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Stop adding <imp-def> operands when coalescing sub-registers.

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We are already setting <undef> flags, and that is good enough. The
<imp-def> operands don't mean anything any more.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152009 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2012-03-04 19:19:07 +00:00
parent fce711cb65
commit 8d9c3a4ee7
1 changed files with 0 additions and 16 deletions
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16
lib/CodeGen/RegisterCoalescer.cpp
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@ -935,13 +935,10 @@ RegisterCoalescer::UpdateRegDefsUses(const CoalescerPair &CP) {
SmallVector<unsigned,8> Ops;
bool Reads, Writes;
tie(Reads, Writes) = UseMI->readsWritesVirtualRegister(SrcReg, &Ops);
bool Kills = false, Deads = false;
// Replace SrcReg with DstReg in all UseMI operands.
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
MachineOperand &MO = UseMI->getOperand(Ops[i]);
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
@ -961,19 +958,6 @@ RegisterCoalescer::UpdateRegDefsUses(const CoalescerPair &CP) {
if (JoinedCopies.count(UseMI))
continue;
if (SubIdx) {
// If UseMI was a simple SrcReg def, make sure we didn't turn it into a
// read-modify-write of DstReg.
if (Deads)
UseMI->addRegisterDead(DstReg, TRI);
else if (!Reads && Writes)
UseMI->addRegisterDefined(DstReg, TRI);
// Kill flags apply to the whole physical register.
if (DstIsPhys && Kills)
UseMI->addRegisterKilled(DstReg, TRI);
}
DEBUG({
dbgs() << "\t\tupdated: ";
if (!UseMI->isDebugValue())