ASDenysPetrov added a comment.
@vsavchenko
I've made some assumptions.
================
Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:459-469
+ if (Origin.From().isMinSignedValue()) {
+ // If mini is a minimal signed value, absolute value of it is greater
+ // than the maximal signed value. In order to avoid these
+ // complications, we simply return the whole range.
+ return {ValueFactory.getMinValue(RangeType),
+ ValueFactory.getMaxValue(RangeType)};
+ }
----------------
I think you should swap `if` statements. I'll explain.
Let's consider the input is an **uint8** range [42, 242] and you will return
[0, 242] in the second `if`.
But if the input is an **uint8** range [128, 242] you will return [0, 255] in
the first `if`, because 128 is an equivalent of -128(INT8_MIN) in binary
representation so the condition in the first if would be true.
What is the great difference between [42, 242] and [128, 242] to have different
results? Or you've just missed this case?
P.S. I think your function's name doesn't fit its body, since //absolute
value// is always positive (without sign) from its definition, but you output
range may have negative values. You'd better write an explanation above the
function and rename it.
================
Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:481
+ // * Otherwise, From <= 0, To >= 0, and
+ // AbsMax == max(abs(From), abs(To))
+ llvm::APSInt AbsMax = std::max(-Origin.From(), Origin.To());
----------------
As for me, the last //reason// fully covers previous special cases, so you can
omit those ones, thus simplify the comment.
================
Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:659
+ //
+ // If we are dealing with unsigned case, we shouldn't move the lower bound.
+ if (Min.isSigned()) {
----------------
Extend the comment, please, why we should move bounds to zero at all.
================
Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:684
+
+ return {RangeFactory, ValueFactory.getValue(Min),
ValueFactory.getValue(Max)};
+}
----------------
Is it OK to return this rangeset in case when one of operands(or both) is
negative, since this rangeset can vary from specific implementation?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D80117/new/
https://reviews.llvm.org/D80117
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