[lldb-dev] Symtab for PECOFF

[Aleksandr Urakov via lldb-dev]

Thanks for the reply!

Yes, the function search is implemented in the way similar to what you have
described (and even the search in a symbol file is done before the search
in a symtab). But for Module::FindSymbolsWithNameAndType function I can't
find any relevant function in the SymbolFile. Do you mean that we need to
extend the SymbolFile interface with such a function (which will search all
public symbols by the name and the type), and then implement it in derived
classes?

On Thu, Aug 30, 2018 at 6:03 PM Zachary Turner <zturner at google.com> wrote:

> It seems reasonable to me to say that if the symbol is not found in the
> executables symtab, it will fall back to searching in the symbol file..
> this logic doesn’t even need to be specific to PDB
> On Thu, Aug 30, 2018 at 7:00 AM Aleksandr Urakov via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
>
>> Hello!
>>
>> I'm working on an expressions evaluation on Windows, and currently I'm
>> trying to make a JIT evaluation working.
>>
>> When I'm trying to evaluate the next expression:
>>
>> print S::x
>>
>>
>> on the next code:
>>
>> struct S {
>>   static int x;
>>   void foo() { }
>> };
>> int S::x = 5;
>>
>> int main() {
>>   S().foo(); // here
>>   return 0;
>> }
>>
>>
>> the evaluation requires JIT (but printing of global variables requires
>> not, and I can't figure out what is the key difference between a class
>> static variable and a global variable in the case?).
>>
>> During symbols resolving IRExecutionUnit::FindInSymbols is used, and it
>> searches a symbol among functions (which is not our case), and then calls
>> Module::FindSymbolsWithNameAndType for each module in the list. This
>> function looks symbols up in a Symtab, which is retrieved through a
>> SymbolVendor, and it retrieves one from an ObjectFile. ELF files contain
>> symbols for such a variables in their symbol tables, but the problem is
>> that PE files usually contain info about exported (and imported) symbols
>> only, so the lookup in Symtab fails.
>>
>> I think that we need somehow to retrieve a symbols info from a symbol
>> file. I thought that we can emit a Symtab from a SymbolFile just like
>> from an ObjectFile (and for now implement it for SymbolFilePDB only),
>> but I'm not sure if this solution is good. How can we solve the problem
>> else?
>>
>> --
>> Aleksandr Urakov
>> Software Developer
>> JetBrains
>> http://www.jetbrains.com
>> The Drive to Develop
>> _______________________________________________
>> lldb-dev mailing list
>> lldb-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>>
>

-- 
Aleksandr Urakov
Software Developer
JetBrains
http://www.jetbrains.com
The Drive to Develop
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