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GCC no longer synthesizing v2sf operations from v4sf operations?
- From: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>
- To: gcc at gcc dot gnu dot org
- Date: Mon, 21 Mar 2005 13:30:59 +0100 (CET)
- Subject: GCC no longer synthesizing v2sf operations from v4sf operations?
Hi!
For
typedef float v4sf __attribute__((vector_size(16)));
void foo(v4sf *a, v4sf *b, v4sf *c)
{
*a = *b + *c;
}
we no longer (since 4.0) synthesize v2sf (aka sse) operations
for f.i. -march=athlon (not that we were too successful at this
in 3.4 - we generated horrible code instead). Instead for !sse2
architectures we generate standard i387 FP code (with some
unnecessary temporaries, but reasonably well).
Does this mean the generic manual vectorization with +-* experiment
has failed? I.e. are we really supposed to use ?mmintrin.h and friends,
or of course rely on auto-vectorization?
Thanks for clarification,
Richard.
--
Richard Guenther <richard dot guenther at uni-tuebingen dot de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/