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- Merge UsedBlocks info after two virtual registers are coalesced.

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- Use distance to closest use to determine whether to abort coalescing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35141 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2007-03-18 09:05:55 +00:00
parent e951cd1647
commit cf596c54d4
1 changed files with 30 additions and 23 deletions
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43
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -940,49 +940,51 @@ bool LiveIntervals::JoinCopy(MachineInstr *CopyMI,
if (ReduceJoinPhys && !isDead && if (ReduceJoinPhys && !isDead &&
MRegisterInfo::isPhysicalRegister(repSrcReg)) { MRegisterInfo::isPhysicalRegister(repSrcReg)) {
// Small function. No need to worry! // Small function. No need to worry!
if (r2iMap_.size() <= allocatableRegs_.size() * 2) unsigned Threshold = allocatableRegs_.count() * 2;
if (r2iMap_.size() <= Threshold)
goto TryJoin; goto TryJoin;
LiveVariables::VarInfo& dvi = lv_->getVarInfo(repDstReg); LiveVariables::VarInfo& dvi = lv_->getVarInfo(repDstReg);
// Is the value used in the current BB or any immediate successroe BB? // Is the value used in the current BB or any immediate successroe BB?
MachineBasicBlock *SrcBB = CopyMI->getParent(); MachineBasicBlock *CopyBB = CopyMI->getParent();
if (!dvi.UsedBlocks[SrcBB->getNumber()]) { if (dvi.UsedBlocks[CopyBB->getNumber()])
for (MachineBasicBlock::succ_iterator SI = SrcBB->succ_begin(), goto TryJoin;
SE = SrcBB->succ_end(); SI != SE; ++SI) { for (MachineBasicBlock::succ_iterator SI = CopyBB->succ_begin(),
SE = CopyBB->succ_end(); SI != SE; ++SI) {
MachineBasicBlock *SuccMBB = *SI; MachineBasicBlock *SuccMBB = *SI;
if (dvi.UsedBlocks[SuccMBB->getNumber()]) if (dvi.UsedBlocks[SuccMBB->getNumber()])
goto TryJoin; goto TryJoin;
} }
}
// Ok, no use in this BB and no use in immediate successor BB's. Be really // Ok, no use in this BB and no use in immediate successor BB's. Be really
// careful now! // careful now!
// It's only used in one BB, forget about it! // It's only used in one BB, forget about it!
if (dvi.UsedBlocks.count() <= 1) { if (dvi.UsedBlocks.count() < 2) {
++numAborts; ++numAborts;
return false; return false;
} }
// Examine all the blocks where the value is used. If any is in the same // Determine whether to allow coalescing based on how far the closest
// loop, then it's ok. Or if the current BB is a preheader of any of the // use is.
// loop that uses this value, that's ok as well. unsigned CopyIdx = getInstructionIndex(CopyMI);
const LoopInfo &LI = getAnalysis<LoopInfo>(); unsigned MinDist = i2miMap_.size() * InstrSlots::NUM;
const Loop *L = LI.getLoopFor(SrcBB->getBasicBlock());
int UseBBNum = dvi.UsedBlocks.find_first(); int UseBBNum = dvi.UsedBlocks.find_first();
while (UseBBNum != -1) { while (UseBBNum != -1) {
MachineBasicBlock *UseBB = mf_->getBlockNumbered(UseBBNum); MachineBasicBlock *UseBB = mf_->getBlockNumbered(UseBBNum);
const Loop *UL = LI.getLoopFor(UseBB->getBasicBlock()); unsigned UseIdx = getMBBStartIdx(UseBB);
if ((UL && UL == L) || // A use in the same loop if (UseIdx > CopyIdx) {
(UL && L && // A use in a loop and this BB is the preheader MinDist = std::min(MinDist, UseIdx - CopyIdx);
UL->getLoopPreheader() == SrcBB->getBasicBlock())) if (MinDist <= Threshold)
goto TryJoin; break;
}
UseBBNum = dvi.UsedBlocks.find_next(UseBBNum); UseBBNum = dvi.UsedBlocks.find_next(UseBBNum);
} }
if (MinDist > Threshold) {
// Don't do it! // Don't do it!
++numAborts; ++numAborts;
return false; return false;
} }
}
TryJoin: TryJoin:
// Okay, attempt to join these two intervals. On failure, this returns false. // Okay, attempt to join these two intervals. On failure, this returns false.
@ -1038,6 +1040,11 @@ TryJoin:
if (MRegisterInfo::isPhysicalRegister(repDstReg)) { if (MRegisterInfo::isPhysicalRegister(repDstReg)) {
for (const unsigned *AS = mri_->getAliasSet(repDstReg); *AS; ++AS) for (const unsigned *AS = mri_->getAliasSet(repDstReg); *AS; ++AS)
getInterval(*AS).MergeInClobberRanges(SrcInt); getInterval(*AS).MergeInClobberRanges(SrcInt);
} else {
// Merge UsedBlocks info if the destination is a virtual register.
LiveVariables::VarInfo& dVI = lv_->getVarInfo(repDstReg);
LiveVariables::VarInfo& sVI = lv_->getVarInfo(repSrcReg);
dVI.UsedBlocks |= sVI.UsedBlocks;
} }
DOUT << "\n\t\tJoined. Result = "; DestInt.print(DOUT, mri_); DOUT << "\n\t\tJoined. Result = "; DestInt.print(DOUT, mri_);