mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194286 91177308-0d34-0410-b5e6-96231b3b80d8
998 lines
35 KiB
C++
998 lines
35 KiB
C++
//===-- RegisterPressure.cpp - Dynamic Register Pressure ------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the RegisterPressure class which can be used to track
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// MachineInstr level register pressure.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/RegisterPressure.h"
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#include "llvm/CodeGen/LiveInterval.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/RegisterClassInfo.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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/// Increase pressure for each pressure set provided by TargetRegisterInfo.
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static void increaseSetPressure(std::vector<unsigned> &CurrSetPressure,
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PSetIterator PSetI) {
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unsigned Weight = PSetI.getWeight();
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for (; PSetI.isValid(); ++PSetI)
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CurrSetPressure[*PSetI] += Weight;
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}
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/// Decrease pressure for each pressure set provided by TargetRegisterInfo.
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static void decreaseSetPressure(std::vector<unsigned> &CurrSetPressure,
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PSetIterator PSetI) {
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unsigned Weight = PSetI.getWeight();
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for (; PSetI.isValid(); ++PSetI) {
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assert(CurrSetPressure[*PSetI] >= Weight && "register pressure underflow");
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CurrSetPressure[*PSetI] -= Weight;
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}
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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void llvm::dumpRegSetPressure(ArrayRef<unsigned> SetPressure,
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const TargetRegisterInfo *TRI) {
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bool Empty = true;
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for (unsigned i = 0, e = SetPressure.size(); i < e; ++i) {
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if (SetPressure[i] != 0) {
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dbgs() << TRI->getRegPressureSetName(i) << "=" << SetPressure[i] << '\n';
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Empty = false;
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}
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}
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if (Empty)
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dbgs() << "\n";
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}
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void RegisterPressure::dump(const TargetRegisterInfo *TRI) const {
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dbgs() << "Max Pressure: ";
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dumpRegSetPressure(MaxSetPressure, TRI);
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dbgs() << "Live In: ";
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for (unsigned i = 0, e = LiveInRegs.size(); i < e; ++i)
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dbgs() << PrintReg(LiveInRegs[i], TRI) << " ";
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dbgs() << '\n';
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dbgs() << "Live Out: ";
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for (unsigned i = 0, e = LiveOutRegs.size(); i < e; ++i)
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dbgs() << PrintReg(LiveOutRegs[i], TRI) << " ";
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dbgs() << '\n';
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}
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void RegPressureTracker::dump() const {
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if (!isTopClosed() || !isBottomClosed()) {
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dbgs() << "Curr Pressure: ";
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dumpRegSetPressure(CurrSetPressure, TRI);
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}
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P.dump(TRI);
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}
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#endif
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/// Increase the current pressure as impacted by these registers and bump
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/// the high water mark if needed.
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void RegPressureTracker::increaseRegPressure(ArrayRef<unsigned> RegUnits) {
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for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
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PSetIterator PSetI = MRI->getPressureSets(RegUnits[i]);
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unsigned Weight = PSetI.getWeight();
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for (; PSetI.isValid(); ++PSetI) {
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CurrSetPressure[*PSetI] += Weight;
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if (CurrSetPressure[*PSetI] > P.MaxSetPressure[*PSetI]) {
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P.MaxSetPressure[*PSetI] = CurrSetPressure[*PSetI];
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}
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}
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}
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}
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/// Simply decrease the current pressure as impacted by these registers.
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void RegPressureTracker::decreaseRegPressure(ArrayRef<unsigned> RegUnits) {
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for (unsigned I = 0, E = RegUnits.size(); I != E; ++I)
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decreaseSetPressure(CurrSetPressure, MRI->getPressureSets(RegUnits[I]));
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}
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/// Clear the result so it can be used for another round of pressure tracking.
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void IntervalPressure::reset() {
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TopIdx = BottomIdx = SlotIndex();
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MaxSetPressure.clear();
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LiveInRegs.clear();
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LiveOutRegs.clear();
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}
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/// Clear the result so it can be used for another round of pressure tracking.
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void RegionPressure::reset() {
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TopPos = BottomPos = MachineBasicBlock::const_iterator();
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MaxSetPressure.clear();
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LiveInRegs.clear();
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LiveOutRegs.clear();
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}
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/// If the current top is not less than or equal to the next index, open it.
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/// We happen to need the SlotIndex for the next top for pressure update.
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void IntervalPressure::openTop(SlotIndex NextTop) {
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if (TopIdx <= NextTop)
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return;
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TopIdx = SlotIndex();
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LiveInRegs.clear();
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}
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/// If the current top is the previous instruction (before receding), open it.
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void RegionPressure::openTop(MachineBasicBlock::const_iterator PrevTop) {
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if (TopPos != PrevTop)
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return;
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TopPos = MachineBasicBlock::const_iterator();
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LiveInRegs.clear();
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}
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/// If the current bottom is not greater than the previous index, open it.
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void IntervalPressure::openBottom(SlotIndex PrevBottom) {
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if (BottomIdx > PrevBottom)
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return;
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BottomIdx = SlotIndex();
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LiveInRegs.clear();
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}
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/// If the current bottom is the previous instr (before advancing), open it.
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void RegionPressure::openBottom(MachineBasicBlock::const_iterator PrevBottom) {
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if (BottomPos != PrevBottom)
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return;
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BottomPos = MachineBasicBlock::const_iterator();
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LiveInRegs.clear();
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}
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const LiveRange *RegPressureTracker::getLiveRange(unsigned Reg) const {
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if (TargetRegisterInfo::isVirtualRegister(Reg))
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return &LIS->getInterval(Reg);
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return LIS->getCachedRegUnit(Reg);
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}
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void RegPressureTracker::reset() {
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MBB = 0;
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LIS = 0;
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CurrSetPressure.clear();
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LiveThruPressure.clear();
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P.MaxSetPressure.clear();
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if (RequireIntervals)
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static_cast<IntervalPressure&>(P).reset();
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else
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static_cast<RegionPressure&>(P).reset();
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LiveRegs.PhysRegs.clear();
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LiveRegs.VirtRegs.clear();
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UntiedDefs.clear();
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}
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/// Setup the RegPressureTracker.
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///
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/// TODO: Add support for pressure without LiveIntervals.
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void RegPressureTracker::init(const MachineFunction *mf,
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const RegisterClassInfo *rci,
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const LiveIntervals *lis,
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const MachineBasicBlock *mbb,
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MachineBasicBlock::const_iterator pos,
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bool ShouldTrackUntiedDefs)
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{
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reset();
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MF = mf;
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TRI = MF->getTarget().getRegisterInfo();
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RCI = rci;
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MRI = &MF->getRegInfo();
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MBB = mbb;
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TrackUntiedDefs = ShouldTrackUntiedDefs;
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if (RequireIntervals) {
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assert(lis && "IntervalPressure requires LiveIntervals");
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LIS = lis;
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}
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CurrPos = pos;
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CurrSetPressure.assign(TRI->getNumRegPressureSets(), 0);
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P.MaxSetPressure = CurrSetPressure;
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LiveRegs.PhysRegs.setUniverse(TRI->getNumRegs());
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LiveRegs.VirtRegs.setUniverse(MRI->getNumVirtRegs());
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if (TrackUntiedDefs)
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UntiedDefs.setUniverse(MRI->getNumVirtRegs());
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}
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/// Does this pressure result have a valid top position and live ins.
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bool RegPressureTracker::isTopClosed() const {
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if (RequireIntervals)
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return static_cast<IntervalPressure&>(P).TopIdx.isValid();
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return (static_cast<RegionPressure&>(P).TopPos ==
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MachineBasicBlock::const_iterator());
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}
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/// Does this pressure result have a valid bottom position and live outs.
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bool RegPressureTracker::isBottomClosed() const {
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if (RequireIntervals)
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return static_cast<IntervalPressure&>(P).BottomIdx.isValid();
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return (static_cast<RegionPressure&>(P).BottomPos ==
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MachineBasicBlock::const_iterator());
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}
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SlotIndex RegPressureTracker::getCurrSlot() const {
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MachineBasicBlock::const_iterator IdxPos = CurrPos;
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while (IdxPos != MBB->end() && IdxPos->isDebugValue())
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++IdxPos;
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if (IdxPos == MBB->end())
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return LIS->getMBBEndIdx(MBB);
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return LIS->getInstructionIndex(IdxPos).getRegSlot();
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}
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/// Set the boundary for the top of the region and summarize live ins.
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void RegPressureTracker::closeTop() {
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if (RequireIntervals)
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static_cast<IntervalPressure&>(P).TopIdx = getCurrSlot();
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else
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static_cast<RegionPressure&>(P).TopPos = CurrPos;
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assert(P.LiveInRegs.empty() && "inconsistent max pressure result");
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P.LiveInRegs.reserve(LiveRegs.PhysRegs.size() + LiveRegs.VirtRegs.size());
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P.LiveInRegs.append(LiveRegs.PhysRegs.begin(), LiveRegs.PhysRegs.end());
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for (SparseSet<unsigned>::const_iterator I =
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LiveRegs.VirtRegs.begin(), E = LiveRegs.VirtRegs.end(); I != E; ++I)
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P.LiveInRegs.push_back(*I);
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std::sort(P.LiveInRegs.begin(), P.LiveInRegs.end());
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P.LiveInRegs.erase(std::unique(P.LiveInRegs.begin(), P.LiveInRegs.end()),
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P.LiveInRegs.end());
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}
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/// Set the boundary for the bottom of the region and summarize live outs.
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void RegPressureTracker::closeBottom() {
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if (RequireIntervals)
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static_cast<IntervalPressure&>(P).BottomIdx = getCurrSlot();
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else
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static_cast<RegionPressure&>(P).BottomPos = CurrPos;
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assert(P.LiveOutRegs.empty() && "inconsistent max pressure result");
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P.LiveOutRegs.reserve(LiveRegs.PhysRegs.size() + LiveRegs.VirtRegs.size());
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P.LiveOutRegs.append(LiveRegs.PhysRegs.begin(), LiveRegs.PhysRegs.end());
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for (SparseSet<unsigned>::const_iterator I =
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LiveRegs.VirtRegs.begin(), E = LiveRegs.VirtRegs.end(); I != E; ++I)
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P.LiveOutRegs.push_back(*I);
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std::sort(P.LiveOutRegs.begin(), P.LiveOutRegs.end());
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P.LiveOutRegs.erase(std::unique(P.LiveOutRegs.begin(), P.LiveOutRegs.end()),
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P.LiveOutRegs.end());
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}
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/// Finalize the region boundaries and record live ins and live outs.
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void RegPressureTracker::closeRegion() {
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if (!isTopClosed() && !isBottomClosed()) {
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assert(LiveRegs.PhysRegs.empty() && LiveRegs.VirtRegs.empty() &&
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"no region boundary");
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return;
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}
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if (!isBottomClosed())
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closeBottom();
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else if (!isTopClosed())
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closeTop();
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// If both top and bottom are closed, do nothing.
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}
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/// The register tracker is unaware of global liveness so ignores normal
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/// live-thru ranges. However, two-address or coalesced chains can also lead
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/// to live ranges with no holes. Count these to inform heuristics that we
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/// can never drop below this pressure.
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void RegPressureTracker::initLiveThru(const RegPressureTracker &RPTracker) {
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LiveThruPressure.assign(TRI->getNumRegPressureSets(), 0);
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assert(isBottomClosed() && "need bottom-up tracking to intialize.");
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for (unsigned i = 0, e = P.LiveOutRegs.size(); i < e; ++i) {
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unsigned Reg = P.LiveOutRegs[i];
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if (TargetRegisterInfo::isVirtualRegister(Reg)
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&& !RPTracker.hasUntiedDef(Reg)) {
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increaseSetPressure(LiveThruPressure, MRI->getPressureSets(Reg));
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}
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}
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}
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/// \brief Convenient wrapper for checking membership in RegisterOperands.
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/// (std::count() doesn't have an early exit).
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static bool containsReg(ArrayRef<unsigned> RegUnits, unsigned RegUnit) {
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return std::find(RegUnits.begin(), RegUnits.end(), RegUnit) != RegUnits.end();
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}
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/// Collect this instruction's unique uses and defs into SmallVectors for
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/// processing defs and uses in order.
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///
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/// FIXME: always ignore tied opers
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class RegisterOperands {
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const TargetRegisterInfo *TRI;
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const MachineRegisterInfo *MRI;
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bool IgnoreDead;
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public:
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SmallVector<unsigned, 8> Uses;
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SmallVector<unsigned, 8> Defs;
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SmallVector<unsigned, 8> DeadDefs;
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RegisterOperands(const TargetRegisterInfo *tri,
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const MachineRegisterInfo *mri, bool ID = false):
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TRI(tri), MRI(mri), IgnoreDead(ID) {}
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/// Push this operand's register onto the correct vector.
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void collect(const MachineOperand &MO) {
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if (!MO.isReg() || !MO.getReg())
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return;
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if (MO.readsReg())
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pushRegUnits(MO.getReg(), Uses);
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if (MO.isDef()) {
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if (MO.isDead()) {
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if (!IgnoreDead)
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pushRegUnits(MO.getReg(), DeadDefs);
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}
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else
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pushRegUnits(MO.getReg(), Defs);
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}
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}
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protected:
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void pushRegUnits(unsigned Reg, SmallVectorImpl<unsigned> &RegUnits) {
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if (TargetRegisterInfo::isVirtualRegister(Reg)) {
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if (containsReg(RegUnits, Reg))
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return;
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RegUnits.push_back(Reg);
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}
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else if (MRI->isAllocatable(Reg)) {
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for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) {
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if (containsReg(RegUnits, *Units))
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continue;
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RegUnits.push_back(*Units);
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}
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}
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}
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};
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/// Collect physical and virtual register operands.
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static void collectOperands(const MachineInstr *MI,
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RegisterOperands &RegOpers) {
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for (ConstMIBundleOperands OperI(MI); OperI.isValid(); ++OperI)
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RegOpers.collect(*OperI);
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// Remove redundant physreg dead defs.
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SmallVectorImpl<unsigned>::iterator I =
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std::remove_if(RegOpers.DeadDefs.begin(), RegOpers.DeadDefs.end(),
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std::bind1st(std::ptr_fun(containsReg), RegOpers.Defs));
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RegOpers.DeadDefs.erase(I, RegOpers.DeadDefs.end());
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}
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/// Initialize an array of N PressureDiffs.
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void PressureDiffs::init(unsigned N) {
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Size = N;
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if (N <= Max) {
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memset(PDiffArray, 0, N * sizeof(PressureDiff));
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return;
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}
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Max = Size;
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free(PDiffArray);
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PDiffArray = reinterpret_cast<PressureDiff*>(calloc(N, sizeof(PressureDiff)));
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}
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/// Add a change in pressure to the pressure diff of a given instruction.
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void PressureDiff::addPressureChange(unsigned RegUnit, bool IsDec,
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const MachineRegisterInfo *MRI) {
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PSetIterator PSetI = MRI->getPressureSets(RegUnit);
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int Weight = IsDec ? -PSetI.getWeight() : PSetI.getWeight();
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for (; PSetI.isValid(); ++PSetI) {
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// Find an existing entry in the pressure diff for this PSet.
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PressureDiff::iterator I = begin(), E = end();
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for (; I != E && I->isValid(); ++I) {
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if (I->getPSet() >= *PSetI)
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break;
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}
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// If all pressure sets are more constrained, skip the remaining PSets.
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if (I == E)
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break;
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// Insert this PressureChange.
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if (!I->isValid() || I->getPSet() != *PSetI) {
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PressureChange PTmp = PressureChange(*PSetI);
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for (PressureDiff::iterator J = I; J != E && PTmp.isValid(); ++J)
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std::swap(*J,PTmp);
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}
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// Update the units for this pressure set.
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I->setUnitInc(I->getUnitInc() + Weight);
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}
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}
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/// Record the pressure difference induced by the given operand list.
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static void collectPDiff(PressureDiff &PDiff, RegisterOperands &RegOpers,
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const MachineRegisterInfo *MRI) {
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assert(!PDiff.begin()->isValid() && "stale PDiff");
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for (unsigned i = 0, e = RegOpers.Defs.size(); i != e; ++i)
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PDiff.addPressureChange(RegOpers.Defs[i], true, MRI);
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for (unsigned i = 0, e = RegOpers.Uses.size(); i != e; ++i)
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PDiff.addPressureChange(RegOpers.Uses[i], false, MRI);
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}
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/// Force liveness of registers.
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void RegPressureTracker::addLiveRegs(ArrayRef<unsigned> Regs) {
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for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
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if (LiveRegs.insert(Regs[i]))
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increaseRegPressure(Regs[i]);
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}
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}
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/// Add Reg to the live in set and increase max pressure.
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void RegPressureTracker::discoverLiveIn(unsigned Reg) {
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assert(!LiveRegs.contains(Reg) && "avoid bumping max pressure twice");
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if (containsReg(P.LiveInRegs, Reg))
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return;
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// At live in discovery, unconditionally increase the high water mark.
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P.LiveInRegs.push_back(Reg);
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increaseSetPressure(P.MaxSetPressure, MRI->getPressureSets(Reg));
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}
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/// Add Reg to the live out set and increase max pressure.
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void RegPressureTracker::discoverLiveOut(unsigned Reg) {
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assert(!LiveRegs.contains(Reg) && "avoid bumping max pressure twice");
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if (containsReg(P.LiveOutRegs, Reg))
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return;
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// At live out discovery, unconditionally increase the high water mark.
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P.LiveOutRegs.push_back(Reg);
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increaseSetPressure(P.MaxSetPressure, MRI->getPressureSets(Reg));
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}
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/// Recede across the previous instruction. If LiveUses is provided, record any
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/// RegUnits that are made live by the current instruction's uses. This includes
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/// registers that are both defined and used by the instruction. If a pressure
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/// difference pointer is provided record the changes is pressure caused by this
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/// instruction independent of liveness.
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bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
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PressureDiff *PDiff) {
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// Check for the top of the analyzable region.
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if (CurrPos == MBB->begin()) {
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closeRegion();
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return false;
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}
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if (!isBottomClosed())
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closeBottom();
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// Open the top of the region using block iterators.
|
|
if (!RequireIntervals && isTopClosed())
|
|
static_cast<RegionPressure&>(P).openTop(CurrPos);
|
|
|
|
// Find the previous instruction.
|
|
do
|
|
--CurrPos;
|
|
while (CurrPos != MBB->begin() && CurrPos->isDebugValue());
|
|
|
|
if (CurrPos->isDebugValue()) {
|
|
closeRegion();
|
|
return false;
|
|
}
|
|
SlotIndex SlotIdx;
|
|
if (RequireIntervals)
|
|
SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
|
|
|
|
// Open the top of the region using slot indexes.
|
|
if (RequireIntervals && isTopClosed())
|
|
static_cast<IntervalPressure&>(P).openTop(SlotIdx);
|
|
|
|
RegisterOperands RegOpers(TRI, MRI);
|
|
collectOperands(CurrPos, RegOpers);
|
|
|
|
if (PDiff)
|
|
collectPDiff(*PDiff, RegOpers, MRI);
|
|
|
|
// Boost pressure for all dead defs together.
|
|
increaseRegPressure(RegOpers.DeadDefs);
|
|
decreaseRegPressure(RegOpers.DeadDefs);
|
|
|
|
// Kill liveness at live defs.
|
|
// TODO: consider earlyclobbers?
|
|
for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Defs[i];
|
|
bool DeadDef = false;
|
|
if (RequireIntervals) {
|
|
const LiveRange *LR = getLiveRange(Reg);
|
|
if (LR) {
|
|
LiveQueryResult LRQ = LR->Query(SlotIdx);
|
|
DeadDef = LRQ.isDeadDef();
|
|
}
|
|
}
|
|
if (!DeadDef) {
|
|
if (LiveRegs.erase(Reg))
|
|
decreaseRegPressure(Reg);
|
|
else
|
|
discoverLiveOut(Reg);
|
|
}
|
|
}
|
|
|
|
// Generate liveness for uses.
|
|
for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Uses[i];
|
|
if (!LiveRegs.contains(Reg)) {
|
|
// Adjust liveouts if LiveIntervals are available.
|
|
if (RequireIntervals) {
|
|
const LiveRange *LR = getLiveRange(Reg);
|
|
if (LR) {
|
|
LiveQueryResult LRQ = LR->Query(SlotIdx);
|
|
if (!LRQ.isKill() && !LRQ.valueDefined())
|
|
discoverLiveOut(Reg);
|
|
}
|
|
}
|
|
increaseRegPressure(Reg);
|
|
LiveRegs.insert(Reg);
|
|
if (LiveUses && !containsReg(*LiveUses, Reg))
|
|
LiveUses->push_back(Reg);
|
|
}
|
|
}
|
|
if (TrackUntiedDefs) {
|
|
for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Defs[i];
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg) && !LiveRegs.contains(Reg))
|
|
UntiedDefs.insert(Reg);
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// Advance across the current instruction.
|
|
bool RegPressureTracker::advance() {
|
|
assert(!TrackUntiedDefs && "unsupported mode");
|
|
|
|
// Check for the bottom of the analyzable region.
|
|
if (CurrPos == MBB->end()) {
|
|
closeRegion();
|
|
return false;
|
|
}
|
|
if (!isTopClosed())
|
|
closeTop();
|
|
|
|
SlotIndex SlotIdx;
|
|
if (RequireIntervals)
|
|
SlotIdx = getCurrSlot();
|
|
|
|
// Open the bottom of the region using slot indexes.
|
|
if (isBottomClosed()) {
|
|
if (RequireIntervals)
|
|
static_cast<IntervalPressure&>(P).openBottom(SlotIdx);
|
|
else
|
|
static_cast<RegionPressure&>(P).openBottom(CurrPos);
|
|
}
|
|
|
|
RegisterOperands RegOpers(TRI, MRI);
|
|
collectOperands(CurrPos, RegOpers);
|
|
|
|
for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Uses[i];
|
|
// Discover live-ins.
|
|
bool isLive = LiveRegs.contains(Reg);
|
|
if (!isLive)
|
|
discoverLiveIn(Reg);
|
|
// Kill liveness at last uses.
|
|
bool lastUse = false;
|
|
if (RequireIntervals) {
|
|
const LiveRange *LR = getLiveRange(Reg);
|
|
lastUse = LR && LR->Query(SlotIdx).isKill();
|
|
}
|
|
else {
|
|
// Allocatable physregs are always single-use before register rewriting.
|
|
lastUse = !TargetRegisterInfo::isVirtualRegister(Reg);
|
|
}
|
|
if (lastUse && isLive) {
|
|
LiveRegs.erase(Reg);
|
|
decreaseRegPressure(Reg);
|
|
}
|
|
else if (!lastUse && !isLive)
|
|
increaseRegPressure(Reg);
|
|
}
|
|
|
|
// Generate liveness for defs.
|
|
for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Defs[i];
|
|
if (LiveRegs.insert(Reg))
|
|
increaseRegPressure(Reg);
|
|
}
|
|
|
|
// Boost pressure for all dead defs together.
|
|
increaseRegPressure(RegOpers.DeadDefs);
|
|
decreaseRegPressure(RegOpers.DeadDefs);
|
|
|
|
// Find the next instruction.
|
|
do
|
|
++CurrPos;
|
|
while (CurrPos != MBB->end() && CurrPos->isDebugValue());
|
|
return true;
|
|
}
|
|
|
|
/// Find the max change in excess pressure across all sets.
|
|
static void computeExcessPressureDelta(ArrayRef<unsigned> OldPressureVec,
|
|
ArrayRef<unsigned> NewPressureVec,
|
|
RegPressureDelta &Delta,
|
|
const RegisterClassInfo *RCI,
|
|
ArrayRef<unsigned> LiveThruPressureVec) {
|
|
Delta.Excess = PressureChange();
|
|
for (unsigned i = 0, e = OldPressureVec.size(); i < e; ++i) {
|
|
unsigned POld = OldPressureVec[i];
|
|
unsigned PNew = NewPressureVec[i];
|
|
int PDiff = (int)PNew - (int)POld;
|
|
if (!PDiff) // No change in this set in the common case.
|
|
continue;
|
|
// Only consider change beyond the limit.
|
|
unsigned Limit = RCI->getRegPressureSetLimit(i);
|
|
if (!LiveThruPressureVec.empty())
|
|
Limit += LiveThruPressureVec[i];
|
|
|
|
if (Limit > POld) {
|
|
if (Limit > PNew)
|
|
PDiff = 0; // Under the limit
|
|
else
|
|
PDiff = PNew - Limit; // Just exceeded limit.
|
|
}
|
|
else if (Limit > PNew)
|
|
PDiff = Limit - POld; // Just obeyed limit.
|
|
|
|
if (PDiff) {
|
|
Delta.Excess = PressureChange(i);
|
|
Delta.Excess.setUnitInc(PDiff);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Find the max change in max pressure that either surpasses a critical PSet
|
|
/// limit or exceeds the current MaxPressureLimit.
|
|
///
|
|
/// FIXME: comparing each element of the old and new MaxPressure vectors here is
|
|
/// silly. It's done now to demonstrate the concept but will go away with a
|
|
/// RegPressureTracker API change to work with pressure differences.
|
|
static void computeMaxPressureDelta(ArrayRef<unsigned> OldMaxPressureVec,
|
|
ArrayRef<unsigned> NewMaxPressureVec,
|
|
ArrayRef<PressureChange> CriticalPSets,
|
|
ArrayRef<unsigned> MaxPressureLimit,
|
|
RegPressureDelta &Delta) {
|
|
Delta.CriticalMax = PressureChange();
|
|
Delta.CurrentMax = PressureChange();
|
|
|
|
unsigned CritIdx = 0, CritEnd = CriticalPSets.size();
|
|
for (unsigned i = 0, e = OldMaxPressureVec.size(); i < e; ++i) {
|
|
unsigned POld = OldMaxPressureVec[i];
|
|
unsigned PNew = NewMaxPressureVec[i];
|
|
if (PNew == POld) // No change in this set in the common case.
|
|
continue;
|
|
|
|
if (!Delta.CriticalMax.isValid()) {
|
|
while (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() < i)
|
|
++CritIdx;
|
|
|
|
if (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() == i) {
|
|
int PDiff = (int)PNew - (int)CriticalPSets[CritIdx].getUnitInc();
|
|
if (PDiff > 0) {
|
|
Delta.CriticalMax = PressureChange(i);
|
|
Delta.CriticalMax.setUnitInc(PDiff);
|
|
}
|
|
}
|
|
}
|
|
// Find the first increase above MaxPressureLimit.
|
|
// (Ignores negative MDiff).
|
|
if (!Delta.CurrentMax.isValid() && PNew > MaxPressureLimit[i]) {
|
|
Delta.CurrentMax = PressureChange(i);
|
|
Delta.CurrentMax.setUnitInc(PNew - POld);
|
|
if (CritIdx == CritEnd || Delta.CriticalMax.isValid())
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Record the upward impact of a single instruction on current register
|
|
/// pressure. Unlike the advance/recede pressure tracking interface, this does
|
|
/// not discover live in/outs.
|
|
///
|
|
/// This is intended for speculative queries. It leaves pressure inconsistent
|
|
/// with the current position, so must be restored by the caller.
|
|
void RegPressureTracker::bumpUpwardPressure(const MachineInstr *MI) {
|
|
assert(!MI->isDebugValue() && "Expect a nondebug instruction.");
|
|
|
|
// Account for register pressure similar to RegPressureTracker::recede().
|
|
RegisterOperands RegOpers(TRI, MRI, /*IgnoreDead=*/true);
|
|
collectOperands(MI, RegOpers);
|
|
|
|
// Boost max pressure for all dead defs together.
|
|
// Since CurrSetPressure and MaxSetPressure
|
|
increaseRegPressure(RegOpers.DeadDefs);
|
|
decreaseRegPressure(RegOpers.DeadDefs);
|
|
|
|
// Kill liveness at live defs.
|
|
for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Defs[i];
|
|
bool DeadDef = false;
|
|
if (RequireIntervals) {
|
|
const LiveRange *LR = getLiveRange(Reg);
|
|
if (LR) {
|
|
SlotIndex SlotIdx = LIS->getInstructionIndex(MI);
|
|
LiveQueryResult LRQ = LR->Query(SlotIdx);
|
|
DeadDef = LRQ.isDeadDef();
|
|
}
|
|
}
|
|
if (!DeadDef) {
|
|
if (!containsReg(RegOpers.Uses, Reg))
|
|
decreaseRegPressure(Reg);
|
|
}
|
|
}
|
|
// Generate liveness for uses.
|
|
for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Uses[i];
|
|
if (!LiveRegs.contains(Reg))
|
|
increaseRegPressure(Reg);
|
|
}
|
|
}
|
|
|
|
/// Consider the pressure increase caused by traversing this instruction
|
|
/// bottom-up. Find the pressure set with the most change beyond its pressure
|
|
/// limit based on the tracker's current pressure, and return the change in
|
|
/// number of register units of that pressure set introduced by this
|
|
/// instruction.
|
|
///
|
|
/// This assumes that the current LiveOut set is sufficient.
|
|
///
|
|
/// FIXME: This is expensive for an on-the-fly query. We need to cache the
|
|
/// result per-SUnit with enough information to adjust for the current
|
|
/// scheduling position. But this works as a proof of concept.
|
|
void RegPressureTracker::
|
|
getMaxUpwardPressureDelta(const MachineInstr *MI, PressureDiff *PDiff,
|
|
RegPressureDelta &Delta,
|
|
ArrayRef<PressureChange> CriticalPSets,
|
|
ArrayRef<unsigned> MaxPressureLimit) {
|
|
// Snapshot Pressure.
|
|
// FIXME: The snapshot heap space should persist. But I'm planning to
|
|
// summarize the pressure effect so we don't need to snapshot at all.
|
|
std::vector<unsigned> SavedPressure = CurrSetPressure;
|
|
std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
|
|
|
|
bumpUpwardPressure(MI);
|
|
|
|
computeExcessPressureDelta(SavedPressure, CurrSetPressure, Delta, RCI,
|
|
LiveThruPressure);
|
|
computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets,
|
|
MaxPressureLimit, Delta);
|
|
assert(Delta.CriticalMax.getUnitInc() >= 0 &&
|
|
Delta.CurrentMax.getUnitInc() >= 0 && "cannot decrease max pressure");
|
|
|
|
// Restore the tracker's state.
|
|
P.MaxSetPressure.swap(SavedMaxPressure);
|
|
CurrSetPressure.swap(SavedPressure);
|
|
|
|
#ifndef NDEBUG
|
|
if (!PDiff)
|
|
return;
|
|
|
|
// Check if the alternate algorithm yields the same result.
|
|
RegPressureDelta Delta2;
|
|
getUpwardPressureDelta(MI, *PDiff, Delta2, CriticalPSets, MaxPressureLimit);
|
|
if (Delta != Delta2) {
|
|
dbgs() << "DELTA: " << *MI;
|
|
if (Delta.Excess.isValid())
|
|
dbgs() << "Excess1 " << TRI->getRegPressureSetName(Delta.Excess.getPSet())
|
|
<< " " << Delta.Excess.getUnitInc() << "\n";
|
|
if (Delta.CriticalMax.isValid())
|
|
dbgs() << "Critic1 " << TRI->getRegPressureSetName(Delta.CriticalMax.getPSet())
|
|
<< " " << Delta.CriticalMax.getUnitInc() << "\n";
|
|
if (Delta.CurrentMax.isValid())
|
|
dbgs() << "CurrMx1 " << TRI->getRegPressureSetName(Delta.CurrentMax.getPSet())
|
|
<< " " << Delta.CurrentMax.getUnitInc() << "\n";
|
|
if (Delta2.Excess.isValid())
|
|
dbgs() << "Excess2 " << TRI->getRegPressureSetName(Delta2.Excess.getPSet())
|
|
<< " " << Delta2.Excess.getUnitInc() << "\n";
|
|
if (Delta2.CriticalMax.isValid())
|
|
dbgs() << "Critic2 " << TRI->getRegPressureSetName(Delta2.CriticalMax.getPSet())
|
|
<< " " << Delta2.CriticalMax.getUnitInc() << "\n";
|
|
if (Delta2.CurrentMax.isValid())
|
|
dbgs() << "CurrMx2 " << TRI->getRegPressureSetName(Delta2.CurrentMax.getPSet())
|
|
<< " " << Delta2.CurrentMax.getUnitInc() << "\n";
|
|
llvm_unreachable("RegP Delta Mismatch");
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/// This is a prototype of the fast version of querying register pressure that
|
|
/// does not directly depend on current liveness. It's still slow because we
|
|
/// recompute pressure change on-the-fly. This implementation only exists to
|
|
/// prove correctness.
|
|
///
|
|
/// @param Delta captures information needed for heuristics.
|
|
///
|
|
/// @param CriticalPSets Are the pressure sets that are known to exceed some
|
|
/// limit within the region, not necessarily at the current position.
|
|
///
|
|
/// @param MaxPressureLimit Is the max pressure within the region, not
|
|
/// necessarily at the current position.
|
|
void RegPressureTracker::
|
|
getUpwardPressureDelta(const MachineInstr *MI, /*const*/ PressureDiff &PDiff,
|
|
RegPressureDelta &Delta,
|
|
ArrayRef<PressureChange> CriticalPSets,
|
|
ArrayRef<unsigned> MaxPressureLimit) const {
|
|
unsigned CritIdx = 0, CritEnd = CriticalPSets.size();
|
|
for (PressureDiff::const_iterator
|
|
PDiffI = PDiff.begin(), PDiffE = PDiff.end();
|
|
PDiffI != PDiffE && PDiffI->isValid(); ++PDiffI) {
|
|
|
|
unsigned PSetID = PDiffI->getPSet();
|
|
unsigned Limit = RCI->getRegPressureSetLimit(PSetID);
|
|
if (!LiveThruPressure.empty())
|
|
Limit += LiveThruPressure[PSetID];
|
|
|
|
unsigned POld = CurrSetPressure[PSetID];
|
|
unsigned MOld = P.MaxSetPressure[PSetID];
|
|
unsigned MNew = MOld;
|
|
// Ignore DeadDefs here because they aren't captured by PressureChange.
|
|
unsigned PNew = POld + PDiffI->getUnitInc();
|
|
assert((PDiffI->getUnitInc() >= 0) == (PNew >= POld) && "PSet overflow");
|
|
if (PNew > MOld)
|
|
MNew = PNew;
|
|
// Check if current pressure has exceeded the limit.
|
|
if (!Delta.Excess.isValid()) {
|
|
unsigned ExcessInc = 0;
|
|
if (PNew > Limit)
|
|
ExcessInc = POld > Limit ? PNew - POld : PNew - Limit;
|
|
else if (POld > Limit)
|
|
ExcessInc = Limit - POld;
|
|
if (ExcessInc) {
|
|
Delta.Excess = PressureChange(PSetID);
|
|
Delta.Excess.setUnitInc(ExcessInc);
|
|
}
|
|
}
|
|
// Check if max pressure has exceeded a critical pressure set max.
|
|
if (MNew == MOld)
|
|
continue;
|
|
if (!Delta.CriticalMax.isValid()) {
|
|
while (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() < PSetID)
|
|
++CritIdx;
|
|
|
|
if (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() == PSetID) {
|
|
int CritInc = (int)MNew - (int)CriticalPSets[CritIdx].getUnitInc();
|
|
if (CritInc > 0 && CritInc <= INT16_MAX) {
|
|
Delta.CriticalMax = PressureChange(PSetID);
|
|
Delta.CriticalMax.setUnitInc(CritInc);
|
|
}
|
|
}
|
|
}
|
|
// Check if max pressure has exceeded the current max.
|
|
if (!Delta.CurrentMax.isValid() && MNew > MaxPressureLimit[PSetID]) {
|
|
Delta.CurrentMax = PressureChange(PSetID);
|
|
Delta.CurrentMax.setUnitInc(MNew - MOld);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Helper to find a vreg use between two indices [PriorUseIdx, NextUseIdx).
|
|
static bool findUseBetween(unsigned Reg,
|
|
SlotIndex PriorUseIdx, SlotIndex NextUseIdx,
|
|
const MachineRegisterInfo *MRI,
|
|
const LiveIntervals *LIS) {
|
|
for (MachineRegisterInfo::use_nodbg_iterator
|
|
UI = MRI->use_nodbg_begin(Reg), UE = MRI->use_nodbg_end();
|
|
UI != UE; UI.skipInstruction()) {
|
|
const MachineInstr* MI = &*UI;
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
SlotIndex InstSlot = LIS->getInstructionIndex(MI).getRegSlot();
|
|
if (InstSlot >= PriorUseIdx && InstSlot < NextUseIdx)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// Record the downward impact of a single instruction on current register
|
|
/// pressure. Unlike the advance/recede pressure tracking interface, this does
|
|
/// not discover live in/outs.
|
|
///
|
|
/// This is intended for speculative queries. It leaves pressure inconsistent
|
|
/// with the current position, so must be restored by the caller.
|
|
void RegPressureTracker::bumpDownwardPressure(const MachineInstr *MI) {
|
|
assert(!MI->isDebugValue() && "Expect a nondebug instruction.");
|
|
|
|
// Account for register pressure similar to RegPressureTracker::recede().
|
|
RegisterOperands RegOpers(TRI, MRI);
|
|
collectOperands(MI, RegOpers);
|
|
|
|
// Kill liveness at last uses. Assume allocatable physregs are single-use
|
|
// rather than checking LiveIntervals.
|
|
SlotIndex SlotIdx;
|
|
if (RequireIntervals)
|
|
SlotIdx = LIS->getInstructionIndex(MI).getRegSlot();
|
|
|
|
for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = RegOpers.Uses[i];
|
|
if (RequireIntervals) {
|
|
// FIXME: allow the caller to pass in the list of vreg uses that remain
|
|
// to be bottom-scheduled to avoid searching uses at each query.
|
|
SlotIndex CurrIdx = getCurrSlot();
|
|
const LiveRange *LR = getLiveRange(Reg);
|
|
if (LR) {
|
|
LiveQueryResult LRQ = LR->Query(SlotIdx);
|
|
if (LRQ.isKill() && !findUseBetween(Reg, CurrIdx, SlotIdx, MRI, LIS)) {
|
|
decreaseRegPressure(Reg);
|
|
}
|
|
}
|
|
}
|
|
else if (!TargetRegisterInfo::isVirtualRegister(Reg)) {
|
|
// Allocatable physregs are always single-use before register rewriting.
|
|
decreaseRegPressure(Reg);
|
|
}
|
|
}
|
|
|
|
// Generate liveness for defs.
|
|
increaseRegPressure(RegOpers.Defs);
|
|
|
|
// Boost pressure for all dead defs together.
|
|
increaseRegPressure(RegOpers.DeadDefs);
|
|
decreaseRegPressure(RegOpers.DeadDefs);
|
|
}
|
|
|
|
/// Consider the pressure increase caused by traversing this instruction
|
|
/// top-down. Find the register class with the most change in its pressure limit
|
|
/// based on the tracker's current pressure, and return the number of excess
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/// register units of that pressure set introduced by this instruction.
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///
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/// This assumes that the current LiveIn set is sufficient.
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void RegPressureTracker::
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getMaxDownwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta,
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ArrayRef<PressureChange> CriticalPSets,
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ArrayRef<unsigned> MaxPressureLimit) {
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// Snapshot Pressure.
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std::vector<unsigned> SavedPressure = CurrSetPressure;
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std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
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bumpDownwardPressure(MI);
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|
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computeExcessPressureDelta(SavedPressure, CurrSetPressure, Delta, RCI,
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|
LiveThruPressure);
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computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets,
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|
MaxPressureLimit, Delta);
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assert(Delta.CriticalMax.getUnitInc() >= 0 &&
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Delta.CurrentMax.getUnitInc() >= 0 && "cannot decrease max pressure");
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|
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// Restore the tracker's state.
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P.MaxSetPressure.swap(SavedMaxPressure);
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CurrSetPressure.swap(SavedPressure);
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|
}
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|
|
|
/// Get the pressure of each PSet after traversing this instruction bottom-up.
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|
void RegPressureTracker::
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|
getUpwardPressure(const MachineInstr *MI,
|
|
std::vector<unsigned> &PressureResult,
|
|
std::vector<unsigned> &MaxPressureResult) {
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|
// Snapshot pressure.
|
|
PressureResult = CurrSetPressure;
|
|
MaxPressureResult = P.MaxSetPressure;
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|
|
|
bumpUpwardPressure(MI);
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|
|
|
// Current pressure becomes the result. Restore current pressure.
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|
P.MaxSetPressure.swap(MaxPressureResult);
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CurrSetPressure.swap(PressureResult);
|
|
}
|
|
|
|
/// Get the pressure of each PSet after traversing this instruction top-down.
|
|
void RegPressureTracker::
|
|
getDownwardPressure(const MachineInstr *MI,
|
|
std::vector<unsigned> &PressureResult,
|
|
std::vector<unsigned> &MaxPressureResult) {
|
|
// Snapshot pressure.
|
|
PressureResult = CurrSetPressure;
|
|
MaxPressureResult = P.MaxSetPressure;
|
|
|
|
bumpDownwardPressure(MI);
|
|
|
|
// Current pressure becomes the result. Restore current pressure.
|
|
P.MaxSetPressure.swap(MaxPressureResult);
|
|
CurrSetPressure.swap(PressureResult);
|
|
}
|