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LiveIntervalAnalysis: Add subregister aware variants pruneValue().

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llvm-svn: 223886
This commit is contained in:
Matthias Braun 2014-12-10 01:12:36 +00:00
parent 3c79d93d70
commit b3f3f853d1
3 changed files with 32 additions and 15 deletions
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13
include/llvm/CodeGen/LiveIntervalAnalysis.h
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@ -164,14 +164,21 @@ namespace llvm {
/// See also LiveRangeCalc::extend().
void extendToIndices(LiveRange &LR, ArrayRef<SlotIndex> Indices);
/// pruneValue - If an LI value is live at Kill, prune its live range by
/// removing any liveness reachable from Kill. Add live range end points to
/// If @p LR has a live value at @p Kill, prune its live range by removing
/// any liveness reachable from Kill. Add live range end points to
/// EndPoints such that extendToIndices(LI, EndPoints) will reconstruct the
/// value's live range.
///
/// Calling pruneValue() and extendToIndices() can be used to reconstruct
/// SSA form after adding defs to a virtual register.
void pruneValue(LiveInterval *LI, SlotIndex Kill,
void pruneValue(LiveRange &LR, SlotIndex Kill,
SmallVectorImpl<SlotIndex> *EndPoints);
/// Subregister aware variant of pruneValue(LiveRange &LR, SlotIndex Kill,
/// SmallVectorImpl<SlotIndex> &EndPoints). Prunes the value in the main
/// range and all sub ranges.
void pruneValue(LiveInterval &LI, SlotIndex Kill,
SmallVectorImpl<SlotIndex> *EndPoints);
SlotIndexes *getSlotIndexes() const {

30
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -542,26 +542,25 @@ void LiveIntervals::extendToIndices(LiveRange &LR,
LRCalc->extend(LR, Indices[i]);
}
void LiveIntervals::pruneValue(LiveInterval *LI, SlotIndex Kill,
void LiveIntervals::pruneValue(LiveRange &LR, SlotIndex Kill,
SmallVectorImpl<SlotIndex> *EndPoints) {
LiveQueryResult LRQ = LI->Query(Kill);
VNInfo *VNI = LRQ.valueOut();
LiveQueryResult LRQ = LR.Query(Kill);
VNInfo *VNI = LRQ.valueOutOrDead();
if (!VNI)
return;
MachineBasicBlock *KillMBB = Indexes->getMBBFromIndex(Kill);
SlotIndex MBBStart, MBBEnd;
std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(KillMBB);
SlotIndex MBBEnd = Indexes->getMBBEndIdx(KillMBB);
// If VNI isn't live out from KillMBB, the value is trivially pruned.
if (LRQ.endPoint() < MBBEnd) {
LI->removeSegment(Kill, LRQ.endPoint());
LR.removeSegment(Kill, LRQ.endPoint());
if (EndPoints) EndPoints->push_back(LRQ.endPoint());
return;
}
// VNI is live out of KillMBB.
LI->removeSegment(Kill, MBBEnd);
LR.removeSegment(Kill, MBBEnd);
if (EndPoints) EndPoints->push_back(MBBEnd);
// Find all blocks that are reachable from KillMBB without leaving VNI's live
@ -578,8 +577,9 @@ void LiveIntervals::pruneValue(LiveInterval *LI, SlotIndex Kill,
MachineBasicBlock *MBB = *I;
// Check if VNI is live in to MBB.
SlotIndex MBBStart, MBBEnd;
std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(MBB);
LiveQueryResult LRQ = LI->Query(MBBStart);
LiveQueryResult LRQ = LR.Query(MBBStart);
if (LRQ.valueIn() != VNI) {
// This block isn't part of the VNI segment. Prune the search.
I.skipChildren();
@ -588,20 +588,30 @@ void LiveIntervals::pruneValue(LiveInterval *LI, SlotIndex Kill,
// Prune the search if VNI is killed in MBB.
if (LRQ.endPoint() < MBBEnd) {
LI->removeSegment(MBBStart, LRQ.endPoint());
LR.removeSegment(MBBStart, LRQ.endPoint());
if (EndPoints) EndPoints->push_back(LRQ.endPoint());
I.skipChildren();
continue;
}
// VNI is live through MBB.
LI->removeSegment(MBBStart, MBBEnd);
LR.removeSegment(MBBStart, MBBEnd);
if (EndPoints) EndPoints->push_back(MBBEnd);
++I;
}
}
}
void LiveIntervals::pruneValue(LiveInterval &LI, SlotIndex Kill,
SmallVectorImpl<SlotIndex> *EndPoints) {
pruneValue((LiveRange&)LI, Kill, EndPoints);
for (LiveInterval::subrange_iterator SR = LI.subrange_begin(),
SE = LI.subrange_end(); SR != SE; ++SR) {
pruneValue(*SR, Kill, nullptr);
}
}
//===----------------------------------------------------------------------===//
// Register allocator hooks.
//

4
lib/CodeGen/RegisterCoalescer.cpp
View File

@ -1917,7 +1917,7 @@ void JoinVals::pruneValues(JoinVals &Other,
break;
case CR_Replace: {
// This value takes precedence over the value in Other.LI.
LIS->pruneValue(&Other.LI, Def, &EndPoints);
LIS->pruneValue(Other.LI, Def, &EndPoints);
// Check if we're replacing an IMPLICIT_DEF value. The IMPLICIT_DEF
// instructions are only inserted to provide a live-out value for PHI
// predecessors, so the instruction should simply go away once its value
@ -1951,7 +1951,7 @@ void JoinVals::pruneValues(JoinVals &Other,
// We can no longer trust the value mapping computed by
// computeAssignment(), the value that was originally copied could have
// been replaced.
LIS->pruneValue(&LI, Def, &EndPoints);
LIS->pruneValue(LI, Def, &EndPoints);
DEBUG(dbgs() << "\t\tpruned all of " << PrintReg(LI.reg) << " at "
<< Def << ": " << LI << '\n');
}