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https://github.com/c64scene-ar/llvm-6502.git
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77e300e8f0
No functional change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163339 91177308-0d34-0410-b5e6-96231b3b80d8
844 lines
30 KiB
C++
844 lines
30 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/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/CodeGen/RegisterPressure.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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/// Increase register pressure for each set impacted by this register class.
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static void increaseSetPressure(std::vector<unsigned> &CurrSetPressure,
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std::vector<unsigned> &MaxSetPressure,
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const TargetRegisterClass *RC,
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const TargetRegisterInfo *TRI) {
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unsigned Weight = TRI->getRegClassWeight(RC).RegWeight;
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for (const int *PSet = TRI->getRegClassPressureSets(RC);
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*PSet != -1; ++PSet) {
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CurrSetPressure[*PSet] += Weight;
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if (&CurrSetPressure != &MaxSetPressure
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&& CurrSetPressure[*PSet] > MaxSetPressure[*PSet]) {
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MaxSetPressure[*PSet] = CurrSetPressure[*PSet];
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}
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}
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}
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/// Decrease register pressure for each set impacted by this register class.
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static void decreaseSetPressure(std::vector<unsigned> &CurrSetPressure,
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const TargetRegisterClass *RC,
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const TargetRegisterInfo *TRI) {
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unsigned Weight = TRI->getRegClassWeight(RC).RegWeight;
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for (const int *PSet = TRI->getRegClassPressureSets(RC);
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*PSet != -1; ++PSet) {
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assert(CurrSetPressure[*PSet] >= Weight && "register pressure underflow");
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CurrSetPressure[*PSet] -= Weight;
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}
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}
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/// Directly increase pressure only within this RegisterPressure result.
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void RegisterPressure::increase(const TargetRegisterClass *RC,
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const TargetRegisterInfo *TRI) {
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increaseSetPressure(MaxSetPressure, MaxSetPressure, RC, TRI);
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}
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/// Directly decrease pressure only within this RegisterPressure result.
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void RegisterPressure::decrease(const TargetRegisterClass *RC,
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const TargetRegisterInfo *TRI) {
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decreaseSetPressure(MaxSetPressure, RC, TRI);
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}
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#ifndef NDEBUG
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void RegisterPressure::dump(const TargetRegisterInfo *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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for (unsigned i = 0, e = MaxSetPressure.size(); i < e; ++i) {
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if (MaxSetPressure[i] != 0)
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dbgs() << TRI->getRegPressureSetName(i) << "=" << MaxSetPressure[i]
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<< '\n';
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}
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}
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#endif
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/// Increase the current pressure as impacted by these physical registers and
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/// bump the high water mark if needed.
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void RegPressureTracker::increasePhysRegPressure(ArrayRef<unsigned> Regs) {
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for (unsigned I = 0, E = Regs.size(); I != E; ++I)
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increaseSetPressure(CurrSetPressure, P.MaxSetPressure,
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TRI->getMinimalPhysRegClass(Regs[I]), TRI);
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}
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/// Simply decrease the current pressure as impacted by these physcial
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/// registers.
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void RegPressureTracker::decreasePhysRegPressure(ArrayRef<unsigned> Regs) {
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for (unsigned I = 0, E = Regs.size(); I != E; ++I)
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decreaseSetPressure(CurrSetPressure, TRI->getMinimalPhysRegClass(Regs[I]),
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TRI);
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}
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/// Increase the current pressure as impacted by these virtual registers and
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/// bump the high water mark if needed.
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void RegPressureTracker::increaseVirtRegPressure(ArrayRef<unsigned> Regs) {
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for (unsigned I = 0, E = Regs.size(); I != E; ++I)
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increaseSetPressure(CurrSetPressure, P.MaxSetPressure,
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MRI->getRegClass(Regs[I]), TRI);
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}
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/// Simply decrease the current pressure as impacted by these virtual registers.
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void RegPressureTracker::decreaseVirtRegPressure(ArrayRef<unsigned> Regs) {
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for (unsigned I = 0, E = Regs.size(); I != E; ++I)
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decreaseSetPressure(CurrSetPressure, MRI->getRegClass(Regs[I]), TRI);
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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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/// 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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{
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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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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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while (CurrPos != MBB->end() && CurrPos->isDebugValue())
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++CurrPos;
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CurrSetPressure.assign(TRI->getNumRegPressureSets(), 0);
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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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P.MaxSetPressure = CurrSetPressure;
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LivePhysRegs.clear();
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LivePhysRegs.setUniverse(TRI->getNumRegs());
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LiveVirtRegs.clear();
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LiveVirtRegs.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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/// 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 =
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LIS->getInstructionIndex(CurrPos).getRegSlot();
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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(LivePhysRegs.size() + LiveVirtRegs.size());
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P.LiveInRegs.append(LivePhysRegs.begin(), LivePhysRegs.end());
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for (SparseSet<unsigned>::const_iterator I =
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LiveVirtRegs.begin(), E = LiveVirtRegs.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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if (CurrPos == MBB->end())
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static_cast<IntervalPressure&>(P).BottomIdx = LIS->getMBBEndIdx(MBB);
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else
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static_cast<IntervalPressure&>(P).BottomIdx =
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LIS->getInstructionIndex(CurrPos).getRegSlot();
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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(LivePhysRegs.size() + LiveVirtRegs.size());
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P.LiveOutRegs.append(LivePhysRegs.begin(), LivePhysRegs.end());
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for (SparseSet<unsigned>::const_iterator I =
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LiveVirtRegs.begin(), E = LiveVirtRegs.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(LivePhysRegs.empty() && LiveVirtRegs.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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/// Return true if Reg aliases a register in Regs SparseSet.
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static bool hasRegAlias(unsigned Reg, SparseSet<unsigned> &Regs,
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const TargetRegisterInfo *TRI) {
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assert(!TargetRegisterInfo::isVirtualRegister(Reg) && "only for physregs");
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for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
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if (Regs.count(*AI))
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return true;
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return false;
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}
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/// Return true if Reg aliases a register in unsorted Regs SmallVector.
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/// This is only valid for physical registers.
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static SmallVectorImpl<unsigned>::iterator
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findRegAlias(unsigned Reg, SmallVectorImpl<unsigned> &Regs,
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const TargetRegisterInfo *TRI) {
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for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
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SmallVectorImpl<unsigned>::iterator I =
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std::find(Regs.begin(), Regs.end(), *AI);
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if (I != Regs.end())
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return I;
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}
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return Regs.end();
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}
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/// Return true if Reg can be inserted into Regs SmallVector. For virtual
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/// register, do a linear search. For physical registers check for aliases.
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static SmallVectorImpl<unsigned>::iterator
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findReg(unsigned Reg, bool isVReg, SmallVectorImpl<unsigned> &Regs,
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const TargetRegisterInfo *TRI) {
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if(isVReg)
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return std::find(Regs.begin(), Regs.end(), Reg);
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return findRegAlias(Reg, Regs, TRI);
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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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template<bool isVReg>
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struct RegisterOperands {
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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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/// Push this operand's register onto the correct vector.
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void collect(const MachineOperand &MO, const TargetRegisterInfo *TRI) {
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if (MO.readsReg()) {
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if (findReg(MO.getReg(), isVReg, Uses, TRI) == Uses.end())
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Uses.push_back(MO.getReg());
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}
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if (MO.isDef()) {
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if (MO.isDead()) {
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if (findReg(MO.getReg(), isVReg, DeadDefs, TRI) == DeadDefs.end())
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DeadDefs.push_back(MO.getReg());
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}
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else {
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if (findReg(MO.getReg(), isVReg, Defs, TRI) == Defs.end())
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Defs.push_back(MO.getReg());
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}
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}
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}
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};
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typedef RegisterOperands<false> PhysRegOperands;
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typedef RegisterOperands<true> VirtRegOperands;
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/// Collect physical and virtual register operands.
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static void collectOperands(const MachineInstr *MI,
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PhysRegOperands &PhysRegOpers,
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VirtRegOperands &VirtRegOpers,
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const TargetRegisterInfo *TRI,
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const RegisterClassInfo *RCI) {
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for(ConstMIBundleOperands OperI(MI); OperI.isValid(); ++OperI) {
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const MachineOperand &MO = *OperI;
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if (!MO.isReg() || !MO.getReg())
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continue;
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if (TargetRegisterInfo::isVirtualRegister(MO.getReg()))
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VirtRegOpers.collect(MO, TRI);
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else if (RCI->isAllocatable(MO.getReg()))
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PhysRegOpers.collect(MO, TRI);
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}
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// Remove redundant physreg dead defs.
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for (unsigned i = PhysRegOpers.DeadDefs.size(); i > 0; --i) {
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unsigned Reg = PhysRegOpers.DeadDefs[i-1];
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if (findRegAlias(Reg, PhysRegOpers.Defs, TRI) != PhysRegOpers.Defs.end())
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PhysRegOpers.DeadDefs.erase(&PhysRegOpers.DeadDefs[i-1]);
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}
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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 (TargetRegisterInfo::isVirtualRegister(Regs[i])) {
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if (LiveVirtRegs.insert(Regs[i]).second)
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increaseVirtRegPressure(Regs[i]);
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}
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else {
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if (!hasRegAlias(Regs[i], LivePhysRegs, TRI)) {
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LivePhysRegs.insert(Regs[i]);
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increasePhysRegPressure(Regs[i]);
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}
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}
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}
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}
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/// Add PhysReg to the live in set and increase max pressure.
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void RegPressureTracker::discoverPhysLiveIn(unsigned Reg) {
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assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
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if (findRegAlias(Reg, P.LiveInRegs, TRI) != P.LiveInRegs.end())
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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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P.increase(TRI->getMinimalPhysRegClass(Reg), TRI);
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}
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/// Add PhysReg to the live out set and increase max pressure.
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void RegPressureTracker::discoverPhysLiveOut(unsigned Reg) {
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assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
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if (findRegAlias(Reg, P.LiveOutRegs, TRI) != P.LiveOutRegs.end())
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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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P.increase(TRI->getMinimalPhysRegClass(Reg), TRI);
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}
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/// Add VirtReg to the live in set and increase max pressure.
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void RegPressureTracker::discoverVirtLiveIn(unsigned Reg) {
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assert(!LiveVirtRegs.count(Reg) && "avoid bumping max pressure twice");
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if (std::find(P.LiveInRegs.begin(), P.LiveInRegs.end(), Reg) !=
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P.LiveInRegs.end())
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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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P.increase(MRI->getRegClass(Reg), TRI);
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}
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/// Add VirtReg to the live out set and increase max pressure.
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void RegPressureTracker::discoverVirtLiveOut(unsigned Reg) {
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assert(!LiveVirtRegs.count(Reg) && "avoid bumping max pressure twice");
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if (std::find(P.LiveOutRegs.begin(), P.LiveOutRegs.end(), Reg) !=
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P.LiveOutRegs.end())
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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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P.increase(MRI->getRegClass(Reg), TRI);
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}
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/// Recede across the previous instruction.
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bool RegPressureTracker::recede() {
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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.
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if (!RequireIntervals && isTopClosed())
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static_cast<RegionPressure&>(P).openTop(CurrPos);
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// Find the previous instruction.
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do
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--CurrPos;
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while (CurrPos != MBB->begin() && CurrPos->isDebugValue());
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if (CurrPos->isDebugValue()) {
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closeRegion();
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return false;
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}
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SlotIndex SlotIdx;
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if (RequireIntervals)
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SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
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// Open the top of the region using slot indexes.
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if (RequireIntervals && isTopClosed())
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static_cast<IntervalPressure&>(P).openTop(SlotIdx);
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PhysRegOperands PhysRegOpers;
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VirtRegOperands VirtRegOpers;
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collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
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// Boost pressure for all dead defs together.
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increasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
increaseVirtRegPressure(VirtRegOpers.DeadDefs);
|
|
decreasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
|
|
|
|
// Kill liveness at live defs.
|
|
// TODO: consider earlyclobbers?
|
|
for (unsigned i = 0, e = PhysRegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = PhysRegOpers.Defs[i];
|
|
if (LivePhysRegs.erase(Reg))
|
|
decreasePhysRegPressure(Reg);
|
|
else
|
|
discoverPhysLiveOut(Reg);
|
|
}
|
|
for (unsigned i = 0, e = VirtRegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = VirtRegOpers.Defs[i];
|
|
if (LiveVirtRegs.erase(Reg))
|
|
decreaseVirtRegPressure(Reg);
|
|
else
|
|
discoverVirtLiveOut(Reg);
|
|
}
|
|
|
|
// Generate liveness for uses.
|
|
for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = PhysRegOpers.Uses[i];
|
|
if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
|
|
increasePhysRegPressure(Reg);
|
|
LivePhysRegs.insert(Reg);
|
|
}
|
|
}
|
|
for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = VirtRegOpers.Uses[i];
|
|
if (!LiveVirtRegs.count(Reg)) {
|
|
// Adjust liveouts if LiveIntervals are available.
|
|
if (RequireIntervals) {
|
|
const LiveInterval *LI = &LIS->getInterval(Reg);
|
|
if (!LI->killedAt(SlotIdx))
|
|
discoverVirtLiveOut(Reg);
|
|
}
|
|
increaseVirtRegPressure(Reg);
|
|
LiveVirtRegs.insert(Reg);
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// Advance across the current instruction.
|
|
bool RegPressureTracker::advance() {
|
|
// Check for the bottom of the analyzable region.
|
|
if (CurrPos == MBB->end()) {
|
|
closeRegion();
|
|
return false;
|
|
}
|
|
if (!isTopClosed())
|
|
closeTop();
|
|
|
|
SlotIndex SlotIdx;
|
|
if (RequireIntervals)
|
|
SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
|
|
|
|
// 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);
|
|
}
|
|
|
|
PhysRegOperands PhysRegOpers;
|
|
VirtRegOperands VirtRegOpers;
|
|
collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
|
|
|
|
// Kill liveness at last uses.
|
|
for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = PhysRegOpers.Uses[i];
|
|
if (!hasRegAlias(Reg, LivePhysRegs, TRI))
|
|
discoverPhysLiveIn(Reg);
|
|
else {
|
|
// Allocatable physregs are always single-use before regalloc.
|
|
decreasePhysRegPressure(Reg);
|
|
LivePhysRegs.erase(Reg);
|
|
}
|
|
}
|
|
for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = VirtRegOpers.Uses[i];
|
|
if (RequireIntervals) {
|
|
const LiveInterval *LI = &LIS->getInterval(Reg);
|
|
if (LI->killedAt(SlotIdx)) {
|
|
if (LiveVirtRegs.erase(Reg))
|
|
decreaseVirtRegPressure(Reg);
|
|
else
|
|
discoverVirtLiveIn(Reg);
|
|
}
|
|
}
|
|
else if (!LiveVirtRegs.count(Reg)) {
|
|
discoverVirtLiveIn(Reg);
|
|
increaseVirtRegPressure(Reg);
|
|
}
|
|
}
|
|
|
|
// Generate liveness for defs.
|
|
for (unsigned i = 0, e = PhysRegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = PhysRegOpers.Defs[i];
|
|
if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
|
|
increasePhysRegPressure(Reg);
|
|
LivePhysRegs.insert(Reg);
|
|
}
|
|
}
|
|
for (unsigned i = 0, e = VirtRegOpers.Defs.size(); i < e; ++i) {
|
|
unsigned Reg = VirtRegOpers.Defs[i];
|
|
if (LiveVirtRegs.insert(Reg).second)
|
|
increaseVirtRegPressure(Reg);
|
|
}
|
|
|
|
// Boost pressure for all dead defs together.
|
|
increasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
increaseVirtRegPressure(VirtRegOpers.DeadDefs);
|
|
decreasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
decreaseVirtRegPressure(VirtRegOpers.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 TargetRegisterInfo *TRI) {
|
|
int ExcessUnits = 0;
|
|
unsigned PSetID = ~0U;
|
|
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 = TRI->getRegPressureSetLimit(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 (std::abs(PDiff) > std::abs(ExcessUnits)) {
|
|
ExcessUnits = PDiff;
|
|
PSetID = i;
|
|
}
|
|
}
|
|
Delta.Excess.PSetID = PSetID;
|
|
Delta.Excess.UnitIncrease = ExcessUnits;
|
|
}
|
|
|
|
/// 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<PressureElement> CriticalPSets,
|
|
ArrayRef<unsigned> MaxPressureLimit,
|
|
RegPressureDelta &Delta) {
|
|
Delta.CriticalMax = PressureElement();
|
|
Delta.CurrentMax = PressureElement();
|
|
|
|
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;
|
|
|
|
while (CritIdx != CritEnd && CriticalPSets[CritIdx].PSetID < i)
|
|
++CritIdx;
|
|
|
|
if (CritIdx != CritEnd && CriticalPSets[CritIdx].PSetID == i) {
|
|
int PDiff = (int)PNew - (int)CriticalPSets[CritIdx].UnitIncrease;
|
|
if (PDiff > Delta.CriticalMax.UnitIncrease) {
|
|
Delta.CriticalMax.PSetID = i;
|
|
Delta.CriticalMax.UnitIncrease = PDiff;
|
|
}
|
|
}
|
|
|
|
// Find the greatest increase above MaxPressureLimit.
|
|
// (Ignores negative MDiff).
|
|
int MDiff = (int)PNew - (int)MaxPressureLimit[i];
|
|
if (MDiff > Delta.CurrentMax.UnitIncrease) {
|
|
Delta.CurrentMax.PSetID = i;
|
|
Delta.CurrentMax.UnitIncrease = PNew;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// 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) {
|
|
// Account for register pressure similar to RegPressureTracker::recede().
|
|
PhysRegOperands PhysRegOpers;
|
|
VirtRegOperands VirtRegOpers;
|
|
collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, RCI);
|
|
|
|
// Boost max pressure for all dead defs together.
|
|
// Since CurrSetPressure and MaxSetPressure
|
|
increasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
increaseVirtRegPressure(VirtRegOpers.DeadDefs);
|
|
decreasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
|
|
|
|
// Kill liveness at live defs.
|
|
decreasePhysRegPressure(PhysRegOpers.Defs);
|
|
decreaseVirtRegPressure(VirtRegOpers.Defs);
|
|
|
|
// Generate liveness for uses.
|
|
for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = PhysRegOpers.Uses[i];
|
|
if (!hasRegAlias(Reg, LivePhysRegs, TRI))
|
|
increasePhysRegPressure(Reg);
|
|
}
|
|
for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = VirtRegOpers.Uses[i];
|
|
if (!LiveVirtRegs.count(Reg))
|
|
increaseVirtRegPressure(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, RegPressureDelta &Delta,
|
|
ArrayRef<PressureElement> 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, TRI);
|
|
computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets,
|
|
MaxPressureLimit, Delta);
|
|
assert(Delta.CriticalMax.UnitIncrease >= 0 &&
|
|
Delta.CurrentMax.UnitIncrease >= 0 && "cannot decrease max pressure");
|
|
|
|
// Restore the tracker's state.
|
|
P.MaxSetPressure.swap(SavedMaxPressure);
|
|
CurrSetPressure.swap(SavedPressure);
|
|
}
|
|
|
|
/// 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;
|
|
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) {
|
|
// Account for register pressure similar to RegPressureTracker::recede().
|
|
PhysRegOperands PhysRegOpers;
|
|
VirtRegOperands VirtRegOpers;
|
|
collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, RCI);
|
|
|
|
// Kill liveness at last uses. Assume allocatable physregs are single-use
|
|
// rather than checking LiveIntervals.
|
|
decreasePhysRegPressure(PhysRegOpers.Uses);
|
|
if (RequireIntervals) {
|
|
SlotIndex SlotIdx = LIS->getInstructionIndex(MI).getRegSlot();
|
|
for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
|
|
unsigned Reg = VirtRegOpers.Uses[i];
|
|
const LiveInterval *LI = &LIS->getInterval(Reg);
|
|
// 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 = LIS->getInstructionIndex(CurrPos).getRegSlot();
|
|
if (LI->killedAt(SlotIdx)
|
|
&& !findUseBetween(Reg, CurrIdx, SlotIdx, MRI, LIS)) {
|
|
decreaseVirtRegPressure(Reg);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Generate liveness for defs.
|
|
increasePhysRegPressure(PhysRegOpers.Defs);
|
|
increaseVirtRegPressure(VirtRegOpers.Defs);
|
|
|
|
// Boost pressure for all dead defs together.
|
|
increasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
increaseVirtRegPressure(VirtRegOpers.DeadDefs);
|
|
decreasePhysRegPressure(PhysRegOpers.DeadDefs);
|
|
decreaseVirtRegPressure(VirtRegOpers.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
|
|
/// register units of that pressure set introduced by this instruction.
|
|
///
|
|
/// This assumes that the current LiveIn set is sufficient.
|
|
void RegPressureTracker::
|
|
getMaxDownwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta,
|
|
ArrayRef<PressureElement> CriticalPSets,
|
|
ArrayRef<unsigned> MaxPressureLimit) {
|
|
// Snapshot Pressure.
|
|
std::vector<unsigned> SavedPressure = CurrSetPressure;
|
|
std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
|
|
|
|
bumpDownwardPressure(MI);
|
|
|
|
computeExcessPressureDelta(SavedPressure, CurrSetPressure, Delta, TRI);
|
|
computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets,
|
|
MaxPressureLimit, Delta);
|
|
assert(Delta.CriticalMax.UnitIncrease >= 0 &&
|
|
Delta.CurrentMax.UnitIncrease >= 0 && "cannot decrease max pressure");
|
|
|
|
// Restore the tracker's state.
|
|
P.MaxSetPressure.swap(SavedMaxPressure);
|
|
CurrSetPressure.swap(SavedPressure);
|
|
}
|
|
|
|
/// Get the pressure of each PSet after traversing this instruction bottom-up.
|
|
void RegPressureTracker::
|
|
getUpwardPressure(const MachineInstr *MI,
|
|
std::vector<unsigned> &PressureResult,
|
|
std::vector<unsigned> &MaxPressureResult) {
|
|
// Snapshot pressure.
|
|
PressureResult = CurrSetPressure;
|
|
MaxPressureResult = P.MaxSetPressure;
|
|
|
|
bumpUpwardPressure(MI);
|
|
|
|
// Current pressure becomes the result. Restore current pressure.
|
|
P.MaxSetPressure.swap(MaxPressureResult);
|
|
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);
|
|
}
|