martong marked 12 inline comments as done.
martong added inline comments.
================
Comment at: clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp:88
typedef uint32_t ArgNo;
- static const ArgNo Ret = std::numeric_limits<ArgNo>::max();
+ static const ArgNo Ret;
+
----------------
Szelethus wrote:
> Why did we remove the initialization here? Can we make this `constexpr`?
I am receiving an undefined reference linker error (I use `gold`) if the
initialization is happening in-class.
Even if `constexpr` is used.
```
/usr/bin/ld.gold: error:
tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/StdLibraryFunctionsChecker.cpp.o:
requires dynamic R_X86_64_PC32 reloc against
'_ZN12_GLOBAL__N_126StdLibraryFunctionsChecker3RetE' which may overflow at
runtime; recompile with -fPIC
tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/StdLibraryFunctionsChecker.cpp.o:StdLibraryFunctionsChecker.cpp:function
(anonymous
namespace)::StdLibraryFunctionsChecker::initFunctionSummaries(clang::ento::CheckerContext&)
const: error: undefined reference to '(anonymous
namespace)::StdLibraryFunctionsChecker::Ret'
```
================
Comment at: clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp:90
+
+ class ValueConstraint {
+ public:
----------------
Szelethus wrote:
> We should totally have a good bit of documentation here.
Ok, I added some comments to the class and to `apply` as well.
================
Comment at: clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp:151
+
+ using ValueConstraintPtr = std::shared_ptr<ValueConstraint>;
+ /// The complete list of constraints that defines a single branch.
----------------
baloghadamsoftware wrote:
> baloghadamsoftware wrote:
> > Szelethus wrote:
> > > martong wrote:
> > > > Szelethus wrote:
> > > > > martong wrote:
> > > > > > martong wrote:
> > > > > > > Szelethus wrote:
> > > > > > > > gamesh411 wrote:
> > > > > > > > > martong wrote:
> > > > > > > > > > Note here, we need a copyable, polymorphic and default
> > > > > > > > > > initializable type (vector needs that). A raw pointer were
> > > > > > > > > > good, however, we cannot default initialize that.
> > > > > > > > > > unique_ptr makes the Summary class non-copyable, therefore
> > > > > > > > > > not an option.
> > > > > > > > > > Releasing the copyablitly requirement would render the
> > > > > > > > > > initialization of the Summary map infeasible.
> > > > > > > > > > Perhaps we could come up with a [[
> > > > > > > > > > https://www.youtube.com/watch?v=bIhUE5uUFOA | type erasure
> > > > > > > > > > technique without inheritance ]] once we consider the
> > > > > > > > > > shared_ptr as restriction, but for now that seems to be
> > > > > > > > > > overkill.
> > > > > > > > > std::variant (with std::monostate for the default
> > > > > > > > > constructibility) would also be an option (if c++17 were
> > > > > > > > > supported). But this is not really an issue, i agree with
> > > > > > > > > that.
> > > > > > > > Ugh, we've historically been very hostile towards virtual
> > > > > > > > functions. We don't mind them that much when they don't have to
> > > > > > > > run a lot, like during bug report construction, but as a core
> > > > > > > > part of the analysis, I'm not sure what the current stance is
> > > > > > > > on it.
> > > > > > > >
> > > > > > > > I'm not inherently (haha) against it, and I'm fine with leaving
> > > > > > > > this as-is for the time being, though I'd prefer if you placed
> > > > > > > > a `TODO` to revisit this issue.
> > > > > > > > std::variant (with std::monostate for the default
> > > > > > > > constructibility) would also be an option (if c++17 were
> > > > > > > > supported). But this is not really an issue, i agree with that.
> > > > > > >
> > > > > > > Variant would be useful if we knew the set of classes prior and
> > > > > > > we wanted to add operations gradually. Class hierarchies (or
> > > > > > > run-time concepts [Sean Parent]) are very useful if we know the
> > > > > > > set of operations prior and we want to add classes gradually, and
> > > > > > > we have this case here.
> > > > > > > Ugh, we've historically been very hostile towards virtual
> > > > > > > functions. We don't mind them that much when they don't have to
> > > > > > > run a lot, like during bug report construction, but as a core
> > > > > > > part of the analysis, I'm not sure what the current stance is on
> > > > > > > it.
> > > > > >
> > > > > > I did not find any evidence for this statement. Consider as a
> > > > > > counter example the ExternalASTSource interface in Clang, which is
> > > > > > filled with virtual functions and is part of the C/C++ lookup
> > > > > > mechanism, which is quite on the hot path of C/C++ parsing I think.
> > > > > > Did not find any prohibition in LLVM coding guidelines neither. I
> > > > > > do believe virtual functions have their use cases exactly where
> > > > > > (runtime) polimorphism is needed, such as in this patch.
> > > > > >
> > > > > I consider myself proven wrong here then.
> > > > Thanks for the review and for considering other alternatives! And
> > > > please accept my apologies, maybe I was pushing too hard on inheritance.
> > > We should definitely decorate this with a `TODO: Can we change this to
> > > not use a shared_ptr?`. Worst case scenario, there it will stay for
> > > eternity :)
> > `FIXME` is the official, not `TODO`, afaik.
> I think that inheritance is the right approach here. However, if it is
> unacceptable for performance reasons it could be replaced by a template-based
> solution.
Actually, this is not necessary something that we need to fix or do. So,
instead of the `TODO` I have added a comment that explains why do we use the
`shared_ptr`.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D74973/new/
https://reviews.llvm.org/D74973
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