Handle critical loop predecessors by making both inside and outside registers
live out.
This doesn't prevent us from inserting a loop preheader later on, if that is
better.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117424 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index cf29756..a89a977 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -512,7 +512,7 @@
// extendTo - Find the last li_ value defined in MBB at or before Idx. The
// parentli_ is assumed to be live at Idx. Extend the live range to Idx.
// Return the found VNInfo, or NULL.
-VNInfo *LiveIntervalMap::extendTo(MachineBasicBlock *MBB, SlotIndex Idx) {
+VNInfo *LiveIntervalMap::extendTo(const MachineBasicBlock *MBB, SlotIndex Idx) {
assert(li_ && "call reset first");
LiveInterval::iterator I = std::upper_bound(li_->begin(), li_->end(), Idx);
if (I == li_->begin())
@@ -861,6 +861,16 @@
dupli_.addSimpleRange(LR.start, LR.end, LR.valno);
}
}
+
+ // Extend dupli_ to be live out of any critical loop predecessors.
+ // This means we have multiple registers live out of those blocks.
+ // The alternative would be to split the critical edges.
+ if (criticalPreds_.empty())
+ return;
+ for (SplitAnalysis::BlockPtrSet::iterator I = criticalPreds_.begin(),
+ E = criticalPreds_.end(); I != E; ++I)
+ dupli_.extendTo(*I, lis_.getMBBEndIdx(*I).getPrevSlot());
+ criticalPreds_.clear();
}
void SplitEditor::finish() {
@@ -924,6 +934,9 @@
sa_.getCriticalExits(Blocks, CriticalExits);
assert(CriticalExits.empty() && "Cannot break critical exits yet");
+ // Get critical predecessors so computeRemainder can deal with them.
+ sa_.getCriticalPreds(Blocks, criticalPreds_);
+
// Create new live interval for the loop.
openIntv();