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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
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@ -451,6 +451,30 @@ SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
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}
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}
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/// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially
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/// extended by a dead copy. Mark the last use (if any) of the val# as kill
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/// as ends the live range there. If there isn't another use, then this
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/// live range is dead.
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void SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li,
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MachineInstr *CopyMI) {
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unsigned CopyIdx = li_->getInstructionIndex(CopyMI);
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LiveInterval::iterator MLR =
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li.FindLiveRangeContaining(li_->getDefIndex(CopyIdx));
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unsigned RemoveStart = MLR->start;
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unsigned RemoveEnd = MLR->end;
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unsigned LastUseIdx;
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MachineOperand *LastUse = lastRegisterUse(RemoveStart, CopyIdx, li.reg,
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LastUseIdx);
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if (LastUse) {
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// Shorten the liveinterval to the end of last use.
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LastUse->setIsKill();
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RemoveStart = li_->getDefIndex(LastUseIdx);
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}
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li.removeRange(RemoveStart, RemoveEnd, true);
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if (li.empty())
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li_->removeInterval(li.reg);
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}
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/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
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/// which are the src/dst of the copy instruction CopyMI. This returns true
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/// if the copy was successfully coalesced away. If it is not currently
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@ -599,23 +623,22 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
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SrcInt.FindLiveRangeContaining(li_->getUseIndex(CopyIdx));
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RemoveStart = SrcStart = SrcLR->start;
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RemoveEnd = SrcEnd = SrcLR->end;
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// The instruction which defines the src is only truly dead if there are
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// no intermediate uses and there isn't a use beyond the copy.
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// FIXME: find the last use, mark is kill and shorten the live range.
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if (SrcEnd > li_->getDefIndex(CopyIdx)) {
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// If there are other uses of SrcReg beyond the copy, there is nothing to do.
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isDead = false;
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} else {
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unsigned LastUseIdx;
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MachineOperand *LastUse =
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lastRegisterUse(SrcStart, CopyIdx, SrcReg, LastUseIdx);
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if (LastUse) {
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// Shorten the liveinterval to the end of last use.
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// There are uses before the copy, just shorten the live range to the end
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// of last use.
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LastUse->setIsKill();
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isDead = false;
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isShorten = true;
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RemoveStart = li_->getDefIndex(LastUseIdx);
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RemoveEnd = SrcEnd;
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} else {
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// This live range is truly dead. Remove it.
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MachineInstr *SrcMI = li_->getInstructionFromIndex(SrcStart);
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if (SrcMI && SrcMI->modifiesRegister(SrcReg, tri_))
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// A dead def should have a single cycle interval.
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@ -1531,16 +1554,10 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
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if (tii_->isMoveInstr(*mii, srcReg, dstReg) && srcReg == dstReg) {
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// remove from def list
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LiveInterval &RegInt = li_->getOrCreateInterval(srcReg);
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MachineOperand *MO = mii->findRegisterDefOperand(dstReg, false);
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// If def of this move instruction is dead, remove its live range from
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// the dstination register's live interval.
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if (MO->isDead()) {
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unsigned MoveIdx = li_->getDefIndex(li_->getInstructionIndex(mii));
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LiveInterval::iterator MLR = RegInt.FindLiveRangeContaining(MoveIdx);
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RegInt.removeRange(MLR->start, MoveIdx+1, true);
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if (RegInt.empty())
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li_->removeInterval(srcReg);
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}
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if (mii->registerDefIsDead(dstReg))
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ShortenDeadCopyLiveRange(RegInt, mii);
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li_->RemoveMachineInstrFromMaps(mii);
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mii = mbbi->erase(mii);
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++numPeep;
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@ -201,6 +201,12 @@ namespace llvm {
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/// subregister.
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void UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg, unsigned SubIdx);
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/// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially
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/// extended by a dead copy. Mark the last use (if any) of the val# as kill
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/// as ends the live range there. If there isn't another use, then this
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/// live range is dead.
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void ShortenDeadCopyLiveRange(LiveInterval &li, MachineInstr *CopyMI);
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/// lastRegisterUse - Returns the last use of the specific register between
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/// cycles Start and End or NULL if there are no uses.
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MachineOperand *lastRegisterUse(unsigned Start, unsigned End, unsigned Reg,
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18
test/CodeGen/PowerPC/2008-03-05-RegScavengerAssert.ll
Normal file
18
test/CodeGen/PowerPC/2008-03-05-RegScavengerAssert.ll
Normal file
@ -0,0 +1,18 @@
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; RUN: llvm-as < %s | llc -mtriple=powerpc-apple-darwin -enable-ppc-regscavenger
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declare i8* @bar(i32)
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define void @foo(i8* %pp) nounwind {
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entry:
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%tmp2 = tail call i8* @bar( i32 14 ) nounwind ; <i8*> [#uses=0]
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%tmp28 = bitcast i8* %pp to void ()** ; <void ()**> [#uses=1]
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%tmp38 = load void ()** %tmp28, align 4 ; <void ()*> [#uses=2]
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br i1 false, label %bb34, label %bb25
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bb25: ; preds = %entry
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%tmp30 = bitcast void ()* %tmp38 to void (i8*)* ; <void (i8*)*> [#uses=1]
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tail call void %tmp30( i8* null ) nounwind
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ret void
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bb34: ; preds = %entry
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tail call void %tmp38( ) nounwind
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ret void
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}
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