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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi all,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>For a front-end pass, I can load the pass from a dynamic shared library using “<span 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?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any advice/suggestions would be greatly appreciated!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks,<o:p></o:p></p><p class=MsoNormal>Ethan Johnson<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><i>Ethan J. Johnson<o:p></o:p></i></p><p class=MsoNormal><i>Computer Science PhD student, Systems group, University of Rochester<o:p></o:p></i></p><p class=MsoNormal><a href="mailto:ejohns48@cs.rochester.edu"><i><span style='color:#0563C1'>ejohns48@cs.rochester.edu</span></i></a><i><o:p></o:p></i></p><p class=MsoNormal><a href="mailto:ethanjohnson@acm.org"><i><span style='color:#0563C1'>ethanjohnson@acm.org</span></i></a><i><o:p></o:p></i></p><p class=MsoNormal><i>PGP pubkey available from public directory or on request<o:p></o:p></i></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>