How do I assign an attribute to a function

How do I assign an attribute to a function

[ballsystemlord]

I'm using C and I decided to read the whole gcc info manual on the subject.
How do I apply an __attribute__ to the function as apposed to what it
returns?
Yes, I've read the docs and am looking for examples.
I want to apply the cold __attribute__ to all the perror statements in my
program, the perror function is declared in the GNU C library so how do I
change it without effecting every other program that's compiled against the
GNU C library?



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Re: How do I assign an attribute to a function

[Ian Lance Taylor]

On Fri, Nov 15, 2013 at 12:03 PM, ballsystemlord <doark@mail.com> wrote:
> I'm using C and I decided to read the whole gcc info manual on the subject.
> How do I apply an __attribute__ to the function as apposed to what it
> returns?
> Yes, I've read the docs and am looking for examples.
> I want to apply the cold __attribute__ to all the perror statements in my
> program, the perror function is declared in the GNU C library so how do I
> change it without effecting every other program that's compiled against the
> GNU C library?

In general, you can't.

In GCC 4.8 or later you can  use the cold attribute on a label.  Then
you can turn your calls to perror into a goto to that label.

Otherwise you can use __builtin_expect, as in

  if (__builtin_expect (ok, true))
    {
      // Normal case.
    }
  else
    perror ("error");

Ian

Re: How do I assign an attribute to a function

[ballsystemlord]

Ian Lance Taylor-3 wrote
>>On Fri, Nov 15, 2013 at 12:03 PM, ballsystemlord <

> doark@

> > wrote:
>>> I'm using C and I decided to read the whole gcc info manual on the
>>> subject.
>>> How do I apply an __attribute__ to the function as apposed to what it
>>> returns?
>>> Yes, I've read the docs and am looking for examples.
>>> I want to apply the cold __attribute__ to all the perror statements in
>>> my
>>> program, the perror function is declared in the GNU C library so how do
>>> I
>>> change it without effecting every other program that's compiled against
>>> the
>>> GNU C library?
>>
>>In general, you can't.
>>
>>In GCC 4.8 or later you can  use the cold attribute on a label.  Then
>>you can turn your calls to perror into a goto to that label.
>>
>>Otherwise you can use __builtin_expect, as in
>>
>>if (__builtin_expect (ok, true))
>>    {
>>      // Normal case.
>>    }
>>  else
>>    perror ("error");
>>
>>Ian
>>

Ok, Thanks.



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