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Speed up eviction by stopping collectInterferingVRegs as soon as the spill

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weight limit has been exceeded.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129305 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-04-11 21:47:01 +00:00
parent 787d41aaa0
commit 3f5bedf5cb
3 changed files with 23 additions and 14 deletions
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22
lib/CodeGen/RegAllocGreedy.cpp
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@ -336,22 +336,24 @@ LiveInterval *RAGreedy::dequeue() {
//===----------------------------------------------------------------------===//
/// canEvict - Return true if all interferences between VirtReg and PhysReg can
/// be evicted. Set maxWeight to the maximal spill weight of an interference.
/// be evicted.
/// Return false if any interference is heavier than MaxWeight.
/// On return, set MaxWeight to the maximal spill weight of an interference.
bool RAGreedy::canEvictInterference(LiveInterval &VirtReg, unsigned PhysReg,
float &MaxWeight) {
float Weight = 0;
for (const unsigned *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI) {
LiveIntervalUnion::Query &Q = query(VirtReg, *AliasI);
// If there is 10 or more interferences, chances are one is smaller.
if (Q.collectInterferingVRegs(10) >= 10)
// If there is 10 or more interferences, chances are one is heavier.
if (Q.collectInterferingVRegs(10, MaxWeight) >= 10)
return false;
// Check if any interfering live range is heavier than VirtReg.
for (unsigned i = 0, e = Q.interferingVRegs().size(); i != e; ++i) {
LiveInterval *Intf = Q.interferingVRegs()[i];
// Check if any interfering live range is heavier than MaxWeight.
for (unsigned i = Q.interferingVRegs().size(); i; --i) {
LiveInterval *Intf = Q.interferingVRegs()[i - 1];
if (TargetRegisterInfo::isPhysicalRegister(Intf->reg))
return false;
if (Intf->weight >= VirtReg.weight)
if (Intf->weight >= MaxWeight)
return false;
Weight = std::max(Weight, Intf->weight);
}
@ -370,17 +372,17 @@ unsigned RAGreedy::tryEvict(LiveInterval &VirtReg,
NamedRegionTimer T("Evict", TimerGroupName, TimePassesIsEnabled);
// Keep track of the lightest single interference seen so far.
float BestWeight = 0;
float BestWeight = VirtReg.weight;
unsigned BestPhys = 0;
Order.rewind();
while (unsigned PhysReg = Order.next()) {
float Weight = 0;
float Weight = BestWeight;
if (!canEvictInterference(VirtReg, PhysReg, Weight))
continue;
// This is an eviction candidate.
DEBUG(dbgs() << "max " << PrintReg(PhysReg, TRI) << " interference = "
DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " interference = "
<< Weight << '\n');
if (BestPhys && Weight >= BestWeight)
continue;