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Add some missing checks for the case where the extract_subregs are

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combined to an insert_subreg, i.e., where the destination register is larger
than the source.  We need to check that the subregs can be composed for that
case in a symmetrical way to the case when the destination is smaller.

llvm-svn: 106004
This commit is contained in:
Bob Wilson 2010-06-15 17:27:54 +00:00
parent 88e1f2b2b5
commit 99baadaee9
1 changed files with 23 additions and 22 deletions
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45
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -1179,7 +1179,7 @@ TwoAddressInstructionPass::CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs,
// If there are no other uses than extract_subreg which feed into
// the reg_sequence, then we might be able to coalesce them.
bool CanCoalesce = true;
SmallVector<unsigned, 4> SubIndices;
SmallVector<unsigned, 4> SrcSubIndices, DstSubIndices;
for (MachineRegisterInfo::use_nodbg_iterator
UI = MRI->use_nodbg_begin(SrcReg),
UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
@ -1190,24 +1190,35 @@ TwoAddressInstructionPass::CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs,
CanCoalesce = false;
break;
}
SubIndices.push_back(UseMI->getOperand(2).getImm());
SrcSubIndices.push_back(UseMI->getOperand(2).getImm());
DstSubIndices.push_back(UseMI->getOperand(0).getSubReg());
}
if (!CanCoalesce || SubIndices.size() < 2)
if (!CanCoalesce || SrcSubIndices.size() < 2)
continue;
std::sort(SubIndices.begin(), SubIndices.end());
// Check that the source subregisters can be combined.
std::sort(SrcSubIndices.begin(), SrcSubIndices.end());
unsigned NewSrcSubIdx = 0;
if (!TRI->canCombineSubRegIndices(MRI->getRegClass(SrcReg), SubIndices,
if (!TRI->canCombineSubRegIndices(MRI->getRegClass(SrcReg), SrcSubIndices,
NewSrcSubIdx))
continue;
// Check that the destination subregisters can also be combined.
std::sort(DstSubIndices.begin(), DstSubIndices.end());
unsigned NewDstSubIdx = 0;
if (!TRI->canCombineSubRegIndices(MRI->getRegClass(DstReg), DstSubIndices,
NewDstSubIdx))
continue;
// If neither source nor destination can be combined to the full register,
// just give up. This could be improved if it ever matters.
if (NewSrcSubIdx != 0 && NewDstSubIdx != 0)
continue;
// Now that we know that all the uses are extract_subregs and that those
// subregs can somehow be combined, scan all the extract_subregs again to
// make sure the subregs are in the right order and can be composed.
// Also keep track of the destination subregisters so we can make sure
// that those can be combined.
SubIndices.clear();
MachineInstr *SomeMI = 0;
CanCoalesce = true;
for (MachineRegisterInfo::use_nodbg_iterator
@ -1218,29 +1229,19 @@ TwoAddressInstructionPass::CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs,
unsigned DstSubIdx = UseMI->getOperand(0).getSubReg();
unsigned SrcSubIdx = UseMI->getOperand(2).getImm();
assert(DstSubIdx != 0 && "missing subreg from RegSequence elimination");
if (TRI->composeSubRegIndices(NewSrcSubIdx, DstSubIdx) != SrcSubIdx) {
if ((NewDstSubIdx == 0 &&
TRI->composeSubRegIndices(NewSrcSubIdx, DstSubIdx) != SrcSubIdx) ||
(NewSrcSubIdx == 0 &&
TRI->composeSubRegIndices(NewDstSubIdx, SrcSubIdx) != DstSubIdx)) {
CanCoalesce = false;
break;
}
SubIndices.push_back(DstSubIdx);
// Keep track of one of the uses.
SomeMI = UseMI;
}
if (!CanCoalesce)
continue;
// Check that the destination subregisters can also be combined.
std::sort(SubIndices.begin(), SubIndices.end());
unsigned NewDstSubIdx = 0;
if (!TRI->canCombineSubRegIndices(MRI->getRegClass(DstReg), SubIndices,
NewDstSubIdx))
continue;
// If neither source nor destination can be combined to the full register,
// just give up. This could be improved if it ever matters.
if (NewSrcSubIdx != 0 && NewDstSubIdx != 0)
continue;
// Insert a copy or an extract to replace the original extracts.
MachineBasicBlock::iterator InsertLoc = SomeMI;
if (NewSrcSubIdx) {