[llvm] r317292 - Avoid PLT for external calls when attribute nonlazybind is used.

[Rafael Avila de Espindola via llvm-commits]

Sriraman Tallam <tmsriram at google.com> writes:

> On Thu, Nov 2, 2017 at 5:43 PM, Rafael Avila de Espindola
> <rafael.espindola at gmail.com> wrote:
>> Why force a call via the got when a direct one could be used?
>>
>> With -fno-plt -fPIC gcc compiles
>>
>> __attribute__((visibility("hidden"))) void foo(void);
>> void bar(void);
>> void zed(void) {
>>   foo();
>>   bar();
>> }
>>
>> to
>>
>>         call    foo
>>         call    *bar at GOTPCREL(%rip)
>>
>> But this patch will use the got for both calls, no?
>
> I did not test this case and if it is true that foo can never be
> external in this case then I got it wrong.  But what if foo was not
> defined by the DSO?

It would be a bug in the program as it is hidden.

The check for plt versus got should at the very least be after the
shouldAssumeDSOLocal call.

Cheers,
Rafael