[lldb-dev] LLDB expressions confused by overloading

Aidan Dodds via lldb-dev lldb-dev at lists.llvm.org
Fri Nov 6 03:12:33 PST 2015

Thanks Siva,
This indeed looks somewhat related to the problems we are seeing here.
I'm just having a read of your patch now and going to try it out here.

On 05/11/2015 18:24, Siva Chandra wrote:
> On Thu, Nov 5, 2015 at 9:43 AM, Aidan Dodds via lldb-dev
> <lldb-dev at lists.llvm.org> wrote:
>> I believe I have tracked down an interesting bug which related to LLDBs
>> expression parser.
>> In my target program I have a math library, a shared object which makes use
>> of clangs __attribute__((overloadable)) extension for C99.  This causes the
>> the function names in the math library to be mangled.
>> A problem arises however since some of the function names mirror those
>> exported by libm.so, and the function names in libm are not mangled.
>> My problem scenario:
>> If I call an expression during a debugging session, the symbol table of
>> libm.so is consulted first and a match will be found.  Later on in the
>> expression setup, any dwarf information will be consulted for functions with
>> this name.  libm.so doesn't have any debugging info attached, however the
>> math library of my target may.  In this case the expression will now call
>> which ever function it could first find dwarf info for, regardless of the
>> name mangling.
>> The net result is that a function will be called in my targets math library
>> that may not match the given function signature.  In my case this causes the
>> expression to raise a SEGFAULT and fail.  I was seeing an expression to call
>> a vector4 function, in fact call the vector 2 version behinds the scenes.
>> One solution to this problem seems to be to have the expression evaluator
>> try and first look for any functions that may have a mangled name for the
>> given function signature, and if that fails fall back to simply checking for
>> the unmangled version, as is currently done.
> Is this similar to the problem tackled by this patch:
> http://reviews.llvm.org/D12809

More information about the lldb-dev mailing list