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Revert "ReMat: fix overly cavalier attitude to sub-register indices"

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Very sorry, this was a premature patch that I still need to investigate and
finish off (for some reason beyond me at the moment it doesn't actually fix the
issue in all cases).

This reverts commit r199091.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199093 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover 2014-01-13 10:49:11 +00:00
parent a917400584
commit eaefef43d7
1 changed files with 24 additions and 4 deletions
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28
lib/CodeGen/RegisterCoalescer.cpp
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@ -816,11 +816,31 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
}
if (TargetRegisterInfo::isVirtualRegister(DstReg)) {
MRI->setRegClass(DstReg, CP.getNewRC());
unsigned NewIdx = NewMI->getOperand(0).getSubReg();
updateRegDefsUses(DstReg, DstReg, DstIdx);
NewMI->getOperand(0).setSubReg(NewIdx);
const TargetRegisterClass *RCForInst;
if (NewIdx)
RCForInst = TRI->getMatchingSuperRegClass(MRI->getRegClass(DstReg), DefRC,
NewIdx);
if (MRI->constrainRegClass(DstReg, DefRC)) {
// The materialized instruction is quite capable of setting DstReg
// directly, but it may still have a now-trivial subregister index which
// we should clear.
NewMI->getOperand(0).setSubReg(0);
} else if (NewIdx && RCForInst) {
// The subreg index on NewMI is essential; we still have to make sure
// DstReg:idx is in a class that NewMI can use.
MRI->constrainRegClass(DstReg, RCForInst);
} else {
// DstReg is actually incompatible with NewMI, we have to move to a
// super-reg's class. This could come from a sequence like:
// GR32 = MOV32r0
// GR8 = COPY GR32:sub_8
MRI->setRegClass(DstReg, CP.getNewRC());
updateRegDefsUses(DstReg, DstReg, DstIdx);
NewMI->getOperand(0).setSubReg(
TRI->composeSubRegIndices(SrcIdx, DefMI->getOperand(0).getSubReg()));
}
} else if (NewMI->getOperand(0).getReg() != CopyDstReg) {
// The New instruction may be defining a sub-register of what's actually
// been asked for. If so it must implicitly define the whole thing.