsigned Opcode) {
return Opcode == AMDGPU::S_SETREG_B32 || Opcode == AMDGPU::S_SETREG_IMM32_B32;
}
static bool isRWLane(unsigned Opcode) {
return Opcode == AMDGPU::V_READLANE_B32 || Opcode == AMDGPU::V_WRITELANE_B32;
}
static bool isRFE(unsigned Opcode) {
return Opcode == AMDGPU::S_RFE_B64;
}
static bool isSMovRel(unsigned Opcode) {
switch (Opcode) {
case AMDGPU::S_MOVRELS_B32:
case AMDGPU::S_MOVRELS_B64:
case AMDGPU::S_MOVRELD_B32:
case AMDGPU::S_MOVRELD_B64:
return true;
default:
return false;
}
}
static bool isSendMsgTraceDataOrGDS(const SIInstrInfo &TII,
const MachineInstr &MI) {
if (TII.isAlwaysGDS(MI.getOpcode()))
return true;
switch (MI.getOpcode()) {
case AMDGPU::S_SENDMSG:
case AMDGPU::S_SENDMSGHALT:
case AMDGPU::S_TTRACEDATA:
return true;
// These DS opcodes don't support GDS.
case AMDGPU::DS_NOP:
case AMDGPU::DS_PERMUTE_B32:
case AMDGPU::DS_BPERMUTE_B32:
return false;
default:
if (TII.isDS(MI.getOpcode())) {
int GDS = AMDGPU::getNamedOperandIdx(MI.getOpcode(),
AMDGPU::OpName::gds);
if (MI.getOperand(GDS).getImm())
return true;
}
return false;
}
}
static bool isPermlane(const MachineInstr &MI) {
unsigned Opcode = MI.getOpcode();
return Opcode == AMDGPU::V_PERMLANE16_B32 ||
Opcode == AMDGPU::V_PERMLANEX16_B32;
}
static unsigned getHWReg(const SIInstrInfo *TII, const MachineInstr &RegInstr) {
const MachineOperand *RegOp = TII->getNamedOperand(RegInstr,
AMDGPU::OpName::simm16);
return RegOp->getImm() & AMDGPU::Hwreg::ID_MASK_;
}
ScheduleHazardRecognizer::HazardType
GCNHazardRecognizer::getHazardType(SUnit *SU, int Stalls) {
MachineInstr *MI = SU->getInstr();
if (MI->isBundle())
return NoHazard;
if (SIInstrInfo::isSMRD(*MI) && checkSMRDHazards(MI) > 0)
return NoopHazard;
// FIXME: Should flat be considered vmem?
if ((SIInstrInfo::isVMEM(*MI) ||
SIInstrInfo::isFLAT(*MI))
&& checkVMEMHazards(MI) > 0)
return NoopHazard;
if (ST.hasNSAtoVMEMBug() && checkNSAtoVMEMHazard(MI) > 0)
return NoopHazard;
if (checkFPAtomicToDenormModeHazard(MI) > 0)
return NoopHazard;
if (ST.hasNoDataDepHazard())
return NoHazard;
if (SIInstrInfo::isVALU(*MI) && checkVALUHazards(MI) > 0)
return NoopHazard;
if (SIInstrInfo::isDPP(*MI) && checkDPPHazards(MI) > 0)
return NoopHazard;
if (isDivFMas(MI->getOpcode()) && checkDivFMasHazards(MI) > 0)
return NoopHazard;
if (isRWLane(MI->getOpcode()) && checkRWLaneHazards(MI) > 0)
return NoopHazard;
if (isSGetReg(MI->getOpcode()) && checkGetRegHazards(MI) > 0)
return NoopHazard;
if (isSSetReg(MI->getOpcode()) && checkSetRegHazards(MI) > 0)
return NoopHazard;
if (isRFE(MI->getOpcode()) && checkRFEHazards(MI) > 0)
return NoopHazard;
if (ST.hasReadM0MovRelInterpHazard() &&
(TII.isVINTRP(*MI) || isSMovRel(MI->getOpcode())) &&
checkReadM0Hazards(MI) > 0)
return NoopHazard;
if (ST.hasReadM0SendMsgHazard() && isSendMsgTraceDataOrGDS(TII, *MI) &&
checkReadM0Hazards(MI) > 0)
return NoopHazard;
if (SIInstrInfo::isMAI(*MI) && checkMAIHazards(MI) > 0)
return NoopHazard;
if (MI->mayLoadOrStore() && checkMAILdStHazards(MI) > 0)
return NoopHazard;
if (MI->isInlineAsm() && checkInlineAsmHazards(MI) > 0)
return NoopHazard;
if (checkAnyInstHazards(MI) > 0)
return NoopHazard;
return NoHazard;
}
static void insertNoopInBundle(MachineInstr *MI, const SIInstrInfo &TII) {
BuildMI(*MI->getParent(), MI, MI->getDebugLoc(), TII.get(AMDGPU::S_NOP))
.addImm(0);
}
void GCNHazardRecognizer::processBundle() {
MachineBasicBlock::instr_iterator MI = std::next(CurrCycleInstr->getIterator());
MachineBasicBlock::instr_iterator E = CurrCycleInstr->getParent()->instr_end();
// Check bundled MachineInstr's for hazards.
for (; MI != E && MI->isInsideBundle(); ++MI) {
CurrCycleInstr = &*MI;
unsigned WaitStates = PreEmitNoopsCommon(CurrCycleInstr);
if (IsHazardRecognizerMode)
fixHazards(CurrCycleInstr);
for (unsigned i = 0; i < WaitStates; ++i)
insertNoopInBundle(CurrCycleInstr, TII);
// It’s unnecessary to track more than MaxLookAhead instructions. Since we
// include the bundled MI directly after, only add a maximum of
// (MaxLookAhead - 1) noops to EmittedInstrs.
for (unsigned i = 0, e = std::min(WaitStates, MaxLookAhead - 1); i < e; ++i)
EmittedInstrs.push_front(nullptr);
EmittedInstrs.push_front(CurrCycleInstr);
EmittedInstrs.resize(MaxLookAhead);
}
CurrCycleInstr = nullptr;
}
unsigned GCNHazardRecognizer::PreEmitNoops(SUnit *SU) {
IsHazardRecognizerMode = false;
return PreEmitNoopsCommon(SU->getInstr());
}
unsigned GCNHazardRecognizer::PreEmitNoops(MachineInstr *MI) {
IsHazardRecognizerMode = true;
CurrCycleInstr = MI;
unsigned W = PreEmitNoopsCommon(MI);
fixHazards(MI);
CurrCycleInstr = nullptr;
return W;
}
unsigned GCNHazardRecognizer::PreEmitNoopsCommon(MachineInstr *MI) {
if (MI->isBundle())
return 0;
int WaitStates = std::max(0, checkAnyInstHazards(MI));
if (SIInstrInfo::isSMRD(*MI))
return std::max(WaitStates, checkSMRDHazards(MI));
if (SIInstrInfo::isVMEM(*MI) || SIInstrInfo::isFLAT(*MI))
WaitStates = std::max(WaitStates, checkVMEMHazards(MI));
if (ST.hasNSAtoVMEMBug())
WaitStates = std::max(WaitStates, checkNSAtoVMEMHazard(MI));
WaitStates = std::max(WaitStates, checkFPAtomicToDenormModeHazard(MI));
if (ST.hasNoDataDepHazard())
return WaitStates;
if (SIInstrInfo::isVALU(*MI))
WaitStates = std::max(WaitStates, checkVALUHazards(MI));
if (SIInstrInfo::isDPP(*MI))
WaitStates = std::max(WaitStates, checkDPPHazards(MI));
if (isDivFMas(MI->getOpcode()))
WaitStates = std::max(WaitStates, checkDivFMasHazards(MI));
if (isRWLane(MI->getOpcode()))
WaitStates = std::max(WaitStates, checkRWLaneHazards(MI));
if (MI->isInlineAsm())
return std::max(WaitStates, checkInlineAsmHazards(MI));
if (isSGetReg(MI->getOpcode()))
return std::max(WaitStates, checkGetRegHazards(MI));
if (isSSetReg(MI->getOpcode()))
return std::max(WaitStates, checkSetRegHazards(MI));
if (isRFE(MI->getOpcode()))
return std::max(WaitStates, checkRFEHazards(MI));
if (ST.hasReadM0MovRelInterpHazard() && (TII.isVINTRP(*MI) ||
isSMovRel(MI->getOpcode())))
return std::max(WaitStates, checkReadM0Hazards(MI));
if (ST.hasReadM0SendMsgHazard() && isSendMsgTraceDataOrGDS(TII, *MI))
return std::max(WaitStates, checkReadM0Hazards(MI));
if (SIInstrInfo::isMAI(*MI))
return std::max(WaitStates, checkMAIHazards(MI));
if (MI->mayLoadOrStore())
return std::max(WaitStates, checkMAILdStHazards(MI));
return WaitStates;
}
void GCNHazardRecognizer::EmitNoop() {
EmittedInstrs.push_front(nullptr);
}
void GCNHazardRecognizer::AdvanceCycle() {
// When the scheduler detects a stall, it will call AdvanceCycle() without
// emitting any instructions.
if (!CurrCycleInstr)
return;
// Do not track non-instructions which do not affect the wait states.
// If included, these instructions can lead to buffer overflow such that
// detectable hazards are missed.
if (CurrCycleInstr->isImplicitDef() || CurrCycleInstr->isDebugInstr() ||
CurrCycleInstr->isKill())
return;
if (CurrCycleInstr->isBundle()) {
processBundle();
return;
}
unsigned NumWaitStates = TII.getNumWaitStates(*CurrCycleInstr);
// Keep track of emitted instructions
EmittedInstrs.push_front(CurrCycleInstr);
// Add a nullptr for each additional wait state after the first. Make sure
// not to add more than getMaxLookAhead() items to the list, since we
// truncate the list to that size right after this loop.
for (unsigned i = 1, e = std::min(NumWaitStates, getMaxLookAhead());
i < e; ++i) {
EmittedInstrs.push_front(nullptr);
}
// getMaxLookahead() is the largest number of wait states we will ever need
// to insert, so there is no point in keeping track of more than that many
// wait states.
EmittedInstrs.resize(getMaxLookAhead());
CurrCycleInstr = nullptr;
}
void GCNHazardRecognizer::RecedeCycle() {
llvm_unreachable("hazard recognizer does not support bottom-up scheduling.");
}
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
typedef function_ref<bool(MachineInstr *, int WaitStates)> IsExpiredFn;
// Returns a minimum wait states since \p I walking all predecessors.
// Only scans until \p IsExpired does not return true.
// Can only be run in a hazard recognizer mode.
static int getWaitStatesSince(GCNHazardRecognizer::IsHazardFn IsHazard,
MachineBasicBlock *MBB,
MachineBasicBlock::reverse_instr_iterator I,
int WaitStates,
IsExpiredFn IsExpired,
DenseSet<const MachineBasicBlock *> &Visited) {
for (auto E = MBB->instr_rend(); I != E; ++I) {
// Don't add WaitStates for parent BUNDLE instructions.
if (I->isBundle())
continue;
if (IsHazard(&*I))
return WaitStates;
if (I->isInlineAsm() || I->isImplicitDef() || I->isDebugInstr())
continue;
WaitStates += SIInstrInfo::getNumWaitStates(*I);
if (IsExpired(&*I, WaitStates))
return std::numeric_limits<int>::max();
}
int MinWaitStates = WaitStates;
bool Found = false;
for (MachineBasicBlock *Pred : MBB->predecessors()) {
if (!Visited.insert(Pred).second)
continue;
int W = getWaitStatesSince(IsHazard, Pred, Pred->instr_rbegin(),
WaitStates, IsExpired, Visited);
if (W == std::numeric_limits<int>::max())
continue;
MinWaitStates = Found ? std::min(MinWaitStates, W) : W;
if (IsExpired(nullptr, MinWaitStates))
return MinWaitStates;
Found = true;
}
if (Found)
return MinWaitStates;
return std::numeric_limits<int>::max();
}
static int getWaitStatesSince(GCNHazardRecognizer::IsHazardFn IsHazard,
MachineInstr *MI,
IsExpiredFn IsExpired) {
DenseSet<const MachineBasicBlock *> Visited;
return getWaitStatesSince(IsHazard, MI->getParent(),
std::next(MI->getReverseIterator()),
0, IsExpired, Visited);
}
int GCNHazardRecognizer::getWaitStatesSince(IsHazardFn IsHazard, int Limit) {
if (IsHazardRecognizerMode) {
auto IsExpiredFn = [Limit] (MachineInstr *, int WaitStates) {
return WaitStates >= Limit;
};
return ::getWaitStatesSince(IsHazard, CurrCycleInstr, IsExpiredFn);
}
int WaitStates = 0;
for (MachineInstr *MI : EmittedInstrs) {
if (MI) {
if (IsHazard(MI))
return WaitStates;
if (MI->isInlineAsm())
continue;
}
++WaitStates;
if (WaitStates >= Limit)
break;
}
return std::numeric_limits<int>::max();
}
int GCNHazardRecognizer::getWaitStatesSinceDef(unsigned Reg,
IsHazardFn IsHazardDef,
int Limit) {
const SIRegisterInfo *TRI = ST.getRegisterInfo();
auto IsHazardFn = [IsHazardDef, TRI, Reg] (MachineInstr *MI) {
return IsHazardDef(MI) && MI->modifiesRegister(Reg, TRI);
};
return getWaitStatesSince(IsHazardFn, Limit);
}
int GCNHazardRecognizer::getWaitStatesSinceSetReg(IsHazardFn IsHazard,
int Limit) {
auto IsHazardFn = [IsHazard] (MachineInstr *MI) {
return isSSetReg(MI->getOpcode()) && IsHazard(MI);
};
return getWaitStatesSince(IsHazardFn, Limit);
}
//===----------------------------------------------------------------------===//
// No-op Hazard Detection
//===----------------------------------------------------------------------===//
static void addRegUnits(const SIRegisterInfo &TRI,
BitVector &BV, unsigned Reg) {
for (MCRegUnitIterator RUI(Reg, &TRI); RUI.isValid(); ++RUI)
BV.set(*RUI);
}
static void addRegsToSet(const SIRegisterInfo &TRI,
iterator_range<MachineInstr::const_mop_iterator> Ops,
BitVector &Set) {
for (const MachineOperand &Op : Ops) {
if (Op.isReg())
addRegUnits(TRI, Set, Op.getReg());
}
}
void GCNHazardRecognizer::addClauseInst(const MachineInstr &MI) {
// XXX: Do we need to worry about implicit operands
addRegsToSet(TRI, MI.defs(), ClauseDefs);
addRegsToSet(TRI, MI.uses(), ClauseUses);
}
int GCNHazardRecognizer::checkSoftClauseHazards(MachineInstr *MEM) {
// SMEM soft clause are only present on VI+, and only matter if xnack is
// enabled.
if (!ST.isXNACKEnabled())
return 0;
bool IsSMRD = TII.isSMRD(*MEM);
resetClause();
// 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 by another instruction in the clause
// (including itself). If we encounter this situaion, we need to break the
// clause by inserting a non SMEM instruction.
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)
break;
if (IsSMRD != SIInstrInfo::isSMRD(*MI))
break;
addClauseInst(*MI);
}
if (ClauseDefs.none())
return 0;
// 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 (MEM->mayStore())
return 1;
addClauseInst(*MEM);
// If the set of defs and uses intersect then we cannot add this instruction
// to the clause, so we have a hazard.
return ClauseDefs.anyCommon(ClauseUses) ? 1 : 0;
}
int GCNHazardRecognizer::checkSMRDHazards(MachineInstr *SMRD) {
int WaitStatesNeeded = 0;
WaitStatesNeeded = checkSoftClauseHazards(SMRD);
// This SMRD hazard only affects SI.
if (!ST.hasSMRDReadVALUDefHazard())
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;
auto IsHazardDefFn = [this] (MachineInstr *MI) { return TII.isVALU(*MI); };
auto IsBufferHazardDefFn = [this] (MachineInstr *MI) { return TII.isSALU(*MI); };
bool IsBufferSMRD = TII.isBufferSMRD(*SMRD);
for (const MachineOperand &Use : SMRD->uses()) {
if (!Use.isReg())
continue;
int WaitStatesNeededForUse =
SmrdSgprWaitStates - getWaitStatesSinceDef(Use.getReg(), IsHazardDefFn,
SmrdSgprWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
// This fixes what appears to be undocumented hardware behavior in SI where
// s_mov writing a descriptor and s_buffer_load_dword reading the descriptor
// needs some number of nops in between. We don't know how many we need, but
// let's use 4. This wasn't discovered before probably because the only
// case when this happens is when we expand a 64-bit pointer into a full
// descriptor and use s_buffer_load_dword instead of s_load_dword, which was
// probably never encountered in the closed-source land.
if (IsBufferSMRD) {
int WaitStatesNeededForUse =
SmrdSgprWaitStates - getWaitStatesSinceDef(Use.getReg(),
IsBufferHazardDefFn,
SmrdSgprWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
}
}
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkVMEMHazards(MachineInstr* VMEM) {
if (!ST.hasVMEMReadSGPRVALUDefHazard())
return 0;
int WaitStatesNeeded = checkSoftClauseHazards(VMEM);
// A read of an SGPR by a VMEM instruction requires 5 wait states when the
// SGPR was written by a VALU Instruction.
const int VmemSgprWaitStates = 5;
auto IsHazardDefFn = [this] (MachineInstr *MI) { return TII.isVALU(*MI); };
for (const MachineOperand &Use : VMEM->uses()) {
if (!Use.isReg() || TRI.isVGPR(MF.getRegInfo(), Use.getReg()))
continue;
int WaitStatesNeededForUse =
VmemSgprWaitStates - getWaitStatesSinceDef(Use.getReg(), IsHazardDefFn,
VmemSgprWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
}
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkDPPHazards(MachineInstr *DPP) {
const SIRegisterInfo *TRI = ST.getRegisterInfo();
const SIInstrInfo *TII = ST.getInstrInfo();
// Check for DPP VGPR read after VALU VGPR write and EXEC write.
int DppVgprWaitStates = 2;
int DppExecWaitStates = 5;
int WaitStatesNeeded = 0;
auto IsHazardDefFn = [TII] (MachineInstr *MI) { return TII->isVALU(*MI); };
for (const MachineOperand &Use : DPP->uses()) {
if (!Use.isReg() || !TRI->isVGPR(MF.getRegInfo(), Use.getReg()))
continue;
int WaitStatesNeededForUse =
DppVgprWaitStates - getWaitStatesSinceDef(Use.getReg(),
[](MachineInstr *) { return true; },
DppVgprWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
}
WaitStatesNeeded = std::max(
WaitStatesNeeded,
DppExecWaitStates - getWaitStatesSinceDef(AMDGPU::EXEC, IsHazardDefFn,
DppExecWaitStates));
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkDivFMasHazards(MachineInstr *DivFMas) {
const SIInstrInfo *TII = ST.getInstrInfo();
// v_div_fmas requires 4 wait states after a write to vcc from a VALU
// instruction.
const int DivFMasWaitStates = 4;
auto IsHazardDefFn = [TII] (MachineInstr *MI) { return TII->isVALU(*MI); };
int WaitStatesNeeded = getWaitStatesSinceDef(AMDGPU::VCC, IsHazardDefFn,
DivFMasWaitStates);
return DivFMasWaitStates - WaitStatesNeeded;
}
int GCNHazardRecognizer::checkGetRegHazards(MachineInstr *GetRegInstr) {
const SIInstrInfo *TII = ST.getInstrInfo();
unsigned GetRegHWReg = getHWReg(TII, *GetRegInstr);
const int GetRegWaitStates = 2;
auto IsHazardFn = [TII, GetRegHWReg] (MachineInstr *MI) {
return GetRegHWReg == getHWReg(TII, *MI);
};
int WaitStatesNeeded = getWaitStatesSinceSetReg(IsHazardFn, GetRegWaitStates);
return GetRegWaitStates - WaitStatesNeeded;
}
int GCNHazardRecognizer::checkSetRegHazards(MachineInstr *SetRegInstr) {
const SIInstrInfo *TII = ST.getInstrInfo();
unsigned HWReg = getHWReg(TII, *SetRegInstr);
const int SetRegWaitStates = ST.getSetRegWaitStates();
auto IsHazardFn = [TII, HWReg] (MachineInstr *MI) {
return HWReg == getHWReg(TII, *MI);
};
int WaitStatesNeeded = getWaitStatesSinceSetReg(IsHazardFn, SetRegWaitStates);
return SetRegWaitStates - WaitStatesNeeded;
}
int GCNHazardRecognizer::createsVALUHazard(const MachineInstr &MI) {
if (!MI.mayStore())
return -1;
const SIInstrInfo *TII = ST.getInstrInfo();
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MI.getDesc();
int VDataIdx = AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::vdata);
int VDataRCID = -1;
if (VDataIdx != -1)
VDataRCID = Desc.OpInfo[VDataIdx].RegClass;
if (TII->isMUBUF(MI) || TII->isMTBUF(MI)) {
// There is no hazard if the instruction does not use vector regs
// (like wbinvl1)
if (VDataIdx == -1)
return -1;
// For MUBUF/MTBUF instructions this hazard only exists if the
// instruction is not using a register in the soffset field.
const MachineOperand *SOffset =
TII->getNamedOperand(MI, AMDGPU::OpName::soffset);
// If we have no soffset operand, then assume this field has been
// hardcoded to zero.
if (AMDGPU::getRegBitWidth(VDataRCID) > 64 &&
(!SOffset || !SOffset->isReg()))
return VDataIdx;
}
// MIMG instructions create a hazard if they don't use a 256-bit T# and
// the store size is greater than 8 bytes and they have more than two bits
// of their dmask set.
// All our MIMG definitions use a 256-bit T#, so we can skip checking for them.
if (TII->isMIMG(MI)) {
int SRsrcIdx = AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::srsrc);
assert(SRsrcIdx != -1 &&
AMDGPU::getRegBitWidth(Desc.OpInfo[SRsrcIdx].RegClass) == 256);
(void)SRsrcIdx;
}
if (TII->isFLAT(MI)) {
int DataIdx = AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::vdata);
if (AMDGPU::getRegBitWidth(Desc.OpInfo[DataIdx].RegClass) > 64)
return DataIdx;
}
return -1;
}
int GCNHazardRecognizer::checkVALUHazardsHelper(const MachineOperand &Def,
const MachineRegisterInfo &MRI) {
// Helper to check for the hazard where VMEM instructions that store more than
// 8 bytes can have there store data over written by the next instruction.
const SIRegisterInfo *TRI = ST.getRegisterInfo();
const int VALUWaitStates = 1;
int WaitStatesNeeded = 0;
if (!TRI->isVGPR(MRI, Def.getReg()))
return WaitStatesNeeded;
Register Reg = Def.getReg();
auto IsHazardFn = [this, Reg, TRI] (MachineInstr *MI) {
int DataIdx = createsVALUHazard(*MI);
return DataIdx >= 0 &&
TRI->regsOverlap(MI->getOperand(DataIdx).getReg(), Reg);
};
int WaitStatesNeededForDef =
VALUWaitStates - getWaitStatesSince(IsHazardFn, VALUWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForDef);
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkVALUHazards(MachineInstr *VALU) {
// This checks for the hazard where VMEM instructions that store more than
// 8 bytes can have there store data over written by the next instruction.
if (!ST.has12DWordStoreHazard())
return 0;
const MachineRegisterInfo &MRI = MF.getRegInfo();
int WaitStatesNeeded = 0;
for (const MachineOperand &Def : VALU->defs()) {
WaitStatesNeeded = std::max(WaitStatesNeeded, checkVALUHazardsHelper(Def, MRI));
}
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkInlineAsmHazards(MachineInstr *IA) {
// This checks for hazards associated with inline asm statements.
// Since inline asms can contain just about anything, we use this
// to call/leverage other check*Hazard routines. Note that
// this function doesn't attempt to address all possible inline asm
// hazards (good luck), but is a collection of what has been
// problematic thus far.
// see checkVALUHazards()
if (!ST.has12DWordStoreHazard())
return 0;
const MachineRegisterInfo &MRI = MF.getRegInfo();
int WaitStatesNeeded = 0;
for (unsigned I = InlineAsm::MIOp_FirstOperand, E = IA->getNumOperands();
I != E; ++I) {
const MachineOperand &Op = IA->getOperand(I);
if (Op.isReg() && Op.isDef()) {
WaitStatesNeeded = std::max(WaitStatesNeeded, checkVALUHazardsHelper(Op, MRI));
}
}
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkRWLaneHazards(MachineInstr *RWLane) {
const SIInstrInfo *TII = ST.getInstrInfo();
const SIRegisterInfo *TRI = ST.getRegisterInfo();
const MachineRegisterInfo &MRI = MF.getRegInfo();
const MachineOperand *LaneSelectOp =
TII->getNamedOperand(*RWLane, AMDGPU::OpName::src1);
if (!LaneSelectOp->isReg() || !TRI->isSGPRReg(MRI, LaneSelectOp->getReg()))
return 0;
Register LaneSelectReg = LaneSelectOp->getReg();
auto IsHazardFn = [TII] (MachineInstr *MI) {
return TII->isVALU(*MI);
};
const int RWLaneWaitStates = 4;
int WaitStatesSince = getWaitStatesSinceDef(LaneSelectReg, IsHazardFn,
RWLaneWaitStates);
return RWLaneWaitStates - WaitStatesSince;
}
int GCNHazardRecognizer::checkRFEHazards(MachineInstr *RFE) {
if (!ST.hasRFEHazards())
return 0;
const SIInstrInfo *TII = ST.getInstrInfo();
const int RFEWaitStates = 1;
auto IsHazardFn = [TII] (MachineInstr *MI) {
return getHWReg(TII, *MI) == AMDGPU::Hwreg::ID_TRAPSTS;
};
int WaitStatesNeeded = getWaitStatesSinceSetReg(IsHazardFn, RFEWaitStates);
return RFEWaitStates - WaitStatesNeeded;
}
int GCNHazardRecognizer::checkAnyInstHazards(MachineInstr *MI) {
if (MI->isDebugInstr())
return 0;
const SIRegisterInfo *TRI = ST.getRegisterInfo();
if (!ST.hasSMovFedHazard())
return 0;
// Check for any instruction reading an SGPR after a write from
// s_mov_fed_b32.
int MovFedWaitStates = 1;
int WaitStatesNeeded = 0;
for (const MachineOperand &Use : MI->uses()) {
if (!Use.isReg() || TRI->isVGPR(MF.getRegInfo(), Use.getReg()))
continue;
auto IsHazardFn = [] (MachineInstr *MI) {
return MI->getOpcode() == AMDGPU::S_MOV_FED_B32;
};
int WaitStatesNeededForUse =
MovFedWaitStates - getWaitStatesSinceDef(Use.getReg(), IsHazardFn,
MovFedWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
}
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkReadM0Hazards(MachineInstr *MI) {
const SIInstrInfo *TII = ST.getInstrInfo();
const int SMovRelWaitStates = 1;
auto IsHazardFn = [TII] (MachineInstr *MI) {
return TII->isSALU(*MI);
};
return SMovRelWaitStates - getWaitStatesSinceDef(AMDGPU::M0, IsHazardFn,
SMovRelWaitStates);
}
void GCNHazardRecognizer::fixHazards(MachineInstr *MI) {
fixVMEMtoScalarWriteHazards(MI);
fixVcmpxPermlaneHazards(MI);
fixSMEMtoVectorWriteHazards(MI);
fixVcmpxExecWARHazard(MI);
fixLdsBranchVmemWARHazard(MI);
}
bool GCNHazardRecognizer::fixVcmpxPermlaneHazards(MachineInstr *MI) {
if (!ST.hasVcmpxPermlaneHazard() || !isPermlane(*MI))
return false;
const SIInstrInfo *TII = ST.getInstrInfo();
auto IsHazardFn = [TII] (MachineInstr *MI) {
return TII->isVOPC(*MI);
};
auto IsExpiredFn = [] (MachineInstr *MI, int) {
if (!MI)
return false;
unsigned Opc = MI->getOpcode();
return SIInstrInfo::isVALU(*MI) &&
Opc != AMDGPU::V_NOP_e32 &&
Opc != AMDGPU::V_NOP_e64 &&
Opc != AMDGPU::V_NOP_sdwa;
};
if (::getWaitStatesSince(IsHazardFn, MI, IsExpiredFn) ==
std::numeric_limits<int>::max())
return false;
// V_NOP will be discarded by SQ.
// Use V_MOB_B32 v?, v?. Register must be alive so use src0 of V_PERMLANE*
// which is always a VGPR and available.
auto *Src0 = TII->getNamedOperand(*MI, AMDGPU::OpName::src0);
Register Reg = Src0->getReg();
bool IsUndef = Src0->isUndef();
BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),
TII->get(AMDGPU::V_MOV_B32_e32))
.addReg(Reg, RegState::Define | (IsUndef ? RegState::Dead : 0))
.addReg(Reg, IsUndef ? RegState::Undef : RegState::Kill);
return true;
}
bool GCNHazardRecognizer::fixVMEMtoScalarWriteHazards(MachineInstr *MI) {
if (!ST.hasVMEMtoScalarWriteHazard())
return false;
if (!SIInstrInfo::isSALU(*MI) && !SIInstrInfo::isSMRD(*MI))
return false;
if (MI->getNumDefs() == 0)
return false;
const SIRegisterInfo *TRI = ST.getRegisterInfo();
auto IsHazardFn = [TRI, MI] (MachineInstr *I) {
if (!SIInstrInfo::isVMEM(*I) && !SIInstrInfo::isDS(*I) &&
!SIInstrInfo::isFLAT(*I))
return false;
for (const MachineOperand &Def : MI->defs()) {
MachineOperand *Op = I->findRegisterUseOperand(Def.getReg(), false, TRI);
if (!Op)
continue;
return true;
}
return false;
};
auto IsExpiredFn = [] (MachineInstr *MI, int) {
return MI && (SIInstrInfo::isVALU(*MI) ||
(MI->getOpcode() == AMDGPU::S_WAITCNT &&
!MI->getOperand(0).getImm()));
};
if (::getWaitStatesSince(IsHazardFn, MI, IsExpiredFn) ==
std::numeric_limits<int>::max())
return false;
const SIInstrInfo *TII = ST.getInstrInfo();
BuildMI(*MI->getParent(), MI, MI->getDebugLoc(), TII->get(AMDGPU::V_NOP_e32));
return true;
}
bool GCNHazardRecognizer::fixSMEMtoVectorWriteHazards(MachineInstr *MI) {
if (!ST.hasSMEMtoVectorWriteHazard())
return false;
if (!SIInstrInfo::isVALU(*MI))
return false;
unsigned SDSTName;
switch (MI->getOpcode()) {
case AMDGPU::V_READLANE_B32:
case AMDGPU::V_READLANE_B32_gfx10:
case AMDGPU::V_READFIRSTLANE_B32:
SDSTName = AMDGPU::OpName::vdst;
break;
default:
SDSTName = AMDGPU::OpName::sdst;
break;
}
const SIInstrInfo *TII = ST.getInstrInfo();
const SIRegisterInfo *TRI = ST.getRegisterInfo();
const AMDGPU::IsaVersion IV = AMDGPU::getIsaVersion(ST.getCPU());
const MachineOperand *SDST = TII->getNamedOperand(*MI, SDSTName);
if (!SDST) {
for (const auto &MO : MI->implicit_operands()) {
if (MO.isDef() && TRI->isSGPRClass(TRI->getPhysRegClass(MO.getReg()))) {
SDST = &MO;
break;
}
}
}
if (!SDST)
return false;
const Register SDSTReg = SDST->getReg();
auto IsHazardFn = [SDSTReg, TRI] (MachineInstr *I) {
return SIInstrInfo::isSMRD(*I) && I->readsRegister(SDSTReg, TRI);
};
auto IsExpiredFn = [TII, IV] (MachineInstr *MI, int) {
if (MI) {
if (TII->isSALU(*MI)) {
switch (MI->getOpcode()) {
case AMDGPU::S_SETVSKIP:
case AMDGPU::S_VERSION:
case AMDGPU::S_WAITCNT_VSCNT:
case AMDGPU::S_WAITCNT_VMCNT:
case AMDGPU::S_WAITCNT_EXPCNT:
// These instructions cannot not mitigate the hazard.
return false;
case AMDGPU::S_WAITCNT_LGKMCNT:
// Reducing lgkmcnt count to 0 always mitigates the hazard.
return (MI->getOperand(1).getImm() == 0) &&
(MI->getOperand(0).getReg() == AMDGPU::SGPR_NULL);
case AMDGPU::S_WAITCNT: {
const int64_t Imm = MI->getOperand(0).getImm();
AMDGPU::Waitcnt Decoded = AMDGPU::decodeWaitcnt(IV, Imm);
return (Decoded.LgkmCnt == 0);
}
default:
// SOPP instructions cannot mitigate the hazard.
if (TII->isSOPP(*MI))
return false;
// At this point the SALU can be assumed to mitigate the hazard
// because either:
// (a) it is independent of the at risk SMEM (breaking chain),
// or
// (b) it is dependent on the SMEM, in which case an appropriate
// s_waitcnt lgkmcnt _must_ exist between it and the at risk
// SMEM instruction.
return true;
}
}
}
return false;
};
if (::getWaitStatesSince(IsHazardFn, MI, IsExpiredFn) ==
std::numeric_limits<int>::max())
return false;
BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),
TII->get(AMDGPU::S_MOV_B32), AMDGPU::SGPR_NULL)
.addImm(0);
return true;
}
bool GCNHazardRecognizer::fixVcmpxExecWARHazard(MachineInstr *MI) {
if (!ST.hasVcmpxExecWARHazard() || !SIInstrInfo::isVALU(*MI))
return false;
const SIRegisterInfo *TRI = ST.getRegisterInfo();
if (!MI->modifiesRegister(AMDGPU::EXEC, TRI))
return false;
auto IsHazardFn = [TRI] (MachineInstr *I) {
if (SIInstrInfo::isVALU(*I))
return false;
return I->readsRegister(AMDGPU::EXEC, TRI);
};
const SIInstrInfo *TII = ST.getInstrInfo();
auto IsExpiredFn = [TII, TRI] (MachineInstr *MI, int) {
if (!MI)
return false;
if (SIInstrInfo::isVALU(*MI)) {
if (TII->getNamedOperand(*MI, AMDGPU::OpName::sdst))
return true;
for (auto MO : MI->implicit_operands())
if (MO.isDef() && TRI->isSGPRClass(TRI->getPhysRegClass(MO.getReg())))
return true;
}
if (MI->getOpcode() == AMDGPU::S_WAITCNT_DEPCTR &&
(MI->getOperand(0).getImm() & 0xfffe) == 0xfffe)
return true;
return false;
};
if (::getWaitStatesSince(IsHazardFn, MI, IsExpiredFn) ==
std::numeric_limits<int>::max())
return false;
BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),
TII->get(AMDGPU::S_WAITCNT_DEPCTR))
.addImm(0xfffe);
return true;
}
bool GCNHazardRecognizer::fixLdsBranchVmemWARHazard(MachineInstr *MI) {
if (!ST.hasLdsBranchVmemWARHazard())
return false;
auto IsHazardInst = [] (const MachineInstr *MI) {
if (SIInstrInfo::isDS(*MI))
return 1;
if (SIInstrInfo::isVMEM(*MI) || SIInstrInfo::isSegmentSpecificFLAT(*MI))
return 2;
return 0;
};
auto InstType = IsHazardInst(MI);
if (!InstType)
return false;
auto IsExpiredFn = [&IsHazardInst] (MachineInstr *I, int) {
return I && (IsHazardInst(I) ||
(I->getOpcode() == AMDGPU::S_WAITCNT_VSCNT &&
I->getOperand(0).getReg() == AMDGPU::SGPR_NULL &&
!I->getOperand(1).getImm()));
};
auto IsHazardFn = [InstType, &IsHazardInst] (MachineInstr *I) {
if (!I->isBranch())
return false;
auto IsHazardFn = [InstType, IsHazardInst] (MachineInstr *I) {
auto InstType2 = IsHazardInst(I);
return InstType2 && InstType != InstType2;
};
auto IsExpiredFn = [InstType, &IsHazardInst] (MachineInstr *I, int) {
if (!I)
return false;
auto InstType2 = IsHazardInst(I);
if (InstType == InstType2)
return true;
return I->getOpcode() == AMDGPU::S_WAITCNT_VSCNT &&
I->getOperand(0).getReg() == AMDGPU::SGPR_NULL &&
!I->getOperand(1).getImm();
};
return ::getWaitStatesSince(IsHazardFn, I, IsExpiredFn) !=
std::numeric_limits<int>::max();
};
if (::getWaitStatesSince(IsHazardFn, MI, IsExpiredFn) ==
std::numeric_limits<int>::max())
return false;
const SIInstrInfo *TII = ST.getInstrInfo();
BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),
TII->get(AMDGPU::S_WAITCNT_VSCNT))
.addReg(AMDGPU::SGPR_NULL, RegState::Undef)
.addImm(0);
return true;
}
int GCNHazardRecognizer::checkNSAtoVMEMHazard(MachineInstr *MI) {
int NSAtoVMEMWaitStates = 1;
if (!ST.hasNSAtoVMEMBug())
return 0;
if (!SIInstrInfo::isMUBUF(*MI) && !SIInstrInfo::isMTBUF(*MI))
return 0;
const SIInstrInfo *TII = ST.getInstrInfo();
const auto *Offset = TII->getNamedOperand(*MI, AMDGPU::OpName::offset);
if (!Offset || (Offset->getImm() & 6) == 0)
return 0;
auto IsHazardFn = [TII] (MachineInstr *I) {
if (!SIInstrInfo::isMIMG(*I))
return false;
const AMDGPU::MIMGInfo *Info = AMDGPU::getMIMGInfo(I->getOpcode());
return Info->MIMGEncoding == AMDGPU::MIMGEncGfx10NSA &&
TII->getInstSizeInBytes(*I) >= 16;
};
return NSAtoVMEMWaitStates - getWaitStatesSince(IsHazardFn, 1);
}
int GCNHazardRecognizer::checkFPAtomicToDenormModeHazard(MachineInstr *MI) {
int FPAtomicToDenormModeWaitStates = 3;
if (MI->getOpcode() != AMDGPU::S_DENORM_MODE)
return 0;
auto IsHazardFn = [] (MachineInstr *I) {
if (!SIInstrInfo::isVMEM(*I) && !SIInstrInfo::isFLAT(*I))
return false;
return SIInstrInfo::isFPAtomic(*I);
};
auto IsExpiredFn = [] (MachineInstr *MI, int WaitStates) {
if (WaitStates >= 3 || SIInstrInfo::isVALU(*MI))
return true;
switch (MI->getOpcode()) {
case AMDGPU::S_WAITCNT:
case AMDGPU::S_WAITCNT_VSCNT:
case AMDGPU::S_WAITCNT_VMCNT:
case AMDGPU::S_WAITCNT_EXPCNT:
case AMDGPU::S_WAITCNT_LGKMCNT:
case AMDGPU::S_WAITCNT_IDLE:
return true;
default:
break;
}
return false;
};
return FPAtomicToDenormModeWaitStates -
::getWaitStatesSince(IsHazardFn, MI, IsExpiredFn);
}
int GCNHazardRecognizer::checkMAIHazards(MachineInstr *MI) {
assert(SIInstrInfo::isMAI(*MI));
int WaitStatesNeeded = 0;
unsigned Opc = MI->getOpcode();
auto IsVALUFn = [] (MachineInstr *MI) {
return SIInstrInfo::isVALU(*MI);
};
if (Opc != AMDGPU::V_ACCVGPR_READ_B32) { // MFMA or v_accvgpr_write
const int LegacyVALUWritesVGPRWaitStates = 2;
const int VALUWritesExecWaitStates = 4;
const int MaxWaitStates = 4;
int WaitStatesNeededForUse = VALUWritesExecWaitStates -
getWaitStatesSinceDef(AMDGPU::EXEC, IsVALUFn, MaxWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
if (WaitStatesNeeded < MaxWaitStates) {
for (const MachineOperand &Use : MI->explicit_uses()) {
const int MaxWaitStates = 2;
if (!Use.isReg() || !TRI.isVGPR(MF.getRegInfo(), Use.getReg()))
continue;
int WaitStatesNeededForUse = LegacyVALUWritesVGPRWaitStates -
getWaitStatesSinceDef(Use.getReg(), IsVALUFn, MaxWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
if (WaitStatesNeeded == MaxWaitStates)
break;
}
}
}
auto IsMFMAFn = [] (MachineInstr *MI) {
return SIInstrInfo::isMAI(*MI) &&
MI->getOpcode() != AMDGPU::V_ACCVGPR_WRITE_B32 &&
MI->getOpcode() != AMDGPU::V_ACCVGPR_READ_B32;
};
for (const MachineOperand &Op : MI->explicit_operands()) {
if (!Op.isReg() || !TRI.isAGPR(MF.getRegInfo(), Op.getReg()))
continue;
if (Op.isDef() && Opc != AMDGPU::V_ACCVGPR_WRITE_B32)
continue;
const int MFMAWritesAGPROverlappedSrcABWaitStates = 4;
const int MFMAWritesAGPROverlappedSrcCWaitStates = 2;
const int MFMA4x4WritesAGPRAccVgprReadWaitStates = 4;
const int MFMA16x16WritesAGPRAccVgprReadWaitStates = 10;
const int MFMA32x32WritesAGPRAccVgprReadWaitStates = 18;
const int MFMA4x4WritesAGPRAccVgprWriteWaitStates = 1;
const int MFMA16x16WritesAGPRAccVgprWriteWaitStates = 7;
const int MFMA32x32WritesAGPRAccVgprWriteWaitStates = 15;
const int MaxWaitStates = 18;
Register Reg = Op.getReg();
unsigned HazardDefLatency = 0;
auto IsOverlappedMFMAFn = [Reg, &IsMFMAFn, &HazardDefLatency, this]
(MachineInstr *MI) {
if (!IsMFMAFn(MI))
return false;
Register DstReg = MI->getOperand(0).getReg();
if (DstReg == Reg)
return false;
HazardDefLatency = std::max(HazardDefLatency,
TSchedModel.computeInstrLatency(MI));
return TRI.regsOverlap(DstReg, Reg);
};
int WaitStatesSinceDef = getWaitStatesSinceDef(Reg, IsOverlappedMFMAFn,
MaxWaitStates);
int NeedWaitStates = MFMAWritesAGPROverlappedSrcABWaitStates;
int SrcCIdx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src2);
int OpNo = MI->getOperandNo(&Op);
if (OpNo == SrcCIdx) {
NeedWaitStates = MFMAWritesAGPROverlappedSrcCWaitStates;
} else if (Opc == AMDGPU::V_ACCVGPR_READ_B32) {
switch (HazardDefLatency) {
case 2: NeedWaitStates = MFMA4x4WritesAGPRAccVgprReadWaitStates;
break;
case 8: NeedWaitStates = MFMA16x16WritesAGPRAccVgprReadWaitStates;
break;
case 16: LLVM_FALLTHROUGH;
default: NeedWaitStates = MFMA32x32WritesAGPRAccVgprReadWaitStates;
break;
}
} else if (Opc == AMDGPU::V_ACCVGPR_WRITE_B32) {
switch (HazardDefLatency) {
case 2: NeedWaitStates = MFMA4x4WritesAGPRAccVgprWriteWaitStates;
break;
case 8: NeedWaitStates = MFMA16x16WritesAGPRAccVgprWriteWaitStates;
break;
case 16: LLVM_FALLTHROUGH;
default: NeedWaitStates = MFMA32x32WritesAGPRAccVgprWriteWaitStates;
break;
}
}
int WaitStatesNeededForUse = NeedWaitStates - WaitStatesSinceDef;
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
if (WaitStatesNeeded == MaxWaitStates)
return WaitStatesNeeded; // Early exit.
auto IsAccVgprWriteFn = [Reg, this] (MachineInstr *MI) {
if (MI->getOpcode() != AMDGPU::V_ACCVGPR_WRITE_B32)
return false;
Register DstReg = MI->getOperand(0).getReg();
return TRI.regsOverlap(Reg, DstReg);
};
const int AccVGPRWriteMFMAReadSrcCWaitStates = 1;
const int AccVGPRWriteMFMAReadSrcABWaitStates = 3;
const int AccVGPRWriteAccVgprReadWaitStates = 3;
NeedWaitStates = AccVGPRWriteMFMAReadSrcABWaitStates;
if (OpNo == SrcCIdx)
NeedWaitStates = AccVGPRWriteMFMAReadSrcCWaitStates;
else if (Opc == AMDGPU::V_ACCVGPR_READ_B32)
NeedWaitStates = AccVGPRWriteAccVgprReadWaitStates;
WaitStatesNeededForUse = NeedWaitStates -
getWaitStatesSinceDef(Reg, IsAccVgprWriteFn, MaxWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
if (WaitStatesNeeded == MaxWaitStates)
return WaitStatesNeeded; // Early exit.
}
if (Opc == AMDGPU::V_ACCVGPR_WRITE_B32) {
const int MFMA4x4ReadSrcCAccVgprWriteWaitStates = 0;
const int MFMA16x16ReadSrcCAccVgprWriteWaitStates = 5;
const int MFMA32x32ReadSrcCAccVgprWriteWaitStates = 13;
const int MaxWaitStates = 13;
Register DstReg = MI->getOperand(0).getReg();
unsigned HazardDefLatency = 0;
auto IsSrcCMFMAFn = [DstReg, &IsMFMAFn, &HazardDefLatency, this]
(MachineInstr *MI) {
if (!IsMFMAFn(MI))
return false;
Register Reg = TII.getNamedOperand(*MI, AMDGPU::OpName::src2)->getReg();
HazardDefLatency = std::max(HazardDefLatency,
TSchedModel.computeInstrLatency(MI));
return TRI.regsOverlap(Reg, DstReg);
};
int WaitStatesSince = getWaitStatesSince(IsSrcCMFMAFn, MaxWaitStates);
int NeedWaitStates;
switch (HazardDefLatency) {
case 2: NeedWaitStates = MFMA4x4ReadSrcCAccVgprWriteWaitStates;
break;
case 8: NeedWaitStates = MFMA16x16ReadSrcCAccVgprWriteWaitStates;
break;
case 16: LLVM_FALLTHROUGH;
default: NeedWaitStates = MFMA32x32ReadSrcCAccVgprWriteWaitStates;
break;
}
int WaitStatesNeededForUse = NeedWaitStates - WaitStatesSince;
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
}
return WaitStatesNeeded;
}
int GCNHazardRecognizer::checkMAILdStHazards(MachineInstr *MI) {
if (!ST.hasMAIInsts())
return 0;
int WaitStatesNeeded = 0;
auto IsAccVgprReadFn = [] (MachineInstr *MI) {
return MI->getOpcode() == AMDGPU::V_ACCVGPR_READ_B32;
};
for (const MachineOperand &Op : MI->explicit_uses()) {
if (!Op.isReg() || !TRI.isVGPR(MF.getRegInfo(), Op.getReg()))
continue;
Register Reg = Op.getReg();
const int AccVgprReadLdStWaitStates = 2;
const int VALUWriteAccVgprReadLdStDepVALUWaitStates = 1;
const int MaxWaitStates = 2;
int WaitStatesNeededForUse = AccVgprReadLdStWaitStates -
getWaitStatesSinceDef(Reg, IsAccVgprReadFn, MaxWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
if (WaitStatesNeeded == MaxWaitStates)
return WaitStatesNeeded; // Early exit.
auto IsVALUAccVgprReadCheckFn = [Reg, this] (MachineInstr *MI) {
if (MI->getOpcode() != AMDGPU::V_ACCVGPR_READ_B32)
return false;
auto IsVALUFn = [] (MachineInstr *MI) {
return SIInstrInfo::isVALU(*MI) && !SIInstrInfo::isMAI(*MI);
};
return getWaitStatesSinceDef(Reg, IsVALUFn, 2 /*MaxWaitStates*/) <
std::numeric_limits<int>::max();
};
WaitStatesNeededForUse = VALUWriteAccVgprReadLdStDepVALUWaitStates -
getWaitStatesSince(IsVALUAccVgprReadCheckFn, MaxWaitStates);
WaitStatesNeeded = std::max(WaitStatesNeeded, WaitStatesNeededForUse);
}
return WaitStatesNeeded;
}
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