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This doesn't require seeking in the live interval union, so it is very cheap. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129187 91177308-0d34-0410-b5e6-96231b3b80d8
156 lines
4.7 KiB
C++
156 lines
4.7 KiB
C++
//===-- InterferenceCache.h - Caching per-block interference ---*- C++ -*--===//
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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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// InterferenceCache remembers per-block interference in LiveIntervalUnions.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "regalloc"
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#include "InterferenceCache.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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using namespace llvm;
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void InterferenceCache::init(MachineFunction *mf,
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LiveIntervalUnion *liuarray,
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SlotIndexes *indexes,
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const TargetRegisterInfo *tri) {
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MF = mf;
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LIUArray = liuarray;
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TRI = tri;
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PhysRegEntries.assign(TRI->getNumRegs(), 0);
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for (unsigned i = 0; i != CacheEntries; ++i)
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Entries[i].clear(mf, indexes);
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}
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InterferenceCache::Entry *InterferenceCache::get(unsigned PhysReg) {
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unsigned E = PhysRegEntries[PhysReg];
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if (E < CacheEntries && Entries[E].getPhysReg() == PhysReg) {
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if (!Entries[E].valid(LIUArray, TRI))
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Entries[E].revalidate();
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return &Entries[E];
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}
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// No valid entry exists, pick the next round-robin entry.
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E = RoundRobin;
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if (++RoundRobin == CacheEntries)
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RoundRobin = 0;
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Entries[E].reset(PhysReg, LIUArray, TRI, MF);
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PhysRegEntries[PhysReg] = E;
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return &Entries[E];
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}
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/// revalidate - LIU contents have changed, update tags.
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void InterferenceCache::Entry::revalidate() {
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// Invalidate all block entries.
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++Tag;
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// Invalidate all iterators.
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PrevPos = SlotIndex();
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for (unsigned i = 0, e = Aliases.size(); i != e; ++i)
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Aliases[i].second = Aliases[i].first->getTag();
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}
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void InterferenceCache::Entry::reset(unsigned physReg,
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LiveIntervalUnion *LIUArray,
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const TargetRegisterInfo *TRI,
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const MachineFunction *MF) {
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// LIU's changed, invalidate cache.
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++Tag;
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PhysReg = physReg;
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Blocks.resize(MF->getNumBlockIDs());
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Aliases.clear();
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for (const unsigned *AS = TRI->getOverlaps(PhysReg); *AS; ++AS) {
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LiveIntervalUnion *LIU = LIUArray + *AS;
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Aliases.push_back(std::make_pair(LIU, LIU->getTag()));
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}
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// Reset iterators.
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PrevPos = SlotIndex();
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unsigned e = Aliases.size();
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Iters.resize(e);
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for (unsigned i = 0; i != e; ++i)
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Iters[i].setMap(Aliases[i].first->getMap());
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}
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bool InterferenceCache::Entry::valid(LiveIntervalUnion *LIUArray,
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const TargetRegisterInfo *TRI) {
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unsigned i = 0, e = Aliases.size();
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for (const unsigned *AS = TRI->getOverlaps(PhysReg); *AS; ++AS, ++i) {
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LiveIntervalUnion *LIU = LIUArray + *AS;
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if (i == e || Aliases[i].first != LIU)
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return false;
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if (LIU->changedSince(Aliases[i].second))
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return false;
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}
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return i == e;
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}
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void InterferenceCache::Entry::update(unsigned MBBNum) {
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SlotIndex Start, Stop;
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tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
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// Use advanceTo only when possible.
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if (PrevPos != Start) {
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if (!PrevPos.isValid() || Start < PrevPos)
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for (unsigned i = 0, e = Iters.size(); i != e; ++i)
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Iters[i].find(Start);
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else
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for (unsigned i = 0, e = Iters.size(); i != e; ++i)
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Iters[i].advanceTo(Start);
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PrevPos = Start;
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}
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MachineFunction::const_iterator MFI = MF->getBlockNumbered(MBBNum);
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BlockInterference *BI = &Blocks[MBBNum];
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for (;;) {
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BI->Tag = Tag;
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BI->First = BI->Last = SlotIndex();
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// Check for first interference.
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for (unsigned i = 0, e = Iters.size(); i != e; ++i) {
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Iter &I = Iters[i];
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if (!I.valid())
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continue;
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SlotIndex StartI = I.start();
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if (StartI >= Stop)
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continue;
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if (!BI->First.isValid() || StartI < BI->First)
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BI->First = StartI;
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}
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PrevPos = Stop;
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if (BI->First.isValid())
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break;
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// No interference in this block? Go ahead and precompute the next block.
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if (++MFI == MF->end())
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return;
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MBBNum = MFI->getNumber();
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BI = &Blocks[MBBNum];
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if (BI->Tag == Tag)
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return;
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tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
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}
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// Check for last interference in block.
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for (unsigned i = 0, e = Iters.size(); i != e; ++i) {
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Iter &I = Iters[i];
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if (!I.valid() || I.start() >= Stop)
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continue;
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I.advanceTo(Stop);
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bool Backup = !I.valid() || I.start() >= Stop;
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if (Backup)
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--I;
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SlotIndex StopI = I.stop();
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if (!BI->Last.isValid() || StopI > BI->Last)
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BI->Last = StopI;
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if (Backup)
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++I;
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}
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}
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