Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n

[Richard Henderson <rth at redhat dot com>]

On Sun, Jun 19, 2005 at 11:34:44PM +0300, Dorit Naishlos wrote:
> you mean if scalar_initial_def is zero?

Yes.

I suppose it probably isn't a big deal, since we're already under
-ffast-math, and the 0.0 should get folded away, but we might as
well spend a couple lines of code and get it right to begin.

I suppose another option here is to defer the decision on which
method to use until rtl expansion.  That is, always produce
REDUC_PLUS_EXPR during vectorization and add code in optabs to
choose the correct expansion.  There we'd be perfectly placed to
notice if the vector shift pattern did a FAIL and then fall back
to the element-by-element operation.



r~