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Only keep the global split candidates that work out.

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Some pysical registers create split solutions that would spill anywhere.
They should not even be considered in future multi-way global splits.

This does not affect code generation (yet).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135080 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-07-13 20:49:46 +00:00
parent 4977eb5eb5
commit 3bae1bf62e
1 changed files with 15 additions and 12 deletions
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27
lib/CodeGen/RegAllocGreedy.cpp
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@ -1243,16 +1243,18 @@ unsigned RAGreedy::tryRegionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
DEBUG(dbgs() << "Cost of isolating all blocks = " << BestCost << '\n');
const unsigned NoCand = ~0u;
unsigned BestCand = NoCand;
unsigned NumCands = 0;
Order.rewind();
for (unsigned Cand = 0; unsigned PhysReg = Order.next(); ++Cand) {
if (GlobalCand.size() <= Cand)
GlobalCand.resize(Cand+1);
GlobalCand[Cand].reset(IntfCache, PhysReg);
while (unsigned PhysReg = Order.next()) {
if (GlobalCand.size() <= NumCands)
GlobalCand.resize(NumCands+1);
GlobalSplitCandidate &Cand = GlobalCand[NumCands];
Cand.reset(IntfCache, PhysReg);
SpillPlacer->prepare(GlobalCand[Cand].LiveBundles);
SpillPlacer->prepare(Cand.LiveBundles);
float Cost;
if (!addSplitConstraints(GlobalCand[Cand].Intf, Cost)) {
if (!addSplitConstraints(Cand.Intf, Cost)) {
DEBUG(dbgs() << PrintReg(PhysReg, TRI) << "\tno positive bundles\n");
continue;
}
@ -1267,28 +1269,29 @@ unsigned RAGreedy::tryRegionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
});
continue;
}
growRegion(GlobalCand[Cand]);
growRegion(Cand);
SpillPlacer->finish();
// No live bundles, defer to splitSingleBlocks().
if (!GlobalCand[Cand].LiveBundles.any()) {
if (!Cand.LiveBundles.any()) {
DEBUG(dbgs() << " no bundles.\n");
continue;
}
Cost += calcGlobalSplitCost(GlobalCand[Cand]);
Cost += calcGlobalSplitCost(Cand);
DEBUG({
dbgs() << ", total = " << Cost << " with bundles";
for (int i = GlobalCand[Cand].LiveBundles.find_first(); i>=0;
i = GlobalCand[Cand].LiveBundles.find_next(i))
for (int i = Cand.LiveBundles.find_first(); i>=0;
i = Cand.LiveBundles.find_next(i))
dbgs() << " EB#" << i;
dbgs() << ".\n";
});
if (Cost < BestCost) {
BestCand = Cand;
BestCand = NumCands;
BestCost = Hysteresis * Cost; // Prevent rounding effects.
}
++NumCands;
}
if (BestCand == NoCand)