When analyzing loop exit conditions combined with and and or, don't
make any assumptions about when the two conditions will agree on when
to permit the loop to exit. This fixes PR7845.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110758 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index f5a762a..b3ddfc0 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -3854,14 +3854,13 @@
else
MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
} else {
- // Both conditions must be true for the loop to exit.
+ // Both conditions must be true at the same time for the loop to exit.
+ // For now, be conservative.
assert(L->contains(FBB) && "Loop block has no successor in loop!");
- if (BTI0.Exact != getCouldNotCompute() &&
- BTI1.Exact != getCouldNotCompute())
- BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max != getCouldNotCompute() &&
- BTI1.Max != getCouldNotCompute())
- MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ if (BTI0.Max == BTI1.Max)
+ MaxBECount = BTI0.Max;
+ if (BTI0.Exact == BTI1.Exact)
+ BECount = BTI0.Exact;
}
return BackedgeTakenInfo(BECount, MaxBECount);
@@ -3889,14 +3888,13 @@
else
MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
} else {
- // Both conditions must be false for the loop to exit.
+ // Both conditions must be false at the same time for the loop to exit.
+ // For now, be conservative.
assert(L->contains(TBB) && "Loop block has no successor in loop!");
- if (BTI0.Exact != getCouldNotCompute() &&
- BTI1.Exact != getCouldNotCompute())
- BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max != getCouldNotCompute() &&
- BTI1.Max != getCouldNotCompute())
- MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ if (BTI0.Max == BTI1.Max)
+ MaxBECount = BTI0.Max;
+ if (BTI0.Exact == BTI1.Exact)
+ BECount = BTI0.Exact;
}
return BackedgeTakenInfo(BECount, MaxBECount);