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Also add <def,undef> flags when coalescing sub-registers.

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RegisterCoalescer can create sub-register defs when it is joining a
register with a sub-register.  Add <undef> flags to these new
sub-register defs where appropriate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141138 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-10-05 00:01:46 +00:00
parent 2fec6c5ff1
commit b077cf338b
1 changed files with 8 additions and 0 deletions
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8
lib/CodeGen/RegisterCoalescer.cpp
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@ -967,6 +967,14 @@ RegisterCoalescer::UpdateRegDefsUses(const CoalescerPair &CP) {
Kills |= MO.isKill();
Deads |= MO.isDead();
// Make sure we don't create read-modify-write defs accidentally. We
// assume here that a SrcReg def cannot be joined into a live DstReg. If
// RegisterCoalescer starts tracking partially live registers, we will
// need to check the actual LiveInterval to determine if DstReg is live
// here.
if (SubIdx && !Reads)
MO.setIsUndef();
if (DstIsPhys)
MO.substPhysReg(DstReg, *TRI);
else