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Re: RFC: Turn on -fomit-frame-pointer and -fasynchronous-unwind-tables for Linux/i386


On Thu, Jul 15, 2010 at 12:49 PM, Roland McGrath <roland@redhat.com> wrote:
>> I updated the spread sheet with glibc 12.0 DSO sizes
>> I think -fomit-frame-pointer and -fasynchronous-unwind-tables
>> will increase size of DSO written in C by about 10%.
>
> Are you talking about code size or text size? ?Of course
> -fasynchronous-unwind-tables increases the size of .eh_frame,
> but that is not usually a performance issue. ?The actual code
> size increase is what affects hot path cache load and so forth.

-fomit-frame-pointer increases libc.so code size by 1%. We
have to save/restore EBP when using it GPR. But for some reason,
gcc will choose EBP even when ECX/EDX are available:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44958


-- 
H.J.


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