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Cc: Joe Buck <jbuck@synopsys.com>,
 Scott Robert Ladd <coyote@coyotegulch.com>,
 Gabriel Dos Reis <gdr@integrable-solutions.net>,
 Alexandre Oliva <aoliva@redhat.com>,
 Steven Bosscher <s.bosscher@student.tudelft.nl>,
  <gcc@gcc.gnu.org>
From: Daniel Berlin <dberlin@dberlin.org>
Subject: Re: std::pow implementation
Date: Wed, 30 Jul 2003 18:22:00 -0000
To: Richard Guenther <rguenth@tat.physik.uni-tuebingen.de>
X-SW-Source: 2003-07/txt/msg02240.txt.bz2


On Wednesday, July 30, 2003, at 1:06 PM, Richard Guenther wrote:

> On Wed, 30 Jul 2003, Joe Buck wrote:
>
>> However, that doesn't get around the fact that we have an -O3 switch,
>> enabling a mode where the compiler has to make decisions to inline
>> additional functions.
>>
>> In such cases, the compiler cannot ignore the effect of constant 
>> arguments
>> causing much of the code in a called function to disappear when the 
>> called
>> function is inlined.
>
> We may be able to do this now with unit-at-a-time and callgraph by
> duplicating the trees for function calls with constant arguments and
> binding the constant arguments and doing the tree-optimizations on 
> these
> bodies before deciding inlining (and we may even just emit this new
> function out of line if not inlined).

Actually, the heuristic is usually something like:
If number of calls to function with constant arguments is estimated or 
actually high (IE function is on some critical performance path):
<clone and optimize>

Otherwise, you would waste so much time trying to determine what to 
clone, it's absurd.

>
> Richard.
>