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Fix 12892.

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Dead code elimination during coalescing could cause a virtual register
to be split into connected components. The following rewriting would be
confused about the already joined copies present in the code, but
without a corresponding value number in the live range.

Erase all joined copies instantly when joining intervals such that the
MI and LiveInterval representations are always in sync.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157135 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2012-05-19 23:34:59 +00:00
parent 9012c57e18
commit 7ebed91fdd
3 changed files with 146 additions and 4 deletions
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24
lib/CodeGen/RegisterCoalescer.cpp
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@@ -1081,9 +1081,10 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
if (!CP.isPhys() && RegClassInfo.isProperSubClass(CP.getNewRC()))
InflateRegs.push_back(CP.getDstReg());
// Remember to delete the copy instruction.
LIS->RemoveMachineInstrFromMaps(CopyMI);
CopyMI->eraseFromParent();
// CopyMI has been erased by joinIntervals at this point. Remove it from
// ErasedInstrs since copyCoalesceWorkList() won't add a successful join back
// to the work list. This keeps ErasedInstrs from growing needlessly.
ErasedInstrs.erase(CopyMI);
// Rewrite all SrcReg operands to DstReg.
// Also update DstReg operands to include DstIdx if it is set.
@@ -1285,6 +1286,7 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
SmallVector<VNInfo*, 16> NewVNInfo;
SmallVector<MachineInstr*, 8> DupCopies;
SmallVector<MachineInstr*, 8> DeadCopies;
LiveInterval &LHS = LIS->getOrCreateInterval(CP.getDstReg());
DEBUG({ dbgs() << "\t\tLHS = "; LHS.print(dbgs(), TRI); dbgs() << "\n"; });
@@ -1313,6 +1315,7 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
continue;
LHSValsDefinedFromRHS[VNI] = lr->valno;
DeadCopies.push_back(MI);
}
// Loop over the value numbers of the RHS, seeing if any are defined from
@@ -1339,6 +1342,7 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
continue;
RHSValsDefinedFromLHS[VNI] = lr->valno;
DeadCopies.push_back(MI);
}
LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
@@ -1438,6 +1442,17 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
if (RHSValNoAssignments.empty())
RHSValNoAssignments.push_back(-1);
// Now erase all the redundant copies.
for (unsigned i = 0, e = DeadCopies.size(); i != e; ++i) {
MachineInstr *MI = DeadCopies[i];
DEBUG(dbgs() << "\t\terased:\t" << LIS->getInstructionIndex(MI)
<< '\t' << *MI);
if (!ErasedInstrs.insert(MI))
continue;
LIS->RemoveMachineInstrFromMaps(MI);
MI->eraseFromParent();
}
SmallVector<unsigned, 8> SourceRegisters;
for (SmallVector<MachineInstr*, 8>::iterator I = DupCopies.begin(),
E = DupCopies.end(); I != E; ++I) {
@@ -1451,7 +1466,8 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
// A = X
unsigned Src = MI->getOperand(1).getReg();
SourceRegisters.push_back(Src);
ErasedInstrs.insert(MI);
if (!ErasedInstrs.insert(MI))
continue;
LIS->RemoveMachineInstrFromMaps(MI);
MI->eraseFromParent();
}