From: gautier_niouzes@hotmail.com
Subject: Re: Modern optimizing compilers
Date: Tue, 22 Aug 2017 00:28:48 -0700 (PDT)
Date: 2017-08-22T00:28:48-07:00 [thread overview]
Message-ID: <0cd56bba-3ed2-4db4-b68e-fa698a824981@googlegroups.com> (raw)
In-Reply-To: <ong0si$1rt1$1@gioia.aioe.org>
> Not sure if the optimizer with -O3 is good, but now the code it much
> shorter, however yet seems for me too long.
It's not good: it's very good!...
On more complex source code, the assembler output is very long, looks confuse to the human reader... but the result is very fast.
Intuition or common sense are helpless in guessing performance from the assembler output.
If you want compact machine code, use -Os instead.
It may be useful to use -O2 plus selected options like loop unrolling for tuning performance.
Side note 1: IIRC id software already delegated the performance of their full-software Quake 1 3D renderer for GCC's optimizer, some 20 years ago!...
Side note 2: A similar full-software 3D renderer in Ada is available @ http://sf.net/projects/engine-3d/
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prev parent reply other threads:[~2017-08-22 7:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-21 20:32 Modern optimizing compilers Victor Porton
2017-08-21 23:19 ` gautier_niouzes
2017-08-22 1:11 ` Victor Porton
2017-08-22 1:17 ` Victor Porton
2017-08-22 1:20 ` Victor Porton
2017-08-22 7:28 ` gautier_niouzes [this message]
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