Fixed logic error in BasicConstraintManager pointed out by Zhongxing Xu.
For checking if a symbol >= value, we need to check if symbol == value || symbol
> value. When checking symbol > value and we know that symbol != value, the path
is infeasible only if value == maximum integer.
For checking if a symbol <= value, we need to check if symbol == value || symbol
< value. When checking symbol < value and we know that symbol != value, the path
is infeasible only if value == minimum integer.
Updated test case exercising this logic: we only prune paths if the values are
unsigned.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@56354 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicConstraintManager.cpp b/lib/Analysis/BasicConstraintManager.cpp
index 9ff44e0..0576eaf 100644
--- a/lib/Analysis/BasicConstraintManager.cpp
+++ b/lib/Analysis/BasicConstraintManager.cpp
@@ -320,24 +320,9 @@
return St;
}
- // sym is not a constant, but it might be not-equal to a constant.
- // Observe: V >= sym is the same as sym <= V.
- // check: is sym != V?
- // check: is sym > V?
- // if both are true, the path is infeasible.
-
- if (isNotEqual(St, sym, V)) {
- // Is sym > V?
- //
- // We're not doing heavy range analysis yet, so all we can accurately
- // reason about are the edge cases.
- //
- // If V == 0, since we know that sym != V, we also know that sym > V.
- isFeasible = V != 0;
- }
- else
- isFeasible = true;
-
+ isFeasible = !isNotEqual(St, sym, V) ||
+ (V != llvm::APSInt::getMaxValue(V.getBitWidth(), V.isSigned()));
+
return St;
}
@@ -352,8 +337,10 @@
isFeasible = *X <= V;
return St;
}
-
- isFeasible = true;
+
+ isFeasible = !isNotEqual(St, sym, V) ||
+ (V != llvm::APSInt::getMinValue(V.getBitWidth(), V.isSigned()));
+
return St;
}