
<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="">There is also the LivePhysReg facility that I would recomment if you just want to query for a free register and do not need the full feature set of the RegisterScavenger.</div><div class=""><br class=""></div><div class="">- Matthias</div><br class=""><div><blockquote type="cite" class=""><div class="">On Jan 19, 2017, at 5:50 AM, Nemanja Ivanovic 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="">I believe what you're after is the register scavenger.<br class=""></div><div class="">It's in: include/llvm/CodeGen/RegisterScavenging.h</div>Implementation: lib/CodeGen/RegisterScavenging.cpp<br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Thu, Jan 19, 2017 at 1:36 PM, Hong Hu via llvm-dev <span dir="ltr" class=""><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank" class="">llvm-dev@lists.llvm.org</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="gmail_default" style="font-size:small">Hi All,</div><div class="gmail_default" style="font-size:small"><br class=""></div><div class="gmail_default" style="font-size:small">Given a machine instruction, is it possible to tell which register(s) is still not in use? </div><div class="gmail_default" style="font-size:small"><br class=""></div><div class="gmail_default" style="font-size:small">For example, given one instruction A, if the one follows it (say B) defines register rax, then I can tell rax should spare at instruction A. </div><div class="gmail_default" style="font-size:small"><br class=""></div><div class="gmail_default" style="font-size:small">The purpose is to use the spare register to replace registers used by A, for instrumentation purpose.</div><div class="gmail_default" style="font-size:small"><br class=""></div><div class=""><div class="m_-6826991358958350244gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class="">Regards,<div class="">Hu Hong</div></div></div></div>

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