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Add a safe-guard against repeated splitting for some rare cases.

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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
This commit is contained in:
Jakob Stoklund Olesen
2011-04-26 22:33:12 +00:00
parent d5c7f7cb5e
commit 9f4b893b84
3 changed files with 43 additions and 3 deletions
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23
lib/CodeGen/SplitKit.cpp
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@ -221,6 +221,29 @@ bool SplitAnalysis::calcLiveBlockInfo() {
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);