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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi Nadav, Arnold,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’ve come across an interesting optimization problem in one of the SPEC benchmarks. There is a loop that can be optimized by both the SLP vectorizer and the loop vectorizer (when I patch the loop vectorizer to deal with fsub reductions).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The SLP vectorizer actually makes the performance worse – I think this is due to a lack of loop unrolling afterwards. The Loop vectorizer can improve the performance.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>However, the loop vectorizer runs after the SLP vectorizer, so it never gets a chance. I’d have thought the ideal order would be Loop Vectorizer -> SLP vectorizer -> BB vectorizer, given that the loop vectorizer if it can run will probably give greater speedup than SLP.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The current sequence is SLP vectorizer -> BB vectorizer -> Loop vectorizer.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>What are your thoughts on this?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Cheers,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>James<o:p></o:p></p></div></body></html>