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

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//===- SIInsertWaitcnts.cpp - Insert Wait Instructions --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
/// \file
/// Insert wait instructions for memory reads and writes.
///
/// Memory reads and writes are issued asynchronously, so we need to insert
/// S_WAITCNT instructions when we want to access any of their results or
/// overwrite any register that's used asynchronously.
//
//===----------------------------------------------------------------------===//
#include "AMDGPU.h"
#include "AMDGPUSubtarget.h"
#include "SIDefines.h"
#include "SIInstrInfo.h"
#include "SIMachineFunctionInfo.h"
#include "SIRegisterInfo.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/DebugCounter.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstring>
#include <memory>
#include <utility>
#include <vector>
using namespace llvm;
#define DEBUG_TYPE "si-insert-waitcnts"
DEBUG_COUNTER(ForceExpCounter, DEBUG_TYPE"-forceexp",
"Force emit s_waitcnt expcnt(0) instrs");
DEBUG_COUNTER(ForceLgkmCounter, DEBUG_TYPE"-forcelgkm",
"Force emit s_waitcnt lgkmcnt(0) instrs");
DEBUG_COUNTER(ForceVMCounter, DEBUG_TYPE"-forcevm",
"Force emit s_waitcnt vmcnt(0) instrs");
static cl::opt<unsigned> ForceEmitZeroFlag(
"amdgpu-waitcnt-forcezero",
cl::desc("Force all waitcnt instrs to be emitted as s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)"),
cl::init(0), cl::Hidden);
namespace {
// Class of object that encapsulates latest instruction counter score
// associated with the operand. Used for determining whether
// s_waitcnt instruction needs to be emited.
#define CNT_MASK(t) (1u << (t))
enum InstCounterType { VM_CNT = 0, LGKM_CNT, EXP_CNT, NUM_INST_CNTS };
using RegInterval = std::pair<signed, signed>;
struct {
int32_t VmcntMax;
int32_t ExpcntMax;
int32_t LgkmcntMax;
int32_t NumVGPRsMax;
int32_t NumSGPRsMax;
} HardwareLimits;
struct {
unsigned VGPR0;
unsigned VGPRL;
unsigned SGPR0;
unsigned SGPRL;
} RegisterEncoding;
enum WaitEventType {
VMEM_ACCESS, // vector-memory read & write
LDS_ACCESS, // lds read & write
GDS_ACCESS, // gds read & write
SQ_MESSAGE, // send message
SMEM_ACCESS, // scalar-memory read & write
EXP_GPR_LOCK, // export holding on its data src
GDS_GPR_LOCK, // GDS holding on its data and addr src
EXP_POS_ACCESS, // write to export position
EXP_PARAM_ACCESS, // write to export parameter
VMW_GPR_LOCK, // vector-memory write holding on its data src
NUM_WAIT_EVENTS,
};
// The mapping is:
// 0 .. SQ_MAX_PGM_VGPRS-1 real VGPRs
// SQ_MAX_PGM_VGPRS .. NUM_ALL_VGPRS-1 extra VGPR-like slots
// NUM_ALL_VGPRS .. NUM_ALL_VGPRS+SQ_MAX_PGM_SGPRS-1 real SGPRs
// We reserve a fixed number of VGPR slots in the scoring tables for
// special tokens like SCMEM_LDS (needed for buffer load to LDS).
enum RegisterMapping {
SQ_MAX_PGM_VGPRS = 256, // Maximum programmable VGPRs across all targets.
SQ_MAX_PGM_SGPRS = 256, // Maximum programmable SGPRs across all targets.
NUM_EXTRA_VGPRS = 1, // A reserved slot for DS.
EXTRA_VGPR_LDS = 0, // This is a placeholder the Shader algorithm uses.
NUM_ALL_VGPRS = SQ_MAX_PGM_VGPRS + NUM_EXTRA_VGPRS, // Where SGPR starts.
};
#define ForAllWaitEventType(w) \
for (enum WaitEventType w = (enum WaitEventType)0; \
(w) < (enum WaitEventType)NUM_WAIT_EVENTS; \
(w) = (enum WaitEventType)((w) + 1))
// This is a per-basic-block object that maintains current score brackets
// of each wait counter, and a per-register scoreboard for each wait counter.
// We also maintain the latest score for every event type that can change the
// waitcnt in order to know if there are multiple types of events within
// the brackets. When multiple types of event happen in the bracket,
// wait count may get decreased out of order, therefore we need to put in
// "s_waitcnt 0" before use.
class BlockWaitcntBrackets {
public:
BlockWaitcntBrackets(const GCNSubtarget *SubTarget) : ST(SubTarget) {
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
memset(VgprScores[T], 0, sizeof(VgprScores[T]));
}
}
~BlockWaitcntBrackets() = default;
static int32_t getWaitCountMax(InstCounterType T) {
switch (T) {
case VM_CNT:
return HardwareLimits.VmcntMax;
case LGKM_CNT:
return HardwareLimits.LgkmcntMax;
case EXP_CNT:
return HardwareLimits.ExpcntMax;
default:
break;
}
return 0;
}
void setScoreLB(InstCounterType T, int32_t Val) {
assert(T < NUM_INST_CNTS);
if (T >= NUM_INST_CNTS)
return;
ScoreLBs[T] = Val;
}
void setScoreUB(InstCounterType T, int32_t Val) {
assert(T < NUM_INST_CNTS);
if (T >= NUM_INST_CNTS)
return;
ScoreUBs[T] = Val;
if (T == EXP_CNT) {
int32_t UB = (int)(ScoreUBs[T] - getWaitCountMax(EXP_CNT));
if (ScoreLBs[T] < UB)
ScoreLBs[T] = UB;
}
}
int32_t getScoreLB(InstCounterType T) {
assert(T < NUM_INST_CNTS);
if (T >= NUM_INST_CNTS)
return 0;
return ScoreLBs[T];
}
int32_t getScoreUB(InstCounterType T) {
assert(T < NUM_INST_CNTS);
if (T >= NUM_INST_CNTS)
return 0;
return ScoreUBs[T];
}
// Mapping from event to counter.
InstCounterType eventCounter(WaitEventType E) {
switch (E) {
case VMEM_ACCESS:
return VM_CNT;
case LDS_ACCESS:
case GDS_ACCESS:
case SQ_MESSAGE:
case SMEM_ACCESS:
return LGKM_CNT;
case EXP_GPR_LOCK:
case GDS_GPR_LOCK:
case VMW_GPR_LOCK:
case EXP_POS_ACCESS:
case EXP_PARAM_ACCESS:
return EXP_CNT;
default:
llvm_unreachable("unhandled event type");
}
return NUM_INST_CNTS;
}
void setRegScore(int GprNo, InstCounterType T, int32_t Val) {
if (GprNo < NUM_ALL_VGPRS) {
if (GprNo > VgprUB) {
VgprUB = GprNo;
}
VgprScores[T][GprNo] = Val;
} else {
assert(T == LGKM_CNT);
if (GprNo - NUM_ALL_VGPRS > SgprUB) {
SgprUB = GprNo - NUM_ALL_VGPRS;
}
SgprScores[GprNo - NUM_ALL_VGPRS] = Val;
}
}
int32_t getRegScore(int GprNo, InstCounterType T) {
if (GprNo < NUM_ALL_VGPRS) {
return VgprScores[T][GprNo];
}
return SgprScores[GprNo - NUM_ALL_VGPRS];
}
void clear() {
memset(ScoreLBs, 0, sizeof(ScoreLBs));
memset(ScoreUBs, 0, sizeof(ScoreUBs));
memset(EventUBs, 0, sizeof(EventUBs));
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
memset(VgprScores[T], 0, sizeof(VgprScores[T]));
}
memset(SgprScores, 0, sizeof(SgprScores));
}
RegInterval getRegInterval(const MachineInstr *MI, const SIInstrInfo *TII,
const MachineRegisterInfo *MRI,
const SIRegisterInfo *TRI, unsigned OpNo,
bool Def) const;
void setExpScore(const MachineInstr *MI, const SIInstrInfo *TII,
const SIRegisterInfo *TRI, const MachineRegisterInfo *MRI,
unsigned OpNo, int32_t Val);
void setWaitAtBeginning() { WaitAtBeginning = true; }
void clearWaitAtBeginning() { WaitAtBeginning = false; }
bool getWaitAtBeginning() const { return WaitAtBeginning; }
void setEventUB(enum WaitEventType W, int32_t Val) { EventUBs[W] = Val; }
int32_t getMaxVGPR() const { return VgprUB; }
int32_t getMaxSGPR() const { return SgprUB; }
int32_t getEventUB(enum WaitEventType W) const {
assert(W < NUM_WAIT_EVENTS);
return EventUBs[W];
}
bool counterOutOfOrder(InstCounterType T);
unsigned int updateByWait(InstCounterType T, int ScoreToWait);
void updateByEvent(const SIInstrInfo *TII, const SIRegisterInfo *TRI,
const MachineRegisterInfo *MRI, WaitEventType E,
MachineInstr &MI);
bool hasPendingSMEM() const {
return (EventUBs[SMEM_ACCESS] > ScoreLBs[LGKM_CNT] &&
EventUBs[SMEM_ACCESS] <= ScoreUBs[LGKM_CNT]);
}
bool hasPendingFlat() const {
return ((LastFlat[LGKM_CNT] > ScoreLBs[LGKM_CNT] &&
LastFlat[LGKM_CNT] <= ScoreUBs[LGKM_CNT]) ||
(LastFlat[VM_CNT] > ScoreLBs[VM_CNT] &&
LastFlat[VM_CNT] <= ScoreUBs[VM_CNT]));
}
void setPendingFlat() {
LastFlat[VM_CNT] = ScoreUBs[VM_CNT];
LastFlat[LGKM_CNT] = ScoreUBs[LGKM_CNT];
}
int pendingFlat(InstCounterType Ct) const { return LastFlat[Ct]; }
void setLastFlat(InstCounterType Ct, int Val) { LastFlat[Ct] = Val; }
bool getRevisitLoop() const { return RevisitLoop; }
void setRevisitLoop(bool RevisitLoopIn) { RevisitLoop = RevisitLoopIn; }
void setPostOrder(int32_t PostOrderIn) { PostOrder = PostOrderIn; }
int32_t getPostOrder() const { return PostOrder; }
void setWaitcnt(MachineInstr *WaitcntIn) { Waitcnt = WaitcntIn; }
void clearWaitcnt() { Waitcnt = nullptr; }
MachineInstr *getWaitcnt() const { return Waitcnt; }
bool mixedExpTypes() const { return MixedExpTypes; }
void setMixedExpTypes(bool MixedExpTypesIn) {
MixedExpTypes = MixedExpTypesIn;
}
void print(raw_ostream &);
void dump() { print(dbgs()); }
private:
const GCNSubtarget *ST = nullptr;
bool WaitAtBeginning = false;
bool RevisitLoop = false;
bool MixedExpTypes = false;
int32_t PostOrder = 0;
MachineInstr *Waitcnt = nullptr;
int32_t ScoreLBs[NUM_INST_CNTS] = {0};
int32_t ScoreUBs[NUM_INST_CNTS] = {0};
int32_t EventUBs[NUM_WAIT_EVENTS] = {0};
// Remember the last flat memory operation.
int32_t LastFlat[NUM_INST_CNTS] = {0};
// wait_cnt scores for every vgpr.
// Keep track of the VgprUB and SgprUB to make merge at join efficient.
int32_t VgprUB = 0;
int32_t SgprUB = 0;
int32_t VgprScores[NUM_INST_CNTS][NUM_ALL_VGPRS];
// Wait cnt scores for every sgpr, only lgkmcnt is relevant.
int32_t SgprScores[SQ_MAX_PGM_SGPRS] = {0};
};
// This is a per-loop-region object that records waitcnt status at the end of
// loop footer from the previous iteration. We also maintain an iteration
// count to track the number of times the loop has been visited. When it
// doesn't converge naturally, we force convergence by inserting s_waitcnt 0
// at the end of the loop footer.
class LoopWaitcntData {
public:
LoopWaitcntData() = default;
~LoopWaitcntData() = default;
void incIterCnt() { IterCnt++; }
void resetIterCnt() { IterCnt = 0; }
unsigned getIterCnt() { return IterCnt; }
void setWaitcnt(MachineInstr *WaitcntIn) { LfWaitcnt = WaitcntIn; }
MachineInstr *getWaitcnt() const { return LfWaitcnt; }
void print() { LLVM_DEBUG(dbgs() << " iteration " << IterCnt << '\n';); }
private:
// s_waitcnt added at the end of loop footer to stablize wait scores
// at the end of the loop footer.
MachineInstr *LfWaitcnt = nullptr;
// Number of iterations the loop has been visited, not including the initial
// walk over.
int32_t IterCnt = 0;
};
class SIInsertWaitcnts : public MachineFunctionPass {
private:
const GCNSubtarget *ST = nullptr;
const SIInstrInfo *TII = nullptr;
const SIRegisterInfo *TRI = nullptr;
const MachineRegisterInfo *MRI = nullptr;
const MachineLoopInfo *MLI = nullptr;
AMDGPU::IsaVersion IV;
DenseSet<MachineBasicBlock *> BlockVisitedSet;
DenseSet<MachineInstr *> TrackedWaitcntSet;
DenseSet<MachineInstr *> VCCZBugHandledSet;
DenseMap<MachineBasicBlock *, std::unique_ptr<BlockWaitcntBrackets>>
BlockWaitcntBracketsMap;
std::vector<MachineBasicBlock *> BlockWaitcntProcessedSet;
DenseMap<MachineLoop *, std::unique_ptr<LoopWaitcntData>> LoopWaitcntDataMap;
std::vector<std::unique_ptr<BlockWaitcntBrackets>> KillWaitBrackets;
// ForceEmitZeroWaitcnts: force all waitcnts insts to be s_waitcnt 0
// because of amdgpu-waitcnt-forcezero flag
bool ForceEmitZeroWaitcnts;
bool ForceEmitWaitcnt[NUM_INST_CNTS];
public:
static char ID;
SIInsertWaitcnts() : MachineFunctionPass(ID) {
(void)ForceExpCounter;
(void)ForceLgkmCounter;
(void)ForceVMCounter;
}
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override {
return "SI insert wait instructions";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
void addKillWaitBracket(BlockWaitcntBrackets *Bracket) {
// The waitcnt information is copied because it changes as the block is
// traversed.
KillWaitBrackets.push_back(
llvm::make_unique<BlockWaitcntBrackets>(*Bracket));
}
bool isForceEmitWaitcnt() const {
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1))
if (ForceEmitWaitcnt[T])
return true;
return false;
}
void setForceEmitWaitcnt() {
// For non-debug builds, ForceEmitWaitcnt has been initialized to false;
// For debug builds, get the debug counter info and adjust if need be
#ifndef NDEBUG
if (DebugCounter::isCounterSet(ForceExpCounter) &&
DebugCounter::shouldExecute(ForceExpCounter)) {
ForceEmitWaitcnt[EXP_CNT] = true;
} else {
ForceEmitWaitcnt[EXP_CNT] = false;
}
if (DebugCounter::isCounterSet(ForceLgkmCounter) &&
DebugCounter::shouldExecute(ForceLgkmCounter)) {
ForceEmitWaitcnt[LGKM_CNT] = true;
} else {
ForceEmitWaitcnt[LGKM_CNT] = false;
}
if (DebugCounter::isCounterSet(ForceVMCounter) &&
DebugCounter::shouldExecute(ForceVMCounter)) {
ForceEmitWaitcnt[VM_CNT] = true;
} else {
ForceEmitWaitcnt[VM_CNT] = false;
}
#endif // NDEBUG
}
bool mayAccessLDSThroughFlat(const MachineInstr &MI) const;
void generateWaitcntInstBefore(MachineInstr &MI,
BlockWaitcntBrackets *ScoreBrackets);
void updateEventWaitcntAfter(MachineInstr &Inst,
BlockWaitcntBrackets *ScoreBrackets);
void mergeInputScoreBrackets(MachineBasicBlock &Block);
bool isLoopBottom(const MachineLoop *Loop, const MachineBasicBlock *Block);
unsigned countNumBottomBlocks(const MachineLoop *Loop);
void insertWaitcntInBlock(MachineFunction &MF, MachineBasicBlock &Block);
void insertWaitcntBeforeCF(MachineBasicBlock &Block, MachineInstr *Inst);
bool isWaitcntStronger(unsigned LHS, unsigned RHS);
unsigned combineWaitcnt(unsigned LHS, unsigned RHS);
};
} // end anonymous namespace
RegInterval BlockWaitcntBrackets::getRegInterval(const MachineInstr *MI,
const SIInstrInfo *TII,
const MachineRegisterInfo *MRI,
const SIRegisterInfo *TRI,
unsigned OpNo,
bool Def) const {
const MachineOperand &Op = MI->getOperand(OpNo);
if (!Op.isReg() || !TRI->isInAllocatableClass(Op.getReg()) ||
(Def && !Op.isDef()))
return {-1, -1};
// A use via a PW operand does not need a waitcnt.
// A partial write is not a WAW.
assert(!Op.getSubReg() || !Op.isUndef());
RegInterval Result;
const MachineRegisterInfo &MRIA = *MRI;
unsigned Reg = TRI->getEncodingValue(Op.getReg());
if (TRI->isVGPR(MRIA, Op.getReg())) {
assert(Reg >= RegisterEncoding.VGPR0 && Reg <= RegisterEncoding.VGPRL);
Result.first = Reg - RegisterEncoding.VGPR0;
assert(Result.first >= 0 && Result.first < SQ_MAX_PGM_VGPRS);
} else if (TRI->isSGPRReg(MRIA, Op.getReg())) {
assert(Reg >= RegisterEncoding.SGPR0 && Reg < SQ_MAX_PGM_SGPRS);
Result.first = Reg - RegisterEncoding.SGPR0 + NUM_ALL_VGPRS;
assert(Result.first >= NUM_ALL_VGPRS &&
Result.first < SQ_MAX_PGM_SGPRS + NUM_ALL_VGPRS);
}
// TODO: Handle TTMP
// else if (TRI->isTTMP(MRIA, Reg.getReg())) ...
else
return {-1, -1};
const MachineInstr &MIA = *MI;
const TargetRegisterClass *RC = TII->getOpRegClass(MIA, OpNo);
unsigned Size = TRI->getRegSizeInBits(*RC);
Result.second = Result.first + (Size / 32);
return Result;
}
void BlockWaitcntBrackets::setExpScore(const MachineInstr *MI,
const SIInstrInfo *TII,
const SIRegisterInfo *TRI,
const MachineRegisterInfo *MRI,
unsigned OpNo, int32_t Val) {
RegInterval Interval = getRegInterval(MI, TII, MRI, TRI, OpNo, false);
LLVM_DEBUG({
const MachineOperand &Opnd = MI->getOperand(OpNo);
assert(TRI->isVGPR(*MRI, Opnd.getReg()));
});
for (signed RegNo = Interval.first; RegNo < Interval.second; ++RegNo) {
setRegScore(RegNo, EXP_CNT, Val);
}
}
void BlockWaitcntBrackets::updateByEvent(const SIInstrInfo *TII,
const SIRegisterInfo *TRI,
const MachineRegisterInfo *MRI,
WaitEventType E, MachineInstr &Inst) {
const MachineRegisterInfo &MRIA = *MRI;
InstCounterType T = eventCounter(E);
int32_t CurrScore = getScoreUB(T) + 1;
// EventUB and ScoreUB need to be update regardless if this event changes
// the score of a register or not.
// Examples including vm_cnt when buffer-store or lgkm_cnt when send-message.
EventUBs[E] = CurrScore;
setScoreUB(T, CurrScore);
if (T == EXP_CNT) {
// Check for mixed export types. If they are mixed, then a waitcnt exp(0)
// is required.
if (!MixedExpTypes) {
MixedExpTypes = counterOutOfOrder(EXP_CNT);
}
// Put score on the source vgprs. If this is a store, just use those
// specific register(s).
if (TII->isDS(Inst) && (Inst.mayStore() || Inst.mayLoad())) {
// All GDS operations must protect their address register (same as
// export.)
if (Inst.getOpcode() != AMDGPU::DS_APPEND &&
Inst.getOpcode() != AMDGPU::DS_CONSUME) {
setExpScore(
&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(), AMDGPU::OpName::addr),
CurrScore);
}
if (Inst.mayStore()) {
setExpScore(
&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(), AMDGPU::OpName::data0),
CurrScore);
if (AMDGPU::getNamedOperandIdx(Inst.getOpcode(),
AMDGPU::OpName::data1) != -1) {
setExpScore(&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(),
AMDGPU::OpName::data1),
CurrScore);
}
} else if (AMDGPU::getAtomicNoRetOp(Inst.getOpcode()) != -1 &&
Inst.getOpcode() != AMDGPU::DS_GWS_INIT &&
Inst.getOpcode() != AMDGPU::DS_GWS_SEMA_V &&
Inst.getOpcode() != AMDGPU::DS_GWS_SEMA_BR &&
Inst.getOpcode() != AMDGPU::DS_GWS_SEMA_P &&
Inst.getOpcode() != AMDGPU::DS_GWS_BARRIER &&
Inst.getOpcode() != AMDGPU::DS_APPEND &&
Inst.getOpcode() != AMDGPU::DS_CONSUME &&
Inst.getOpcode() != AMDGPU::DS_ORDERED_COUNT) {
for (unsigned I = 0, E = Inst.getNumOperands(); I != E; ++I) {
const MachineOperand &Op = Inst.getOperand(I);
if (Op.isReg() && !Op.isDef() && TRI->isVGPR(MRIA, Op.getReg())) {
setExpScore(&Inst, TII, TRI, MRI, I, CurrScore);
}
}
}
} else if (TII->isFLAT(Inst)) {
if (Inst.mayStore()) {
setExpScore(
&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(), AMDGPU::OpName::data),
CurrScore);
} else if (AMDGPU::getAtomicNoRetOp(Inst.getOpcode()) != -1) {
setExpScore(
&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(), AMDGPU::OpName::data),
CurrScore);
}
} else if (TII->isMIMG(Inst)) {
if (Inst.mayStore()) {
setExpScore(&Inst, TII, TRI, MRI, 0, CurrScore);
} else if (AMDGPU::getAtomicNoRetOp(Inst.getOpcode()) != -1) {
setExpScore(
&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(), AMDGPU::OpName::data),
CurrScore);
}
} else if (TII->isMTBUF(Inst)) {
if (Inst.mayStore()) {
setExpScore(&Inst, TII, TRI, MRI, 0, CurrScore);
}
} else if (TII->isMUBUF(Inst)) {
if (Inst.mayStore()) {
setExpScore(&Inst, TII, TRI, MRI, 0, CurrScore);
} else if (AMDGPU::getAtomicNoRetOp(Inst.getOpcode()) != -1) {
setExpScore(
&Inst, TII, TRI, MRI,
AMDGPU::getNamedOperandIdx(Inst.getOpcode(), AMDGPU::OpName::data),
CurrScore);
}
} else {
if (TII->isEXP(Inst)) {
// For export the destination registers are really temps that
// can be used as the actual source after export patching, so
// we need to treat them like sources and set the EXP_CNT
// score.
for (unsigned I = 0, E = Inst.getNumOperands(); I != E; ++I) {
MachineOperand &DefMO = Inst.getOperand(I);
if (DefMO.isReg() && DefMO.isDef() &&
TRI->isVGPR(MRIA, DefMO.getReg())) {
setRegScore(TRI->getEncodingValue(DefMO.getReg()), EXP_CNT,
CurrScore);
}
}
}
for (unsigned I = 0, E = Inst.getNumOperands(); I != E; ++I) {
MachineOperand &MO = Inst.getOperand(I);
if (MO.isReg() && !MO.isDef() && TRI->isVGPR(MRIA, MO.getReg())) {
setExpScore(&Inst, TII, TRI, MRI, I, CurrScore);
}
}
}
#if 0 // TODO: check if this is handled by MUBUF code above.
} else if (Inst.getOpcode() == AMDGPU::BUFFER_STORE_DWORD ||
Inst.getOpcode() == AMDGPU::BUFFER_STORE_DWORDX2 ||
Inst.getOpcode() == AMDGPU::BUFFER_STORE_DWORDX4) {
MachineOperand *MO = TII->getNamedOperand(Inst, AMDGPU::OpName::data);
unsigned OpNo;//TODO: find the OpNo for this operand;
RegInterval Interval = getRegInterval(&Inst, TII, MRI, TRI, OpNo, false);
for (signed RegNo = Interval.first; RegNo < Interval.second;
++RegNo) {
setRegScore(RegNo + NUM_ALL_VGPRS, t, CurrScore);
}
#endif
} else {
// Match the score to the destination registers.
for (unsigned I = 0, E = Inst.getNumOperands(); I != E; ++I) {
RegInterval Interval = getRegInterval(&Inst, TII, MRI, TRI, I, true);
if (T == VM_CNT && Interval.first >= NUM_ALL_VGPRS)
continue;
for (signed RegNo = Interval.first; RegNo < Interval.second; ++RegNo) {
setRegScore(RegNo, T, CurrScore);
}
}
if (TII->isDS(Inst) && Inst.mayStore()) {
setRegScore(SQ_MAX_PGM_VGPRS + EXTRA_VGPR_LDS, T, CurrScore);
}
}
}
void BlockWaitcntBrackets::print(raw_ostream &OS) {
OS << '\n';
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
int LB = getScoreLB(T);
int UB = getScoreUB(T);
switch (T) {
case VM_CNT:
OS << " VM_CNT(" << UB - LB << "): ";
break;
case LGKM_CNT:
OS << " LGKM_CNT(" << UB - LB << "): ";
break;
case EXP_CNT:
OS << " EXP_CNT(" << UB - LB << "): ";
break;
default:
OS << " UNKNOWN(" << UB - LB << "): ";
break;
}
if (LB < UB) {
// Print vgpr scores.
for (int J = 0; J <= getMaxVGPR(); J++) {
int RegScore = getRegScore(J, T);
if (RegScore <= LB)
continue;
int RelScore = RegScore - LB - 1;
if (J < SQ_MAX_PGM_VGPRS + EXTRA_VGPR_LDS) {
OS << RelScore << ":v" << J << " ";
} else {
OS << RelScore << ":ds ";
}
}
// Also need to print sgpr scores for lgkm_cnt.
if (T == LGKM_CNT) {
for (int J = 0; J <= getMaxSGPR(); J++) {
int RegScore = getRegScore(J + NUM_ALL_VGPRS, LGKM_CNT);
if (RegScore <= LB)
continue;
int RelScore = RegScore - LB - 1;
OS << RelScore << ":s" << J << " ";
}
}
}
OS << '\n';
}
OS << '\n';
}
unsigned int BlockWaitcntBrackets::updateByWait(InstCounterType T,
int ScoreToWait) {
unsigned int NeedWait = 0;
if (ScoreToWait == -1) {
// The score to wait is unknown. This implies that it was not encountered
// during the path of the CFG walk done during the current traversal but
// may be seen on a different path. Emit an s_wait counter with a
// conservative value of 0 for the counter.
NeedWait = CNT_MASK(T);
setScoreLB(T, getScoreUB(T));
return NeedWait;
}
// If the score of src_operand falls within the bracket, we need an
// s_waitcnt instruction.
const int32_t LB = getScoreLB(T);
const int32_t UB = getScoreUB(T);
if ((UB >= ScoreToWait) && (ScoreToWait > LB)) {
if ((T == VM_CNT || T == LGKM_CNT) &&
hasPendingFlat() &&
!ST->hasFlatLgkmVMemCountInOrder()) {
// If there is a pending FLAT operation, and this is a VMem or LGKM
// waitcnt and the target can report early completion, then we need
// to force a waitcnt 0.
NeedWait = CNT_MASK(T);
setScoreLB(T, getScoreUB(T));
} else if (counterOutOfOrder(T)) {
// Counter can get decremented out-of-order when there
// are multiple types event in the bracket. Also emit an s_wait counter
// with a conservative value of 0 for the counter.
NeedWait = CNT_MASK(T);
setScoreLB(T, getScoreUB(T));
} else {
NeedWait = CNT_MASK(T);
setScoreLB(T, ScoreToWait);
}
}
return NeedWait;
}
// Where there are multiple types of event in the bracket of a counter,
// the decrement may go out of order.
bool BlockWaitcntBrackets::counterOutOfOrder(InstCounterType T) {
switch (T) {
case VM_CNT:
return false;
case LGKM_CNT: {
if (EventUBs[SMEM_ACCESS] > ScoreLBs[LGKM_CNT] &&
EventUBs[SMEM_ACCESS] <= ScoreUBs[LGKM_CNT]) {
// Scalar memory read always can go out of order.
return true;
}
int NumEventTypes = 0;
if (EventUBs[LDS_ACCESS] > ScoreLBs[LGKM_CNT] &&
EventUBs[LDS_ACCESS] <= ScoreUBs[LGKM_CNT]) {
NumEventTypes++;
}
if (EventUBs[GDS_ACCESS] > ScoreLBs[LGKM_CNT] &&
EventUBs[GDS_ACCESS] <= ScoreUBs[LGKM_CNT]) {
NumEventTypes++;
}
if (EventUBs[SQ_MESSAGE] > ScoreLBs[LGKM_CNT] &&
EventUBs[SQ_MESSAGE] <= ScoreUBs[LGKM_CNT]) {
NumEventTypes++;
}
if (NumEventTypes <= 1) {
return false;
}
break;
}
case EXP_CNT: {
// If there has been a mixture of export types, then a waitcnt exp(0) is
// required.
if (MixedExpTypes)
return true;
int NumEventTypes = 0;
if (EventUBs[EXP_GPR_LOCK] > ScoreLBs[EXP_CNT] &&
EventUBs[EXP_GPR_LOCK] <= ScoreUBs[EXP_CNT]) {
NumEventTypes++;
}
if (EventUBs[GDS_GPR_LOCK] > ScoreLBs[EXP_CNT] &&
EventUBs[GDS_GPR_LOCK] <= ScoreUBs[EXP_CNT]) {
NumEventTypes++;
}
if (EventUBs[VMW_GPR_LOCK] > ScoreLBs[EXP_CNT] &&
EventUBs[VMW_GPR_LOCK] <= ScoreUBs[EXP_CNT]) {
NumEventTypes++;
}
if (EventUBs[EXP_PARAM_ACCESS] > ScoreLBs[EXP_CNT] &&
EventUBs[EXP_PARAM_ACCESS] <= ScoreUBs[EXP_CNT]) {
NumEventTypes++;
}
if (EventUBs[EXP_POS_ACCESS] > ScoreLBs[EXP_CNT] &&
EventUBs[EXP_POS_ACCESS] <= ScoreUBs[EXP_CNT]) {
NumEventTypes++;
}
if (NumEventTypes <= 1) {
return false;
}
break;
}
default:
break;
}
return true;
}
INITIALIZE_PASS_BEGIN(SIInsertWaitcnts, DEBUG_TYPE, "SI Insert Waitcnts", false,
false)
INITIALIZE_PASS_END(SIInsertWaitcnts, DEBUG_TYPE, "SI Insert Waitcnts", false,
false)
char SIInsertWaitcnts::ID = 0;
char &llvm::SIInsertWaitcntsID = SIInsertWaitcnts::ID;
FunctionPass *llvm::createSIInsertWaitcntsPass() {
return new SIInsertWaitcnts();
}
static bool readsVCCZ(const MachineInstr &MI) {
unsigned Opc = MI.getOpcode();
return (Opc == AMDGPU::S_CBRANCH_VCCNZ || Opc == AMDGPU::S_CBRANCH_VCCZ) &&
!MI.getOperand(1).isUndef();
}
/// Given wait count encodings checks if LHS is stronger than RHS.
bool SIInsertWaitcnts::isWaitcntStronger(unsigned LHS, unsigned RHS) {
if (AMDGPU::decodeVmcnt(IV, LHS) > AMDGPU::decodeVmcnt(IV, RHS))
return false;
if (AMDGPU::decodeLgkmcnt(IV, LHS) > AMDGPU::decodeLgkmcnt(IV, RHS))
return false;
if (AMDGPU::decodeExpcnt(IV, LHS) > AMDGPU::decodeExpcnt(IV, RHS))
return false;
return true;
}
/// Given wait count encodings create a new encoding which is stronger
/// or equal to both.
unsigned SIInsertWaitcnts::combineWaitcnt(unsigned LHS, unsigned RHS) {
unsigned VmCnt = std::min(AMDGPU::decodeVmcnt(IV, LHS),
AMDGPU::decodeVmcnt(IV, RHS));
unsigned LgkmCnt = std::min(AMDGPU::decodeLgkmcnt(IV, LHS),
AMDGPU::decodeLgkmcnt(IV, RHS));
unsigned ExpCnt = std::min(AMDGPU::decodeExpcnt(IV, LHS),
AMDGPU::decodeExpcnt(IV, RHS));
return AMDGPU::encodeWaitcnt(IV, VmCnt, ExpCnt, LgkmCnt);
}
/// Generate s_waitcnt instruction to be placed before cur_Inst.
/// Instructions of a given type are returned in order,
/// but instructions of different types can complete out of order.
/// We rely on this in-order completion
/// and simply assign a score to the memory access instructions.
/// We keep track of the active "score bracket" to determine
/// if an access of a memory read requires an s_waitcnt
/// and if so what the value of each counter is.
/// The "score bracket" is bound by the lower bound and upper bound
/// scores (*_score_LB and *_score_ub respectively).
void SIInsertWaitcnts::generateWaitcntInstBefore(
MachineInstr &MI, BlockWaitcntBrackets *ScoreBrackets) {
// To emit, or not to emit - that's the question!
// Start with an assumption that there is no need to emit.
unsigned int EmitWaitcnt = 0;
// No need to wait before phi. If a phi-move exists, then the wait should
// has been inserted before the move. If a phi-move does not exist, then
// wait should be inserted before the real use. The same is true for
// sc-merge. It is not a coincident that all these cases correspond to the
// instructions that are skipped in the assembling loop.
bool NeedLineMapping = false; // TODO: Check on this.
// ForceEmitZeroWaitcnt: force a single s_waitcnt 0 due to hw bug
bool ForceEmitZeroWaitcnt = false;
setForceEmitWaitcnt();
bool IsForceEmitWaitcnt = isForceEmitWaitcnt();
if (MI.isDebugInstr() &&
// TODO: any other opcode?
!NeedLineMapping) {
return;
}
// See if an s_waitcnt is forced at block entry, or is needed at
// program end.
if (ScoreBrackets->getWaitAtBeginning()) {
// Note that we have already cleared the state, so we don't need to update
// it.
ScoreBrackets->clearWaitAtBeginning();
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
EmitWaitcnt |= CNT_MASK(T);
ScoreBrackets->setScoreLB(T, ScoreBrackets->getScoreUB(T));
}
}
// See if this instruction has a forced S_WAITCNT VM.
// TODO: Handle other cases of NeedsWaitcntVmBefore()
else if (MI.getOpcode() == AMDGPU::BUFFER_WBINVL1 ||
MI.getOpcode() == AMDGPU::BUFFER_WBINVL1_SC ||
MI.getOpcode() == AMDGPU::BUFFER_WBINVL1_VOL) {
EmitWaitcnt |=
ScoreBrackets->updateByWait(VM_CNT, ScoreBrackets->getScoreUB(VM_CNT));
}
// All waits must be resolved at call return.
// NOTE: this could be improved with knowledge of all call sites or
// with knowledge of the called routines.
if (MI.getOpcode() == AMDGPU::SI_RETURN_TO_EPILOG ||
MI.getOpcode() == AMDGPU::S_SETPC_B64_return) {
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
if (ScoreBrackets->getScoreUB(T) > ScoreBrackets->getScoreLB(T)) {
ScoreBrackets->setScoreLB(T, ScoreBrackets->getScoreUB(T));
EmitWaitcnt |= CNT_MASK(T);
}
}
}
// Resolve vm waits before gs-done.
else if ((MI.getOpcode() == AMDGPU::S_SENDMSG ||
MI.getOpcode() == AMDGPU::S_SENDMSGHALT) &&
((MI.getOperand(0).getImm() & AMDGPU::SendMsg::ID_MASK_) ==
AMDGPU::SendMsg::ID_GS_DONE)) {
if (ScoreBrackets->getScoreUB(VM_CNT) > ScoreBrackets->getScoreLB(VM_CNT)) {
ScoreBrackets->setScoreLB(VM_CNT, ScoreBrackets->getScoreUB(VM_CNT));
EmitWaitcnt |= CNT_MASK(VM_CNT);
}
}
#if 0 // TODO: the following blocks of logic when we have fence.
else if (MI.getOpcode() == SC_FENCE) {
const unsigned int group_size =
context->shader_info->GetMaxThreadGroupSize();
// group_size == 0 means thread group size is unknown at compile time
const bool group_is_multi_wave =
(group_size == 0 || group_size > target_info->GetWaveFrontSize());
const bool fence_is_global = !((SCInstInternalMisc*)Inst)->IsGroupFence();
for (unsigned int i = 0; i < Inst->NumSrcOperands(); i++) {
SCRegType src_type = Inst->GetSrcType(i);
switch (src_type) {
case SCMEM_LDS:
if (group_is_multi_wave ||
context->OptFlagIsOn(OPT_R1100_LDSMEM_FENCE_CHICKEN_BIT)) {
EmitWaitcnt |= ScoreBrackets->updateByWait(LGKM_CNT,
ScoreBrackets->getScoreUB(LGKM_CNT));
// LDS may have to wait for VM_CNT after buffer load to LDS
if (target_info->HasBufferLoadToLDS()) {
EmitWaitcnt |= ScoreBrackets->updateByWait(VM_CNT,
ScoreBrackets->getScoreUB(VM_CNT));
}
}
break;
case SCMEM_GDS:
if (group_is_multi_wave || fence_is_global) {
EmitWaitcnt |= ScoreBrackets->updateByWait(EXP_CNT,
ScoreBrackets->getScoreUB(EXP_CNT));
EmitWaitcnt |= ScoreBrackets->updateByWait(LGKM_CNT,
ScoreBrackets->getScoreUB(LGKM_CNT));
}
break;
case SCMEM_UAV:
case SCMEM_TFBUF:
case SCMEM_RING:
case SCMEM_SCATTER:
if (group_is_multi_wave || fence_is_global) {
EmitWaitcnt |= ScoreBrackets->updateByWait(EXP_CNT,
ScoreBrackets->getScoreUB(EXP_CNT));
EmitWaitcnt |= ScoreBrackets->updateByWait(VM_CNT,
ScoreBrackets->getScoreUB(VM_CNT));
}
break;
case SCMEM_SCRATCH:
default:
break;
}
}
}
#endif
// Export & GDS instructions do not read the EXEC mask until after the export
// is granted (which can occur well after the instruction is issued).
// The shader program must flush all EXP operations on the export-count
// before overwriting the EXEC mask.
else {
if (MI.modifiesRegister(AMDGPU::EXEC, TRI)) {
// Export and GDS are tracked individually, either may trigger a waitcnt
// for EXEC.
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getEventUB(EXP_GPR_LOCK));
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getEventUB(EXP_PARAM_ACCESS));
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getEventUB(EXP_POS_ACCESS));
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getEventUB(GDS_GPR_LOCK));
}
#if 0 // TODO: the following code to handle CALL.
// The argument passing for CALLs should suffice for VM_CNT and LGKM_CNT.
// However, there is a problem with EXP_CNT, because the call cannot
// easily tell if a register is used in the function, and if it did, then
// the referring instruction would have to have an S_WAITCNT, which is
// dependent on all call sites. So Instead, force S_WAITCNT for EXP_CNTs
// before the call.
if (MI.getOpcode() == SC_CALL) {
if (ScoreBrackets->getScoreUB(EXP_CNT) >
ScoreBrackets->getScoreLB(EXP_CNT)) {
ScoreBrackets->setScoreLB(EXP_CNT, ScoreBrackets->getScoreUB(EXP_CNT));
EmitWaitcnt |= CNT_MASK(EXP_CNT);
}
}
#endif
// FIXME: Should not be relying on memoperands.
// Look at the source operands of every instruction to see if
// any of them results from a previous memory operation that affects
// its current usage. If so, an s_waitcnt instruction needs to be
// emitted.
// If the source operand was defined by a load, add the s_waitcnt
// instruction.
for (const MachineMemOperand *Memop : MI.memoperands()) {
unsigned AS = Memop->getAddrSpace();
if (AS != AMDGPUAS::LOCAL_ADDRESS)
continue;
unsigned RegNo = SQ_MAX_PGM_VGPRS + EXTRA_VGPR_LDS;
// VM_CNT is only relevant to vgpr or LDS.
EmitWaitcnt |= ScoreBrackets->updateByWait(
VM_CNT, ScoreBrackets->getRegScore(RegNo, VM_CNT));
}
for (unsigned I = 0, E = MI.getNumOperands(); I != E; ++I) {
const MachineOperand &Op = MI.getOperand(I);
const MachineRegisterInfo &MRIA = *MRI;
RegInterval Interval =
ScoreBrackets->getRegInterval(&MI, TII, MRI, TRI, I, false);
for (signed RegNo = Interval.first; RegNo < Interval.second; ++RegNo) {
if (TRI->isVGPR(MRIA, Op.getReg())) {
// VM_CNT is only relevant to vgpr or LDS.
EmitWaitcnt |= ScoreBrackets->updateByWait(
VM_CNT, ScoreBrackets->getRegScore(RegNo, VM_CNT));
}
EmitWaitcnt |= ScoreBrackets->updateByWait(
LGKM_CNT, ScoreBrackets->getRegScore(RegNo, LGKM_CNT));
}
}
// End of for loop that looks at all source operands to decide vm_wait_cnt
// and lgk_wait_cnt.
// Two cases are handled for destination operands:
// 1) If the destination operand was defined by a load, add the s_waitcnt
// instruction to guarantee the right WAW order.
// 2) If a destination operand that was used by a recent export/store ins,
// add s_waitcnt on exp_cnt to guarantee the WAR order.
if (MI.mayStore()) {
// FIXME: Should not be relying on memoperands.
for (const MachineMemOperand *Memop : MI.memoperands()) {
unsigned AS = Memop->getAddrSpace();
if (AS != AMDGPUAS::LOCAL_ADDRESS)
continue;
unsigned RegNo = SQ_MAX_PGM_VGPRS + EXTRA_VGPR_LDS;
EmitWaitcnt |= ScoreBrackets->updateByWait(
VM_CNT, ScoreBrackets->getRegScore(RegNo, VM_CNT));
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getRegScore(RegNo, EXP_CNT));
}
}
for (unsigned I = 0, E = MI.getNumOperands(); I != E; ++I) {
MachineOperand &Def = MI.getOperand(I);
const MachineRegisterInfo &MRIA = *MRI;
RegInterval Interval =
ScoreBrackets->getRegInterval(&MI, TII, MRI, TRI, I, true);
for (signed RegNo = Interval.first; RegNo < Interval.second; ++RegNo) {
if (TRI->isVGPR(MRIA, Def.getReg())) {
EmitWaitcnt |= ScoreBrackets->updateByWait(
VM_CNT, ScoreBrackets->getRegScore(RegNo, VM_CNT));
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getRegScore(RegNo, EXP_CNT));
}
EmitWaitcnt |= ScoreBrackets->updateByWait(
LGKM_CNT, ScoreBrackets->getRegScore(RegNo, LGKM_CNT));
}
} // End of for loop that looks at all dest operands.
}
// Check to see if this is an S_BARRIER, and if an implicit S_WAITCNT 0
// occurs before the instruction. Doing it here prevents any additional
// S_WAITCNTs from being emitted if the instruction was marked as
// requiring a WAITCNT beforehand.
if (MI.getOpcode() == AMDGPU::S_BARRIER &&
!ST->hasAutoWaitcntBeforeBarrier()) {
EmitWaitcnt |=
ScoreBrackets->updateByWait(VM_CNT, ScoreBrackets->getScoreUB(VM_CNT));
EmitWaitcnt |= ScoreBrackets->updateByWait(
EXP_CNT, ScoreBrackets->getScoreUB(EXP_CNT));
EmitWaitcnt |= ScoreBrackets->updateByWait(
LGKM_CNT, ScoreBrackets->getScoreUB(LGKM_CNT));
}
// TODO: Remove this work-around, enable the assert for Bug 457939
// after fixing the scheduler. Also, the Shader Compiler code is
// independent of target.
if (readsVCCZ(MI) && ST->getGeneration() <= AMDGPUSubtarget::SEA_ISLANDS) {
if (ScoreBrackets->getScoreLB(LGKM_CNT) <
ScoreBrackets->getScoreUB(LGKM_CNT) &&
ScoreBrackets->hasPendingSMEM()) {
// Wait on everything, not just LGKM. vccz reads usually come from
// terminators, and we always wait on everything at the end of the
// block, so if we only wait on LGKM here, we might end up with
// another s_waitcnt inserted right after this if there are non-LGKM
// instructions still outstanding.
// FIXME: this is too conservative / the comment is wrong.
// We don't wait on everything at the end of the block and we combine
// waitcnts so we should never have back-to-back waitcnts.
ForceEmitZeroWaitcnt = true;
EmitWaitcnt = true;
}
}
// Does this operand processing indicate s_wait counter update?
if (EmitWaitcnt || IsForceEmitWaitcnt) {
int CntVal[NUM_INST_CNTS];
bool UseDefaultWaitcntStrategy = true;
if (ForceEmitZeroWaitcnt || ForceEmitZeroWaitcnts) {
// Force all waitcnts to 0.
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
ScoreBrackets->setScoreLB(T, ScoreBrackets->getScoreUB(T));
}
CntVal[VM_CNT] = 0;
CntVal[EXP_CNT] = 0;
CntVal[LGKM_CNT] = 0;
UseDefaultWaitcntStrategy = false;
}
if (UseDefaultWaitcntStrategy) {
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
if (EmitWaitcnt & CNT_MASK(T)) {
int Delta =
ScoreBrackets->getScoreUB(T) - ScoreBrackets->getScoreLB(T);
int MaxDelta = ScoreBrackets->getWaitCountMax(T);
if (Delta >= MaxDelta) {
Delta = -1;
if (T != EXP_CNT) {
ScoreBrackets->setScoreLB(
T, ScoreBrackets->getScoreUB(T) - MaxDelta);
}
EmitWaitcnt &= ~CNT_MASK(T);
}
CntVal[T] = Delta;
} else {
// If we are not waiting for a particular counter then encode
// it as -1 which means "don't care."
CntVal[T] = -1;
}
}
}
// If we are not waiting on any counter we can skip the wait altogether.
if (EmitWaitcnt != 0 || IsForceEmitWaitcnt) {
MachineInstr *OldWaitcnt = ScoreBrackets->getWaitcnt();
int Imm = (!OldWaitcnt) ? 0 : OldWaitcnt->getOperand(0).getImm();
if (!OldWaitcnt ||
(AMDGPU::decodeVmcnt(IV, Imm) !=
(CntVal[VM_CNT] & AMDGPU::getVmcntBitMask(IV))) ||
(AMDGPU::decodeExpcnt(IV, Imm) !=
(CntVal[EXP_CNT] & AMDGPU::getExpcntBitMask(IV))) ||
(AMDGPU::decodeLgkmcnt(IV, Imm) !=
(CntVal[LGKM_CNT] & AMDGPU::getLgkmcntBitMask(IV)))) {
MachineLoop *ContainingLoop = MLI->getLoopFor(MI.getParent());
if (ContainingLoop) {
MachineBasicBlock *TBB = ContainingLoop->getHeader();
BlockWaitcntBrackets *ScoreBracket =
BlockWaitcntBracketsMap[TBB].get();
if (!ScoreBracket) {
assert(!BlockVisitedSet.count(TBB));
BlockWaitcntBracketsMap[TBB] =
llvm::make_unique<BlockWaitcntBrackets>(ST);
ScoreBracket = BlockWaitcntBracketsMap[TBB].get();
}
ScoreBracket->setRevisitLoop(true);
LLVM_DEBUG(dbgs()
<< "set-revisit2: Block"
<< ContainingLoop->getHeader()->getNumber() << '\n';);
}
}
// Update an existing waitcount, or make a new one.
unsigned Enc = AMDGPU::encodeWaitcnt(IV,
ForceEmitWaitcnt[VM_CNT] ? 0 : CntVal[VM_CNT],
ForceEmitWaitcnt[EXP_CNT] ? 0 : CntVal[EXP_CNT],
ForceEmitWaitcnt[LGKM_CNT] ? 0 : CntVal[LGKM_CNT]);
// We don't remove waitcnts that existed prior to the waitcnt
// pass. Check if the waitcnt to-be-inserted can be avoided
// or if the prev waitcnt can be updated.
bool insertSWaitInst = true;
for (MachineBasicBlock::iterator I = MI.getIterator(),
B = MI.getParent()->begin();
insertSWaitInst && I != B; --I) {
if (I == MI.getIterator())
continue;
switch (I->getOpcode()) {
case AMDGPU::S_WAITCNT:
if (isWaitcntStronger(I->getOperand(0).getImm(), Enc))
insertSWaitInst = false;
else if (!OldWaitcnt) {
OldWaitcnt = &*I;
Enc = combineWaitcnt(I->getOperand(0).getImm(), Enc);
}
break;
// TODO: skip over instructions which never require wait.
}
break;
}
if (insertSWaitInst) {
if (OldWaitcnt && OldWaitcnt->getOpcode() == AMDGPU::S_WAITCNT) {
if (ForceEmitZeroWaitcnts)
LLVM_DEBUG(
dbgs()
<< "Force emit s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)\n");
if (IsForceEmitWaitcnt)
LLVM_DEBUG(dbgs()
<< "Force emit a s_waitcnt due to debug counter\n");
OldWaitcnt->getOperand(0).setImm(Enc);
if (!OldWaitcnt->getParent())
MI.getParent()->insert(MI, OldWaitcnt);
LLVM_DEBUG(dbgs() << "updateWaitcntInBlock\n"
<< "Old Instr: " << MI << '\n'
<< "New Instr: " << *OldWaitcnt << '\n');
} else {
auto SWaitInst = BuildMI(*MI.getParent(), MI.getIterator(),
MI.getDebugLoc(), TII->get(AMDGPU::S_WAITCNT))
.addImm(Enc);
TrackedWaitcntSet.insert(SWaitInst);
LLVM_DEBUG(dbgs() << "insertWaitcntInBlock\n"
<< "Old Instr: " << MI << '\n'
<< "New Instr: " << *SWaitInst << '\n');
}
}
if (CntVal[EXP_CNT] == 0) {
ScoreBrackets->setMixedExpTypes(false);
}
}
}
}
void SIInsertWaitcnts::insertWaitcntBeforeCF(MachineBasicBlock &MBB,
MachineInstr *Waitcnt) {
if (MBB.empty()) {
MBB.push_back(Waitcnt);
return;
}
MachineBasicBlock::iterator It = MBB.end();
MachineInstr *MI = &*(--It);
if (MI->isBranch()) {
MBB.insert(It, Waitcnt);
} else {
MBB.push_back(Waitcnt);
}
}
// This is a flat memory operation. Check to see if it has memory
// tokens for both LDS and Memory, and if so mark it as a flat.
bool SIInsertWaitcnts::mayAccessLDSThroughFlat(const MachineInstr &MI) const {
if (MI.memoperands_empty())
return true;
for (const MachineMemOperand *Memop : MI.memoperands()) {
unsigned AS = Memop->getAddrSpace();
if (AS == AMDGPUAS::LOCAL_ADDRESS || AS == AMDGPUAS::FLAT_ADDRESS)
return true;
}
return false;
}
void SIInsertWaitcnts::updateEventWaitcntAfter(
MachineInstr &Inst, BlockWaitcntBrackets *ScoreBrackets) {
// Now look at the instruction opcode. If it is a memory access
// instruction, update the upper-bound of the appropriate counter's
// bracket and the destination operand scores.
// TODO: Use the (TSFlags & SIInstrFlags::LGKM_CNT) property everywhere.
if (TII->isDS(Inst) && TII->usesLGKM_CNT(Inst)) {
if (TII->hasModifiersSet(Inst, AMDGPU::OpName::gds)) {
ScoreBrackets->updateByEvent(TII, TRI, MRI, GDS_ACCESS, Inst);
ScoreBrackets->updateByEvent(TII, TRI, MRI, GDS_GPR_LOCK, Inst);
} else {
ScoreBrackets->updateByEvent(TII, TRI, MRI, LDS_ACCESS, Inst);
}
} else if (TII->isFLAT(Inst)) {
assert(Inst.mayLoad() || Inst.mayStore());
if (TII->usesVM_CNT(Inst))
ScoreBrackets->updateByEvent(TII, TRI, MRI, VMEM_ACCESS, Inst);
if (TII->usesLGKM_CNT(Inst)) {
ScoreBrackets->updateByEvent(TII, TRI, MRI, LDS_ACCESS, Inst);
// This is a flat memory operation, so note it - it will require
// that both the VM and LGKM be flushed to zero if it is pending when
// a VM or LGKM dependency occurs.
if (mayAccessLDSThroughFlat(Inst))
ScoreBrackets->setPendingFlat();
}
} else if (SIInstrInfo::isVMEM(Inst) &&
// TODO: get a better carve out.
Inst.getOpcode() != AMDGPU::BUFFER_WBINVL1 &&
Inst.getOpcode() != AMDGPU::BUFFER_WBINVL1_SC &&
Inst.getOpcode() != AMDGPU::BUFFER_WBINVL1_VOL) {
ScoreBrackets->updateByEvent(TII, TRI, MRI, VMEM_ACCESS, Inst);
if (ST->vmemWriteNeedsExpWaitcnt() &&
(Inst.mayStore() || AMDGPU::getAtomicNoRetOp(Inst.getOpcode()) != -1)) {
ScoreBrackets->updateByEvent(TII, TRI, MRI, VMW_GPR_LOCK, Inst);
}
} else if (TII->isSMRD(Inst)) {
ScoreBrackets->updateByEvent(TII, TRI, MRI, SMEM_ACCESS, Inst);
} else {
switch (Inst.getOpcode()) {
case AMDGPU::S_SENDMSG:
case AMDGPU::S_SENDMSGHALT:
ScoreBrackets->updateByEvent(TII, TRI, MRI, SQ_MESSAGE, Inst);
break;
case AMDGPU::EXP:
case AMDGPU::EXP_DONE: {
int Imm = TII->getNamedOperand(Inst, AMDGPU::OpName::tgt)->getImm();
if (Imm >= 32 && Imm <= 63)
ScoreBrackets->updateByEvent(TII, TRI, MRI, EXP_PARAM_ACCESS, Inst);
else if (Imm >= 12 && Imm <= 15)
ScoreBrackets->updateByEvent(TII, TRI, MRI, EXP_POS_ACCESS, Inst);
else
ScoreBrackets->updateByEvent(TII, TRI, MRI, EXP_GPR_LOCK, Inst);
break;
}
case AMDGPU::S_MEMTIME:
case AMDGPU::S_MEMREALTIME:
ScoreBrackets->updateByEvent(TII, TRI, MRI, SMEM_ACCESS, Inst);
break;
default:
break;
}
}
}
// Merge the score brackets of the Block's predecessors;
// this merged score bracket is used when adding waitcnts to the Block
void SIInsertWaitcnts::mergeInputScoreBrackets(MachineBasicBlock &Block) {
BlockWaitcntBrackets *ScoreBrackets = BlockWaitcntBracketsMap[&Block].get();
int32_t MaxPending[NUM_INST_CNTS] = {0};
int32_t MaxFlat[NUM_INST_CNTS] = {0};
bool MixedExpTypes = false;
// For single basic block loops, we need to retain the Block's
// score bracket to have accurate Pred info. So, make a copy of Block's
// score bracket, clear() it (which retains several important bits of info),
// populate, and then replace en masse. For non-single basic block loops,
// just clear Block's current score bracket and repopulate in-place.
bool IsSelfPred;
std::unique_ptr<BlockWaitcntBrackets> S;
IsSelfPred = (std::find(Block.pred_begin(), Block.pred_end(), &Block))
!= Block.pred_end();
if (IsSelfPred) {
S = llvm::make_unique<BlockWaitcntBrackets>(*ScoreBrackets);
ScoreBrackets = S.get();
}
ScoreBrackets->clear();
// See if there are any uninitialized predecessors. If so, emit an
// s_waitcnt 0 at the beginning of the block.
for (MachineBasicBlock *Pred : Block.predecessors()) {
BlockWaitcntBrackets *PredScoreBrackets =
BlockWaitcntBracketsMap[Pred].get();
bool Visited = BlockVisitedSet.count(Pred);
if (!Visited || PredScoreBrackets->getWaitAtBeginning()) {
continue;
}
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
int span =
PredScoreBrackets->getScoreUB(T) - PredScoreBrackets->getScoreLB(T);
MaxPending[T] = std::max(MaxPending[T], span);
span =
PredScoreBrackets->pendingFlat(T) - PredScoreBrackets->getScoreLB(T);
MaxFlat[T] = std::max(MaxFlat[T], span);
}
MixedExpTypes |= PredScoreBrackets->mixedExpTypes();
}
// TODO: Is SC Block->IsMainExit() same as Block.succ_empty()?
// Also handle kills for exit block.
if (Block.succ_empty() && !KillWaitBrackets.empty()) {
for (unsigned int I = 0; I < KillWaitBrackets.size(); I++) {
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
int Span = KillWaitBrackets[I]->getScoreUB(T) -
KillWaitBrackets[I]->getScoreLB(T);
MaxPending[T] = std::max(MaxPending[T], Span);
Span = KillWaitBrackets[I]->pendingFlat(T) -
KillWaitBrackets[I]->getScoreLB(T);
MaxFlat[T] = std::max(MaxFlat[T], Span);
}
MixedExpTypes |= KillWaitBrackets[I]->mixedExpTypes();
}
}
// Special handling for GDS_GPR_LOCK and EXP_GPR_LOCK.
for (MachineBasicBlock *Pred : Block.predecessors()) {
BlockWaitcntBrackets *PredScoreBrackets =
BlockWaitcntBracketsMap[Pred].get();
bool Visited = BlockVisitedSet.count(Pred);
if (!Visited || PredScoreBrackets->getWaitAtBeginning()) {
continue;
}
int GDSSpan = PredScoreBrackets->getEventUB(GDS_GPR_LOCK) -
PredScoreBrackets->getScoreLB(EXP_CNT);
MaxPending[EXP_CNT] = std::max(MaxPending[EXP_CNT], GDSSpan);
int EXPSpan = PredScoreBrackets->getEventUB(EXP_GPR_LOCK) -
PredScoreBrackets->getScoreLB(EXP_CNT);
MaxPending[EXP_CNT] = std::max(MaxPending[EXP_CNT], EXPSpan);
}
// TODO: Is SC Block->IsMainExit() same as Block.succ_empty()?
if (Block.succ_empty() && !KillWaitBrackets.empty()) {
for (unsigned int I = 0; I < KillWaitBrackets.size(); I++) {
int GDSSpan = KillWaitBrackets[I]->getEventUB(GDS_GPR_LOCK) -
KillWaitBrackets[I]->getScoreLB(EXP_CNT);
MaxPending[EXP_CNT] = std::max(MaxPending[EXP_CNT], GDSSpan);
int EXPSpan = KillWaitBrackets[I]->getEventUB(EXP_GPR_LOCK) -
KillWaitBrackets[I]->getScoreLB(EXP_CNT);
MaxPending[EXP_CNT] = std::max(MaxPending[EXP_CNT], EXPSpan);
}
}
#if 0
// LC does not (unlike) add a waitcnt at beginning. Leaving it as marker.
// TODO: how does LC distinguish between function entry and main entry?
// If this is the entry to a function, force a wait.
MachineBasicBlock &Entry = Block.getParent()->front();
if (Entry.getNumber() == Block.getNumber()) {
ScoreBrackets->setWaitAtBeginning();
return;
}
#endif
// Now set the current Block's brackets to the largest ending bracket.
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
ScoreBrackets->setScoreUB(T, MaxPending[T]);
ScoreBrackets->setScoreLB(T, 0);
ScoreBrackets->setLastFlat(T, MaxFlat[T]);
}
ScoreBrackets->setMixedExpTypes(MixedExpTypes);
// Set the register scoreboard.
for (MachineBasicBlock *Pred : Block.predecessors()) {
if (!BlockVisitedSet.count(Pred)) {
continue;
}
BlockWaitcntBrackets *PredScoreBrackets =
BlockWaitcntBracketsMap[Pred].get();
// Now merge the gpr_reg_score information
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
int PredLB = PredScoreBrackets->getScoreLB(T);
int PredUB = PredScoreBrackets->getScoreUB(T);
if (PredLB < PredUB) {
int PredScale = MaxPending[T] - PredUB;
// Merge vgpr scores.
for (int J = 0; J <= PredScoreBrackets->getMaxVGPR(); J++) {
int PredRegScore = PredScoreBrackets->getRegScore(J, T);
if (PredRegScore <= PredLB)
continue;
int NewRegScore = PredScale + PredRegScore;
ScoreBrackets->setRegScore(
J, T, std::max(ScoreBrackets->getRegScore(J, T), NewRegScore));
}
// Also need to merge sgpr scores for lgkm_cnt.
if (T == LGKM_CNT) {
for (int J = 0; J <= PredScoreBrackets->getMaxSGPR(); J++) {
int PredRegScore =
PredScoreBrackets->getRegScore(J + NUM_ALL_VGPRS, LGKM_CNT);
if (PredRegScore <= PredLB)
continue;
int NewRegScore = PredScale + PredRegScore;
ScoreBrackets->setRegScore(
J + NUM_ALL_VGPRS, LGKM_CNT,
std::max(
ScoreBrackets->getRegScore(J + NUM_ALL_VGPRS, LGKM_CNT),
NewRegScore));
}
}
}
}
// Also merge the WaitEvent information.
ForAllWaitEventType(W) {
enum InstCounterType T = PredScoreBrackets->eventCounter(W);
int PredEventUB = PredScoreBrackets->getEventUB(W);
if (PredEventUB > PredScoreBrackets->getScoreLB(T)) {
int NewEventUB =
MaxPending[T] + PredEventUB - PredScoreBrackets->getScoreUB(T);
if (NewEventUB > 0) {
ScoreBrackets->setEventUB(
W, std::max(ScoreBrackets->getEventUB(W), NewEventUB));
}
}
}
}
// TODO: Is SC Block->IsMainExit() same as Block.succ_empty()?
// Set the register scoreboard.
if (Block.succ_empty() && !KillWaitBrackets.empty()) {
for (unsigned int I = 0; I < KillWaitBrackets.size(); I++) {
// Now merge the gpr_reg_score information.
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
int PredLB = KillWaitBrackets[I]->getScoreLB(T);
int PredUB = KillWaitBrackets[I]->getScoreUB(T);
if (PredLB < PredUB) {
int PredScale = MaxPending[T] - PredUB;
// Merge vgpr scores.
for (int J = 0; J <= KillWaitBrackets[I]->getMaxVGPR(); J++) {
int PredRegScore = KillWaitBrackets[I]->getRegScore(J, T);
if (PredRegScore <= PredLB)
continue;
int NewRegScore = PredScale + PredRegScore;
ScoreBrackets->setRegScore(
J, T, std::max(ScoreBrackets->getRegScore(J, T), NewRegScore));
}
// Also need to merge sgpr scores for lgkm_cnt.
if (T == LGKM_CNT) {
for (int J = 0; J <= KillWaitBrackets[I]->getMaxSGPR(); J++) {
int PredRegScore =
KillWaitBrackets[I]->getRegScore(J + NUM_ALL_VGPRS, LGKM_CNT);
if (PredRegScore <= PredLB)
continue;
int NewRegScore = PredScale + PredRegScore;
ScoreBrackets->setRegScore(
J + NUM_ALL_VGPRS, LGKM_CNT,
std::max(
ScoreBrackets->getRegScore(J + NUM_ALL_VGPRS, LGKM_CNT),
NewRegScore));
}
}
}
}
// Also merge the WaitEvent information.
ForAllWaitEventType(W) {
enum InstCounterType T = KillWaitBrackets[I]->eventCounter(W);
int PredEventUB = KillWaitBrackets[I]->getEventUB(W);
if (PredEventUB > KillWaitBrackets[I]->getScoreLB(T)) {
int NewEventUB =
MaxPending[T] + PredEventUB - KillWaitBrackets[I]->getScoreUB(T);
if (NewEventUB > 0) {
ScoreBrackets->setEventUB(
W, std::max(ScoreBrackets->getEventUB(W), NewEventUB));
}
}
}
}
}
// Special case handling of GDS_GPR_LOCK and EXP_GPR_LOCK. Merge this for the
// sequencing predecessors, because changes to EXEC require waitcnts due to
// the delayed nature of these operations.
for (MachineBasicBlock *Pred : Block.predecessors()) {
if (!BlockVisitedSet.count(Pred)) {
continue;
}
BlockWaitcntBrackets *PredScoreBrackets =
BlockWaitcntBracketsMap[Pred].get();
int pred_gds_ub = PredScoreBrackets->getEventUB(GDS_GPR_LOCK);
if (pred_gds_ub > PredScoreBrackets->getScoreLB(EXP_CNT)) {
int new_gds_ub = MaxPending[EXP_CNT] + pred_gds_ub -
PredScoreBrackets->getScoreUB(EXP_CNT);
if (new_gds_ub > 0) {
ScoreBrackets->setEventUB(
GDS_GPR_LOCK,
std::max(ScoreBrackets->getEventUB(GDS_GPR_LOCK), new_gds_ub));
}
}
int pred_exp_ub = PredScoreBrackets->getEventUB(EXP_GPR_LOCK);
if (pred_exp_ub > PredScoreBrackets->getScoreLB(EXP_CNT)) {
int new_exp_ub = MaxPending[EXP_CNT] + pred_exp_ub -
PredScoreBrackets->getScoreUB(EXP_CNT);
if (new_exp_ub > 0) {
ScoreBrackets->setEventUB(
EXP_GPR_LOCK,
std::max(ScoreBrackets->getEventUB(EXP_GPR_LOCK), new_exp_ub));
}
}
}
// if a single block loop, update the score brackets. Not needed for other
// blocks, as we did this in-place
if (IsSelfPred) {
BlockWaitcntBracketsMap[&Block] = llvm::make_unique<BlockWaitcntBrackets>(*ScoreBrackets);
}
}
/// Return true if the given basic block is a "bottom" block of a loop.
/// This works even if the loop is discontiguous. This also handles
/// multiple back-edges for the same "header" block of a loop.
bool SIInsertWaitcnts::isLoopBottom(const MachineLoop *Loop,
const MachineBasicBlock *Block) {
for (MachineBasicBlock *MBB : Loop->blocks()) {
if (MBB == Block && MBB->isSuccessor(Loop->getHeader())) {
return true;
}
}
return false;
}
/// Count the number of "bottom" basic blocks of a loop.
unsigned SIInsertWaitcnts::countNumBottomBlocks(const MachineLoop *Loop) {
unsigned Count = 0;
for (MachineBasicBlock *MBB : Loop->blocks()) {
if (MBB->isSuccessor(Loop->getHeader())) {
Count++;
}
}
return Count;
}
// Generate s_waitcnt instructions where needed.
void SIInsertWaitcnts::insertWaitcntInBlock(MachineFunction &MF,
MachineBasicBlock &Block) {
// Initialize the state information.
mergeInputScoreBrackets(Block);
BlockWaitcntBrackets *ScoreBrackets = BlockWaitcntBracketsMap[&Block].get();
LLVM_DEBUG({
dbgs() << "*** Block" << Block.getNumber() << " ***";
ScoreBrackets->dump();
});
// Walk over the instructions.
for (MachineBasicBlock::iterator Iter = Block.begin(), E = Block.end();
Iter != E;) {
MachineInstr &Inst = *Iter;
// Remove any previously existing waitcnts.
if (Inst.getOpcode() == AMDGPU::S_WAITCNT) {
// Leave pre-existing waitcnts, but note their existence via setWaitcnt.
// Remove the waitcnt-pass-generated waitcnts; the pass will add them back
// as needed.
if (!TrackedWaitcntSet.count(&Inst))
++Iter;
else {
++Iter;
Inst.removeFromParent();
}
ScoreBrackets->setWaitcnt(&Inst);
continue;
}
// Kill instructions generate a conditional branch to the endmain block.
// Merge the current waitcnt state into the endmain block information.
// TODO: Are there other flavors of KILL instruction?
if (Inst.getOpcode() == AMDGPU::KILL) {
addKillWaitBracket(ScoreBrackets);
}
bool VCCZBugWorkAround = false;
if (readsVCCZ(Inst) &&
(!VCCZBugHandledSet.count(&Inst))) {
if (ScoreBrackets->getScoreLB(LGKM_CNT) <
ScoreBrackets->getScoreUB(LGKM_CNT) &&
ScoreBrackets->hasPendingSMEM()) {
if (ST->getGeneration() <= AMDGPUSubtarget::SEA_ISLANDS)
VCCZBugWorkAround = true;
}
}
// Generate an s_waitcnt instruction to be placed before
// cur_Inst, if needed.
generateWaitcntInstBefore(Inst, ScoreBrackets);
updateEventWaitcntAfter(Inst, ScoreBrackets);
#if 0 // TODO: implement resource type check controlled by options with ub = LB.
// If this instruction generates a S_SETVSKIP because it is an
// indexed resource, and we are on Tahiti, then it will also force
// an S_WAITCNT vmcnt(0)
if (RequireCheckResourceType(Inst, context)) {
// Force the score to as if an S_WAITCNT vmcnt(0) is emitted.
ScoreBrackets->setScoreLB(VM_CNT,
ScoreBrackets->getScoreUB(VM_CNT));
}
#endif
ScoreBrackets->clearWaitcnt();
LLVM_DEBUG({
Inst.print(dbgs());
ScoreBrackets->dump();
});
// Check to see if this is a GWS instruction. If so, and if this is CI or
// VI, then the generated code sequence will include an S_WAITCNT 0.
// TODO: Are these the only GWS instructions?
if (Inst.getOpcode() == AMDGPU::DS_GWS_INIT ||
Inst.getOpcode() == AMDGPU::DS_GWS_SEMA_V ||
Inst.getOpcode() == AMDGPU::DS_GWS_SEMA_BR ||
Inst.getOpcode() == AMDGPU::DS_GWS_SEMA_P ||
Inst.getOpcode() == AMDGPU::DS_GWS_BARRIER) {
// TODO: && context->target_info->GwsRequiresMemViolTest() ) {
ScoreBrackets->updateByWait(VM_CNT, ScoreBrackets->getScoreUB(VM_CNT));
ScoreBrackets->updateByWait(EXP_CNT, ScoreBrackets->getScoreUB(EXP_CNT));
ScoreBrackets->updateByWait(LGKM_CNT,
ScoreBrackets->getScoreUB(LGKM_CNT));
}
// TODO: Remove this work-around after fixing the scheduler and enable the
// assert above.
if (VCCZBugWorkAround) {
// Restore the vccz bit. Any time a value is written to vcc, the vcc
// bit is updated, so we can restore the bit by reading the value of
// vcc and then writing it back to the register.
BuildMI(Block, Inst, Inst.getDebugLoc(), TII->get(AMDGPU::S_MOV_B64),
AMDGPU::VCC)
.addReg(AMDGPU::VCC);
VCCZBugHandledSet.insert(&Inst);
}
++Iter;
}
// Check if we need to force convergence at loop footer.
MachineLoop *ContainingLoop = MLI->getLoopFor(&Block);
if (ContainingLoop && isLoopBottom(ContainingLoop, &Block)) {
LoopWaitcntData *WaitcntData = LoopWaitcntDataMap[ContainingLoop].get();
WaitcntData->print();
LLVM_DEBUG(dbgs() << '\n';);
// The iterative waitcnt insertion algorithm aims for optimal waitcnt
// placement, but doesn't guarantee convergence for a loop. Each
// loop should take at most (n+1) iterations for it to converge naturally,
// where n is the number of bottom blocks. If this threshold is reached and
// the result hasn't converged, then we force convergence by inserting
// a s_waitcnt at the end of loop footer.
if (WaitcntData->getIterCnt() > (countNumBottomBlocks(ContainingLoop) + 1)) {
// To ensure convergence, need to make wait events at loop footer be no
// more than those from the previous iteration.
// As a simplification, instead of tracking individual scores and
// generating the precise wait count, just wait on 0.
bool HasPending = false;
MachineInstr *SWaitInst = WaitcntData->getWaitcnt();
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1)) {
if (ScoreBrackets->getScoreUB(T) > ScoreBrackets->getScoreLB(T)) {
ScoreBrackets->setScoreLB(T, ScoreBrackets->getScoreUB(T));
HasPending = true;
break;
}
}
if (HasPending) {
if (!SWaitInst) {
SWaitInst = BuildMI(Block, Block.getFirstNonPHI(),
DebugLoc(), TII->get(AMDGPU::S_WAITCNT))
.addImm(0);
TrackedWaitcntSet.insert(SWaitInst);
#if 0 // TODO: Format the debug output
OutputTransformBanner("insertWaitcntInBlock",0,"Create:",context);
OutputTransformAdd(SWaitInst, context);
#endif
}
#if 0 // TODO: ??
_DEV( REPORTED_STATS->force_waitcnt_converge = 1; )
#endif
}
if (SWaitInst) {
LLVM_DEBUG({
SWaitInst->print(dbgs());
dbgs() << "\nAdjusted score board:";
ScoreBrackets->dump();
});
// Add this waitcnt to the block. It is either newly created or
// created in previous iterations and added back since block traversal
// always removes waitcnts.
insertWaitcntBeforeCF(Block, SWaitInst);
WaitcntData->setWaitcnt(SWaitInst);
}
}
}
}
bool SIInsertWaitcnts::runOnMachineFunction(MachineFunction &MF) {
ST = &MF.getSubtarget<GCNSubtarget>();
TII = ST->getInstrInfo();
TRI = &TII->getRegisterInfo();
MRI = &MF.getRegInfo();
MLI = &getAnalysis<MachineLoopInfo>();
IV = AMDGPU::getIsaVersion(ST->getCPU());
const SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();
ForceEmitZeroWaitcnts = ForceEmitZeroFlag;
for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
T = (enum InstCounterType)(T + 1))
ForceEmitWaitcnt[T] = false;
HardwareLimits.VmcntMax = AMDGPU::getVmcntBitMask(IV);
HardwareLimits.ExpcntMax = AMDGPU::getExpcntBitMask(IV);
HardwareLimits.LgkmcntMax = AMDGPU::getLgkmcntBitMask(IV);
HardwareLimits.NumVGPRsMax = ST->getAddressableNumVGPRs();
HardwareLimits.NumSGPRsMax = ST->getAddressableNumSGPRs();
assert(HardwareLimits.NumVGPRsMax <= SQ_MAX_PGM_VGPRS);
assert(HardwareLimits.NumSGPRsMax <= SQ_MAX_PGM_SGPRS);
RegisterEncoding.VGPR0 = TRI->getEncodingValue(AMDGPU::VGPR0);
RegisterEncoding.VGPRL =
RegisterEncoding.VGPR0 + HardwareLimits.NumVGPRsMax - 1;
RegisterEncoding.SGPR0 = TRI->getEncodingValue(AMDGPU::SGPR0);
RegisterEncoding.SGPRL =
RegisterEncoding.SGPR0 + HardwareLimits.NumSGPRsMax - 1;
TrackedWaitcntSet.clear();
BlockVisitedSet.clear();
VCCZBugHandledSet.clear();
LoopWaitcntDataMap.clear();
BlockWaitcntProcessedSet.clear();
// Walk over the blocks in reverse post-dominator order, inserting
// s_waitcnt where needed.
ReversePostOrderTraversal<MachineFunction *> RPOT(&MF);
bool Modified = false;
for (ReversePostOrderTraversal<MachineFunction *>::rpo_iterator
I = RPOT.begin(),
E = RPOT.end(), J = RPOT.begin();
I != E;) {
MachineBasicBlock &MBB = **I;
BlockVisitedSet.insert(&MBB);
BlockWaitcntBrackets *ScoreBrackets = BlockWaitcntBracketsMap[&MBB].get();
if (!ScoreBrackets) {
BlockWaitcntBracketsMap[&MBB] = llvm::make_unique<BlockWaitcntBrackets>(ST);
ScoreBrackets = BlockWaitcntBracketsMap[&MBB].get();
}
ScoreBrackets->setPostOrder(MBB.getNumber());
MachineLoop *ContainingLoop = MLI->getLoopFor(&MBB);
if (ContainingLoop && LoopWaitcntDataMap[ContainingLoop] == nullptr)
LoopWaitcntDataMap[ContainingLoop] = llvm::make_unique<LoopWaitcntData>();
// If we are walking into the block from before the loop, then guarantee
// at least 1 re-walk over the loop to propagate the information, even if
// no S_WAITCNT instructions were generated.
if (ContainingLoop && ContainingLoop->getHeader() == &MBB) {
unsigned Count = countNumBottomBlocks(ContainingLoop);
// If the loop has multiple back-edges, and so more than one "bottom"
// basic block, we have to guarantee a re-walk over every blocks.
if ((std::count(BlockWaitcntProcessedSet.begin(),
BlockWaitcntProcessedSet.end(), &MBB) < (int)Count)) {
BlockWaitcntBracketsMap[&MBB]->setRevisitLoop(true);
LLVM_DEBUG(dbgs() << "set-revisit1: Block"
<< ContainingLoop->getHeader()->getNumber() << '\n';);
}
}
// Walk over the instructions.
insertWaitcntInBlock(MF, MBB);
// Record that waitcnts have been processed at least once for this block.
BlockWaitcntProcessedSet.push_back(&MBB);
// See if we want to revisit the loop. If a loop has multiple back-edges,
// we shouldn't revisit the same "bottom" basic block.
if (ContainingLoop && isLoopBottom(ContainingLoop, &MBB) &&
std::count(BlockWaitcntProcessedSet.begin(),
BlockWaitcntProcessedSet.end(), &MBB) == 1) {
MachineBasicBlock *EntryBB = ContainingLoop->getHeader();
BlockWaitcntBrackets *EntrySB = BlockWaitcntBracketsMap[EntryBB].get();
if (EntrySB && EntrySB->getRevisitLoop()) {
EntrySB->setRevisitLoop(false);
J = I;
int32_t PostOrder = EntrySB->getPostOrder();
// TODO: Avoid this loop. Find another way to set I.
for (ReversePostOrderTraversal<MachineFunction *>::rpo_iterator
X = RPOT.begin(),
Y = RPOT.end();
X != Y; ++X) {
MachineBasicBlock &MBBX = **X;
if (MBBX.getNumber() == PostOrder) {
I = X;
break;
}
}
LoopWaitcntData *WaitcntData = LoopWaitcntDataMap[ContainingLoop].get();
WaitcntData->incIterCnt();
LLVM_DEBUG(dbgs() << "revisit: Block" << EntryBB->getNumber() << '\n';);
continue;
} else {
LoopWaitcntData *WaitcntData = LoopWaitcntDataMap[ContainingLoop].get();
// Loop converged, reset iteration count. If this loop gets revisited,
// it must be from an outer loop, the counter will restart, this will
// ensure we don't force convergence on such revisits.
WaitcntData->resetIterCnt();
}
}
J = I;
++I;
}
SmallVector<MachineBasicBlock *, 4> EndPgmBlocks;
bool HaveScalarStores = false;
for (MachineFunction::iterator BI = MF.begin(), BE = MF.end(); BI != BE;
++BI) {
MachineBasicBlock &MBB = *BI;
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E;
++I) {
if (!HaveScalarStores && TII->isScalarStore(*I))
HaveScalarStores = true;
if (I->getOpcode() == AMDGPU::S_ENDPGM ||
I->getOpcode() == AMDGPU::SI_RETURN_TO_EPILOG)
EndPgmBlocks.push_back(&MBB);
}
}
if (HaveScalarStores) {
// If scalar writes are used, the cache must be flushed or else the next
// wave to reuse the same scratch memory can be clobbered.
//
// Insert s_dcache_wb at wave termination points if there were any scalar
// stores, and only if the cache hasn't already been flushed. This could be
// improved by looking across blocks for flushes in postdominating blocks
// from the stores but an explicitly requested flush is probably very rare.
for (MachineBasicBlock *MBB : EndPgmBlocks) {
bool SeenDCacheWB = false;
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
++I) {
if (I->getOpcode() == AMDGPU::S_DCACHE_WB)
SeenDCacheWB = true;
else if (TII->isScalarStore(*I))
SeenDCacheWB = false;
// FIXME: It would be better to insert this before a waitcnt if any.
if ((I->getOpcode() == AMDGPU::S_ENDPGM ||
I->getOpcode() == AMDGPU::SI_RETURN_TO_EPILOG) &&
!SeenDCacheWB) {
Modified = true;
BuildMI(*MBB, I, I->getDebugLoc(), TII->get(AMDGPU::S_DCACHE_WB));
}
}
}
}
if (!MFI->isEntryFunction()) {
// Wait for any outstanding memory operations that the input registers may
// depend on. We can't track them and it's better to the wait after the
// costly call sequence.
// TODO: Could insert earlier and schedule more liberally with operations
// that only use caller preserved registers.
MachineBasicBlock &EntryBB = MF.front();
BuildMI(EntryBB, EntryBB.getFirstNonPHI(), DebugLoc(), TII->get(AMDGPU::S_WAITCNT))
.addImm(0);
Modified = true;
}
return Modified;
}
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