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llvm-6502/lib/CodeGen/InterferenceCache.cpp
Jakob Stoklund Olesen 042888db2b Convert RAGreedy to LiveRegMatrix interference checking.
Stop depending on the LiveIntervalUnions in RegAllocBase, they are about
to be removed.

The changes are mostly replacing register alias iterators with regunit
iterators, and querying LiveRegMatrix instrad of RegAllocBase.

InterferenceCache is converted to work with per-regunit
LiveIntervalUnions, and it checks fixed regunit interference separately,
using the fixed live intervals provided by LiveIntervalAnalysis.

The local splitting helper calcGapWeights() is also considering fixed
regunit interference which is kept on the side now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158867 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-20 22:52:26 +00:00

232 lines
7.5 KiB
C++

//===-- InterferenceCache.cpp - Caching per-block interference ---------*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// InterferenceCache remembers per-block interference in LiveIntervalUnions.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "regalloc"
#include "InterferenceCache.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
using namespace llvm;
// Static member used for null interference cursors.
InterferenceCache::BlockInterference InterferenceCache::Cursor::NoInterference;
void InterferenceCache::init(MachineFunction *mf,
LiveIntervalUnion *liuarray,
SlotIndexes *indexes,
LiveIntervals *lis,
const TargetRegisterInfo *tri) {
MF = mf;
LIUArray = liuarray;
TRI = tri;
PhysRegEntries.assign(TRI->getNumRegs(), 0);
for (unsigned i = 0; i != CacheEntries; ++i)
Entries[i].clear(mf, indexes, lis);
}
InterferenceCache::Entry *InterferenceCache::get(unsigned PhysReg) {
unsigned E = PhysRegEntries[PhysReg];
if (E < CacheEntries && Entries[E].getPhysReg() == PhysReg) {
if (!Entries[E].valid(LIUArray, TRI))
Entries[E].revalidate(LIUArray, TRI);
return &Entries[E];
}
// No valid entry exists, pick the next round-robin entry.
E = RoundRobin;
if (++RoundRobin == CacheEntries)
RoundRobin = 0;
for (unsigned i = 0; i != CacheEntries; ++i) {
// Skip entries that are in use.
if (Entries[E].hasRefs()) {
if (++E == CacheEntries)
E = 0;
continue;
}
Entries[E].reset(PhysReg, LIUArray, TRI, MF);
PhysRegEntries[PhysReg] = E;
return &Entries[E];
}
llvm_unreachable("Ran out of interference cache entries.");
}
/// revalidate - LIU contents have changed, update tags.
void InterferenceCache::Entry::revalidate(LiveIntervalUnion *LIUArray,
const TargetRegisterInfo *TRI) {
// Invalidate all block entries.
++Tag;
// Invalidate all iterators.
PrevPos = SlotIndex();
unsigned i = 0;
for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units, ++i)
RegUnits[i].VirtTag = LIUArray[*Units].getTag();
}
void InterferenceCache::Entry::reset(unsigned physReg,
LiveIntervalUnion *LIUArray,
const TargetRegisterInfo *TRI,
const MachineFunction *MF) {
assert(!hasRefs() && "Cannot reset cache entry with references");
// LIU's changed, invalidate cache.
++Tag;
PhysReg = physReg;
Blocks.resize(MF->getNumBlockIDs());
// Reset iterators.
PrevPos = SlotIndex();
RegUnits.clear();
for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
RegUnits.push_back(LIUArray[*Units]);
RegUnits.back().Fixed = &LIS->getRegUnit(*Units);
}
}
bool InterferenceCache::Entry::valid(LiveIntervalUnion *LIUArray,
const TargetRegisterInfo *TRI) {
unsigned i = 0, e = RegUnits.size();
for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units, ++i) {
if (i == e)
return false;
if (LIUArray[*Units].changedSince(RegUnits[i].VirtTag))
return false;
}
return i == e;
}
void InterferenceCache::Entry::update(unsigned MBBNum) {
SlotIndex Start, Stop;
tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
// Use advanceTo only when possible.
if (PrevPos != Start) {
if (!PrevPos.isValid() || Start < PrevPos) {
for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
RegUnitInfo &RUI = RegUnits[i];
RUI.VirtI.find(Start);
RUI.FixedI = RUI.Fixed->find(Start);
}
} else {
for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
RegUnitInfo &RUI = RegUnits[i];
RUI.VirtI.advanceTo(Start);
if (RUI.FixedI != RUI.Fixed->end())
RUI.FixedI = RUI.Fixed->advanceTo(RUI.FixedI, Start);
}
}
PrevPos = Start;
}
MachineFunction::const_iterator MFI = MF->getBlockNumbered(MBBNum);
BlockInterference *BI = &Blocks[MBBNum];
ArrayRef<SlotIndex> RegMaskSlots;
ArrayRef<const uint32_t*> RegMaskBits;
for (;;) {
BI->Tag = Tag;
BI->First = BI->Last = SlotIndex();
// Check for first interference from virtregs.
for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
LiveIntervalUnion::SegmentIter &I = RegUnits[i].VirtI;
if (!I.valid())
continue;
SlotIndex StartI = I.start();
if (StartI >= Stop)
continue;
if (!BI->First.isValid() || StartI < BI->First)
BI->First = StartI;
}
// Same thing for fixed interference.
for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
LiveInterval::const_iterator I = RegUnits[i].FixedI;
LiveInterval::const_iterator E = RegUnits[i].Fixed->end();
if (I == E)
continue;
SlotIndex StartI = I->start;
if (StartI >= Stop)
continue;
if (!BI->First.isValid() || StartI < BI->First)
BI->First = StartI;
}
// Also check for register mask interference.
RegMaskSlots = LIS->getRegMaskSlotsInBlock(MBBNum);
RegMaskBits = LIS->getRegMaskBitsInBlock(MBBNum);
SlotIndex Limit = BI->First.isValid() ? BI->First : Stop;
for (unsigned i = 0, e = RegMaskSlots.size();
i != e && RegMaskSlots[i] < Limit; ++i)
if (MachineOperand::clobbersPhysReg(RegMaskBits[i], PhysReg)) {
// Register mask i clobbers PhysReg before the LIU interference.
BI->First = RegMaskSlots[i];
break;
}
PrevPos = Stop;
if (BI->First.isValid())
break;
// No interference in this block? Go ahead and precompute the next block.
if (++MFI == MF->end())
return;
MBBNum = MFI->getNumber();
BI = &Blocks[MBBNum];
if (BI->Tag == Tag)
return;
tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
}
// Check for last interference in block.
for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
LiveIntervalUnion::SegmentIter &I = RegUnits[i].VirtI;
if (!I.valid() || I.start() >= Stop)
continue;
I.advanceTo(Stop);
bool Backup = !I.valid() || I.start() >= Stop;
if (Backup)
--I;
SlotIndex StopI = I.stop();
if (!BI->Last.isValid() || StopI > BI->Last)
BI->Last = StopI;
if (Backup)
++I;
}
// Fixed interference.
for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) {
LiveInterval::iterator &I = RegUnits[i].FixedI;
LiveInterval *LI = RegUnits[i].Fixed;
if (I == LI->end() || I->start >= Stop)
continue;
I = LI->advanceTo(I, Stop);
bool Backup = I == LI->end() || I->start >= Stop;
if (Backup)
--I;
SlotIndex StopI = I->end;
if (!BI->Last.isValid() || StopI > BI->Last)
BI->Last = StopI;
if (Backup)
++I;
}
// Also check for register mask interference.
SlotIndex Limit = BI->Last.isValid() ? BI->Last : Start;
for (unsigned i = RegMaskSlots.size();
i && RegMaskSlots[i-1].getDeadSlot() > Limit; --i)
if (MachineOperand::clobbersPhysReg(RegMaskBits[i-1], PhysReg)) {
// Register mask i-1 clobbers PhysReg after the LIU interference.
// Model the regmask clobber as a dead def.
BI->Last = RegMaskSlots[i-1].getDeadSlot();
break;
}
}