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Fix a conversion from a forward iterator to a reverse iterator in 

MachineBasicBlock::SplitCriticalEdge. Since this is an iterator rather than
an instr_iterator, the isBundled() check only passes if getFirstTerminator()
returned end() and the garbage memory happens to lean that way.

Multiple successors can be present without any terminator instructions in the
case of exception handling with a fallthrough.

llvm-svn: 175383
This commit is contained in:
Cameron Zwarich 2013-02-17 01:45:04 +00:00
parent bfebb41984
commit ddeabf78a0
1 changed files with 7 additions and 6 deletions
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13
llvm/lib/CodeGen/MachineBasicBlock.cpp
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@ -852,12 +852,13 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
// Update all intervals for registers whose uses may have been modified by
// updateTerminator().
iterator FirstTerminator = getFirstTerminator();
MachineInstr *FirstTerminatorMI = FirstTerminator;
if (FirstTerminatorMI->isBundled())
FirstTerminatorMI = getBundleStart(FirstTerminatorMI);
reverse_iterator PreTerminators =
(FirstTerminator == begin()) ? rend()
: reverse_iterator(FirstTerminatorMI);
reverse_iterator PreTerminators;
if (FirstTerminator == begin())
PreTerminators = rend();
else if (FirstTerminator == end())
PreTerminators = rbegin();
else
PreTerminators = reverse_iterator(FirstTerminator);
LIS->repairIntervalsInRange(this, rbegin(), PreTerminators, UsedRegs);
}