<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 Mar 8, 2017, at 4:44 PM, David Blaikie <<a href="mailto:dblaikie@gmail.com" class="">dblaikie@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Wed, Mar 8, 2017 at 3:52 PM Matthias Braun via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;"><div class="gmail_msg" style="word-wrap: break-word;"><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg">On Mar 8, 2017, at 3:14 PM, Chris Bieneman via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="gmail_msg" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="m_-168022494174270928Apple-interchange-newline gmail_msg"><div class="gmail_msg"><div class="gmail_msg" style="word-wrap: break-word;"><br class="gmail_msg"><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg">On Mar 8, 2017, at 3:08 PM, Hal Finkel <<a href="mailto:hfinkel@anl.gov" class="gmail_msg" target="_blank">hfinkel@anl.gov</a>> wrote:</div><br class="m_-168022494174270928Apple-interchange-newline gmail_msg"><div class="gmail_msg"><div class="gmail_msg m_-168022494174270928moz-cite-prefix" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255);"><br class="m_-168022494174270928Apple-interchange-newline gmail_msg">On 03/08/2017 04:55 PM, Chris Bieneman via llvm-dev wrote:<br class="gmail_msg"></div><blockquote type="cite" class="gmail_msg" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255);">David,<div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">This is an area that has had a lot of development over the last two years.</div><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">There are two supported ways in the LLVM build system to build compiler-rt with the just-built compiler.<div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">1) The legacy way is for if compiler-rt is under LLVM/projects. You can specify -DLLVM_BUILD_EXTERNAL_COMPILER_RT=On, which will configure compiler-rt using the just-built clang after clang is built.</div></div></blockquote><br class="gmail_msg" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255);"><span class="gmail_msg" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); float: none; display: inline !important;">Why is this not the default?</span><br class="gmail_msg" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255);"></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Two reasons. (1) It is buggy, and nobody fixed the issues because (2) the long-term plan is to not support building compiler-rt (or any other runtime library) under llvm/projects. The goal is to migrate entirely to llvm/runtimes where the support is more complete.</div></div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div></div></div><div class="gmail_msg" style="word-wrap: break-word;"><div class="gmail_msg"><div class="gmail_msg">From a compiler developers point of view I wanted to stress that we at least should keep the option not to do it, as in my experience development workflow heavily slows down if you have to wait around for compiler-rt to rebuild after every small change you make to the compiler.</div></div></div></blockquote><div class=""><br class=""></div><div class="">If that's a valid option, I'd be open to it - it does really slow down the dev cycle & it's one of the reasons I often end up moving compiler-rt out/not building it anymore.<br class=""><br class="">I'm not sure if that's an option at the moment - if it is, I'd love to know how to do that & it might at least unblock my use case anyway, even if there's still a need for a broader fix.<br class=""></div></div></div></div></blockquote><div>The legacy way (I wasn't aware it is legacy) of "-DLLVM_BUILD_EXTERNAL_COMPILER_RT=On/Off" has worked fine for me so far. I haven't tried the runtimes directory style yet, but it looks like a nicer more explicit way than specifying cmake flags and is just suffering from a bit probably?</div><div><br class=""></div><div>- Matthias</div></div></body></html>