The number of blocks covered by a live range must be strictly decreasing when
splitting, otherwise we can't allow repeated splitting.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130249
91177308-0d34-0410-b5e6-
96231b3b80d8
SmallVector<unsigned, 8> IntvMap;
SE->finish(&IntvMap);
LRStage.resize(MRI->getNumVirtRegs());
+ unsigned OrigBlocks = SA->getNumThroughBlocks() + SA->getUseBlocks().size();
// Sort out the new intervals created by splitting. We get four kinds:
// - Remainder intervals should not be split again.
continue;
}
- // Other intervals are treated as new. This includes the main interval,
- // local intervals created for blocks with multiple uses, and anything
- // created by DCE.
+ // Main interval. Allow repeated splitting as long as the number of live
+ // blocks is strictly decreasing.
+ if (IntvMap[i] == MainIntv) {
+ if (SA->countLiveBlocks(LREdit.get(i)) >= OrigBlocks) {
+ DEBUG(dbgs() << "Main interval covers the same " << OrigBlocks
+ << " blocks as original.\n");
+ // Don't allow repeated splitting as a safe guard against looping.
+ LRStage[Reg] = RS_Global;
+ }
+ continue;
+ }
+
+ // Other intervals are treated as new. This includes local intervals created
+ // for blocks with multiple uses, and anything created by DCE.
}
if (VerifyEnabled)
return true;
}
+unsigned SplitAnalysis::countLiveBlocks(const LiveInterval *cli) const {
+ if (cli->empty())
+ return 0;
+ LiveInterval *li = const_cast<LiveInterval*>(cli);
+ LiveInterval::iterator LVI = li->begin();
+ LiveInterval::iterator LVE = li->end();
+ unsigned Count = 0;
+
+ // Loop over basic blocks where li is live.
+ MachineFunction::const_iterator MFI = LIS.getMBBFromIndex(LVI->start);
+ SlotIndex Stop = LIS.getMBBEndIdx(MFI);
+ for (;;) {
+ ++Count;
+ LVI = li->advanceTo(LVI, Stop);
+ if (LVI == LVE)
+ return Count;
+ do {
+ ++MFI;
+ Stop = LIS.getMBBEndIdx(MFI);
+ } while (Stop <= LVI->start);
+ }
+}
+
bool SplitAnalysis::isOriginalEndpoint(SlotIndex Idx) const {
unsigned OrigReg = VRM.getOriginal(CurLI->reg);
const LiveInterval &Orig = LIS.getInterval(OrigReg);
/// getThroughBlocks - Return the set of through blocks.
const BitVector &getThroughBlocks() const { return ThroughBlocks; }
+ /// countLiveBlocks - Return the number of blocks where li is live.
+ /// This is guaranteed to return the same number as getNumThroughBlocks() +
+ /// getUseBlocks().size() after calling analyze(li).
+ unsigned countLiveBlocks(const LiveInterval *li) const;
+
typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet;
/// getMultiUseBlocks - Add basic blocks to Blocks that may benefit from