[cfe-dev] libclang crash when parsing MS-style inline assembly

[mcrosier at codeaurora.org]

> Hi Chad,
>
> So now I understand that there is no way to parse MS-style inline assembly
> without a target asm parser.
> But I still need to figure out if I can and how to tell libclang to
> initialize a specific target.

Unfortunately, I don't have an answer here.  Perhaps Alp or another member
of the list has a solution.

>
> On Wed, Oct 30, 2013 at 4:27 PM, <mcrosier at codeaurora.org> wrote:
>
>> Hi William,
>> I can answer your second question.  GCC style inline assembly does not
>> require a target AsmParser.  MS-style inline assembly requires a parser
>> because this is how we discover the constraints.  Hope this helps.
>>
>>  Chad
>>
>> > Hi Alp,
>> >
>> > Thanks for helping !
>> >
>> > 1] Is there a way I could tell libclang which target to initialize
>> without
>> > modifying it ?
>> > 2] How does it work for gcc style assembly, is there a similar error
>> > message or does it work without the need of any targets ?
>> > 3] Since you decided to diagnose this, you might also want to check
>> the
>> > case were the target have been initialized, but not the used function
>> > pointers of this target
>> >
>> > William.
>> >
>> >
>> > On Wed, Oct 30, 2013 at 3:53 PM, Alp Toker <alp at nuanti.com> wrote:
>> >
>> >>  Hello William,
>> >>
>> >> I've landed a fix in r193685 to diagnose this instead of crashing:
>> >>
>> >> clang/test/Index/ms-asm-no-target.cpp:8:3: error: MS-style inline
>> >> assembly
>> >> is not available: Unable to find target for this triple (no targets
>> are
>> >> registered)
>> >>
>> >> It's up to the embedder to decide what targets are linked in, so how
>> the
>> >> API exposes that is still an open question.
>> >>
>> >> Alp.
>> >>
>> >>
>> >>
>> >> On 30/10/2013 11:50, William Ledoux wrote:
>> >>
>> >> Hello,
>> >>
>> >> The following minimal code that contain MS-style inline assembly will
>> >> compile fine with clang, but libclang fails to parse it
>> >> (clang_parseTranslationUnit will return NULL).
>> >>
>> >>    void Break(){ __asm { int 3 } }
>> >>
>> >> In yesterday's llvm and clang sources, the problem occurs in
>> >> ParseMicrosoftAsmStatement.
>> >> In the code below, because no target have been registered, the first
>> >> line
>> >> will set TheTarget to NULL, and the second line will dereference
>> >> TheTarget,
>> >> thus causing the problem.
>> >>
>> >>    const llvm::Target *TheTarget =
>> >> llvm::TargetRegistry::lookupTarget(TT,
>> >> Error);
>> >>    OwningPtr<llvm::MCRegisterInfo>
>> MRI(TheTarget->createMCRegInfo(TT));
>> >>
>> >> For what I understood, clang, in cc1_main, will initialize targets
>> and
>> >> targets' functions with the following 4 lines, whereas libclang
>> won't.
>> >>
>> >>   llvm::InitializeAllTargets();
>> >>   llvm::InitializeAllTargetMCs();
>> >>   llvm::InitializeAllAsmPrinters();
>> >>   llvm::InitializeAllAsmParsers();
>> >>
>> >> Just for testing purpose, adding those 4 lines somewhere in
>> >> clang_createIndex fixes the problem. I know this is probably wrong,
>> but
>> >> did
>> >> it just to see if more problems were hiding behind.
>> >>
>> >> So my questions are:
>> >>   1] Is it wanted that libclang doesn't initialize any target ?
>> >>   2] if yes, how shloud it behave with MS inline assembly ?
>> >>   3] if no, what is the proper way to make it initialize targets ?
>> >>
>> >> Many thanks for you work !
>> >> William
>> >>
>> >>
>> >>
>> >>
>> >> --
>> >> View this message in context:
>> >>
>> http://clang-developers.42468.n3.nabble.com/libclang-crash-when-parsing-MS-style-inline-assembly-tp4035432.html
>> >> Sent from the Clang Developers mailing list archive at Nabble.com.
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