Re: std::pow implementation

[Daniel Berlin <dberlin at dberlin dot org>]

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.