Work around a coalescer bug.
The coalescer can in very rare cases leave too large live intervals around after
rematerializing cheap-as-a-move instructions.
Linear scan doesn't really care, but live range splitting gets very confused
when a live range is killed by a ghost instruction.
I will fix this properly in the coalescer after 2.9 branches.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127096 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 4adf8f7..c4ae8c4 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -81,7 +81,20 @@
UsingBlocks[MBB]++;
}
array_pod_sort(UseSlots.begin(), UseSlots.end());
- calcLiveBlockInfo();
+
+ // Compute per-live block info.
+ if (!calcLiveBlockInfo()) {
+ // FIXME: calcLiveBlockInfo found inconsistencies in the live range.
+ // I am looking at you, SimpleRegisterCoalescing!
+ DEBUG(dbgs() << "*** Fixing inconsistent live interval! ***\n");
+ const_cast<LiveIntervals&>(LIS)
+ .shrinkToUses(const_cast<LiveInterval*>(CurLI));
+ LiveBlocks.clear();
+ bool fixed = calcLiveBlockInfo();
+ (void)fixed;
+ assert(fixed && "Couldn't fix broken live interval");
+ }
+
DEBUG(dbgs() << " counted "
<< UsingInstrs.size() << " instrs, "
<< UsingBlocks.size() << " blocks.\n");
@@ -89,9 +102,9 @@
/// calcLiveBlockInfo - Fill the LiveBlocks array with information about blocks
/// where CurLI is live.
-void SplitAnalysis::calcLiveBlockInfo() {
+bool SplitAnalysis::calcLiveBlockInfo() {
if (CurLI->empty())
- return;
+ return true;
LiveInterval::const_iterator LVI = CurLI->begin();
LiveInterval::const_iterator LVE = CurLI->end();
@@ -154,6 +167,11 @@
BI.LiveThrough = !hasGap && BI.LiveIn && BI.LiveOut;
LiveBlocks.push_back(BI);
+ // FIXME: This should never happen. The live range stops or starts without a
+ // corresponding use. An earlier pass did something wrong.
+ if (!BI.LiveThrough && !BI.Uses)
+ return false;
+
// LVI is now at LVE or LVI->end >= Stop.
if (LVI == LVE)
break;
@@ -168,6 +186,7 @@
else
MFI = LIS.getMBBFromIndex(LVI->start);
}
+ return true;
}
bool SplitAnalysis::isOriginalEndpoint(SlotIndex Idx) const {