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

[mcrosier at codeaurora.org]

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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>>
>> -- http://www.nuanti.com
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>>
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