Re: [PATCH] tools/perf: build issues with Clang on arm64 and CFLAGS

Masami Hiramatsu
2021-05-11T10:36:47Z

On Mon, 10 May 2021 09:14:01 -0300
Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

> Em Fri, May 07, 2021 at 05:54:25PM +0900, Masami Hiramatsu escreveu:
> > Hi Arnaldo,
> >
> > Recently, I tested the perf build by clang on arm64 and found an issue
>
> Cross building? What toolchain? I regularly build perf with lots of
> clang versions, but cross building with clang isn't yet performed in my
> tests.
>
> > in arch/arm64/util/kvm-stat.c, related to missing-field-initializers warning.
> >
> > ----
> > tools/perf $ make CC=clang LLVM=1
> > ...
> > arch/arm64/util/kvm-stat.c:74:9: error: missing field 'ops' initializer [-Werror,-Wmissing-field-initializers]
> > { NULL },
> > ^
> > 1 error generated.
> > ----
> >
> > That error itself can be fixed easily by just adding field initializers
> > [1/1] Note that I didn't add Fixes tag, because I'm not sure clang build
> > of perf is officially supported or not, and this seems correct C code
> > to initialize a data structure with zero.(*)
>
> I'd say it is supported, at least by me, for quite a while, as can be
> seen in all pull requests I send upstream, for instance:
>
> https://lore.kernel.org/linux-perf-users/YIxSJ7bdtjv4wHok@kernel.org/
>
> # export PERF_TARBALL=http://192.168.86.5/perf/perf-5.12.0.tar.xz
> # dm
> 1 72.92 alpine:3.4 : Ok gcc (Alpine 5.3.0) 5.3.0 , clang version 3.8.0 (tags/RELEASE_380/final)
> 2 74.56 alpine:3.5 : Ok gcc (Alpine 6.2.1) 6.2.1 20160822 , clang version 3.8.1 (tags/RELEASE_381/final)
> 3 81.19 alpine:3.6 : Ok gcc (Alpine 6.3.0) 6.3.0 , clang version 4.0.0 (tags/RELEASE_400/final)
> 4 90.07 alpine:3.7 : Ok gcc (Alpine 6.4.0) 6.4.0 , Alpine clang version 5.0.0 (tags/RELEASE_500/final) (based on LLVM 5.0.0)
> 5 83.40 alpine:3.8 : Ok gcc (Alpine 6.4.0) 6.4.0 , Alpine clang version 5.0.1 (tags/RELEASE_501/final) (based on LLVM 5.0.1)
> 6 85.30 alpine:3.9 : Ok gcc (Alpine 8.3.0) 8.3.0 , Alpine clang version 5.0.1 (tags/RELEASE_502/final) (based on LLVM 5.0.1)
> 7 110.88 alpine:3.10 : Ok gcc (Alpine 8.3.0) 8.3.0 , Alpine clang version 8.0.0 (tags/RELEASE_800/final) (based on LLVM 8.0.0)
> 8 140.86 alpine:3.11 : Ok gcc (Alpine 9.3.0) 9.3.0 , Alpine clang version 9.0.0 (https://git.alpinelinux.org/aports f7f0d2c2b8bcd6a5843401a9a702029556492689) (based on LLVM 9.0.0)
> 9 127.60 alpine:3.12 : Ok gcc (Alpine 9.3.0) 9.3.0 , Alpine clang version 10.0.0 (https://gitlab.alpinelinux.org/alpine/aports.git 7445adce501f8473efdb93b17b5eaf2f1445ed4c)
> 10 278.42 alpine:3.13 : Ok gcc (Alpine 10.2.1_pre1) 10.2.1 20201203 , Alpine clang version 10.0.1
> 11 235.62 alpine:edge : Ok gcc (Alpine 10.3.1_git20210424) 10.3.1 20210424 , Alpine clang version 11.1.0
> 12 161.23 alt:p8 : Ok x86_64-alt-linux-gcc (GCC) 5.3.1 20151207 (ALT p8 5.3.1-alt3.M80P.1) , clang version 3.8.0 (tags/RELEASE_380/final)
> 13 390.70 alt:p9 : Ok x86_64-alt-linux-gcc (GCC) 8.4.1 20200305 (ALT p9 8.4.1-alt0.p9.1) , clang version 10.0.0
> 14 95.00 alt:sisyphus : Ok x86_64-alt-linux-gcc (GCC) 10.2.1 20210313 (ALT Sisyphus 10.2.1-alt3) , clang version 10.0.1
> 15 77.78 amazonlinux:1 : Ok gcc (GCC) 7.2.1 20170915 (Red Hat 7.2.1-2) , clang version 3.6.2 (tags/RELEASE_362/final)
> 16 103.23 amazonlinux:2 : Ok gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-12) , clang version 7.0.1 (Amazon Linux 2 7.0.1-1.amzn2.0.2)
> 17 22.16 android-ndk:r12b-arm : Ok arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
> 18 22.10 android-ndk:r15c-arm : Ok arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
> 19 25.74 centos:6 : Ok gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23)
> 20 31.40 centos:7 : Ok gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)
> 21 97.31 centos:8 : Ok gcc (GCC) 8.3.1 20191121 (Red Hat 8.3.1-5) , clang version 10.0.1 (Red Hat 10.0.1-1.module_el8.3.0+467+cb298d5b)
> 22 60.94 clearlinux:latest : Ok gcc (Clear Linux OS for Intel Architecture) 10.2.1 20201217 releases/gcc-10.2.0-643-g7cbb07d2fc , clang version 10.0.1
> 23 77.23 debian:8 : Ok gcc (Debian 4.9.2-10+deb8u2) 4.9.2 , Debian clang version 3.5.0-10 (tags/RELEASE_350/final) (based on LLVM 3.5.0)
> 24 82.00 debian:9 : Ok gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516 , clang version 3.8.1-24 (tags/RELEASE_381/final)
> 25 75.27 debian:10 : Ok gcc (Debian 8.3.0-6) 8.3.0 , clang version 7.0.1-8+deb10u2 (tags/RELEASE_701/final)
> 26 74.40 debian:experimental : Ok gcc (Debian 10.2.1-6) 10.2.1 20210110 , Debian clang version 11.0.1-2
> 27 32.81 debian:experimental-x-arm64 : Ok aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110
> 28 28.53 debian:experimental-x-mips : Ok mips-linux-gnu-gcc (Debian 10.2.1-3) 10.2.1 20201224
> 29 30.96 debian:experimental-x-mips64 : Ok mips64-linux-gnuabi64-gcc (Debian 10.2.1-3) 10.2.1 20201224
> 30 31.13 debian:experimental-x-mipsel : Ok mipsel-linux-gnu-gcc (Debian 10.2.1-3) 10.2.1 20201224
> 31 29.13 fedora:20 : Ok gcc (GCC) 4.8.3 20140911 (Red Hat 4.8.3-7)
> 32 29.51 fedora:22 : Ok gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) , clang version 3.5.0 (tags/RELEASE_350/final)
> 33 68.17 fedora:23 : Ok gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) , clang version 3.7.0 (tags/RELEASE_370/final)
> 34 80.83 fedora:24 : Ok gcc (GCC) 6.3.1 20161221 (Red Hat 6.3.1-1) , clang version 3.8.1 (tags/RELEASE_381/final)
> 35 26.32 fedora:24-x-ARC-uClibc : Ok arc-linux-gcc (ARCompact ISA Linux uClibc toolchain 2017.09-rc2) 7.1.1 20170710
> 36 82.85 fedora:25 : Ok gcc (GCC) 6.4.1 20170727 (Red Hat 6.4.1-1) , clang version 3.9.1 (tags/RELEASE_391/final)
> 37 94.47 fedora:26 : Ok gcc (GCC) 7.3.1 20180130 (Red Hat 7.3.1-2) , clang version 4.0.1 (tags/RELEASE_401/final)
> 38 96.40 fedora:27 : Ok gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-6) , clang version 5.0.2 (tags/RELEASE_502/final)
> 39 108.54 fedora:28 : Ok gcc (GCC) 8.3.1 20190223 (Red Hat 8.3.1-2) , clang version 6.0.1 (tags/RELEASE_601/final)
> 40 113.97 fedora:29 : Ok gcc (GCC) 8.3.1 20190223 (Red Hat 8.3.1-2) , clang version 7.0.1 (Fedora 7.0.1-6.fc29)
> 41 119.26 fedora:30 : Ok gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2) , clang version 8.0.0 (Fedora 8.0.0-3.fc30)
> 42 25.92 fedora:30-x-ARC-uClibc : Ok arc-linux-gcc (ARCv2 ISA Linux uClibc toolchain 2019.03-rc1) 8.3.1 20190225
> 43 117.82 fedora:31 : Ok gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2) , clang version 9.0.1 (Fedora 9.0.1-4.fc31)
> 44 97.12 fedora:32 : Ok gcc (GCC) 10.2.1 20201125 (Red Hat 10.2.1-9) , clang version 10.0.1 (Fedora 10.0.1-3.fc32)
> 45 94.80 fedora:33 : Ok gcc (GCC) 10.3.1 20210422 (Red Hat 10.3.1-1) , clang version 11.0.0 (Fedora 11.0.0-2.fc33)
> 46 99.46 fedora:34 : Ok gcc (GCC) 11.0.1 20210324 (Red Hat 11.0.1-0) , clang version 12.0.0 (Fedora 12.0.0-0.3.rc1.fc34)
> 47 98.91 fedora:rawhide : Ok gcc (GCC) 11.0.1 20210423 (Red Hat 11.0.1-0) , clang version 12.0.0 (Fedora 12.0.0-1.fc35)
> 48 34.11 gentoo-stage3-amd64:latest : Ok gcc (Gentoo 9.3.0-r1 p3) 9.3.0
> 49 66.98 mageia:5 : Ok gcc (GCC) 4.9.2 , clang version 3.5.2 (tags/RELEASE_352/final)
> 50 83.81 mageia:6 : Ok gcc (Mageia 5.5.0-1.mga6) 5.5.0 , clang version 3.9.1 (tags/RELEASE_391/final)
> 51 48.52 mageia:7 : FAIL clang version 8.0.0 (Mageia 8.0.0-1.mga7)
> yychar = yylex (&yylval, &yylloc, scanner);
> ^
> #define yylex parse_events_lex
> ^
> 1 error generated.
> make[3]: *** [/git/perf-5.12.0/tools/build/Makefile.build:139: util] Error 2
> 52 221.66 openmandriva:cooker : Ok gcc (GCC) 10.3.0 20210408 (OpenMandriva) , OpenMandriva 12.0.0-1 clang version 12.0.0 (/builddir/build/BUILD/llvm-project-llvmorg-12.0.0/clang b3a1e025e0452bb54d01ab5281bbf509ac4e3c72)
> 53 119.19 opensuse:15.0 : Ok gcc (SUSE Linux) 7.4.1 20190905 [gcc-7-branch revision 275407] , clang version 5.0.1 (tags/RELEASE_501/final 312548)
> 54 127.85 opensuse:15.1 : Ok gcc (SUSE Linux) 7.5.0 , clang version 7.0.1 (tags/RELEASE_701/final 349238)
> 55 117.53 opensuse:15.2 : Ok gcc (SUSE Linux) 7.5.0 , clang version 9.0.1
> 56 131.22 opensuse:15.3 : Ok gcc (SUSE Linux) 7.5.0 , clang version 7.0.1 (tags/RELEASE_701/final 349238)
> 57 114.64 opensuse:42.3 : Ok gcc (SUSE Linux) 4.8.5 , clang version 3.8.0 (tags/RELEASE_380/final 262553)
> 58 108.83 opensuse:tumbleweed : Ok gcc (SUSE Linux) 10.2.1 20200825 [revision c0746a1beb1ba073c7981eb09f55b3d993b32e5c] , clang version 10.0.1
> 59 25.02 oraclelinux:6 : Ok gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23.0.1)
> 60 30.76 oraclelinux:7 : Ok gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44.0.3)
> 61 95.29 oraclelinux:8 : Ok gcc (GCC) 8.3.1 20191121 (Red Hat 8.3.1-5.0.2) , clang version 10.0.1 (Red Hat 10.0.1-1.0.1.module+el8.3.0+7827+89335dbf)
> 62 25.85 ubuntu:12.04 : Ok gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 , Ubuntu clang version 3.0-6ubuntu3 (tags/RELEASE_30/final) (based on LLVM 3.0)
> 63 29.09 ubuntu:14.04 : Ok gcc (Ubuntu 4.8.4-2ubuntu1~14.04.4) 4.8.4
> 64 81.27 ubuntu:16.04 : Ok gcc (Ubuntu 5.4.0-6ubuntu1~16.04.12) 5.4.0 20160609 , clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final)
> 65 27.09 ubuntu:16.04-x-arm : Ok arm-linux-gnueabihf-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
> 66 27.59 ubuntu:16.04-x-arm64 : Ok aarch64-linux-gnu-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
> 67 26.25 ubuntu:16.04-x-powerpc : Ok powerpc-linux-gnu-gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
> 68 26.87 ubuntu:16.04-x-powerpc64 : Ok powerpc64-linux-gnu-gcc (Ubuntu/IBM 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
> 69 27.69 ubuntu:16.04-x-powerpc64el : Ok powerpc64le-linux-gnu-gcc (Ubuntu/IBM 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
> 70 26.58 ubuntu:16.04-x-s390 : Ok s390x-linux-gnu-gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
> 71 88.21 ubuntu:18.04 : Ok gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0 , clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
> 72 28.46 ubuntu:18.04-x-arm : Ok arm-linux-gnueabihf-gcc (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04) 7.5.0
> 73 29.25 ubuntu:18.04-x-arm64 : Ok aarch64-linux-gnu-gcc (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04) 7.5.0
> 74 23.59 ubuntu:18.04-x-m68k : Ok m68k-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 75 27.97 ubuntu:18.04-x-powerpc : Ok powerpc-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 76 29.83 ubuntu:18.04-x-powerpc64 : Ok powerpc64-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 77 30.41 ubuntu:18.04-x-powerpc64el : Ok powerpc64le-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 78 172.25 ubuntu:18.04-x-riscv64 : Ok riscv64-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 79 26.09 ubuntu:18.04-x-s390 : Ok s390x-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 80 28.18 ubuntu:18.04-x-sh4 : Ok sh4-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 81 26.43 ubuntu:18.04-x-sparc64 : Ok sparc64-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
> 82 76.46 ubuntu:20.04 : Ok gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0 , clang version 10.0.0-4ubuntu1
> 83 31.35 ubuntu:20.04-x-powerpc64el : Ok powerpc64le-linux-gnu-gcc (Ubuntu 10.2.0-5ubuntu1~20.04) 10.2.0
> 84 74.85 ubuntu:20.10 : Ok gcc (Ubuntu 10.2.0-13ubuntu1) 10.2.0 , Ubuntu clang version 11.0.0-2
> 85 71.63 ubuntu:21.04 : Ok gcc (Ubuntu 10.3.0-1ubuntu1) 10.3.0 , Ubuntu clang version 12.0.0-1ubuntu1
>
>
> But I couldn't find so far, and I haven't researched this lately, a distro that has all the
> devel packages cross-built so that I could cross build a full featured perf tool, are you
> aware of one? In the -x-ARCH tests above I end up just manually cross-building elfutils and zlib
> to get a minimal perf cross build.

Actually, this only happens with clang, not with gcc. And clang's cross build
is different from GCC (clang only needs the target option, but you can use
same tool, no need to add aarch64-linux-gnu-*).
Anders works on this and he made a hack.

> > And while investigating the error, I found another issue in the Makefile.config.
> >
> > It seems to make CFLAGS from CORE_CFLAGS, INC_FLAGS, EXTRA_CFLAGS, EXTRA_WARNINGS
> > in the following order;
> >
> > CFLAGS = $EXTRA_CFLAGS $EXTRA_WARNINGS $CORE_CFLAGS $INC_FLAGS
> >
> > But since CORE_CFLAGS includes -Wall and -Wextra, the other -Wno-XXXX in
> > EXTRA_CFLAGS and EXTRA_WARNINGS are overriden and ignored.
> > So, I think it is better to define it as
> >
> > CFLAGS = $CORE_CFLAGS $INC_FLAGS $EXTRA_CFLAGS $EXTRA_WARNINGS
> >
> > But I also saw some configs tweaks CFLAGS directly. I think they should
> > modify EXTRA_CFLAGS.
> >
> > My question is that this order is intentional or not. I might
> > miss something on it.
>
> Oh the joy with Makefiles.. Most likely unintentional, please submit a patch, please reuse
> your wording above to justify it.

OK, I'll fix that.

> > (*) BTW, there seems a discussion on the clang warning behavior,
> > because gcc doesn't warn it anymore
> > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750).
> > It might be better to add -Wno-missing-field-initializers in case
> > of CC=clang by default.
>
> Humm, unsure about that, I applied your patch, but I'd say it'd be better to
> use the variant that initialized the first field to zero/NULL and then all the
> other (not explicitely initialized) ones will be zeroed.

OK, then I'll add this option.

Thank you!

--
Masami Hiramatsu <mhiramat@kernel.org>