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It is always good to do a cross-class join when the large register has a tiny interval.
Also avoid division by zero. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95917 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1148,12 +1148,14 @@ SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned LargeReg,
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LiveInterval &SmallInt = li_->getInterval(SmallReg);
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unsigned LargeSize = li_->getApproximateInstructionCount(LargeInt);
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unsigned SmallSize = li_->getApproximateInstructionCount(SmallInt);
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if (SmallSize > Threshold || LargeSize > Threshold)
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if ((float)std::distance(mri_->use_nodbg_begin(SmallReg),
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mri_->use_nodbg_end()) / SmallSize <
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(float)std::distance(mri_->use_nodbg_begin(LargeReg),
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mri_->use_nodbg_end()) / LargeSize)
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if (LargeSize > Threshold) {
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unsigned SmallUses = std::distance(mri_->use_nodbg_begin(SmallReg),
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mri_->use_nodbg_end());
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unsigned LargeUses = std::distance(mri_->use_nodbg_begin(LargeReg),
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mri_->use_nodbg_end());
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if (SmallUses*LargeSize < LargeUses*SmallSize)
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return false;
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}
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return true;
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}
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@ -1561,7 +1563,10 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
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(isExtSubReg || DstRC->isASubClass()) &&
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!isWinToJoinCrossClass(LargeReg, SmallReg,
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allocatableRCRegs_[NewRC].count())) {
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DEBUG(dbgs() << "\tSrc/Dest are different register classes.\n");
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DEBUG(dbgs() << "\tSrc/Dest are different register classes: "
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<< SrcRC->getName() << "/"
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<< DstRC->getName() << " -> "
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<< NewRC->getName() << ".\n");
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// Allow the coalescer to try again in case either side gets coalesced to
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// a physical register that's compatible with the other side. e.g.
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// r1024 = MOV32to32_ r1025
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