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Fix for PR1306.

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- A register def / use now implicitly affects sub-register liveness but does
not affect liveness information of super-registers.
- Def of a larger register (if followed by a use later) is treated as
read/mod/write of a smaller register.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36434 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2007-04-25 07:30:23 +00:00
parent b2f2e64c07
commit 24a3cc4c83
4 changed files with 199 additions and 49 deletions
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58
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -675,8 +675,12 @@ void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
exit:
assert(start < end && "did not find end of interval?");
LiveRange LR(start, end, interval.getNextValue(SrcReg != 0 ? start : ~0U,
SrcReg));
// Already exists? Extend old live interval.
LiveInterval::iterator OldLR = interval.FindLiveRangeContaining(start);
unsigned Id = (OldLR != interval.end())
? OldLR->ValId
: interval.getNextValue(SrcReg != 0 ? start : ~0U, SrcReg);
LiveRange LR(start, end, Id);
interval.addRange(LR);
DOUT << " +" << LR << '\n';
}
@ -692,14 +696,17 @@ void LiveIntervals::handleRegisterDef(MachineBasicBlock *MBB,
if (!tii_->isMoveInstr(*MI, SrcReg, DstReg))
SrcReg = 0;
handlePhysicalRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(reg), SrcReg);
for (const unsigned* AS = mri_->getAliasSet(reg); *AS; ++AS)
handlePhysicalRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(*AS), 0);
// Def of a register also defines its sub-registers.
for (const unsigned* AS = mri_->getSubRegisters(reg); *AS; ++AS)
// Avoid processing some defs more than once.
if (!MI->findRegisterDefOperand(*AS))
handlePhysicalRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(*AS), 0);
}
}
void LiveIntervals::handleLiveInRegister(MachineBasicBlock *MBB,
unsigned MIIdx,
LiveInterval &interval) {
LiveInterval &interval, bool isAlias) {
DOUT << "\t\tlivein register: "; DEBUG(printRegName(interval.reg));
// Look for kills, if it reaches a def before it's killed, then it shouldn't
@ -728,6 +735,12 @@ void LiveIntervals::handleLiveInRegister(MachineBasicBlock *MBB,
}
exit:
// Alias of a live-in register might not be used at all.
if (isAlias && end == 0) {
DOUT << " dead";
end = getDefIndex(start) + 1;
}
assert(start < end && "did not find end of interval?");
LiveRange LR(start, end, interval.getNextValue(~0U, 0));
@ -757,8 +770,10 @@ void LiveIntervals::computeIntervals() {
for (MachineBasicBlock::const_livein_iterator LI = MBB->livein_begin(),
LE = MBB->livein_end(); LI != LE; ++LI) {
handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*LI));
for (const unsigned* AS = mri_->getAliasSet(*LI); *AS; ++AS)
handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*AS));
// Multiple live-ins can alias the same register.
for (const unsigned* AS = mri_->getSubRegisters(*LI); *AS; ++AS)
if (!hasInterval(*AS))
handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*AS), true);
}
}
@ -856,7 +871,8 @@ bool LiveIntervals::AdjustCopiesBackFrom(LiveInterval &IntA, LiveInterval &IntB,
// If the IntB live range is assigned to a physical register, and if that
// physreg has aliases,
if (MRegisterInfo::isPhysicalRegister(IntB.reg)) {
for (const unsigned *AS = mri_->getAliasSet(IntB.reg); *AS; ++AS) {
// Update the liveintervals of sub-registers.
for (const unsigned *AS = mri_->getSubRegisters(IntB.reg); *AS; ++AS) {
LiveInterval &AliasLI = getInterval(*AS);
AliasLI.addRange(LiveRange(FillerStart, FillerEnd,
AliasLI.getNextValue(~0U, 0)));
@ -1055,8 +1071,9 @@ bool LiveIntervals::JoinCopy(MachineInstr *CopyMI,
// we have to update any aliased register's live ranges to indicate that they
// have clobbered values for this range.
if (MRegisterInfo::isPhysicalRegister(repDstReg)) {
for (const unsigned *AS = mri_->getAliasSet(repDstReg); *AS; ++AS)
getInterval(*AS).MergeInClobberRanges(SrcInt);
// Update the liveintervals of sub-registers.
for (const unsigned *AS = mri_->getSubRegisters(repDstReg); *AS; ++AS)
getInterval(*AS).MergeInClobberRanges(SrcInt);
} else {
// Merge use info if the destination is a virtual register.
LiveVariables::VarInfo& dVI = lv_->getVarInfo(repDstReg);
@ -1279,6 +1296,27 @@ bool LiveIntervals::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS) {
SmallVector<int, 16> LHSValNoAssignments;
SmallVector<int, 16> RHSValNoAssignments;
SmallVector<std::pair<unsigned,unsigned>, 16> ValueNumberInfo;
// If a live interval is a physical register, conservatively check if any
// of its sub-registers is overlapping the live interval of the virtual
// register. If so, do not coalesce.
if (MRegisterInfo::isPhysicalRegister(LHS.reg) &&
*mri_->getSubRegisters(LHS.reg)) {
for (const unsigned* SR = mri_->getSubRegisters(LHS.reg); *SR; ++SR)
if (hasInterval(*SR) && RHS.overlaps(getInterval(*SR))) {
DOUT << "Interfere with sub-register ";
DEBUG(getInterval(*SR).print(DOUT, mri_));
return false;
}
} else if (MRegisterInfo::isPhysicalRegister(RHS.reg) &&
*mri_->getSubRegisters(RHS.reg)) {
for (const unsigned* SR = mri_->getSubRegisters(RHS.reg); *SR; ++SR)
if (hasInterval(*SR) && LHS.overlaps(getInterval(*SR))) {
DOUT << "Interfere with sub-register ";
DEBUG(getInterval(*SR).print(DOUT, mri_));
return false;
}
}
// Compute ultimate value numbers for the LHS and RHS values.
if (RHS.containsOneValue()) {