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PR11868. The previous loop in LiveIntervals::join would sometimes fall over if

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more than two adjacent ranges needed to be merged. The new version should be
able to handle an arbitrary sequence of adjancent ranges.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149588 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames
2012-02-02 05:37:34 +00:00
parent 3f5b107a4b
commit 02e08d5b4d
2 changed files with 38 additions and 11 deletions
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23
lib/CodeGen/LiveInterval.cpp
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@ -389,29 +389,30 @@ void LiveInterval::join(LiveInterval &Other,
// now.
if (MustMapCurValNos) {
// Map the first live range.
iterator OutIt = begin();
OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]];
++OutIt;
for (iterator I = OutIt, E = end(); I != E; ++I) {
OutIt->valno = NewVNInfo[LHSValNoAssignments[I->valno->id]];
for (iterator I = next(OutIt), E = end(); I != E; ++I) {
VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]];
assert(nextValNo != 0 && "Huh?");
// If this live range has the same value # as its immediate predecessor,
// and if they are neighbors, remove one LiveRange. This happens when we
// have [0,3:0)[4,7:1) and map 0/1 onto the same value #.
if (OutIt->valno == (OutIt-1)->valno && (OutIt-1)->end == OutIt->start) {
(OutIt-1)->end = OutIt->end;
// have [0,4:0)[4,7:1) and map 0/1 onto the same value #.
if (OutIt->valno == nextValNo && OutIt->end == I->start) {
OutIt->end = I->end;
} else {
if (I != OutIt) {
// Didn't merge. Move OutIt to the next interval,
++OutIt;
OutIt->valno = nextValNo;
if (OutIt != I) {
OutIt->start = I->start;
OutIt->end = I->end;
}
// Didn't merge, on to the next one.
++OutIt;
}
}
// If we merge some live ranges, chop off the end.
++OutIt;
ranges.erase(OutIt, end());
}