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From: ak@muc.de
Subject: Re: Performance Ada and C
Date: 1998/07/04
Message-ID: <m3yaual5ms.fsf@fred.muc.de>#1/1
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Sender: andi@fred.muc.de
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Distribution: world
Organization: [posted via] Leibniz-Rechenzentrum, Muenchen (Germany)
Newsgroups: comp.lang.ada
Date: 1998-07-04T00:00:00+00:00
List-Id: <comp.lang.ada>


Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk> writes:
> 
> Basically the only difference is that I replaced the macros in the C
> version by inline functions. Are as far as performance and optimization
> are concerned, I just think of inlined functions as a sort of macros
> with type checking, so this should not cause the difference.

At least in the C frontend inline functions are not equivalent to macros
(in contrary to the documenation). The gcc backend seems to miss several
optimizations that it does with C-style macros (mainly CSE). Also the 
register allocator (on x86) seems to have some problems with inline functions.

I assume Gnat has the same problem. 

egcs-current has a new GCSE pass that might help a bit, but there are 
still other problems (e.g. if you work with objects gcc is very bad to
keep small objects in registers if you use inline functions - it always
flushes them at the border of the inline etc.)

-Andi

P.S.: Is something like the Stepanov Benchmark available for Ada95?