<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=""><div class="">I think those should be considered internal options for (llvm codegen) developers, a normal compiler user should not need to use any of them. Of course you can look around the llvm sourcecode (esp. in lib/CodeGen/MachineScheduler.cpp) and see what cl::opt options are available and how they affect the scheduler operation.</div><div class=""><br class=""></div><div class="">In case of the MachineScheduler all settings are the same regardless of the optimisation level, however the MachineScheduler is disabled as a whole in TargetPassConfig.cpp when optimized regalloc is not enabled (which I believe happens for everything except -O0).</div><div class=""><br class=""></div><div class="">- Matthias</div><br class=""><div><blockquote type="cite" class=""><div class="">On Sep 12, 2016, at 10:41 AM, Phil Tomson via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">As a follow on question: which of these options are already enabled when compiling with -O3?<br class=""><br class=""></div>Phil<br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Mon, Sep 12, 2016 at 10:37 AM, Phil Tomson <span dir="ltr" class=""><<a href="mailto:phil.a.tomson@gmail.com" target="_blank" class="">phil.a.tomson@gmail.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class=""><div class=""><div class=""><div class="">I see that there are several options to influence instruction scheduling, but there doesn't seem to be a lot of information about what they do, for example:<br class=""><br class="">-misched-topdown -misched-bottomup<br class=""><br class=""></div>The description in MachineScheduler.cpp says:<br class=""><br class="">"Force top-down list scheduling" and "Force bottom-up list scheduling"<br class=""><br class=""></div>Which isn't too helpful - where might I want to use these? Under what conditions might they improve an instruction schedule?<br class=""><br class=""></div>Similar questions for the instruction scheduler strategies: <br class=""><br class="">-misched=(default, converge,<br class=""><div class=""><div class="">ilpmax, ilpmin, or shuffle)<br class=""><br class=""></div><div class="">And for the analysis heuristics: <br class=""><br class="">-misched-cluster,<br class="">-misched-cyclicpath, -misched-regpressure, and -misched-<br class="">fusion<br class=""><br class=""></div><div class="">Are these things mutually exclusive or can they be combined? What combination will give the most rigorous analysis and improve scheduling (at the cost of longer runtime of llc)<span class="HOEnZb"><font color="#888888" class=""><br class=""><br class=""></font></span></div><span class="HOEnZb"><font color="#888888" class=""><div class="">Phil<br class=""></div></font></span></div></div>
</blockquote></div><br class=""></div>
_______________________________________________<br class="">LLVM Developers mailing list<br class=""><a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a><br class="">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev<br class=""></div></blockquote></div><br class=""></body></html>