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author | Evan Cheng <evan.cheng@apple.com> | 2008-03-05 22:09:42 +0000 |
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committer | Evan Cheng <evan.cheng@apple.com> | 2008-03-05 22:09:42 +0000 |
commit | ecb2a8b9bc727308a0ccfbd92c87b7533c68aab8 (patch) | |
tree | 4314f6810c9b690c54dd12139bffae6b5c113344 /lib | |
parent | c5eb380b60689c0993e07025872a9038be967b40 (diff) | |
download | external_llvm-ecb2a8b9bc727308a0ccfbd92c87b7533c68aab8.zip external_llvm-ecb2a8b9bc727308a0ccfbd92c87b7533c68aab8.tar.gz external_llvm-ecb2a8b9bc727308a0ccfbd92c87b7533c68aab8.tar.bz2 |
Fix a coalescer bug wrt how dead copy interval is shortened.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47966 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/CodeGen/SimpleRegisterCoalescing.cpp | 43 | ||||
-rw-r--r-- | lib/CodeGen/SimpleRegisterCoalescing.h | 6 |
2 files changed, 36 insertions, 13 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp index 03b27ac..d7c2d96 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -451,6 +451,30 @@ SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg, } } +/// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially +/// extended by a dead copy. Mark the last use (if any) of the val# as kill +/// as ends the live range there. If there isn't another use, then this +/// live range is dead. +void SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li, + MachineInstr *CopyMI) { + unsigned CopyIdx = li_->getInstructionIndex(CopyMI); + LiveInterval::iterator MLR = + li.FindLiveRangeContaining(li_->getDefIndex(CopyIdx)); + unsigned RemoveStart = MLR->start; + unsigned RemoveEnd = MLR->end; + unsigned LastUseIdx; + MachineOperand *LastUse = lastRegisterUse(RemoveStart, CopyIdx, li.reg, + LastUseIdx); + if (LastUse) { + // Shorten the liveinterval to the end of last use. + LastUse->setIsKill(); + RemoveStart = li_->getDefIndex(LastUseIdx); + } + li.removeRange(RemoveStart, RemoveEnd, true); + if (li.empty()) + li_->removeInterval(li.reg); +} + /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg, /// which are the src/dst of the copy instruction CopyMI. This returns true /// if the copy was successfully coalesced away. If it is not currently @@ -599,23 +623,22 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) { SrcInt.FindLiveRangeContaining(li_->getUseIndex(CopyIdx)); RemoveStart = SrcStart = SrcLR->start; RemoveEnd = SrcEnd = SrcLR->end; - // The instruction which defines the src is only truly dead if there are - // no intermediate uses and there isn't a use beyond the copy. - // FIXME: find the last use, mark is kill and shorten the live range. if (SrcEnd > li_->getDefIndex(CopyIdx)) { + // If there are other uses of SrcReg beyond the copy, there is nothing to do. isDead = false; } else { unsigned LastUseIdx; MachineOperand *LastUse = lastRegisterUse(SrcStart, CopyIdx, SrcReg, LastUseIdx); if (LastUse) { - // Shorten the liveinterval to the end of last use. + // There are uses before the copy, just shorten the live range to the end + // of last use. LastUse->setIsKill(); isDead = false; isShorten = true; RemoveStart = li_->getDefIndex(LastUseIdx); - RemoveEnd = SrcEnd; } else { + // This live range is truly dead. Remove it. MachineInstr *SrcMI = li_->getInstructionFromIndex(SrcStart); if (SrcMI && SrcMI->modifiesRegister(SrcReg, tri_)) // A dead def should have a single cycle interval. @@ -1531,16 +1554,10 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) { if (tii_->isMoveInstr(*mii, srcReg, dstReg) && srcReg == dstReg) { // remove from def list LiveInterval &RegInt = li_->getOrCreateInterval(srcReg); - MachineOperand *MO = mii->findRegisterDefOperand(dstReg, false); // If def of this move instruction is dead, remove its live range from // the dstination register's live interval. - if (MO->isDead()) { - unsigned MoveIdx = li_->getDefIndex(li_->getInstructionIndex(mii)); - LiveInterval::iterator MLR = RegInt.FindLiveRangeContaining(MoveIdx); - RegInt.removeRange(MLR->start, MoveIdx+1, true); - if (RegInt.empty()) - li_->removeInterval(srcReg); - } + if (mii->registerDefIsDead(dstReg)) + ShortenDeadCopyLiveRange(RegInt, mii); li_->RemoveMachineInstrFromMaps(mii); mii = mbbi->erase(mii); ++numPeep; diff --git a/lib/CodeGen/SimpleRegisterCoalescing.h b/lib/CodeGen/SimpleRegisterCoalescing.h index 1c21620..543d470 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.h +++ b/lib/CodeGen/SimpleRegisterCoalescing.h @@ -201,6 +201,12 @@ namespace llvm { /// subregister. void UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg, unsigned SubIdx); + /// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially + /// extended by a dead copy. Mark the last use (if any) of the val# as kill + /// as ends the live range there. If there isn't another use, then this + /// live range is dead. + void ShortenDeadCopyLiveRange(LiveInterval &li, MachineInstr *CopyMI); + /// lastRegisterUse - Returns the last use of the specific register between /// cycles Start and End or NULL if there are no uses. MachineOperand *lastRegisterUse(unsigned Start, unsigned End, unsigned Reg, |