Reapply r135074 and r135080 with a fix.
The cache entry referenced by the best split candidate could become
clobbered by an unsuccessful candidate.
The correct fix here is to use reference counts on the cache entries.
Coming up.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135113 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp
index d79573c..4728a05 100644
--- a/lib/CodeGen/RegAllocGreedy.cpp
+++ b/lib/CodeGen/RegAllocGreedy.cpp
@@ -160,11 +160,13 @@
/// Global live range splitting candidate info.
struct GlobalSplitCandidate {
unsigned PhysReg;
+ InterferenceCache::Cursor Intf;
BitVector LiveBundles;
SmallVector<unsigned, 8> ActiveBlocks;
- void reset(unsigned Reg) {
+ void reset(InterferenceCache &Cache, unsigned Reg) {
PhysReg = Reg;
+ Intf.setPhysReg(Cache, Reg);
LiveBundles.clear();
ActiveBlocks.clear();
}
@@ -206,8 +208,8 @@
float calcSpillCost();
bool addSplitConstraints(InterferenceCache::Cursor, float&);
void addThroughConstraints(InterferenceCache::Cursor, ArrayRef<unsigned>);
- void growRegion(GlobalSplitCandidate &Cand, InterferenceCache::Cursor);
- float calcGlobalSplitCost(GlobalSplitCandidate&, InterferenceCache::Cursor);
+ void growRegion(GlobalSplitCandidate &Cand);
+ float calcGlobalSplitCost(GlobalSplitCandidate&);
void splitAroundRegion(LiveInterval&, GlobalSplitCandidate&,
SmallVectorImpl<LiveInterval*>&);
void calcGapWeights(unsigned, SmallVectorImpl<float>&);
@@ -720,8 +722,7 @@
SpillPlacer->addLinks(ArrayRef<unsigned>(TBS, T));
}
-void RAGreedy::growRegion(GlobalSplitCandidate &Cand,
- InterferenceCache::Cursor Intf) {
+void RAGreedy::growRegion(GlobalSplitCandidate &Cand) {
// Keep track of through blocks that have not been added to SpillPlacer.
BitVector Todo = SA->getThroughBlocks();
SmallVectorImpl<unsigned> &ActiveBlocks = Cand.ActiveBlocks;
@@ -753,7 +754,7 @@
// Any new blocks to add?
if (ActiveBlocks.size() == AddedTo)
break;
- addThroughConstraints(Intf,
+ addThroughConstraints(Cand.Intf,
ArrayRef<unsigned>(ActiveBlocks).slice(AddedTo));
AddedTo = ActiveBlocks.size();
@@ -794,8 +795,7 @@
/// pattern in LiveBundles. This cost should be added to the local cost of the
/// interference pattern in SplitConstraints.
///
-float RAGreedy::calcGlobalSplitCost(GlobalSplitCandidate &Cand,
- InterferenceCache::Cursor Intf) {
+float RAGreedy::calcGlobalSplitCost(GlobalSplitCandidate &Cand) {
float GlobalCost = 0;
const BitVector &LiveBundles = Cand.LiveBundles;
ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
@@ -822,8 +822,8 @@
continue;
if (RegIn && RegOut) {
// We need double spill code if this block has interference.
- Intf.moveToBlock(Number);
- if (Intf.hasInterference())
+ Cand.Intf.moveToBlock(Number);
+ if (Cand.Intf.hasInterference())
GlobalCost += 2*SpillPlacer->getBlockFrequency(Number);
continue;
}
@@ -853,7 +853,12 @@
dbgs() << ".\n";
});
- InterferenceCache::Cursor Intf(IntfCache, Cand.PhysReg);
+ InterferenceCache::Cursor &Intf = Cand.Intf;
+
+ // FIXME: We need cache reference counts to guarantee that Intf hasn't been
+ // clobbered.
+ Intf.setPhysReg(IntfCache, Cand.PhysReg);
+
LiveRangeEdit LREdit(VirtReg, NewVRegs, this);
SE->reset(LREdit);
@@ -1243,17 +1248,18 @@
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(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;
- InterferenceCache::Cursor Intf(IntfCache, PhysReg);
- if (!addSplitConstraints(Intf, Cost)) {
+ if (!addSplitConstraints(Cand.Intf, Cost)) {
DEBUG(dbgs() << PrintReg(PhysReg, TRI) << "\tno positive bundles\n");
continue;
}
@@ -1268,28 +1274,29 @@
});
continue;
}
- growRegion(GlobalCand[Cand], Intf);
+ 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], Intf);
+ 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)