Le Lundi 3 Novembre 2003 00:26, SN a �crit :
> -fomit-frame-pointer
> Don't keep the frame pointer in a register for functions that don't need
> one. This avoids the instructions to save, set up and restore frame
> pointers; it also makes an extra register available in many functions. It
> also makes debugging impossible on some machines.
> On some machines, such as the VAX, this flag has no effect, because the
> standard calling sequence automatically handles the frame pointer and
> nothing is saved by pretending it doesn't exist. The machine-description
> macro FRAME_POINTER_REQUIRED controls whether a target machine supports
> this flag. See Register Usage.
>
> Enabled at levels -O, -O2, -O3, -Os.
That is true BUT man gcc says also :
<snip>
-O also turns on -fomit-frame-pointer on machines where doing so
does not interfere with debugging.
</snap>
and it does interfere on x86 architecture so it is not turned on by default on
x86 at least.
Martin
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