PR11868. The previous loop in LiveIntervals::join would sometimes fall over if
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
diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index a85639f..0dbaaf8 100644
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -389,29 +389,30 @@
// 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());
}