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

[William Ledoux]

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
>
>
>
>
> --
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