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https://github.com/c64scene-ar/llvm-6502.git
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Add prototype code for recomputing a live interval's ranges and valnos through recursive phi construction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61458 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
parent
3037eda1ef
commit
60d4f6ded2
@ -171,7 +171,15 @@ namespace {
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int& SS,
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SmallPtrSet<MachineInstr*, 4>& RefsInMBB);
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void RenumberValno(VNInfo* VN);
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};
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void ReconstructLiveInterval(LiveInterval* LI);
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VNInfo* PerformPHIConstruction(MachineBasicBlock::iterator use,
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LiveInterval* LI,
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DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Defs,
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DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Uses,
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DenseMap<MachineInstr*, VNInfo*>& NewVNs,
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DenseMap<MachineBasicBlock*, VNInfo*>& Visited,
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bool toplevel = false);
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};
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} // end anonymous namespace
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char PreAllocSplitting::ID = 0;
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@ -577,6 +585,257 @@ PreAllocSplitting::ShrinkWrapToLastUse(MachineBasicBlock *MBB, VNInfo *ValNo,
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return LastMI;
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}
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/// PerformPHIConstruction - From properly set up use and def lists, use a PHI
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/// construction algorithm to compute the ranges and valnos for an interval.
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VNInfo* PreAllocSplitting::PerformPHIConstruction(
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MachineBasicBlock::iterator use,
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LiveInterval* LI,
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DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Defs,
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DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Uses,
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DenseMap<MachineInstr*, VNInfo*>& NewVNs,
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DenseMap<MachineBasicBlock*, VNInfo*>& Visited,
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bool toplevel) {
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// Return memoized result if it's available.
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if (Visited.count(use->getParent()))
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return Visited[use->getParent()];
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typedef DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> > RegMap;
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// Check if our block contains any uses or defs.
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bool ContainsDefs = Defs.count(use->getParent());
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bool ContainsUses = Uses.count(use->getParent());
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VNInfo* ret = 0;
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// Enumerate the cases of use/def contaning blocks.
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if (!ContainsDefs && !ContainsUses) {
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Fallback:
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// NOTE: Because this is the fallback case from other cases, we do NOT
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// assume that we are not at toplevel here.
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// If there are no uses or defs between our starting point and the beginning
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// of the block, then recursive perform phi construction on our predecessors
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MachineBasicBlock* MBB = use->getParent();
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DenseMap<MachineBasicBlock*, VNInfo*> IncomingVNs;
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for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
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PE = MBB->pred_end(); PI != PE; ++PI) {
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VNInfo* Incoming = PerformPHIConstruction((*PI)->end(), LI, Defs, Uses,
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NewVNs, Visited, false);
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IncomingVNs[*PI] = Incoming;
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}
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// If only one VNInfo came back from our predecessors, just use that one...
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if (IncomingVNs.size() == 1) {
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ret = IncomingVNs.begin()->second;
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unsigned StartIndex = LIs->getMBBStartIdx(use->getParent());
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unsigned EndIndex = 0;
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if (toplevel) {
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EndIndex = LIs->getInstructionIndex(use);
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EndIndex = LiveIntervals::getUseIndex(EndIndex);
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} else
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EndIndex = LIs->getMBBEndIdx(use->getParent());
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LI->addRange(LiveRange(StartIndex, EndIndex, ret));
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} else {
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// Otherwise, merge the incoming VNInfos with a phi join. Create a new
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// VNInfo to represent the joined value.
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for (DenseMap<MachineBasicBlock*, VNInfo*>::iterator I =
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IncomingVNs.begin(), E = IncomingVNs.end(); I != E; ++I) {
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I->second->hasPHIKill = true;
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unsigned KillIndex = LIs->getMBBEndIdx(I->first);
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LI->addKill(I->second, KillIndex);
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}
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unsigned StartIndex = LIs->getMBBStartIdx(use->getParent());
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unsigned EndIndex = 0;
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if (toplevel) {
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EndIndex = LIs->getInstructionIndex(use);
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EndIndex = LiveIntervals::getUseIndex(EndIndex);
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} else
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EndIndex = LIs->getMBBEndIdx(use->getParent());
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ret = LI->getNextValue(StartIndex, /*FIXME*/ 0,
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LIs->getVNInfoAllocator());
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LI->addRange(LiveRange(StartIndex, EndIndex, ret));
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}
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} else if (ContainsDefs && !ContainsUses) {
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SmallPtrSet<MachineInstr*, 2>& BlockDefs = Defs[use->getParent()];
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// Search for the def in this block. If we don't find it before the
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// instruction we care about, go to the fallback case. Note that that
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// should never happen: this cannot be a toplevel block, so use should
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// always be an end() iterator.
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assert(use == use->getParent()->end() && "No use marked in toplevel block");
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MachineBasicBlock::iterator walker = use;
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--walker;
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while (walker != use->getParent()->begin())
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if (BlockDefs.count(walker)) {
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break;
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} else
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--walker;
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// Once we've found it, extend its VNInfo to our instruction.
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unsigned DefIndex = LIs->getInstructionIndex(walker);
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DefIndex = LiveIntervals::getDefIndex(DefIndex);
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unsigned EndIndex = LIs->getMBBEndIdx(use->getParent());
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ret = NewVNs[walker];
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LI->addRange(LiveRange(DefIndex, EndIndex, ret));
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} else if (!ContainsDefs && ContainsUses) {
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SmallPtrSet<MachineInstr*, 2>& BlockUses = Uses[use->getParent()];
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// Search for the use in this block that precedes the instruction we care
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// about, going to the fallback case if we don't find it.
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if (use == use->getParent()->begin())
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goto Fallback;
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MachineBasicBlock::iterator walker = use;
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--walker;
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bool found = false;
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while (walker != use->getParent()->begin())
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if (BlockUses.count(walker)) {
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found = true;
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break;
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} else
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--walker;
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// Must check begin() too.
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if (!found)
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if (BlockUses.count(walker))
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found = true;
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else
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goto Fallback;
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unsigned UseIndex = LIs->getInstructionIndex(walker);
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UseIndex = LiveIntervals::getUseIndex(UseIndex);
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unsigned EndIndex = 0;
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if (toplevel) {
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EndIndex = LIs->getInstructionIndex(walker);
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EndIndex = LiveIntervals::getUseIndex(EndIndex);
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} else
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EndIndex = LIs->getMBBEndIdx(use->getParent());
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// Now, recursively phi construct the VNInfo for the use we found,
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// and then extend it to include the instruction we care about
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ret = PerformPHIConstruction(walker, LI, Defs, Uses,
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NewVNs, Visited, false);
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// FIXME: Need to set kills properly for inter-block stuff.
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if (toplevel) {
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if (LI->isKill(ret, UseIndex)) LI->removeKill(ret, UseIndex);
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LI->addKill(ret, EndIndex);
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}
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LI->addRange(LiveRange(UseIndex, EndIndex, ret));
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} else if (ContainsDefs && ContainsUses){
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SmallPtrSet<MachineInstr*, 2>& BlockDefs = Defs[use->getParent()];
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SmallPtrSet<MachineInstr*, 2>& BlockUses = Uses[use->getParent()];
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// This case is basically a merging of the two preceding case, with the
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// special note that checking for defs must take precedence over checking
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// for uses, because of two-address instructions.
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if (use == use->getParent()->begin())
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goto Fallback;
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MachineBasicBlock::iterator walker = use;
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--walker;
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bool foundDef = false;
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bool foundUse = false;
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while (walker != use->getParent()->begin())
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if (BlockDefs.count(walker)) {
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foundDef = true;
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break;
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} else if (BlockUses.count(walker)) {
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foundUse = true;
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break;
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} else
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--walker;
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// Must check begin() too.
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if (!foundDef && !foundUse)
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if (BlockDefs.count(walker))
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foundDef = true;
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else if (BlockUses.count(walker))
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foundUse = true;
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else
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goto Fallback;
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unsigned StartIndex = LIs->getInstructionIndex(walker);
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StartIndex = foundDef ? LiveIntervals::getDefIndex(StartIndex) :
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LiveIntervals::getUseIndex(StartIndex);
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unsigned EndIndex = 0;
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if (toplevel) {
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EndIndex = LIs->getInstructionIndex(walker);
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EndIndex = LiveIntervals::getUseIndex(EndIndex);
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} else
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EndIndex = LIs->getMBBEndIdx(use->getParent());
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if (foundDef)
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ret = NewVNs[walker];
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else
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ret = PerformPHIConstruction(walker, LI, Defs, Uses,
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NewVNs, Visited, false);
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// FIXME: Need to set kills properly for inter-block stuff.
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if (toplevel) {
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if (foundUse && LI->isKill(ret, StartIndex))
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LI->removeKill(ret, StartIndex);
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LI->addKill(ret, EndIndex);
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}
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LI->addRange(LiveRange(StartIndex, EndIndex, ret));
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}
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// Memoize results so we don't have to recompute them.
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if (!toplevel) Visited[use->getParent()] = ret;
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return ret;
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}
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/// ReconstructLiveInterval - Recompute a live interval from scratch.
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void PreAllocSplitting::ReconstructLiveInterval(LiveInterval* LI) {
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BumpPtrAllocator& Alloc = LIs->getVNInfoAllocator();
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// Clear the old ranges and valnos;
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LI->clear();
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// Cache the uses and defs of the register
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typedef DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> > RegMap;
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RegMap Defs, Uses;
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// Keep track of the new VNs we're creating.
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DenseMap<MachineInstr*, VNInfo*> NewVNs;
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SmallPtrSet<VNInfo*, 2> PhiVNs;
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// Cache defs, and create a new VNInfo for each def.
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for (MachineRegisterInfo::def_iterator DI = MRI->def_begin(LI->reg),
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DE = MRI->def_end(); DI != DE; ++DI) {
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Defs[(*DI).getParent()].insert(&*DI);
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unsigned DefIdx = LIs->getInstructionIndex(&*DI);
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DefIdx = LiveIntervals::getDefIndex(DefIdx);
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VNInfo* NewVN = LI->getNextValue(DefIdx, /*FIXME*/ 0, Alloc);
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NewVNs[&*DI] = NewVN;
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}
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// Cache uses as a separate pass from actually processing them.
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for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(LI->reg),
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UE = MRI->use_end(); UI != UE; ++UI)
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Uses[(*UI).getParent()].insert(&*UI);
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// Now, actually process every use and use a phi construction algorithm
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// to walk from it to its reaching definitions, building VNInfos along
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// the way.
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for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(LI->reg),
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UE = MRI->use_end(); UI != UE; ++UI) {
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DenseMap<MachineBasicBlock*, VNInfo*> Visited;
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PerformPHIConstruction(&*UI, LI, Defs, Uses, NewVNs, Visited, true);
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}
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}
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/// ShrinkWrapLiveInterval - Recursively traverse the predecessor
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/// chain to find the new 'kills' and shrink wrap the live interval to the
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/// new kill indices.
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