Re: huge object files. Expectable?

On 03/22/2010 04:29 AM, IainS wrote:
> On 22 Mar 2010, at 07:39, IainS wrote:
> > looking at this ... the darwin assembler has :
> >
> > ----
> > .zerofill
> > SYNOPSIS
> >
> > .zerofill segname , sectname [ , symbolname , size [ ,
> > align_expression ]]
> > The .zerofill directive causes symbolname to be created as
> > uninitialized data in the section given by segname and sectname, with
> > a size in bytes given by size. A power of 2 between 0 and 15 may be
> > given for align_expression to indicate what alignment should be forced
> > on symbolname, which is placed on the next expression boundary having
> > the given alignment. See “.align” for details.
> >
> > -----
> >
> > if I have a chance later - I might try to hand-edit the .s files to
> > see if the .zerofill directive would produce an improved result in the
> > specific case.
>
> simplified testcase, clipped from the .s file generated by Andrew's
> testcase :
>
> space.s:
> .machine ppc7400
> .globl ___pmdata_MOD_accrate
> .data
> .align 3
> ___pmdata_MOD_accrate:
> .space 16
> .globl ___pmdata_MOD_angl
>
> #replacing this....
> # .align 3
> #___pmdata_MOD_angl:
> # .space 16000000
>
> # with this....
> .zerofill DATA, data, ___pmdata_MOD_angl, 16000000, 3
>
> ===
>
> with the .space directive the object is 15Mb
> with the .zerofill the object is 476 bytes...
>
> I'll have to do a little more research as to whether this is always a
> legitimate substitution for the zero case - and, if so, where it needs
> to be done.
>
>
> Iain
Probably need to open a tracking PR somewhere.  A missed optimization. Who 
generates the .s file. ?

;)

Jerry