<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 26, 2016, at 12:39 PM, Xinliang David Li <<a href="mailto:davidxl@google.com" class="">davidxl@google.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><br class=""><div class="gmail_extra"><br class=""><div class="gmail_quote">On Wed, Oct 26, 2016 at 10:08 AM, Gerolf Hoflehner <span dir="ltr" class=""><<a href="mailto:ghoflehner@apple.com" target="_blank" class="">ghoflehner@apple.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Gerolf added a comment.<br class="">
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Hi,<br class="">
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Could you provide more background on this idea? What is your motivational use case? When the trip count is low why optimize?</blockquote><div class=""><br class=""></div><div class="">Low trip count loop can be hot too.</div></div></div></div></div></blockquote><div><br class=""></div><div>But then you would optimize differently. Can you share the example where you actually see gains? </div><div><br class=""></div><div>Thanks</div><div>Gerolf</div><div><br class=""></div><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""><br class=""></div><div class="">David</div><div class=""><br class=""></div><div class=""> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> If the profile is wrong and it actually is a hot loop for a regular/different input set peeling could hurt. There are also side effects on code size, register pressure etc. that could hurt performance.<br class="">
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Thanks<br class="">
Gerolf<br class="">
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<a href="https://reviews.llvm.org/D25963" rel="noreferrer" target="_blank" class="">https://reviews.llvm.org/<wbr class="">D25963</a><br class="">
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