<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></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 Jul 2, 2015, at 2:05 PM, Jim Grosbach <<a href="mailto:grosbach@apple.com" class="">grosbach@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On Jul 2, 2015, at 1:17 PM, Ethan J. Johnson <<a href="mailto:ejohns48@cs.rochester.edu" class="">ejohns48@cs.rochester.edu</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">Hi all,<o:p class=""></o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p class=""> </o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">I am working on creating a MachineFunctionPass to perform an analysis on X86 code. After a bit of trouble, I was able to get my pass compiling and running correctly in llc. However, since a machine pass is compiled directly into the code generator, rerunning “make” across the LLVM build tree involves re-linking most of the major libraries and executables. This is a rather intense process, both in terms of CPU usage and memory (some of the bigger binaries, especially clang, use as much as 5 GB peak memory during linking). With a powerful multicore machine and plenty of RAM, this is doable, but still very time-consuming, and seems wastefully repetitive.<o:p class=""></o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p class=""> </o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">For a front-end pass, I can load the pass from a dynamic shared library using “<span class="" style="font-family: Consolas;">opt –l path_to_library</span>”; thus I only need to rebuild the pass itself to test a code change. There does not appear to be such an option in llc for dynamically linking a machine pass as a plugin. Does anyone know of a way to achieve something similar?</div></div></div></blockquote><div class=""><br class=""></div><div class="">There is unfortunately no way to do that currently.</div><br class=""><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p class=""></o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p class=""> </o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">At the very least, it would be nice to be able to just re-compile the parts of the LLVM tree I need (perhaps just llc). It seems particularly odd that clang, which is a front-end, would need to be relinked for a code change in a back-end pass. (clang, and some of its related components, are responsible for the lion’s share of the time-consuming CPU/memory-intensive linking phase.)<o:p class=""></o:p></div><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p class=""> </o:p></div></div></div></blockquote><div class=""><br class=""></div><div class="">clang the project is the front end, but clang the executable program is the full compiler, including all of optimization, codegen, object emission, etc..</div><br class=""><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">FYI, I am using the Autotools (./configure, make) process to build LLVM, but have also successfully built with CMake and would be willing to try suggestions involving either.</div></div></div></blockquote><div class=""><br class=""></div><div class="">This, however, can be done, at least w/ CMake+ninja (probably other permutations, too, but that’s the one I use these days). Just do “ninja llc” and it will build just what’s required for llc. Same for any of the other tools.</div></div></div></blockquote><div><br class=""></div>Also enabling shared libraries "cmake -DBUILD_SHARED_LIBS=ON" reduces link times dramatically in my experience.</div><div><br class=""></div><div>- Matthias</div></body></html>