[lldb-dev] Stackoverflow crash when evaluating an invalid expression

[Ben Ruthig via lldb-dev]

Hey Raphael,

Yes, you did advise me to drop a D->dumpColor() call in to
getASTRecordLayout().  For frustrating reasons I still haven't been able to
capture those logs but when I do I will report back.

Thanks so much for your help and quick response!

Ben

On Thu, Mar 7, 2019 at 12:56 PM Raphael Isemann <teemperor at gmail.com> wrote:

> Hi Ben,
>
> I think I already answered this last week:
> http://lists.llvm.org/pipermail/lldb-dev/2019-February/014789.html
>
> I don't think you'll get an answer here without posting the
> problematic source or giving any more information as I described in my
> mail.
>
> Cheers,
> - Raphael
>
> Am Do., 7. März 2019 um 18:13 Uhr schrieb Ben Ruthig via lldb-dev
> <lldb-dev at lists.llvm.org>:
> >
> > Hello all,
> >
> > I am currently investigating an issue where LLDB is crashing due to a
> stack overflow when attempting to evaluate an expression.  I have seen the
> same issue in 6.0.1 and have reproduced it in 7.0.1.  Any help to diagnose
> and fix would be greatly appreciated as I am trying to meet a release
> deadline early next week!
> >
> > The facts:
> > - The expression being evaluated is not a valid expression in the C++
> domain. For example the expression is a datatype like 'Foobar'.  (For
> reasons unexplained I am constrained to supporting this use case.)
> > - The crash occurs when using the C++ LLDB API but not when trying to
> evaluate the expression via the LLDB shell or the LLDB Python script
> shell.  However, when doing 'expr Foobar' there is no output and the
> operation is completely silent.  It is similar when trying to do
> 'lldb.frame.EvaluateExpression("Foobar")' in the Python shell as well.  I
> would expect to get some error output or an SbValue in an error state but
> no such luck.
> > - I was able to capture a stack trace (attached) and it seems to be a
> recursive loop bottoming out.  For brevity two 'loops' of stacktrace are
> included here:
> >
> > 3387.      liblldb.dll!clang::ASTContext::getASTRecordLayout(const
> clang::RecordDecl * D) Line 2965    C++
> > 3388.      liblldb.dll!`anonymous
> namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes() Line 216    C++
> > 3389.      liblldb.dll!`anonymous
> namespace'::EmptySubobjectMap::EmptySubobjectMap(const clang::ASTContext &
> Context, const clang::CXXRecordDecl * Class) Line 172    C++
> > 3390.      liblldb.dll!clang::ASTContext::getASTRecordLayout(const
> clang::RecordDecl * D) Line 2965    C++
> > 3391.      liblldb.dll!`anonymous
> namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes() Line 216    C++
> > 3392.      liblldb.dll!`anonymous
> namespace'::EmptySubobjectMap::EmptySubobjectMap(const clang::ASTContext &
> Context, const clang::CXXRecordDecl * Class) Line 172    C++
> > 3393.      liblldb.dll!clang::ASTContext::getASTRecordLayout(const
> clang::RecordDecl * D) Line 2965    C++
> >
> > Help please :S
> >
> > Thanks,
> > Ben
> >
> >
> > _______________________________________________
> > lldb-dev mailing list
> > lldb-dev at lists.llvm.org
> > https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>


-- 
"Sometimes I've believed as many as six impossible things before breakfast"
- Alice in Wonderland
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