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llvm-mirror/lib/CodeGen/LiveIntervalAnalysis.cpp
Matthias Braun 036b32dcef LiveIntervalAnalysis: Improve some comments 
As recommended by Justin.

llvm-svn: 258771
2016-01-26 01:40:48 +00:00

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//===-- LiveIntervalAnalysis.cpp - Live Interval Analysis -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the LiveInterval analysis pass which is used
// by the Linear Scan Register allocator. This pass linearizes the
// basic blocks of the function in DFS order and uses the
// LiveVariables pass to conservatively compute live intervals for
// each virtual and physical register.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "LiveRangeCalc.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/BlockFrequency.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <algorithm>
#include <cmath>
#include <limits>
using namespace llvm;
#define DEBUG_TYPE "regalloc"
char LiveIntervals::ID = 0;
char &llvm::LiveIntervalsID = LiveIntervals::ID;
INITIALIZE_PASS_BEGIN(LiveIntervals, "liveintervals",
"Live Interval Analysis", false, false)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LiveVariables)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
INITIALIZE_PASS_END(LiveIntervals, "liveintervals",
"Live Interval Analysis", false, false)
#ifndef NDEBUG
static cl::opt<bool> EnablePrecomputePhysRegs(
"precompute-phys-liveness", cl::Hidden,
cl::desc("Eagerly compute live intervals for all physreg units."));
#else
static bool EnablePrecomputePhysRegs = false;
#endif // NDEBUG
static cl::opt<bool> EnableSubRegLiveness(
"enable-subreg-liveness", cl::Hidden, cl::init(true),
cl::desc("Enable subregister liveness tracking."));
namespace llvm {
cl::opt<bool> UseSegmentSetForPhysRegs(
"use-segment-set-for-physregs", cl::Hidden, cl::init(true),
cl::desc(
"Use segment set for the computation of the live ranges of physregs."));
}
void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<AAResultsWrapperPass>();
AU.addPreserved<AAResultsWrapperPass>();
// LiveVariables isn't really required by this analysis, it is only required
// here to make sure it is live during TwoAddressInstructionPass and
// PHIElimination. This is temporary.
AU.addRequired<LiveVariables>();
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addRequiredTransitiveID(MachineDominatorsID);
AU.addPreservedID(MachineDominatorsID);
AU.addPreserved<SlotIndexes>();
AU.addRequiredTransitive<SlotIndexes>();
MachineFunctionPass::getAnalysisUsage(AU);
}
LiveIntervals::LiveIntervals() : MachineFunctionPass(ID),
DomTree(nullptr), LRCalc(nullptr) {
initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
}
LiveIntervals::~LiveIntervals() {
delete LRCalc;
}
void LiveIntervals::releaseMemory() {
// Free the live intervals themselves.
for (unsigned i = 0, e = VirtRegIntervals.size(); i != e; ++i)
delete VirtRegIntervals[TargetRegisterInfo::index2VirtReg(i)];
VirtRegIntervals.clear();
RegMaskSlots.clear();
RegMaskBits.clear();
RegMaskBlocks.clear();
for (unsigned i = 0, e = RegUnitRanges.size(); i != e; ++i)
delete RegUnitRanges[i];
RegUnitRanges.clear();
// Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
VNInfoAllocator.Reset();
}
/// runOnMachineFunction - calculates LiveIntervals
///
bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
MF = &fn;
MRI = &MF->getRegInfo();
TRI = MF->getSubtarget().getRegisterInfo();
TII = MF->getSubtarget().getInstrInfo();
AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
Indexes = &getAnalysis<SlotIndexes>();
DomTree = &getAnalysis<MachineDominatorTree>();
if (EnableSubRegLiveness && MF->getSubtarget().enableSubRegLiveness())
MRI->enableSubRegLiveness(true);
if (!LRCalc)
LRCalc = new LiveRangeCalc();
// Allocate space for all virtual registers.
VirtRegIntervals.resize(MRI->getNumVirtRegs());
computeVirtRegs();
computeRegMasks();
computeLiveInRegUnits();
if (EnablePrecomputePhysRegs) {
// For stress testing, precompute live ranges of all physical register
// units, including reserved registers.
for (unsigned i = 0, e = TRI->getNumRegUnits(); i != e; ++i)
getRegUnit(i);
}
DEBUG(dump());
return true;
}
/// print - Implement the dump method.
void LiveIntervals::print(raw_ostream &OS, const Module* ) const {
OS << "********** INTERVALS **********\n";
// Dump the regunits.
for (unsigned i = 0, e = RegUnitRanges.size(); i != e; ++i)
if (LiveRange *LR = RegUnitRanges[i])
OS << PrintRegUnit(i, TRI) << ' ' << *LR << '\n';
// Dump the virtregs.
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
if (hasInterval(Reg))
OS << getInterval(Reg) << '\n';
}
OS << "RegMasks:";
for (unsigned i = 0, e = RegMaskSlots.size(); i != e; ++i)
OS << ' ' << RegMaskSlots[i];
OS << '\n';
printInstrs(OS);
}
void LiveIntervals::printInstrs(raw_ostream &OS) const {
OS << "********** MACHINEINSTRS **********\n";
MF->print(OS, Indexes);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void LiveIntervals::dumpInstrs() const {
printInstrs(dbgs());
}
#endif
LiveInterval* LiveIntervals::createInterval(unsigned reg) {
float Weight = TargetRegisterInfo::isPhysicalRegister(reg) ?
llvm::huge_valf : 0.0F;
return new LiveInterval(reg, Weight);
}
/// computeVirtRegInterval - Compute the live interval of a virtual register,
/// based on defs and uses.
void LiveIntervals::computeVirtRegInterval(LiveInterval &LI) {
assert(LRCalc && "LRCalc not initialized.");
assert(LI.empty() && "Should only compute empty intervals.");
bool ShouldTrackSubRegLiveness = MRI->shouldTrackSubRegLiveness(LI.reg);
LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
LRCalc->calculate(LI, ShouldTrackSubRegLiveness);
bool SeparatedComponents = computeDeadValues(LI, nullptr);
if (SeparatedComponents) {
assert(ShouldTrackSubRegLiveness
&& "Separated components should only occur for unused subreg defs");
SmallVector<LiveInterval*, 8> SplitLIs;
splitSeparateComponents(LI, SplitLIs);
}
}
void LiveIntervals::computeVirtRegs() {
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
if (MRI->reg_nodbg_empty(Reg))
continue;
createAndComputeVirtRegInterval(Reg);
}
}
void LiveIntervals::computeRegMasks() {
RegMaskBlocks.resize(MF->getNumBlockIDs());
// Find all instructions with regmask operands.
for (MachineBasicBlock &MBB : *MF) {
std::pair<unsigned, unsigned> &RMB = RegMaskBlocks[MBB.getNumber()];
RMB.first = RegMaskSlots.size();
// Some block starts, such as EH funclets, create masks.
if (const uint32_t *Mask = MBB.getBeginClobberMask(TRI)) {
RegMaskSlots.push_back(Indexes->getMBBStartIdx(&MBB));
RegMaskBits.push_back(Mask);
}
for (MachineInstr &MI : MBB) {
for (const MachineOperand &MO : MI.operands()) {
if (!MO.isRegMask())
continue;
RegMaskSlots.push_back(Indexes->getInstructionIndex(&MI).getRegSlot());
RegMaskBits.push_back(MO.getRegMask());
}
}
// Some block ends, such as funclet returns, create masks.
if (const uint32_t *Mask = MBB.getEndClobberMask(TRI)) {
RegMaskSlots.push_back(Indexes->getMBBEndIdx(&MBB));
RegMaskBits.push_back(Mask);
}
// Compute the number of register mask instructions in this block.
RMB.second = RegMaskSlots.size() - RMB.first;
}
}
//===----------------------------------------------------------------------===//
// Register Unit Liveness
//===----------------------------------------------------------------------===//
//
// Fixed interference typically comes from ABI boundaries: Function arguments
// and return values are passed in fixed registers, and so are exception
// pointers entering landing pads. Certain instructions require values to be
// present in specific registers. That is also represented through fixed
// interference.
//
/// computeRegUnitInterval - Compute the live range of a register unit, based
/// on the uses and defs of aliasing registers. The range should be empty,
/// or contain only dead phi-defs from ABI blocks.
void LiveIntervals::computeRegUnitRange(LiveRange &LR, unsigned Unit) {
assert(LRCalc && "LRCalc not initialized.");
LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
// The physregs aliasing Unit are the roots and their super-registers.
// Create all values as dead defs before extending to uses. Note that roots
// may share super-registers. That's OK because createDeadDefs() is
// idempotent. It is very rare for a register unit to have multiple roots, so
// uniquing super-registers is probably not worthwhile.
for (MCRegUnitRootIterator Roots(Unit, TRI); Roots.isValid(); ++Roots) {
for (MCSuperRegIterator Supers(*Roots, TRI, /*IncludeSelf=*/true);
Supers.isValid(); ++Supers) {
if (!MRI->reg_empty(*Supers))
LRCalc->createDeadDefs(LR, *Supers);
}
}
// Now extend LR to reach all uses.
// Ignore uses of reserved registers. We only track defs of those.
for (MCRegUnitRootIterator Roots(Unit, TRI); Roots.isValid(); ++Roots) {
for (MCSuperRegIterator Supers(*Roots, TRI, /*IncludeSelf=*/true);
Supers.isValid(); ++Supers) {
unsigned Reg = *Supers;
if (!MRI->isReserved(Reg) && !MRI->reg_empty(Reg))
LRCalc->extendToUses(LR, Reg);
}
}
// Flush the segment set to the segment vector.
if (UseSegmentSetForPhysRegs)
LR.flushSegmentSet();
}
/// computeLiveInRegUnits - Precompute the live ranges of any register units
/// that are live-in to an ABI block somewhere. Register values can appear
/// without a corresponding def when entering the entry block or a landing pad.
///
void LiveIntervals::computeLiveInRegUnits() {
RegUnitRanges.resize(TRI->getNumRegUnits());
DEBUG(dbgs() << "Computing live-in reg-units in ABI blocks.\n");
// Keep track of the live range sets allocated.
SmallVector<unsigned, 8> NewRanges;
// Check all basic blocks for live-ins.
for (MachineFunction::const_iterator MFI = MF->begin(), MFE = MF->end();
MFI != MFE; ++MFI) {
const MachineBasicBlock *MBB = &*MFI;
// We only care about ABI blocks: Entry + landing pads.
if ((MFI != MF->begin() && !MBB->isEHPad()) || MBB->livein_empty())
continue;
// Create phi-defs at Begin for all live-in registers.
SlotIndex Begin = Indexes->getMBBStartIdx(MBB);
DEBUG(dbgs() << Begin << "\tBB#" << MBB->getNumber());
for (const auto &LI : MBB->liveins()) {
for (MCRegUnitIterator Units(LI.PhysReg, TRI); Units.isValid(); ++Units) {
unsigned Unit = *Units;
LiveRange *LR = RegUnitRanges[Unit];
if (!LR) {
// Use segment set to speed-up initial computation of the live range.
LR = RegUnitRanges[Unit] = new LiveRange(UseSegmentSetForPhysRegs);
NewRanges.push_back(Unit);
}
VNInfo *VNI = LR->createDeadDef(Begin, getVNInfoAllocator());
(void)VNI;
DEBUG(dbgs() << ' ' << PrintRegUnit(Unit, TRI) << '#' << VNI->id);
}
}
DEBUG(dbgs() << '\n');
}
DEBUG(dbgs() << "Created " << NewRanges.size() << " new intervals.\n");
// Compute the 'normal' part of the ranges.
for (unsigned i = 0, e = NewRanges.size(); i != e; ++i) {
unsigned Unit = NewRanges[i];
computeRegUnitRange(*RegUnitRanges[Unit], Unit);
}
}
static void createSegmentsForValues(LiveRange &LR,
iterator_range<LiveInterval::vni_iterator> VNIs) {
for (auto VNI : VNIs) {
if (VNI->isUnused())
continue;
SlotIndex Def = VNI->def;
LR.addSegment(LiveRange::Segment(Def, Def.getDeadSlot(), VNI));
}
}
typedef SmallVector<std::pair<SlotIndex, VNInfo*>, 16> ShrinkToUsesWorkList;
static void extendSegmentsToUses(LiveRange &LR, const SlotIndexes &Indexes,
ShrinkToUsesWorkList &WorkList,
const LiveRange &OldRange) {
// Keep track of the PHIs that are in use.
SmallPtrSet<VNInfo*, 8> UsedPHIs;
// Blocks that have already been added to WorkList as live-out.
SmallPtrSet<MachineBasicBlock*, 16> LiveOut;
// Extend intervals to reach all uses in WorkList.
while (!WorkList.empty()) {
SlotIndex Idx = WorkList.back().first;
VNInfo *VNI = WorkList.back().second;
WorkList.pop_back();
const MachineBasicBlock *MBB = Indexes.getMBBFromIndex(Idx.getPrevSlot());
SlotIndex BlockStart = Indexes.getMBBStartIdx(MBB);
// Extend the live range for VNI to be live at Idx.
if (VNInfo *ExtVNI = LR.extendInBlock(BlockStart, Idx)) {
assert(ExtVNI == VNI && "Unexpected existing value number");
(void)ExtVNI;
// Is this a PHIDef we haven't seen before?
if (!VNI->isPHIDef() || VNI->def != BlockStart ||
!UsedPHIs.insert(VNI).second)
continue;
// The PHI is live, make sure the predecessors are live-out.
for (auto &Pred : MBB->predecessors()) {
if (!LiveOut.insert(Pred).second)
continue;
SlotIndex Stop = Indexes.getMBBEndIdx(Pred);
// A predecessor is not required to have a live-out value for a PHI.
if (VNInfo *PVNI = OldRange.getVNInfoBefore(Stop))
WorkList.push_back(std::make_pair(Stop, PVNI));
}
continue;
}
// VNI is live-in to MBB.
DEBUG(dbgs() << " live-in at " << BlockStart << '\n');
LR.addSegment(LiveRange::Segment(BlockStart, Idx, VNI));
// Make sure VNI is live-out from the predecessors.
for (auto &Pred : MBB->predecessors()) {
if (!LiveOut.insert(Pred).second)
continue;
SlotIndex Stop = Indexes.getMBBEndIdx(Pred);
assert(OldRange.getVNInfoBefore(Stop) == VNI &&
"Wrong value out of predecessor");
WorkList.push_back(std::make_pair(Stop, VNI));
}
}
}
bool LiveIntervals::shrinkToUses(LiveInterval *li,
SmallVectorImpl<MachineInstr*> *dead) {
DEBUG(dbgs() << "Shrink: " << *li << '\n');
assert(TargetRegisterInfo::isVirtualRegister(li->reg)
&& "Can only shrink virtual registers");
// Shrink subregister live ranges.
bool NeedsCleanup = false;
for (LiveInterval::SubRange &S : li->subranges()) {
shrinkToUses(S, li->reg);
if (S.empty())
NeedsCleanup = true;
}
if (NeedsCleanup)
li->removeEmptySubRanges();
// Find all the values used, including PHI kills.
ShrinkToUsesWorkList WorkList;
// Visit all instructions reading li->reg.
for (MachineRegisterInfo::reg_instr_iterator
I = MRI->reg_instr_begin(li->reg), E = MRI->reg_instr_end();
I != E; ) {
MachineInstr *UseMI = &*(I++);
if (UseMI->isDebugValue() || !UseMI->readsVirtualRegister(li->reg))
continue;
SlotIndex Idx = getInstructionIndex(UseMI).getRegSlot();
LiveQueryResult LRQ = li->Query(Idx);
VNInfo *VNI = LRQ.valueIn();
if (!VNI) {
// This shouldn't happen: readsVirtualRegister returns true, but there is
// no live value. It is likely caused by a target getting <undef> flags
// wrong.
DEBUG(dbgs() << Idx << '\t' << *UseMI
<< "Warning: Instr claims to read non-existent value in "
<< *li << '\n');
continue;
}
// Special case: An early-clobber tied operand reads and writes the
// register one slot early.
if (VNInfo *DefVNI = LRQ.valueDefined())
Idx = DefVNI->def;
WorkList.push_back(std::make_pair(Idx, VNI));
}
// Create new live ranges with only minimal live segments per def.
LiveRange NewLR;
createSegmentsForValues(NewLR, make_range(li->vni_begin(), li->vni_end()));
extendSegmentsToUses(NewLR, *Indexes, WorkList, *li);
// Move the trimmed segments back.
li->segments.swap(NewLR.segments);
// Handle dead values.
bool CanSeparate = computeDeadValues(*li, dead);
DEBUG(dbgs() << "Shrunk: " << *li << '\n');
return CanSeparate;
}
bool LiveIntervals::computeDeadValues(LiveInterval &LI,
SmallVectorImpl<MachineInstr*> *dead) {
bool MayHaveSplitComponents = false;
for (auto VNI : LI.valnos) {
if (VNI->isUnused())
continue;
SlotIndex Def = VNI->def;
LiveRange::iterator I = LI.FindSegmentContaining(Def);
assert(I != LI.end() && "Missing segment for VNI");
// Is the register live before? Otherwise we may have to add a read-undef
// flag for subregister defs.
bool DeadBeforeDef = false;
unsigned VReg = LI.reg;
if (MRI->shouldTrackSubRegLiveness(VReg)) {
if ((I == LI.begin() || std::prev(I)->end < Def) && !VNI->isPHIDef()) {
MachineInstr *MI = getInstructionFromIndex(Def);
MI->setRegisterDefReadUndef(VReg);
DeadBeforeDef = true;
}
}
if (I->end != Def.getDeadSlot())
continue;
if (VNI->isPHIDef()) {
// This is a dead PHI. Remove it.
VNI->markUnused();
LI.removeSegment(I);
DEBUG(dbgs() << "Dead PHI at " << Def << " may separate interval\n");
MayHaveSplitComponents = true;
} else {
// This is a dead def. Make sure the instruction knows.
MachineInstr *MI = getInstructionFromIndex(Def);
assert(MI && "No instruction defining live value");
MI->addRegisterDead(VReg, TRI);
// If we have a dead def that is completely separate from the rest of
// the liverange then we rewrite it to use a different VReg to not violate
// the rule that the liveness of a virtual register forms a connected
// component. This should only happen if subregister liveness is tracked.
if (DeadBeforeDef)
MayHaveSplitComponents = true;
if (dead && MI->allDefsAreDead()) {
DEBUG(dbgs() << "All defs dead: " << Def << '\t' << *MI);
dead->push_back(MI);
}
}
}
return MayHaveSplitComponents;
}
void LiveIntervals::shrinkToUses(LiveInterval::SubRange &SR, unsigned Reg)
{
DEBUG(dbgs() << "Shrink: " << SR << '\n');
assert(TargetRegisterInfo::isVirtualRegister(Reg)
&& "Can only shrink virtual registers");
// Find all the values used, including PHI kills.
ShrinkToUsesWorkList WorkList;
// Visit all instructions reading Reg.
SlotIndex LastIdx;
for (MachineOperand &MO : MRI->reg_operands(Reg)) {
MachineInstr *UseMI = MO.getParent();
if (UseMI->isDebugValue())
continue;
// Maybe the operand is for a subregister we don't care about.
unsigned SubReg = MO.getSubReg();
if (SubReg != 0) {
LaneBitmask LaneMask = TRI->getSubRegIndexLaneMask(SubReg);
if ((LaneMask & SR.LaneMask) == 0)
continue;
}
// We only need to visit each instruction once.
SlotIndex Idx = getInstructionIndex(UseMI).getRegSlot();
if (Idx == LastIdx)
continue;
LastIdx = Idx;
LiveQueryResult LRQ = SR.Query(Idx);
VNInfo *VNI = LRQ.valueIn();
// For Subranges it is possible that only undef values are left in that
// part of the subregister, so there is no real liverange at the use
if (!VNI)
continue;
// Special case: An early-clobber tied operand reads and writes the
// register one slot early.
if (VNInfo *DefVNI = LRQ.valueDefined())
Idx = DefVNI->def;
WorkList.push_back(std::make_pair(Idx, VNI));
}
// Create a new live ranges with only minimal live segments per def.
LiveRange NewLR;
createSegmentsForValues(NewLR, make_range(SR.vni_begin(), SR.vni_end()));
extendSegmentsToUses(NewLR, *Indexes, WorkList, SR);
// Move the trimmed ranges back.
SR.segments.swap(NewLR.segments);
// Remove dead PHI value numbers
for (auto VNI : SR.valnos) {
if (VNI->isUnused())
continue;
const LiveRange::Segment *Segment = SR.getSegmentContaining(VNI->def);
assert(Segment != nullptr && "Missing segment for VNI");
if (Segment->end != VNI->def.getDeadSlot())
continue;
if (VNI->isPHIDef()) {
// This is a dead PHI. Remove it.
VNI->markUnused();
SR.removeSegment(*Segment);
DEBUG(dbgs() << "Dead PHI at " << VNI->def << " may separate interval\n");
}
}
DEBUG(dbgs() << "Shrunk: " << SR << '\n');
}
void LiveIntervals::extendToIndices(LiveRange &LR,
ArrayRef<SlotIndex> Indices) {
assert(LRCalc && "LRCalc not initialized.");
LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
for (unsigned i = 0, e = Indices.size(); i != e; ++i)
LRCalc->extend(LR, Indices[i]);
}
void LiveIntervals::pruneValue(LiveRange &LR, SlotIndex Kill,
SmallVectorImpl<SlotIndex> *EndPoints) {
LiveQueryResult LRQ = LR.Query(Kill);
VNInfo *VNI = LRQ.valueOutOrDead();
if (!VNI)
return;
MachineBasicBlock *KillMBB = Indexes->getMBBFromIndex(Kill);
SlotIndex MBBEnd = Indexes->getMBBEndIdx(KillMBB);
// If VNI isn't live out from KillMBB, the value is trivially pruned.
if (LRQ.endPoint() < MBBEnd) {
LR.removeSegment(Kill, LRQ.endPoint());
if (EndPoints) EndPoints->push_back(LRQ.endPoint());
return;
}
// VNI is live out of KillMBB.
LR.removeSegment(Kill, MBBEnd);
if (EndPoints) EndPoints->push_back(MBBEnd);
// Find all blocks that are reachable from KillMBB without leaving VNI's live
// range. It is possible that KillMBB itself is reachable, so start a DFS
// from each successor.
typedef SmallPtrSet<MachineBasicBlock*, 9> VisitedTy;
VisitedTy Visited;
for (MachineBasicBlock::succ_iterator
SuccI = KillMBB->succ_begin(), SuccE = KillMBB->succ_end();
SuccI != SuccE; ++SuccI) {
for (df_ext_iterator<MachineBasicBlock*, VisitedTy>
I = df_ext_begin(*SuccI, Visited), E = df_ext_end(*SuccI, Visited);
I != E;) {
MachineBasicBlock *MBB = *I;
// Check if VNI is live in to MBB.
SlotIndex MBBStart, MBBEnd;
std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(MBB);
LiveQueryResult LRQ = LR.Query(MBBStart);
if (LRQ.valueIn() != VNI) {
// This block isn't part of the VNI segment. Prune the search.
I.skipChildren();
continue;
}
// Prune the search if VNI is killed in MBB.
if (LRQ.endPoint() < MBBEnd) {
LR.removeSegment(MBBStart, LRQ.endPoint());
if (EndPoints) EndPoints->push_back(LRQ.endPoint());
I.skipChildren();
continue;
}
// VNI is live through MBB.
LR.removeSegment(MBBStart, MBBEnd);
if (EndPoints) EndPoints->push_back(MBBEnd);
++I;
}
}
}
//===----------------------------------------------------------------------===//
// Register allocator hooks.
//
void LiveIntervals::addKillFlags(const VirtRegMap *VRM) {
// Keep track of regunit ranges.
SmallVector<std::pair<const LiveRange*, LiveRange::const_iterator>, 8> RU;
// Keep track of subregister ranges.
SmallVector<std::pair<const LiveInterval::SubRange*,
LiveRange::const_iterator>, 4> SRs;
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
if (MRI->reg_nodbg_empty(Reg))
continue;
const LiveInterval &LI = getInterval(Reg);
if (LI.empty())
continue;
// Find the regunit intervals for the assigned register. They may overlap
// the virtual register live range, cancelling any kills.
RU.clear();
for (MCRegUnitIterator Units(VRM->getPhys(Reg), TRI); Units.isValid();
++Units) {
const LiveRange &RURange = getRegUnit(*Units);
if (RURange.empty())
continue;
RU.push_back(std::make_pair(&RURange, RURange.find(LI.begin()->end)));
}
if (MRI->subRegLivenessEnabled()) {
SRs.clear();
for (const LiveInterval::SubRange &SR : LI.subranges()) {
SRs.push_back(std::make_pair(&SR, SR.find(LI.begin()->end)));
}
}
// Every instruction that kills Reg corresponds to a segment range end
// point.
for (LiveInterval::const_iterator RI = LI.begin(), RE = LI.end(); RI != RE;
++RI) {
// A block index indicates an MBB edge.
if (RI->end.isBlock())
continue;
MachineInstr *MI = getInstructionFromIndex(RI->end);
if (!MI)
continue;
// Check if any of the regunits are live beyond the end of RI. That could
// happen when a physreg is defined as a copy of a virtreg:
//
// %EAX = COPY %vreg5
// FOO %vreg5 <--- MI, cancel kill because %EAX is live.
// BAR %EAX<kill>
//
// There should be no kill flag on FOO when %vreg5 is rewritten as %EAX.
for (auto &RUP : RU) {
const LiveRange &RURange = *RUP.first;
LiveRange::const_iterator &I = RUP.second;
if (I == RURange.end())
continue;
I = RURange.advanceTo(I, RI->end);
if (I == RURange.end() || I->start >= RI->end)
continue;
// I is overlapping RI.
goto CancelKill;
}
if (MRI->subRegLivenessEnabled()) {
// When reading a partial undefined value we must not add a kill flag.
// The regalloc might have used the undef lane for something else.
// Example:
// %vreg1 = ... ; R32: %vreg1
// %vreg2:high16 = ... ; R64: %vreg2
// = read %vreg2<kill> ; R64: %vreg2
// = read %vreg1 ; R32: %vreg1
// The <kill> flag is correct for %vreg2, but the register allocator may
// assign R0L to %vreg1, and R0 to %vreg2 because the low 32bits of R0
// are actually never written by %vreg2. After assignment the <kill>
// flag at the read instruction is invalid.
LaneBitmask DefinedLanesMask;
if (!SRs.empty()) {
// Compute a mask of lanes that are defined.
DefinedLanesMask = 0;
for (auto &SRP : SRs) {
const LiveInterval::SubRange &SR = *SRP.first;
LiveRange::const_iterator &I = SRP.second;
if (I == SR.end())
continue;
I = SR.advanceTo(I, RI->end);
if (I == SR.end() || I->start >= RI->end)
continue;
// I is overlapping RI
DefinedLanesMask |= SR.LaneMask;
}
} else
DefinedLanesMask = ~0u;
bool IsFullWrite = false;
for (const MachineOperand &MO : MI->operands()) {
if (!MO.isReg() || MO.getReg() != Reg)
continue;
if (MO.isUse()) {
// Reading any undefined lanes?
LaneBitmask UseMask = TRI->getSubRegIndexLaneMask(MO.getSubReg());
if ((UseMask & ~DefinedLanesMask) != 0)
goto CancelKill;
} else if (MO.getSubReg() == 0) {
// Writing to the full register?
assert(MO.isDef());
IsFullWrite = true;
}
}
// If an instruction writes to a subregister, a new segment starts in
// the LiveInterval. But as this is only overriding part of the register
// adding kill-flags is not correct here after registers have been
// assigned.
if (!IsFullWrite) {
// Next segment has to be adjacent in the subregister write case.
LiveRange::const_iterator N = std::next(RI);
if (N != LI.end() && N->start == RI->end)
goto CancelKill;
}
}
MI->addRegisterKilled(Reg, nullptr);
continue;
CancelKill:
MI->clearRegisterKills(Reg, nullptr);
}
}
}
MachineBasicBlock*
LiveIntervals::intervalIsInOneMBB(const LiveInterval &LI) const {
// A local live range must be fully contained inside the block, meaning it is
// defined and killed at instructions, not at block boundaries. It is not
// live in or or out of any block.
//
// It is technically possible to have a PHI-defined live range identical to a
// single block, but we are going to return false in that case.
SlotIndex Start = LI.beginIndex();
if (Start.isBlock())
return nullptr;
SlotIndex Stop = LI.endIndex();
if (Stop.isBlock())
return nullptr;
// getMBBFromIndex doesn't need to search the MBB table when both indexes
// belong to proper instructions.
MachineBasicBlock *MBB1 = Indexes->getMBBFromIndex(Start);
MachineBasicBlock *MBB2 = Indexes->getMBBFromIndex(Stop);
return MBB1 == MBB2 ? MBB1 : nullptr;
}
bool
LiveIntervals::hasPHIKill(const LiveInterval &LI, const VNInfo *VNI) const {
for (const VNInfo *PHI : LI.valnos) {
if (PHI->isUnused() || !PHI->isPHIDef())
continue;
const MachineBasicBlock *PHIMBB = getMBBFromIndex(PHI->def);
// Conservatively return true instead of scanning huge predecessor lists.
if (PHIMBB->pred_size() > 100)
return true;
for (MachineBasicBlock::const_pred_iterator
PI = PHIMBB->pred_begin(), PE = PHIMBB->pred_end(); PI != PE; ++PI)
if (VNI == LI.getVNInfoBefore(Indexes->getMBBEndIdx(*PI)))
return true;
}
return false;
}
float
LiveIntervals::getSpillWeight(bool isDef, bool isUse,
const MachineBlockFrequencyInfo *MBFI,
const MachineInstr *MI) {
BlockFrequency Freq = MBFI->getBlockFreq(MI->getParent());
const float Scale = 1.0f / MBFI->getEntryFreq();
return (isDef + isUse) * (Freq.getFrequency() * Scale);
}
LiveRange::Segment
LiveIntervals::addSegmentToEndOfBlock(unsigned reg, MachineInstr* startInst) {
LiveInterval& Interval = createEmptyInterval(reg);
VNInfo* VN = Interval.getNextValue(
SlotIndex(getInstructionIndex(startInst).getRegSlot()),
getVNInfoAllocator());
LiveRange::Segment S(
SlotIndex(getInstructionIndex(startInst).getRegSlot()),
getMBBEndIdx(startInst->getParent()), VN);
Interval.addSegment(S);
return S;
}
//===----------------------------------------------------------------------===//
// Register mask functions
//===----------------------------------------------------------------------===//
bool LiveIntervals::checkRegMaskInterference(LiveInterval &LI,
BitVector &UsableRegs) {
if (LI.empty())
return false;
LiveInterval::iterator LiveI = LI.begin(), LiveE = LI.end();
// Use a smaller arrays for local live ranges.
ArrayRef<SlotIndex> Slots;
ArrayRef<const uint32_t*> Bits;
if (MachineBasicBlock *MBB = intervalIsInOneMBB(LI)) {
Slots = getRegMaskSlotsInBlock(MBB->getNumber());
Bits = getRegMaskBitsInBlock(MBB->getNumber());
} else {
Slots = getRegMaskSlots();
Bits = getRegMaskBits();
}
// We are going to enumerate all the register mask slots contained in LI.
// Start with a binary search of RegMaskSlots to find a starting point.
ArrayRef<SlotIndex>::iterator SlotI =
std::lower_bound(Slots.begin(), Slots.end(), LiveI->start);
ArrayRef<SlotIndex>::iterator SlotE = Slots.end();
// No slots in range, LI begins after the last call.
if (SlotI == SlotE)
return false;
bool Found = false;
for (;;) {
assert(*SlotI >= LiveI->start);
// Loop over all slots overlapping this segment.
while (*SlotI < LiveI->end) {
// *SlotI overlaps LI. Collect mask bits.
if (!Found) {
// This is the first overlap. Initialize UsableRegs to all ones.
UsableRegs.clear();
UsableRegs.resize(TRI->getNumRegs(), true);
Found = true;
}
// Remove usable registers clobbered by this mask.
UsableRegs.clearBitsNotInMask(Bits[SlotI-Slots.begin()]);
if (++SlotI == SlotE)
return Found;
}
// *SlotI is beyond the current LI segment.
LiveI = LI.advanceTo(LiveI, *SlotI);
if (LiveI == LiveE)
return Found;
// Advance SlotI until it overlaps.
while (*SlotI < LiveI->start)
if (++SlotI == SlotE)
return Found;
}
}
//===----------------------------------------------------------------------===//
// IntervalUpdate class.
//===----------------------------------------------------------------------===//
// HMEditor is a toolkit used by handleMove to trim or extend live intervals.
class LiveIntervals::HMEditor {
private:
LiveIntervals& LIS;
const MachineRegisterInfo& MRI;
const TargetRegisterInfo& TRI;
SlotIndex OldIdx;
SlotIndex NewIdx;
SmallPtrSet<LiveRange*, 8> Updated;
bool UpdateFlags;
public:
HMEditor(LiveIntervals& LIS, const MachineRegisterInfo& MRI,
const TargetRegisterInfo& TRI,
SlotIndex OldIdx, SlotIndex NewIdx, bool UpdateFlags)
: LIS(LIS), MRI(MRI), TRI(TRI), OldIdx(OldIdx), NewIdx(NewIdx),
UpdateFlags(UpdateFlags) {}
// FIXME: UpdateFlags is a workaround that creates live intervals for all
// physregs, even those that aren't needed for regalloc, in order to update
// kill flags. This is wasteful. Eventually, LiveVariables will strip all kill
// flags, and postRA passes will use a live register utility instead.
LiveRange *getRegUnitLI(unsigned Unit) {
if (UpdateFlags)
return &LIS.getRegUnit(Unit);
return LIS.getCachedRegUnit(Unit);
}
/// Update all live ranges touched by MI, assuming a move from OldIdx to
/// NewIdx.
void updateAllRanges(MachineInstr *MI) {
DEBUG(dbgs() << "handleMove " << OldIdx << " -> " << NewIdx << ": " << *MI);
bool hasRegMask = false;
for (MachineOperand &MO : MI->operands()) {
if (MO.isRegMask())
hasRegMask = true;
if (!MO.isReg())
continue;
// Aggressively clear all kill flags.
// They are reinserted by VirtRegRewriter.
if (MO.isUse())
MO.setIsKill(false);
unsigned Reg = MO.getReg();
if (!Reg)
continue;
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
LiveInterval &LI = LIS.getInterval(Reg);
if (LI.hasSubRanges()) {
unsigned SubReg = MO.getSubReg();
LaneBitmask LaneMask = TRI.getSubRegIndexLaneMask(SubReg);
for (LiveInterval::SubRange &S : LI.subranges()) {
if ((S.LaneMask & LaneMask) == 0)
continue;
updateRange(S, Reg, S.LaneMask);
}
}
updateRange(LI, Reg, 0);
continue;
}
// For physregs, only update the regunits that actually have a
// precomputed live range.
for (MCRegUnitIterator Units(Reg, &TRI); Units.isValid(); ++Units)
if (LiveRange *LR = getRegUnitLI(*Units))
updateRange(*LR, *Units, 0);
}
if (hasRegMask)
updateRegMaskSlots();
}
private:
/// Update a single live range, assuming an instruction has been moved from
/// OldIdx to NewIdx.
void updateRange(LiveRange &LR, unsigned Reg, LaneBitmask LaneMask) {
if (!Updated.insert(&LR).second)
return;
DEBUG({
dbgs() << " ";
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
dbgs() << PrintReg(Reg);
if (LaneMask != 0)
dbgs() << " L" << PrintLaneMask(LaneMask);
} else {
dbgs() << PrintRegUnit(Reg, &TRI);
}
dbgs() << ":\t" << LR << '\n';
});
if (SlotIndex::isEarlierInstr(OldIdx, NewIdx))
handleMoveDown(LR);
else
handleMoveUp(LR, Reg, LaneMask);
DEBUG(dbgs() << " -->\t" << LR << '\n');
LR.verify();
}
/// Update LR to reflect an instruction has been moved downwards from OldIdx
/// to NewIdx (OldIdx < NewIdx).
void handleMoveDown(LiveRange &LR) {
LiveRange::iterator E = LR.end();
// Segment going into OldIdx.
LiveRange::iterator OldIdxIn = LR.find(OldIdx.getBaseIndex());
// No value live before or after OldIdx? Nothing to do.
if (OldIdxIn == E || SlotIndex::isEarlierInstr(OldIdx, OldIdxIn->start))
return;
LiveRange::iterator OldIdxOut;
// Do we have a value live-in to OldIdx?
if (SlotIndex::isEarlierInstr(OldIdxIn->start, OldIdx)) {
// If the live-in value already extends to NewIdx, there is nothing to do.
if (SlotIndex::isEarlierEqualInstr(NewIdx, OldIdxIn->end))
return;
// Aggressively remove all kill flags from the old kill point.
// Kill flags shouldn't be used while live intervals exist, they will be
// reinserted by VirtRegRewriter.
if (MachineInstr *KillMI = LIS.getInstructionFromIndex(OldIdxIn->end))
for (MIBundleOperands MO(KillMI); MO.isValid(); ++MO)
if (MO->isReg() && MO->isUse())
MO->setIsKill(false);
// Adjust OldIdxIn->end to reach NewIdx. This may temporarily make LR
// invalid by overlapping ranges.
bool isKill = SlotIndex::isSameInstr(OldIdx, OldIdxIn->end);
OldIdxIn->end = NewIdx.getRegSlot(OldIdxIn->end.isEarlyClobber());
// If this was not a kill, then there was no def and we're done.
if (!isKill)
return;
// Did we have a Def at OldIdx?
OldIdxOut = std::next(OldIdxIn);
if (OldIdxOut == E || !SlotIndex::isSameInstr(OldIdx, OldIdxOut->start))
return;
} else {
OldIdxOut = OldIdxIn;
}
// If we are here then there is a Definition at OldIdx. OldIdxOut points
// to the segment starting there.
assert(OldIdxOut != E && SlotIndex::isSameInstr(OldIdx, OldIdxOut->start) &&
"No def?");
VNInfo *OldIdxVNI = OldIdxOut->valno;
assert(OldIdxVNI->def == OldIdxOut->start && "Inconsistent def");
// If the defined value extends beyond NewIdx, just move the beginning
// of the segment to NewIdx.
SlotIndex NewIdxDef = NewIdx.getRegSlot(OldIdxOut->start.isEarlyClobber());
if (SlotIndex::isEarlierInstr(NewIdxDef, OldIdxOut->end)) {
OldIdxVNI->def = NewIdxDef;
OldIdxOut->start = OldIdxVNI->def;
return;
}
// If we are here then we have a Definition at OldIdx which ends before
// NewIdx. Moving across unrelated defs is not allowed; That means we either
// had a dead-def at OldIdx or the OldIdxOut segment ends at NewIdx.
assert((OldIdxOut->end == OldIdx.getDeadSlot() ||
SlotIndex::isSameInstr(OldIdxOut->end, NewIdxDef)) &&
"Cannot move def below kill");
// Is there an existing Def at NewIdx?
LiveRange::iterator AfterNewIdx
= LR.advanceTo(OldIdxOut, NewIdx.getRegSlot());
if (AfterNewIdx != E &&
SlotIndex::isSameInstr(AfterNewIdx->start, NewIdxDef)) {
// There is an existing def at NewIdx. The def at OldIdx is coalesced into
// that value.
assert(AfterNewIdx->valno != OldIdxVNI && "Multiple defs of value?");
LR.removeValNo(OldIdxVNI);
} else {
// There was no existing def at NewIdx. We need to create a dead def
// at NewIdx. Shift segments over the old OldIdxOut segment, this frees
// a new segment at the place where we want to construct the dead def.
// |- OldIdxOut -| |- X0 -| ... |- Xn -| |- AfterNewIdx -|
// => |- X0/OldIdxOut -| ... |- Xn -| |- undef/NewS. -| |- AfterNewIdx -|
assert(AfterNewIdx != OldIdxOut && "Inconsistent iterators");
std::copy(std::next(OldIdxOut), AfterNewIdx, OldIdxOut);
// We can reuse OldIdxVNI now.
LiveRange::iterator NewSegment = std::prev(AfterNewIdx);
VNInfo *NewSegmentVNI = OldIdxVNI;
NewSegmentVNI->def = NewIdxDef;
*NewSegment = LiveRange::Segment(NewIdxDef, NewIdxDef.getDeadSlot(),
NewSegmentVNI);
}
}
/// Update LR to reflect an instruction has been moved upwards from OldIdx
/// to NewIdx (NewIdx < OldIdx).
void handleMoveUp(LiveRange &LR, unsigned Reg, LaneBitmask LaneMask) {
LiveRange::iterator E = LR.end();
// Segment going into OldIdx.
LiveRange::iterator OldIdxIn = LR.find(OldIdx.getBaseIndex());
// No value live before or after OldIdx? Nothing to do.
if (OldIdxIn == E || SlotIndex::isEarlierInstr(OldIdx, OldIdxIn->start))
return;
LiveRange::iterator OldIdxOut;
// Do we have a value live-in to OldIdx?
if (SlotIndex::isEarlierInstr(OldIdxIn->start, OldIdx)) {
// If the live-in value isn't killed here, then we have no Def at
// OldIdx, moreover the value must be live at NewIdx so there is nothing
// to do.
bool isKill = SlotIndex::isSameInstr(OldIdx, OldIdxIn->end);
if (!isKill)
return;
// At this point we have to move OldIdxIn->end back to the nearest
// previous use but no further than NewIdx. Moreover OldIdx is a Def then
// we cannot have any intermediate uses or the move would be illegal.
OldIdxOut = std::next(OldIdxIn);
// Did we have a Def at OldIdx?
if (OldIdxOut == E || !SlotIndex::isSameInstr(OldIdx, OldIdxOut->start)) {
// No def, search for the nearest previous use.
// This can never be an early clobber kill since there is no def.
OldIdxIn->end = findLastUseBefore(Reg, LaneMask).getRegSlot();
// We are done if there is no def at OldIdx.
return;
} else {
// There can't have been any intermediate uses or defs, so move
// OldIdxIn->end to NewIdx.
OldIdxIn->end = NewIdx.getRegSlot(OldIdxIn->end.isEarlyClobber());
}
} else {
OldIdxOut = OldIdxIn;
}
// If we are here then there is a Definition at OldIdx. OldIdxOut points
// to the segment starting there.
assert(OldIdxOut != E && SlotIndex::isSameInstr(OldIdx, OldIdxOut->start) &&
"No def?");
VNInfo *OldIdxVNI = OldIdxOut->valno;
assert(OldIdxVNI->def == OldIdxOut->start && "Inconsistent def");
bool OldIdxDefIsDead = OldIdxOut->end.isDead();
// Is there an existing def at NewIdx?
SlotIndex NewIdxDef = NewIdx.getRegSlot(OldIdxOut->start.isEarlyClobber());
LiveRange::iterator NewIdxOut = LR.find(NewIdx.getRegSlot());
if (SlotIndex::isSameInstr(NewIdxOut->start, NewIdx)) {
assert(NewIdxOut->valno != OldIdxVNI &&
"Same value defined more than once?");
// If OldIdx was a dead def remove it.
if (!OldIdxDefIsDead) {
// Remove segment starting at NewIdx and move begin of OldIdxOut to
// NewIdx so it can take its place.
OldIdxVNI->def = NewIdxDef;
OldIdxOut->start = NewIdxDef;
LR.removeValNo(NewIdxOut->valno);
} else {
// Simply remove the dead def at OldIdx.
LR.removeValNo(OldIdxVNI);
}
} else {
// Previously nothing was live after NewIdx, so all we have to do now is
// move the begin of OldIdxOut to NewIdx.
if (!OldIdxDefIsDead) {
// Leave the end point of a live def.
OldIdxVNI->def = NewIdxDef;
OldIdxOut->start = NewIdxDef;
} else {
// OldIdxVNI is a dead def. It may have been moved across other values
// in LR, so move OldIdxOut up to NewIdxOut. Slide [NewIdxOut;OldIdxOut)
// down one position.
// |- X0/NewIdxOut -| ... |- Xn-1 -| |- Xn/OldIdxOut -| |- next - |
// => |- undef/NewIdxOut -| |- X0 -| ... |- Xn-1 -| |- next -|
std::copy_backward(NewIdxOut, OldIdxOut, std::next(OldIdxOut));
// OldIdxVNI can be reused now to build a new dead def segment.
LiveRange::iterator NewSegment = NewIdxOut;
VNInfo *NewSegmentVNI = OldIdxVNI;
*NewSegment = LiveRange::Segment(NewIdxDef, NewIdxDef.getDeadSlot(),
NewSegmentVNI);
NewSegmentVNI->def = NewIdxDef;
}
}
}
void updateRegMaskSlots() {
SmallVectorImpl<SlotIndex>::iterator RI =
std::lower_bound(LIS.RegMaskSlots.begin(), LIS.RegMaskSlots.end(),
OldIdx);
assert(RI != LIS.RegMaskSlots.end() && *RI == OldIdx.getRegSlot() &&
"No RegMask at OldIdx.");
*RI = NewIdx.getRegSlot();
assert((RI == LIS.RegMaskSlots.begin() ||
SlotIndex::isEarlierInstr(*std::prev(RI), *RI)) &&
"Cannot move regmask instruction above another call");
assert((std::next(RI) == LIS.RegMaskSlots.end() ||
SlotIndex::isEarlierInstr(*RI, *std::next(RI))) &&
"Cannot move regmask instruction below another call");
}
// Return the last use of reg between NewIdx and OldIdx.
SlotIndex findLastUseBefore(unsigned Reg, LaneBitmask LaneMask) {
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
SlotIndex LastUse = NewIdx;
for (MachineOperand &MO : MRI.use_nodbg_operands(Reg)) {
unsigned SubReg = MO.getSubReg();
if (SubReg != 0 && LaneMask != 0
&& (TRI.getSubRegIndexLaneMask(SubReg) & LaneMask) == 0)
continue;
const MachineInstr *MI = MO.getParent();
SlotIndex InstSlot = LIS.getSlotIndexes()->getInstructionIndex(MI);
if (InstSlot > LastUse && InstSlot < OldIdx)
LastUse = InstSlot;
}
return LastUse;
}
// This is a regunit interval, so scanning the use list could be very
// expensive. Scan upwards from OldIdx instead.
assert(NewIdx < OldIdx && "Expected upwards move");
SlotIndexes *Indexes = LIS.getSlotIndexes();
MachineBasicBlock *MBB = Indexes->getMBBFromIndex(NewIdx);
// OldIdx may not correspond to an instruction any longer, so set MII to
// point to the next instruction after OldIdx, or MBB->end().
MachineBasicBlock::iterator MII = MBB->end();
if (MachineInstr *MI = Indexes->getInstructionFromIndex(
Indexes->getNextNonNullIndex(OldIdx)))
if (MI->getParent() == MBB)
MII = MI;
MachineBasicBlock::iterator Begin = MBB->begin();
while (MII != Begin) {
if ((--MII)->isDebugValue())
continue;
SlotIndex Idx = Indexes->getInstructionIndex(MII);
// Stop searching when NewIdx is reached.
if (!SlotIndex::isEarlierInstr(NewIdx, Idx))
return NewIdx;
// Check if MII uses Reg.
for (MIBundleOperands MO(MII); MO.isValid(); ++MO)
if (MO->isReg() &&
TargetRegisterInfo::isPhysicalRegister(MO->getReg()) &&
TRI.hasRegUnit(MO->getReg(), Reg))
return Idx;
}
// Didn't reach NewIdx. It must be the first instruction in the block.
return NewIdx;
}
};
void LiveIntervals::handleMove(MachineInstr* MI, bool UpdateFlags) {
assert(!MI->isBundled() && "Can't handle bundled instructions yet.");
SlotIndex OldIndex = Indexes->getInstructionIndex(MI);
Indexes->removeMachineInstrFromMaps(MI);
SlotIndex NewIndex = Indexes->insertMachineInstrInMaps(MI);
assert(getMBBStartIdx(MI->getParent()) <= OldIndex &&
OldIndex < getMBBEndIdx(MI->getParent()) &&
"Cannot handle moves across basic block boundaries.");
HMEditor HME(*this, *MRI, *TRI, OldIndex, NewIndex, UpdateFlags);
HME.updateAllRanges(MI);
}
void LiveIntervals::handleMoveIntoBundle(MachineInstr* MI,
MachineInstr* BundleStart,
bool UpdateFlags) {
SlotIndex OldIndex = Indexes->getInstructionIndex(MI);
SlotIndex NewIndex = Indexes->getInstructionIndex(BundleStart);
HMEditor HME(*this, *MRI, *TRI, OldIndex, NewIndex, UpdateFlags);
HME.updateAllRanges(MI);
}
void LiveIntervals::repairOldRegInRange(const MachineBasicBlock::iterator Begin,
const MachineBasicBlock::iterator End,
const SlotIndex endIdx,
LiveRange &LR, const unsigned Reg,
LaneBitmask LaneMask) {
LiveInterval::iterator LII = LR.find(endIdx);
SlotIndex lastUseIdx;
if (LII != LR.end() && LII->start < endIdx)
lastUseIdx = LII->end;
else
--LII;
for (MachineBasicBlock::iterator I = End; I != Begin;) {
--I;
MachineInstr *MI = I;
if (MI->isDebugValue())
continue;
SlotIndex instrIdx = getInstructionIndex(MI);
bool isStartValid = getInstructionFromIndex(LII->start);
bool isEndValid = getInstructionFromIndex(LII->end);
// FIXME: This doesn't currently handle early-clobber or multiple removed
// defs inside of the region to repair.
for (MachineInstr::mop_iterator OI = MI->operands_begin(),
OE = MI->operands_end(); OI != OE; ++OI) {
const MachineOperand &MO = *OI;
if (!MO.isReg() || MO.getReg() != Reg)
continue;
unsigned SubReg = MO.getSubReg();
LaneBitmask Mask = TRI->getSubRegIndexLaneMask(SubReg);
if ((Mask & LaneMask) == 0)
continue;
if (MO.isDef()) {
if (!isStartValid) {
if (LII->end.isDead()) {
SlotIndex prevStart;
if (LII != LR.begin())
prevStart = std::prev(LII)->start;
// FIXME: This could be more efficient if there was a
// removeSegment method that returned an iterator.
LR.removeSegment(*LII, true);
if (prevStart.isValid())
LII = LR.find(prevStart);
else
LII = LR.begin();
} else {
LII->start = instrIdx.getRegSlot();
LII->valno->def = instrIdx.getRegSlot();
if (MO.getSubReg() && !MO.isUndef())
lastUseIdx = instrIdx.getRegSlot();
else
lastUseIdx = SlotIndex();
continue;
}
}
if (!lastUseIdx.isValid()) {
VNInfo *VNI = LR.getNextValue(instrIdx.getRegSlot(), VNInfoAllocator);
LiveRange::Segment S(instrIdx.getRegSlot(),
instrIdx.getDeadSlot(), VNI);
LII = LR.addSegment(S);
} else if (LII->start != instrIdx.getRegSlot()) {
VNInfo *VNI = LR.getNextValue(instrIdx.getRegSlot(), VNInfoAllocator);
LiveRange::Segment S(instrIdx.getRegSlot(), lastUseIdx, VNI);
LII = LR.addSegment(S);
}
if (MO.getSubReg() && !MO.isUndef())
lastUseIdx = instrIdx.getRegSlot();
else
lastUseIdx = SlotIndex();
} else if (MO.isUse()) {
// FIXME: This should probably be handled outside of this branch,
// either as part of the def case (for defs inside of the region) or
// after the loop over the region.
if (!isEndValid && !LII->end.isBlock())
LII->end = instrIdx.getRegSlot();
if (!lastUseIdx.isValid())
lastUseIdx = instrIdx.getRegSlot();
}
}
}
}
void
LiveIntervals::repairIntervalsInRange(MachineBasicBlock *MBB,
MachineBasicBlock::iterator Begin,
MachineBasicBlock::iterator End,
ArrayRef<unsigned> OrigRegs) {
// Find anchor points, which are at the beginning/end of blocks or at
// instructions that already have indexes.
while (Begin != MBB->begin() && !Indexes->hasIndex(Begin))
--Begin;
while (End != MBB->end() && !Indexes->hasIndex(End))
++End;
SlotIndex endIdx;
if (End == MBB->end())
endIdx = getMBBEndIdx(MBB).getPrevSlot();
else
endIdx = getInstructionIndex(End);
Indexes->repairIndexesInRange(MBB, Begin, End);
for (MachineBasicBlock::iterator I = End; I != Begin;) {
--I;
MachineInstr *MI = I;
if (MI->isDebugValue())
continue;
for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
MOE = MI->operands_end(); MOI != MOE; ++MOI) {
if (MOI->isReg() &&
TargetRegisterInfo::isVirtualRegister(MOI->getReg()) &&
!hasInterval(MOI->getReg())) {
createAndComputeVirtRegInterval(MOI->getReg());
}
}
}
for (unsigned i = 0, e = OrigRegs.size(); i != e; ++i) {
unsigned Reg = OrigRegs[i];
if (!TargetRegisterInfo::isVirtualRegister(Reg))
continue;
LiveInterval &LI = getInterval(Reg);
// FIXME: Should we support undefs that gain defs?
if (!LI.hasAtLeastOneValue())
continue;
for (LiveInterval::SubRange &S : LI.subranges()) {
repairOldRegInRange(Begin, End, endIdx, S, Reg, S.LaneMask);
}
repairOldRegInRange(Begin, End, endIdx, LI, Reg);
}
}
void LiveIntervals::removePhysRegDefAt(unsigned Reg, SlotIndex Pos) {
for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) {
if (LiveRange *LR = getCachedRegUnit(*Units))
if (VNInfo *VNI = LR->getVNInfoAt(Pos))
LR->removeValNo(VNI);
}
}
void LiveIntervals::removeVRegDefAt(LiveInterval &LI, SlotIndex Pos) {
VNInfo *VNI = LI.getVNInfoAt(Pos);
if (VNI == nullptr)
return;
LI.removeValNo(VNI);
// Also remove the value in subranges.
for (LiveInterval::SubRange &S : LI.subranges()) {
if (VNInfo *SVNI = S.getVNInfoAt(Pos))
S.removeValNo(SVNI);
}
LI.removeEmptySubRanges();
}
void LiveIntervals::splitSeparateComponents(LiveInterval &LI,
SmallVectorImpl<LiveInterval*> &SplitLIs) {
ConnectedVNInfoEqClasses ConEQ(*this);
unsigned NumComp = ConEQ.Classify(LI);
if (NumComp <= 1)
return;
DEBUG(dbgs() << " Split " << NumComp << " components: " << LI << '\n');
unsigned Reg = LI.reg;
const TargetRegisterClass *RegClass = MRI->getRegClass(Reg);
for (unsigned I = 1; I < NumComp; ++I) {
unsigned NewVReg = MRI->createVirtualRegister(RegClass);
LiveInterval &NewLI = createEmptyInterval(NewVReg);
SplitLIs.push_back(&NewLI);
}
ConEQ.Distribute(LI, SplitLIs.data(), *MRI);
}
void LiveIntervals::renameDisconnectedComponents() {
ConnectedSubRegClasses SubRegClasses(*this, *MRI);
// Iterate over all vregs. Note that we query getNumVirtRegs() the newly
// created vregs end up with higher numbers but do not need to be visited as
// there can't be any further splitting.
for (size_t I = 0, E = MRI->getNumVirtRegs(); I < E; ++I) {
unsigned Reg = TargetRegisterInfo::index2VirtReg(I);
LiveInterval *LI = VirtRegIntervals[Reg];
if (LI == nullptr || !LI->hasSubRanges())
continue;
SubRegClasses.renameComponents(*LI);
}
}
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