[vox-tech] gcc question

Gabriel Rosa vox-tech@lists.lugod.org
Wed, 27 Feb 2002 09:33:49 -0800 (PST)


I think -funroll-all-loops adds run-time loop unrolling, which may or may
not speed up code execution. At least, that's what I've always deciphered it
to be.

However, I am not an expert :)

-Gabe

On Wed, 27 Feb 2002, Peter Jay Salzman wrote:

> hi everyone,
>
>        -funroll-loops
>               Perform the optimization of loop  unrolling.   This
>               is  only  done for loops whose number of iterations
>               can be determined at compile time or run time.
>
>        -funroll-all-loops
>               Perform the optimization of loop  unrolling.   This
>               is done for all loops.  This usually makes programs
>               run more slowly.
>
> ok, -funroll-all-loops usually makes programs run more slowly.  it also
> clearly makes the executable larger.
>
> so what exactly are we optimizing here?
>
> pete
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