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Create new intervals for isolated blocks during region splitting.

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This merges the behavior of splitSingleBlocks into splitAroundRegion, so the
RS_Region and RS_Block register stages can be coalesced. That means the leftover
intervals after region splitting go directly to spilling instead of a second
pass of per-block splitting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129379 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-04-12 19:32:53 +00:00
parent 5d7dcd3335
commit fd5c51342a
3 changed files with 46 additions and 37 deletions
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44
lib/CodeGen/RegAllocGreedy.cpp
View File

@ -95,8 +95,7 @@ class RAGreedy : public MachineFunctionPass,
RS_New, ///< Never seen before.
RS_First, ///< First time in the queue.
RS_Second, ///< Second time in the queue.
RS_Region, ///< Produced by region splitting.
RS_Block, ///< Produced by per-block splitting.
RS_Global, ///< Produced by global splitting.
RS_Local, ///< Produced by local splitting.
RS_Spill ///< Produced by spilling.
};
@ -636,7 +635,7 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
SE->reset(LREdit);
// Create the main cross-block interval.
SE->openIntv();
const unsigned MainIntv = SE->openIntv();
// First add all defs that are live out of a block.
ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
@ -645,6 +644,14 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
bool RegIn = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
bool RegOut = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
// Create separate intervals for isolated blocks with multiple uses.
if (!RegIn && !RegOut && BI.FirstUse != BI.LastUse) {
DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " isolated.\n");
SE->splitSingleBlock(BI);
SE->selectIntv(MainIntv);
continue;
}
// Should the register be live out?
if (!BI.LiveOut || !RegOut)
continue;
@ -894,7 +901,7 @@ unsigned RAGreedy::tryRegionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
return 0;
splitAroundRegion(VirtReg, BestReg, BestBundles, NewVRegs);
setStage(NewVRegs.begin(), NewVRegs.end(), RS_Region);
setStage(NewVRegs.begin(), NewVRegs.end(), RS_Global);
return 0;
}
@ -1185,30 +1192,25 @@ unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order,
// Don't iterate global splitting.
// Move straight to spilling if this range was produced by a global split.
LiveRangeStage Stage = getStage(VirtReg);
if (Stage >= RS_Block)
if (getStage(VirtReg) >= RS_Global)
return 0;
SA->analyze(&VirtReg);
// First try to split around a region spanning multiple blocks.
if (Stage < RS_Region) {
unsigned PhysReg = tryRegionSplit(VirtReg, Order, NewVRegs);
if (PhysReg || !NewVRegs.empty())
return PhysReg;
}
unsigned PhysReg = tryRegionSplit(VirtReg, Order, NewVRegs);
if (PhysReg || !NewVRegs.empty())
return PhysReg;
// Then isolate blocks with multiple uses.
if (Stage < RS_Block) {
SplitAnalysis::BlockPtrSet Blocks;
if (SA->getMultiUseBlocks(Blocks)) {
LiveRangeEdit LREdit(VirtReg, NewVRegs, this);
SE->reset(LREdit);
SE->splitSingleBlocks(Blocks);
setStage(NewVRegs.begin(), NewVRegs.end(), RS_Block);
if (VerifyEnabled)
MF->verify(this, "After splitting live range around basic blocks");
}
SplitAnalysis::BlockPtrSet Blocks;
if (SA->getMultiUseBlocks(Blocks)) {
LiveRangeEdit LREdit(VirtReg, NewVRegs, this);
SE->reset(LREdit);
SE->splitSingleBlocks(Blocks);
setStage(NewVRegs.begin(), NewVRegs.end(), RS_Global);
if (VerifyEnabled)
MF->verify(this, "After splitting live range around basic blocks");
}
// Don't assign any physregs.

34
lib/CodeGen/SplitKit.cpp
View File

@ -935,6 +935,22 @@ bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) {
return !Blocks.empty();
}
void SplitEditor::splitSingleBlock(const SplitAnalysis::BlockInfo &BI) {
openIntv();
SlotIndex LastSplitPoint = SA.getLastSplitPoint(BI.MBB->getNumber());
SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstUse,
LastSplitPoint));
if (!BI.LiveOut || BI.LastUse < LastSplitPoint) {
useIntv(SegStart, leaveIntvAfter(BI.LastUse));
} else {
// The last use is after the last valid split point.
SlotIndex SegStop = leaveIntvBefore(LastSplitPoint);
useIntv(SegStart, SegStop);
overlapIntv(SegStop, BI.LastUse);
}
closeIntv();
}
/// splitSingleBlocks - Split CurLI into a separate live interval inside each
/// basic block in Blocks.
void SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) {
@ -942,22 +958,8 @@ void SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) {
ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA.getUseBlocks();
for (unsigned i = 0; i != UseBlocks.size(); ++i) {
const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
if (!Blocks.count(BI.MBB))
continue;
openIntv();
SlotIndex LastSplitPoint = SA.getLastSplitPoint(BI.MBB->getNumber());
SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstUse,
LastSplitPoint));
if (!BI.LiveOut || BI.LastUse < LastSplitPoint) {
useIntv(SegStart, leaveIntvAfter(BI.LastUse));
} else {
// The last use is after the last valid split point.
SlotIndex SegStop = leaveIntvBefore(LastSplitPoint);
useIntv(SegStart, SegStop);
overlapIntv(SegStop, BI.LastUse);
}
closeIntv();
if (Blocks.count(BI.MBB))
splitSingleBlock(BI);
}
finish();
}

5
lib/CodeGen/SplitKit.h
View File

@ -347,6 +347,11 @@ public:
// ===--- High level methods ---===
/// splitSingleBlock - Split CurLI into a separate live interval around the
/// uses in a single block. This is intended to be used as part of a larger
/// split, and doesn't call finish().
void splitSingleBlock(const SplitAnalysis::BlockInfo &BI);
/// splitSingleBlocks - Split CurLI into a separate live interval inside each
/// basic block in Blocks.
void splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks);