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Properly shrink live ranges after deleting dead copies. Clean up after all joined copies.

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LiveInterval::shrinkToUses recomputes the live range from scratch instead of
removing snippets. This should avoid the problem with dangling live ranges.

Leave physreg identity copies alone. They can be created when joining a virtreg
with a physreg. They don't affect register allocation, and they will be removed
by the rewriter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131521 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-05-18 04:18:19 +00:00
parent 141ec63962
commit fc2fcb4165
1 changed files with 5 additions and 24 deletions
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29
lib/CodeGen/SimpleRegisterCoalescing.cpp
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@ -1038,6 +1038,7 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
// If they are already joined we continue.
if (CP.getSrcReg() == CP.getDstReg()) {
markAsJoined(CopyMI);
DEBUG(dbgs() << "\tCopy already coalesced.\n");
return false; // Not coalescable.
}
@ -1696,13 +1697,11 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
// or else the scavenger may complain. LowerSubregs will
// delete them later.
DoDelete = false;
if (MI->allDefsAreDead()) {
if (li_->hasInterval(SrcReg)) {
LiveInterval &li = li_->getInterval(SrcReg);
if (!ShortenDeadCopySrcLiveRange(li, MI))
ShortenDeadCopyLiveRange(li, MI);
}
if (TargetRegisterInfo::isVirtualRegister(SrcReg) &&
li_->hasInterval(SrcReg))
li_->shrinkToUses(&li_->getInterval(SrcReg));
DoDelete = true;
}
if (!DoDelete) {
@ -1754,24 +1753,6 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
DeadDefs.clear();
}
// If the move will be an identity move delete it
if (MI->isIdentityCopy()) {
unsigned SrcReg = MI->getOperand(1).getReg();
if (li_->hasInterval(SrcReg)) {
LiveInterval &RegInt = li_->getInterval(SrcReg);
// If def of this move instruction is dead, remove its live range
// from the destination register's live interval.
if (MI->allDefsAreDead()) {
if (!ShortenDeadCopySrcLiveRange(RegInt, MI))
ShortenDeadCopyLiveRange(RegInt, MI);
}
}
li_->RemoveMachineInstrFromMaps(MI);
mii = mbbi->erase(mii);
++numPeep;
continue;
}
++mii;
// Check for now unnecessary kill flags.