[FFmpeg-cvslog] r20497 - trunk/configure

[Måns Rullgård]

David Conrad <lessen42 at gmail.com> writes:

> On Nov 15, 2009, at 2:43 PM, M?ns Rullg?rd wrote:
>
>>>>>> Maybe it shouldn't be using the same variable for PIC being
>>>>>> detected and the user specifically requesting it, but that won't
>>>>>> fix this check, which either needs to not run for Darwin or to run
>>>>>> after the flag is added.
>>>>> 
>>>>> Why is adding that flag conditional on PIC anyway?
>>>> 
>>>> IIRC it was supposed to do something allowing non-pic code in shared
>>>> libs.  Now that doesn't make much sense if, as you say, PIC is always
>>>> on with that compiler.
>>>> 
>>>> So which way is it?
>>> 
>>> No, it is supposed to allow avoiding some of the cost of PIC for binaries
>>> by using PIC only where necessary (I think something like ebx must have
>>> a specific value when calling system functions etc.).
>> 
>> Does not adding that flag break anything.  If not, screw OSX and
>> remove the hack.  Nobody is forced to use OSX anyway, so they have
>> only themselves to blame if it's slow.
>
> It breaks gcc 4.2 and newer, which I see as unlikely to be fixed
> ever given that the gcc darwin maintainers work on llvm instead
> nowadays.
>
> The only two hosts in the section that care about PIC are OpenBSD
> and Darwin, OpenBSD unconditionally enables PIC, and the check is
> broken on Darwin. The only other reason I can see it might not be
> safe is check_cc, but that's already used before the arch section.
>
> Not running the check on Darwin at all is another option, since PIC
> is always enabled by default, but it's uglier.

Now I'm totally confused.  Can someone please complete the table below:

        static  shared  -fPIC   -mdynamic-no-pic  |  works
--------------------------------------------------+--------
1       x                                         |
2       x               x                         |
3       x                       x                 |
4       x               x       x                 |
5               x                                 |
6               x       x                         |
7               x               x                 |
8               x       x       x                 |

-- 
M?ns Rullg?rd
mans at mansr.com