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From Branko ─îibej <br...@xbc.nu>
Subject Re: Modifying Win32 default optimizations?
Date Wed, 11 May 2005 13:46:27 GMT
William A. Rowe, Jr. wrote:

>I'd like to modify the Win32 build projects (of mod_jk, and
>httpd 1.3/2.0/2.1-dev, along with apr); 
>
>The /O2 optimization option is extremely agressive, unfortunately 
>it produces less than ideal crash traceback information.  That 
>is due to the (implicit) /Oy flag, which omits respecible stack
>framing.  I'd like to change this to /O2 /Oy- to disable this
>optimization; processing will be unmeasurably slower, but far
>more useful when crashes do occur.
>  
>
Well, "unmeasurably" is obviously wrong :)
But yes, I don't think an extra cycle per non-inlined function call 
would show up all that much.

>The /O2 optimization also simplifies the stack frame checking
>for many functions.  The /Gs0 option would restore full frame
>checks, to ensure we don't overflow the stack in the processing
>of any function.  With FirstBill's (wise) choice to reduce the
>size of our default stack frames within httpd, it seems wise to
>be extra diligent.  However, MS's docs state that /O2 implies
>/Gs - and I can't determine if that is /Gs0 (implied) or some
>other behavior.  Thoughts from someone with more experience 
>playing in stack probes would be appreciated.
>  
>
/Gs0 is a bad idea, IMHO, because it only makes sense if you write your 
own stack probe routine. The default /Gs will probe a page at a time, 
which works well with NT's virtual memory manager, and still makes the 
stack grow enough.


>All in all - comments?
>  
>
How about moving away from MSVC 6 to (say) VC.Net 2003, while we're at 
it? It's time, to say the least.

-- Brane


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