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Don't completely eliminate identity copies that also modify super register liveness.

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Turn them into noop KILL instructions instead. This lets the scavenger know when
super-registers are killed and defined.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128645 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-03-31 17:55:25 +00:00
parent 8901e6ff3d
commit 280ea1a746
2 changed files with 13 additions and 6 deletions
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18
lib/CodeGen/VirtRegMap.cpp
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@ -309,12 +309,18 @@ void VirtRegMap::rewrite(SlotIndexes *Indexes) {
// Finally, remove any identity copies.
if (MI->isIdentityCopy()) {
DEBUG(dbgs() << "Deleting identity copy.\n");
RemoveMachineInstrFromMaps(MI);
if (Indexes)
Indexes->removeMachineInstrFromMaps(MI);
// It's safe to erase MI because MII has already been incremented.
MI->eraseFromParent();
if (MI->getNumOperands() == 2) {
DEBUG(dbgs() << "Deleting identity copy.\n");
RemoveMachineInstrFromMaps(MI);
if (Indexes)
Indexes->removeMachineInstrFromMaps(MI);
// It's safe to erase MI because MII has already been incremented.
MI->eraseFromParent();
} else {
// Transform identity copy to a KILL to deal with subregisters.
MI->setDesc(TII->get(TargetOpcode::KILL));
DEBUG(dbgs() << "Identity copy: " << *MI);
}
}
}
}

1
test/CodeGen/Blackfin/2009-08-04-LowerExtract-Live.ll
View File

@ -1,4 +1,5 @@
; RUN: llc < %s -march=bfin -join-liveintervals=0 -verify-machineinstrs
; RUN: llc < %s -march=bfin -join-liveintervals=0 -verify-machineinstrs -regalloc=greedy
; Provoke an error in LowerSubregsPass::LowerExtract where the live range of a
; super-register is illegally extended.