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Handle critical loop predecessors by making both inside and outside registers

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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
This commit is contained in:
Jakob Stoklund Olesen 2010-10-27 00:39:07 +00:00
parent 0960a650b7
commit c95c1465fd
2 changed files with 19 additions and 2 deletions
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15
lib/CodeGen/SplitKit.cpp
View File

@ -512,7 +512,7 @@ VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx,
// 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 @@ void SplitEditor::computeRemainder() {
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 @@ void SplitEditor::splitAroundLoop(const MachineLoop *Loop) {
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();

6
lib/CodeGen/SplitKit.h
View File

@ -200,7 +200,7 @@ public:
// 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 include
// Idx. Return the found VNInfo, or NULL.
VNInfo *extendTo(MachineBasicBlock *MBB, SlotIndex Idx);
VNInfo *extendTo(const MachineBasicBlock *MBB, SlotIndex Idx);
/// isMapped - Return true is ParentVNI is a known mapped value. It may be a
/// simple 1-1 mapping or a complex mapping to later defs.
@ -271,6 +271,10 @@ class SplitEditor {
/// truncating any overlap with intervals_.
void addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI);
/// criticalPreds_ - Set of basic blocks where both dupli and openli should be
/// live out because of a critical edge.
SplitAnalysis::BlockPtrSet criticalPreds_;
/// computeRemainder - Compute the dupli liveness as the complement of all the
/// new intervals.
void computeRemainder();