On Tue, Nov 28, 2017 at 01:34:00AM +0100, Jan Beich wrote: > I'd like to build www/firefox with both DTrace and LTO support. Both > Clang and GCC emit code that dtrace(1) doesn't understand.
Unfortunately, both gcc and clang's LTO implementations are completely incompatible with the way that dtrace -G works. clang -flto produces LLVM bitcode files, and gcc -flto produces ELF files with custom sections. dtrace -G works by looking for relocations against symbols named __dtrace_probe_*, and recording and overwriting the relocation address, but the object files generated when using -flto are really only meant for consumption by the static linker. I think it might be possible to implement USDT for clang using LLVM's patchpoint instrinsic, but this would still require some support in the compiler. Anyway, I don't think it'll be possible to reconcile -flto and dtrace -G without substantial work. _______________________________________________ freebsd-toolchain@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain To unsubscribe, send any mail to "freebsd-toolchain-unsubscr...@freebsd.org"
