Date: Tue, 14 Sep 2021 08:07:11 +0000 From: bugzilla-noreply@freebsd.org To: erlang@FreeBSD.org Subject: maintainer-feedback requested: [Bug 258494] lang/erlang lang/erlang-runtime21 lang/erlang-runtime23: clang 13 build breaks dtrace if PGO is enabled Message-ID: <bug-258494-38768-kMVMCikf4y@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-258494-38768@https.bugs.freebsd.org/bugzilla/> References: <bug-258494-38768@https.bugs.freebsd.org/bugzilla/>
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Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-erlang (Nobody) <erlang@FreeBSD.org> for maintainer-feedback: Bug 258494: lang/erlang lang/erlang-runtime21 lang/erlang-runtime23: clang = 13 build breaks dtrace if PGO is enabled https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D258494 --- Description --- During an exp-run for llvm 13 (see bug 258209), it turned out that lang/erl= ang and lang/erlang-runtime2[1-3] fail to build with clang 13: http://gohan04.nyi.freebsd.org/data/mainamd64PR258209-default/2021-09-05_20= h27m 09s/logs/errors/erlang-21.3.8.24_1,4.log http://gohan04.nyi.freebsd.org/data/mainamd64PR258209-default/2021-09-05_20= h27m 09s/logs/errors/erlang-runtime21-21.3.8.24_1.log http://gohan04.nyi.freebsd.org/data/mainamd64PR258209-default/2021-09-05_20= h27m 09s/logs/errors/erlang-runtime23-23.3.4.6.log What appears to happen is that for these versions of erlang, PGO is enabled, and it first builds a PGO-enabled beam.smp: gmake[5]: Entering directory '/wrkdirs/usr/ports/lang/erlang/work/otp-OTP-21.3.8.24/erts/emulator' if utils/gen_git_version amd64-portbld-freebsd14.0/gen_git_version.mk; then touch beam/erl_bif_info.c; fi echo " PROFILE beam.prof.smp" PROFILE beam.prof.smp rm -f obj/amd64-portbld-freebsd14.0/opt/smp/erl*.profraw set -e; LLVM_PROFILE_FILE=3D"obj/amd64-portbld-freebsd14.0/opt/smp/erlc-%m.profraw"= \ ERL_FLAGS=3D"-emu_type prof +S 1" erlc -W -DPGO \ -o obj/amd64-portbld-freebsd14.0/opt/smp test/estone_SUITE.erl > obj/amd64-portbld-freebsd14.0/opt/smp/PROFILE_LOG after which it does a test run, and uses llvm-profdata to merge the profili= ng data into beam_emu_pu.o: llvm-profdata merge -output obj/amd64-portbld-freebsd14.0/opt/smp/default.profdata obj/amd64-portbld-freebsd14.0/opt/smp/*.profraw cc -fprofile-instr-use=3Dobj/amd64-portbld-freebsd14.0/opt/smp/default.prof= data=20 -Werror=3Dundef -Werror=3Dimplicit -Werror=3Dreturn-type -O3 -fomit-frame= -pointer -pipe -fno-omit-frame-pointer -DMAP_N ORESERVE=3D0 -fstack-protector-strong -fno-strict-aliasing=20 -I/wrkdirs/usr/ports/lang/erlang/work/otp-OTP-21.3.8.24/erts/amd64-portbld-= free bsd14.0 -DHAVE_CONFIG_H -Wall -Wstrict-prototypes -Wmis sing-prototypes -Wdeclaration-after-statement -DUSE_THREADS -D_THREAD_SAFE -D_REENTRANT -DPOSIX_THREADS -Iamd64-portbld-freebsd14.0/opt/smp -Ibeam -Isys/unix -Isys/common -Iamd64-portbld-freebs d14.0 -Ipcre -Ihipe -I../include -I../include/amd64-portbld-freebsd14.0 -I../include/internal -I../include/internal/amd64-portbld-freebsd14.0 -c beam/beam_emu.c -o obj/amd64-portbld-freebsd14.0/o pt/smp/beam_emu_pu.o Later, it runs dtrace over all the collected objects, and this dies: dtrace -G -C -Ibeam \ -s beam/erlang_dtrace.d \ -o obj/amd64-portbld-freebsd14.0/opt/smp/erlang_pu_dtrace.o ... long list of objects ... dtrace: failed to link script beam/erlang_dtrace.d: an error was encountered while processing obj/amd64-portbld-freebsd14.0/opt/smp/beam_emu_pu.o gmake[5]: *** [amd64-portbld-freebsd14.0/Makefile:1005: obj/amd64-portbld-freebsd14.0/opt/smp/erlang_pu_dtrace.o] Error 1 gmake[5]: Leaving directory '/wrkdirs/usr/ports/lang/erlang/work/otp-OTP-21.3.8.24/erts/emulator' Something in beam_emu_pu.o (emitted by clang or llvm 13) is tripping up dtr= ace, but I have very little knowledge about dtrace so I need help here. :) Now some other erlang runtimes such as lang/erlang-runtime24 *do* build successfully with clang 13, but this is only because upstream disabled the = PGO feature, as a side effect of https://github.com/erlang/otp/commit/b165524c7= 32 ("erts: Implement the BeamAsm JIT"):=20 --- a/erts/configure.in +++ b/erts/configure.in ... @@ -704,6 +719,9 @@ else fi fi +dnl Disable pgo for now +USE_PGO=3Dfalse + AC_SUBST(USE_PGO) AC_SUBST(PROFILE_COMPILER) (This took a *lot* of time to bisect due to erlang's afwul non-linear history... :) So, I'm unsure why upstream disabled this "for now", as it has been disabled for more than a year. We could work around the other erlang failures by also disabling PGO there, or with help from someone knowledgeable about dtrace, = try to get to the bottom of why dtrace dies on clang 13 produced PGO object fil= es.
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