[cfe-dev] exit() emits exception handling?

[Welson Sun via cfe-dev]

Thanks Reid,

That explains. And the local variables turn out to be of type
"std::string". Although it is not possible to ask the customer not to use
std::string, at least I can explain it :-)  Adapting my analysis pass is
another thing.

Thanks,
Welson

On Tue, Oct 6, 2015 at 9:47 AM, Reid Kleckner <rnk at google.com> wrote:

> If you have local variables with non-trivial destructors (say,
> std::unique_ptr or std::vector), then Clang will turn calls into invokes.
> The unwind edge of the invoke executes when an exception is thrown from the
> call, and the code along that edge destroys local objects in scope before
> resuming unwinding.
>
> On Tue, Oct 6, 2015 at 9:25 AM, Welson Sun via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Hi,
>>
>> I am trying to understand some LLVM IR Clang generates. Since I cannot
>> publish the source code, I can only describe what I see and my guess.
>>
>> This is the main() function of some code, which allocates some memory and
>> sequentially calls a list of functions. There are no explicit exception
>> handling code in the source code, however, *for each function call*, the
>> LLVM IR for the function call becomes "invoke ... unwind ...". I am
>> wondering what causes the generation of such code. One thing I noticed in
>> the source code is the exit() call in main().
>>
>> If I compile with -fno-exceptions, all function calls become normal
>> "call", without any "unwind" attribute.
>>
>>
>> Thanks
>> - Welson
>>
>>
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>>
>>
>


-- 
- Welson
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