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508 lines
16 KiB
C++
508 lines
16 KiB
C++
//===- GCNRegPressure.cpp -------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "GCNRegPressure.h"
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#include "AMDGPUSubtarget.h"
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#include "SIRegisterInfo.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/CodeGen/LiveInterval.h"
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#include "llvm/CodeGen/LiveIntervals.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineOperand.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/RegisterPressure.h"
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#include "llvm/CodeGen/SlotIndexes.h"
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#include "llvm/CodeGen/TargetRegisterInfo.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/MC/LaneBitmask.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#include <algorithm>
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#include <cassert>
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using namespace llvm;
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#define DEBUG_TYPE "machine-scheduler"
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD
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void llvm::printLivesAt(SlotIndex SI,
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const LiveIntervals &LIS,
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const MachineRegisterInfo &MRI) {
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dbgs() << "Live regs at " << SI << ": "
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<< *LIS.getInstructionFromIndex(SI);
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unsigned Num = 0;
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for (unsigned I = 0, E = MRI.getNumVirtRegs(); I != E; ++I) {
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const unsigned Reg = TargetRegisterInfo::index2VirtReg(I);
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if (!LIS.hasInterval(Reg))
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continue;
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const auto &LI = LIS.getInterval(Reg);
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if (LI.hasSubRanges()) {
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bool firstTime = true;
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for (const auto &S : LI.subranges()) {
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if (!S.liveAt(SI)) continue;
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if (firstTime) {
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dbgs() << " " << printReg(Reg, MRI.getTargetRegisterInfo())
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<< '\n';
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firstTime = false;
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}
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dbgs() << " " << S << '\n';
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++Num;
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}
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} else if (LI.liveAt(SI)) {
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dbgs() << " " << LI << '\n';
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++Num;
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}
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}
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if (!Num) dbgs() << " <none>\n";
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}
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#endif
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bool llvm::isEqual(const GCNRPTracker::LiveRegSet &S1,
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const GCNRPTracker::LiveRegSet &S2) {
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if (S1.size() != S2.size())
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return false;
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for (const auto &P : S1) {
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auto I = S2.find(P.first);
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if (I == S2.end() || I->second != P.second)
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return false;
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}
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return true;
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}
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///////////////////////////////////////////////////////////////////////////////
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// GCNRegPressure
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unsigned GCNRegPressure::getRegKind(unsigned Reg,
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const MachineRegisterInfo &MRI) {
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assert(TargetRegisterInfo::isVirtualRegister(Reg));
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const auto RC = MRI.getRegClass(Reg);
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auto STI = static_cast<const SIRegisterInfo*>(MRI.getTargetRegisterInfo());
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return STI->isSGPRClass(RC) ?
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(STI->getRegSizeInBits(*RC) == 32 ? SGPR32 : SGPR_TUPLE) :
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(STI->getRegSizeInBits(*RC) == 32 ? VGPR32 : VGPR_TUPLE);
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}
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void GCNRegPressure::inc(unsigned Reg,
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LaneBitmask PrevMask,
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LaneBitmask NewMask,
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const MachineRegisterInfo &MRI) {
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if (NewMask == PrevMask)
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return;
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int Sign = 1;
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if (NewMask < PrevMask) {
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std::swap(NewMask, PrevMask);
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Sign = -1;
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}
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#ifndef NDEBUG
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const auto MaxMask = MRI.getMaxLaneMaskForVReg(Reg);
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#endif
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switch (auto Kind = getRegKind(Reg, MRI)) {
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case SGPR32:
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case VGPR32:
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assert(PrevMask.none() && NewMask == MaxMask);
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Value[Kind] += Sign;
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break;
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case SGPR_TUPLE:
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case VGPR_TUPLE:
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assert(NewMask < MaxMask || NewMask == MaxMask);
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assert(PrevMask < NewMask);
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Value[Kind == SGPR_TUPLE ? SGPR32 : VGPR32] +=
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Sign * (~PrevMask & NewMask).getNumLanes();
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if (PrevMask.none()) {
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assert(NewMask.any());
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Value[Kind] += Sign * MRI.getPressureSets(Reg).getWeight();
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}
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break;
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default: llvm_unreachable("Unknown register kind");
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}
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}
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bool GCNRegPressure::less(const GCNSubtarget &ST,
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const GCNRegPressure& O,
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unsigned MaxOccupancy) const {
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const auto SGPROcc = std::min(MaxOccupancy,
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ST.getOccupancyWithNumSGPRs(getSGPRNum()));
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const auto VGPROcc = std::min(MaxOccupancy,
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ST.getOccupancyWithNumVGPRs(getVGPRNum()));
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const auto OtherSGPROcc = std::min(MaxOccupancy,
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ST.getOccupancyWithNumSGPRs(O.getSGPRNum()));
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const auto OtherVGPROcc = std::min(MaxOccupancy,
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ST.getOccupancyWithNumVGPRs(O.getVGPRNum()));
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const auto Occ = std::min(SGPROcc, VGPROcc);
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const auto OtherOcc = std::min(OtherSGPROcc, OtherVGPROcc);
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if (Occ != OtherOcc)
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return Occ > OtherOcc;
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bool SGPRImportant = SGPROcc < VGPROcc;
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const bool OtherSGPRImportant = OtherSGPROcc < OtherVGPROcc;
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// if both pressures disagree on what is more important compare vgprs
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if (SGPRImportant != OtherSGPRImportant) {
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SGPRImportant = false;
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}
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// compare large regs pressure
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bool SGPRFirst = SGPRImportant;
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for (int I = 2; I > 0; --I, SGPRFirst = !SGPRFirst) {
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if (SGPRFirst) {
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auto SW = getSGPRTuplesWeight();
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auto OtherSW = O.getSGPRTuplesWeight();
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if (SW != OtherSW)
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return SW < OtherSW;
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} else {
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auto VW = getVGPRTuplesWeight();
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auto OtherVW = O.getVGPRTuplesWeight();
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if (VW != OtherVW)
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return VW < OtherVW;
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}
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}
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return SGPRImportant ? (getSGPRNum() < O.getSGPRNum()):
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(getVGPRNum() < O.getVGPRNum());
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD
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void GCNRegPressure::print(raw_ostream &OS, const GCNSubtarget *ST) const {
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OS << "VGPRs: " << getVGPRNum();
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if (ST) OS << "(O" << ST->getOccupancyWithNumVGPRs(getVGPRNum()) << ')';
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OS << ", SGPRs: " << getSGPRNum();
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if (ST) OS << "(O" << ST->getOccupancyWithNumSGPRs(getSGPRNum()) << ')';
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OS << ", LVGPR WT: " << getVGPRTuplesWeight()
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<< ", LSGPR WT: " << getSGPRTuplesWeight();
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if (ST) OS << " -> Occ: " << getOccupancy(*ST);
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OS << '\n';
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}
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#endif
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static LaneBitmask getDefRegMask(const MachineOperand &MO,
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const MachineRegisterInfo &MRI) {
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assert(MO.isDef() && MO.isReg() &&
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TargetRegisterInfo::isVirtualRegister(MO.getReg()));
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// We don't rely on read-undef flag because in case of tentative schedule
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// tracking it isn't set correctly yet. This works correctly however since
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// use mask has been tracked before using LIS.
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return MO.getSubReg() == 0 ?
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MRI.getMaxLaneMaskForVReg(MO.getReg()) :
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MRI.getTargetRegisterInfo()->getSubRegIndexLaneMask(MO.getSubReg());
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}
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static LaneBitmask getUsedRegMask(const MachineOperand &MO,
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const MachineRegisterInfo &MRI,
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const LiveIntervals &LIS) {
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assert(MO.isUse() && MO.isReg() &&
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TargetRegisterInfo::isVirtualRegister(MO.getReg()));
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if (auto SubReg = MO.getSubReg())
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return MRI.getTargetRegisterInfo()->getSubRegIndexLaneMask(SubReg);
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auto MaxMask = MRI.getMaxLaneMaskForVReg(MO.getReg());
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if (MaxMask == LaneBitmask::getLane(0)) // cannot have subregs
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return MaxMask;
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// For a tentative schedule LIS isn't updated yet but livemask should remain
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// the same on any schedule. Subreg defs can be reordered but they all must
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// dominate uses anyway.
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auto SI = LIS.getInstructionIndex(*MO.getParent()).getBaseIndex();
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return getLiveLaneMask(MO.getReg(), SI, LIS, MRI);
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}
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static SmallVector<RegisterMaskPair, 8>
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collectVirtualRegUses(const MachineInstr &MI, const LiveIntervals &LIS,
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const MachineRegisterInfo &MRI) {
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SmallVector<RegisterMaskPair, 8> Res;
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for (const auto &MO : MI.operands()) {
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if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()))
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continue;
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if (!MO.isUse() || !MO.readsReg())
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continue;
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auto const UsedMask = getUsedRegMask(MO, MRI, LIS);
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auto Reg = MO.getReg();
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auto I = std::find_if(Res.begin(), Res.end(), [Reg](const RegisterMaskPair &RM) {
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return RM.RegUnit == Reg;
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});
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if (I != Res.end())
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I->LaneMask |= UsedMask;
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else
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Res.push_back(RegisterMaskPair(Reg, UsedMask));
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}
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return Res;
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}
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///////////////////////////////////////////////////////////////////////////////
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// GCNRPTracker
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LaneBitmask llvm::getLiveLaneMask(unsigned Reg,
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SlotIndex SI,
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const LiveIntervals &LIS,
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const MachineRegisterInfo &MRI) {
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LaneBitmask LiveMask;
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const auto &LI = LIS.getInterval(Reg);
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if (LI.hasSubRanges()) {
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for (const auto &S : LI.subranges())
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if (S.liveAt(SI)) {
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LiveMask |= S.LaneMask;
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assert(LiveMask < MRI.getMaxLaneMaskForVReg(Reg) ||
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LiveMask == MRI.getMaxLaneMaskForVReg(Reg));
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}
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} else if (LI.liveAt(SI)) {
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LiveMask = MRI.getMaxLaneMaskForVReg(Reg);
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}
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return LiveMask;
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}
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GCNRPTracker::LiveRegSet llvm::getLiveRegs(SlotIndex SI,
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const LiveIntervals &LIS,
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const MachineRegisterInfo &MRI) {
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GCNRPTracker::LiveRegSet LiveRegs;
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for (unsigned I = 0, E = MRI.getNumVirtRegs(); I != E; ++I) {
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auto Reg = TargetRegisterInfo::index2VirtReg(I);
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if (!LIS.hasInterval(Reg))
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continue;
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auto LiveMask = getLiveLaneMask(Reg, SI, LIS, MRI);
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if (LiveMask.any())
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LiveRegs[Reg] = LiveMask;
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}
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return LiveRegs;
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}
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void GCNRPTracker::reset(const MachineInstr &MI,
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const LiveRegSet *LiveRegsCopy,
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bool After) {
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const MachineFunction &MF = *MI.getMF();
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MRI = &MF.getRegInfo();
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if (LiveRegsCopy) {
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if (&LiveRegs != LiveRegsCopy)
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LiveRegs = *LiveRegsCopy;
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} else {
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LiveRegs = After ? getLiveRegsAfter(MI, LIS)
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: getLiveRegsBefore(MI, LIS);
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}
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MaxPressure = CurPressure = getRegPressure(*MRI, LiveRegs);
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}
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void GCNUpwardRPTracker::reset(const MachineInstr &MI,
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const LiveRegSet *LiveRegsCopy) {
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GCNRPTracker::reset(MI, LiveRegsCopy, true);
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}
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void GCNUpwardRPTracker::recede(const MachineInstr &MI) {
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assert(MRI && "call reset first");
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LastTrackedMI = &MI;
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if (MI.isDebugInstr())
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return;
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auto const RegUses = collectVirtualRegUses(MI, LIS, *MRI);
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// calc pressure at the MI (defs + uses)
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auto AtMIPressure = CurPressure;
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for (const auto &U : RegUses) {
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auto LiveMask = LiveRegs[U.RegUnit];
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AtMIPressure.inc(U.RegUnit, LiveMask, LiveMask | U.LaneMask, *MRI);
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}
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// update max pressure
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MaxPressure = max(AtMIPressure, MaxPressure);
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for (const auto &MO : MI.defs()) {
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if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()) ||
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MO.isDead())
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continue;
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auto Reg = MO.getReg();
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auto I = LiveRegs.find(Reg);
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if (I == LiveRegs.end())
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continue;
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auto &LiveMask = I->second;
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auto PrevMask = LiveMask;
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LiveMask &= ~getDefRegMask(MO, *MRI);
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CurPressure.inc(Reg, PrevMask, LiveMask, *MRI);
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if (LiveMask.none())
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LiveRegs.erase(I);
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}
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for (const auto &U : RegUses) {
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auto &LiveMask = LiveRegs[U.RegUnit];
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auto PrevMask = LiveMask;
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LiveMask |= U.LaneMask;
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CurPressure.inc(U.RegUnit, PrevMask, LiveMask, *MRI);
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}
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assert(CurPressure == getRegPressure(*MRI, LiveRegs));
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}
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bool GCNDownwardRPTracker::reset(const MachineInstr &MI,
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const LiveRegSet *LiveRegsCopy) {
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MRI = &MI.getParent()->getParent()->getRegInfo();
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LastTrackedMI = nullptr;
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MBBEnd = MI.getParent()->end();
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NextMI = &MI;
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NextMI = skipDebugInstructionsForward(NextMI, MBBEnd);
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if (NextMI == MBBEnd)
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return false;
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GCNRPTracker::reset(*NextMI, LiveRegsCopy, false);
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return true;
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}
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bool GCNDownwardRPTracker::advanceBeforeNext() {
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assert(MRI && "call reset first");
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NextMI = skipDebugInstructionsForward(NextMI, MBBEnd);
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if (NextMI == MBBEnd)
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return false;
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SlotIndex SI = LIS.getInstructionIndex(*NextMI).getBaseIndex();
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assert(SI.isValid());
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// Remove dead registers or mask bits.
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for (auto &It : LiveRegs) {
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const LiveInterval &LI = LIS.getInterval(It.first);
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if (LI.hasSubRanges()) {
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for (const auto &S : LI.subranges()) {
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if (!S.liveAt(SI)) {
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auto PrevMask = It.second;
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It.second &= ~S.LaneMask;
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CurPressure.inc(It.first, PrevMask, It.second, *MRI);
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}
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}
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} else if (!LI.liveAt(SI)) {
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auto PrevMask = It.second;
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It.second = LaneBitmask::getNone();
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CurPressure.inc(It.first, PrevMask, It.second, *MRI);
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}
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if (It.second.none())
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LiveRegs.erase(It.first);
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}
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MaxPressure = max(MaxPressure, CurPressure);
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return true;
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}
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void GCNDownwardRPTracker::advanceToNext() {
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LastTrackedMI = &*NextMI++;
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// Add new registers or mask bits.
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for (const auto &MO : LastTrackedMI->defs()) {
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if (!MO.isReg())
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continue;
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unsigned Reg = MO.getReg();
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if (!TargetRegisterInfo::isVirtualRegister(Reg))
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continue;
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auto &LiveMask = LiveRegs[Reg];
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auto PrevMask = LiveMask;
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LiveMask |= getDefRegMask(MO, *MRI);
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CurPressure.inc(Reg, PrevMask, LiveMask, *MRI);
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}
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MaxPressure = max(MaxPressure, CurPressure);
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}
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bool GCNDownwardRPTracker::advance() {
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// If we have just called reset live set is actual.
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if ((NextMI == MBBEnd) || (LastTrackedMI && !advanceBeforeNext()))
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return false;
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advanceToNext();
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return true;
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}
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bool GCNDownwardRPTracker::advance(MachineBasicBlock::const_iterator End) {
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while (NextMI != End)
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if (!advance()) return false;
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return true;
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}
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bool GCNDownwardRPTracker::advance(MachineBasicBlock::const_iterator Begin,
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MachineBasicBlock::const_iterator End,
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const LiveRegSet *LiveRegsCopy) {
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reset(*Begin, LiveRegsCopy);
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return advance(End);
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD
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static void reportMismatch(const GCNRPTracker::LiveRegSet &LISLR,
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const GCNRPTracker::LiveRegSet &TrackedLR,
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const TargetRegisterInfo *TRI) {
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for (auto const &P : TrackedLR) {
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auto I = LISLR.find(P.first);
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if (I == LISLR.end()) {
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dbgs() << " " << printReg(P.first, TRI)
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<< ":L" << PrintLaneMask(P.second)
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<< " isn't found in LIS reported set\n";
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}
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else if (I->second != P.second) {
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dbgs() << " " << printReg(P.first, TRI)
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<< " masks doesn't match: LIS reported "
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<< PrintLaneMask(I->second)
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<< ", tracked "
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<< PrintLaneMask(P.second)
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<< '\n';
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}
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}
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for (auto const &P : LISLR) {
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auto I = TrackedLR.find(P.first);
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if (I == TrackedLR.end()) {
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dbgs() << " " << printReg(P.first, TRI)
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<< ":L" << PrintLaneMask(P.second)
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<< " isn't found in tracked set\n";
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}
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}
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}
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bool GCNUpwardRPTracker::isValid() const {
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const auto &SI = LIS.getInstructionIndex(*LastTrackedMI).getBaseIndex();
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const auto LISLR = llvm::getLiveRegs(SI, LIS, *MRI);
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const auto &TrackedLR = LiveRegs;
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if (!isEqual(LISLR, TrackedLR)) {
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dbgs() << "\nGCNUpwardRPTracker error: Tracked and"
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" LIS reported livesets mismatch:\n";
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printLivesAt(SI, LIS, *MRI);
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reportMismatch(LISLR, TrackedLR, MRI->getTargetRegisterInfo());
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return false;
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|
}
|
|
|
|
auto LISPressure = getRegPressure(*MRI, LISLR);
|
|
if (LISPressure != CurPressure) {
|
|
dbgs() << "GCNUpwardRPTracker error: Pressure sets different\nTracked: ";
|
|
CurPressure.print(dbgs());
|
|
dbgs() << "LIS rpt: ";
|
|
LISPressure.print(dbgs());
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void GCNRPTracker::printLiveRegs(raw_ostream &OS, const LiveRegSet& LiveRegs,
|
|
const MachineRegisterInfo &MRI) {
|
|
const TargetRegisterInfo *TRI = MRI.getTargetRegisterInfo();
|
|
for (unsigned I = 0, E = MRI.getNumVirtRegs(); I != E; ++I) {
|
|
unsigned Reg = TargetRegisterInfo::index2VirtReg(I);
|
|
auto It = LiveRegs.find(Reg);
|
|
if (It != LiveRegs.end() && It->second.any())
|
|
OS << ' ' << printVRegOrUnit(Reg, TRI) << ':'
|
|
<< PrintLaneMask(It->second);
|
|
}
|
|
OS << '\n';
|
|
}
|
|
#endif
|