Re: [PATCH] perf python: better clang detection

[Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>]

Em Mon, Mar 09, 2020 at 10:56:17AM +0200, Ilie Halip escreveu:
> Currently, the setup.py script detects the clang compiler only when invoked
> with CC=clang. But when using a specific version (e.g. CC=clang-11), this
> doesn't work correctly and wrong compiler flags are set, leading to build
> errors.
> 
> To properly detect clang, invoke the compiler with -v and check the output.
> The first line should start with "clang version ...".
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/903
> Signed-off-by: Ilie Halip <ilie.halip@gmail.com>

Thanks, tested, added the testing performed (see below) to the cset
message and applied,

- Arnaldo

commit a7ffd416d80497f03d1f62c0b330cff76a86d5ad
Author: Ilie Halip <ilie.halip@gmail.com>
Date:   Mon Mar 9 10:56:17 2020 +0200

    perf python: Fix clang detection when using CC=clang-version
    
    Currently, the setup.py script detects the clang compiler only when invoked
    with CC=clang. But when using a specific version (e.g. CC=clang-11), this
    doesn't work correctly and wrong compiler flags are set, leading to build
    errors.
    
    To properly detect clang, invoke the compiler with -v and check the output.
    The first line should start with "clang version ...".
    
    Committer testing:
    
      $ make CC=clang-9 O=/tmp/build/perf -C tools/perf install-bin
      <SNIP>
      $ readelf -wi /tmp/build/perf/python/perf.cpython-37m-x86_64-linux-gnu.so | grep DW_AT_producer | head -1
        <c>   DW_AT_producer    : (indirect string, offset: 0x0): clang version 9.0.1 (Fedora 9.0.1-2.fc31) /usr/bin/clang-9 -Wno-unused-result -Wsign-compare -D DYNAMIC_ANNOTATIONS_ENABLED=1 -D NDEBUG -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-command-line -m64 -mtune=generic -fasynchronous-unwind-tables -fcf-protection=full -D _GNU_SOURCE -fPIC -fwrapv -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat-y2k -Winit-self -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-system-headers -Wold-style-definition -Wpacked -Wredundant-decls -Wstrict-prototypes -Wswitch-default -Wswitch-enum -Wundef -Wwrite-strings -Wformat -Wshadow -D HAVE_ARCH_X86_64_SUPPORT -I /tmp/build/perf/arch/x86/include/generated -D HAVE_SYSCALL_TABLE_SUPPORT -D HAVE_PERF_REGS_SUPPORT -D HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET -Werror -O3 -fno-omit-frame-pointer -ggdb3 -funwind-tables -Wall -Wextra -std=gnu99 -fstack-protector-all -D _FORTIFY_SOURCE=2 -D _LARGEFILE64_SOURCE -D _FILE_OFFSET_BITS=64 -D _GNU_SOURCE -I /home/acme/git/perf/tools/lib/perf/include -I /home/acme/git/perf/tools/perf/util/include -I /home/acme/git/perf/tools/perf/arch/x86/include -I /home/acme/git/perf/tools/include/ -I /home/acme/git/perf/tools/arch/x86/include/uapi -I /home/acme/git/perf/tools/include/uapi -I /home/acme/git/perf/tools/arch/x86/include/ -I /home/acme/git/perf/tools/arch/x86/ -I /tmp/build/perf//util -I /tmp/build/perf/ -I /home/acme/git/perf/tools/perf/util -I /home/acme/git/perf/tools/perf -I /home/acme/git/perf/tools/lib/ -D HAVE_PTHREAD_ATTR_SETAFFINITY_NP -D HAVE_PTHREAD_BARRIER -D HAVE_EVENTFD -D HAVE_GET_CURRENT_DIR_NAME -D HAVE_GETTID -D HAVE_DWARF_GETLOCATIONS_SUPPORT -D HAVE_GLIBC_SUPPORT -D HAVE_AIO_SUPPORT -D HAVE_SCHED_GETCPU_SUPPORT -D HAVE_SETNS_SUPPORT -D HAVE_LIBELF_SUPPORT -D HAVE_LIBELF_MMAP_SUPPORT -D HAVE_ELF_GETPHDRNUM_SUPPORT -D HAVE_GELF_GETNOTE_SUPPORT -D HAVE_ELF_GETSHDRSTRNDX_SUPPORT -D HAVE_DWARF_SUPPORT -D HAVE_LIBBPF_SUPPORT -D HAVE_BPF_PROLOGUE -D HAVE_SDT_EVENT -D HAVE_JITDUMP -D HAVE_DWARF_UNWIND_SUPPORT -D NO_LIBUNWIND_DEBUG_FRAME -D HAVE_LIBUNWIND_SUPPORT -D HAVE_LIBCRYPTO_SUPPORT -D HAVE_SLANG_SUPPORT -D HAVE_GTK2_SUPPORT -D NO_LIBPERL -D HAVE_TIMERFD_SUPPORT -D HAVE_LIBPYTHON_SUPPORT -D HAVE_CPLUS_DEMANGLE_SUPPORT -D HAVE_LIBBFD_SUPPORT -D HAVE_ZLIB_SUPPORT -D HAVE_LZMA_SUPPORT -D HAVE_ZSTD_SUPPORT -D HAVE_LIBCAP_SUPPORT -D HAVE_BACKTRACE_SUPPORT -D HAVE_LIBNUMA_SUPPORT -D HAVE_KVM_STAT_SUPPORT -D DISASM_FOUR_ARGS_SIGNATURE -D HAVE_LIBBABELTRACE_SUPPORT -D HAVE_AUXTRACE_SUPPORT -D HAVE_JVMTI_CMLR -I /tmp/build/perf/ -fPIC -I util/include -I /usr/include/python3.7m -c /home/acme/git/perf/tools/perf/util/python.c -o /tmp/build/perf/python_ext_build/tmp/home/acme/git/perf/tools/perf/util/python.o -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat-y2k -Winit-self -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-system-headers -Wold-style-definition -Wpacked -Wredundant-decls -Wstrict-prototypes -Wswitch-default -Wswitch-enum -Wundef -Wwrite-strings -Wformat -Wshadow -D HAVE_ARCH_X86_64_SUPPORT -I /tmp/build/perf/arch/x86/include/generated -D HAVE_SYSCALL_TABLE_SUPPORT -D HAVE_PERF_REGS_SUPPORT -D HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET -Werror -O3 -fno-omit-frame-pointer -ggdb3 -funwind-tables -Wall -Wextra -std=gnu99 -fstack-protector-all -D _FORTIFY_SOURCE=2 -D _LARGEFILE64_SOURCE -D _FILE_OFFSET_BITS=64 -D _GNU_SOURCE -I /home/acme/git/perf/tools/lib/perf/include -I /home/acme/git/perf/tools/perf/util/include -I /home/acme/git/perf/tools/perf/arch/x86/include -I /home/acme/git/perf/tools/include/ -I /home/acme/git/perf/tools/arch/x86/include/uapi -I /home/acme/git/perf/tools/include/uapi -I /home/acme/git/perf/tools/arch/x86/include/ -I /home/acme/git/perf/tools/arch/x86/ -I /tmp/build/perf//util -I /tmp/build/perf/ -I /home/acme/git/perf/tools/perf/util -I /home/acme/git/perf/tools/perf -I /home/acme/git/perf/tools/lib/ -D HAVE_PTHREAD_ATTR_SETAFFINITY_NP -D HAVE_PTHREAD_BARRIER -D HAVE_EVENTFD -D HAVE_GET_CURRENT_DIR_NAME -D HAVE_GETTID -D HAVE_DWARF_GETLOCATIONS_SUPPORT -D HAVE_GLIBC_SUPPORT -D HAVE_AIO_SUPPORT -D HAVE_SCHED_GETCPU_SUPPORT -D HAVE_SETNS_SUPPORT -D HAVE_LIBELF_SUPPORT -D HAVE_LIBELF_MMAP_SUPPORT -D HAVE_ELF_GETPHDRNUM_SUPPORT -D HAVE_GELF_GETNOTE_SUPPORT -D HAVE_ELF_GETSHDRSTRNDX_SUPPORT -D HAVE_DWARF_SUPPORT -D HAVE_LIBBPF_SUPPORT -D HAVE_BPF_PROLOGUE -D HAVE_SDT_EVENT -D HAVE_JITDUMP -D HAVE_DWARF_UNWIND_SUPPORT -D NO_LIBUNWIND_DEBUG_FRAME -D HAVE_LIBUNWIND_SUPPORT -D HAVE_LIBCRYPTO_SUPPORT -D HAVE_SLANG_SUPPORT -D HAVE_GTK2_SUPPORT -D NO_LIBPERL -D HAVE_TIMERFD_SUPPORT -D HAVE_LIBPYTHON_SUPPORT -D HAVE_CPLUS_DEMANGLE_SUPPORT -D HAVE_LIBBFD_SUPPORT -D HAVE_ZLIB_SUPPORT -D HAVE_LZMA_SUPPORT -D HAVE_ZSTD_SUPPORT -D HAVE_LIBCAP_SUPPORT -D HAVE_BACKTRACE_SUPPORT -D HAVE_LIBNUMA_SUPPORT -D HAVE_KVM_STAT_SUPPORT -D DISASM_FOUR_ARGS_SIGNATURE -D HAVE_LIBBABELTRACE_SUPPORT -D HAVE_AUXTRACE_SUPPORT -D HAVE_JVMTI_CMLR -I /tmp/build/perf/ -fno-strict-aliasing -Wno-write-strings -Wno-unused-parameter -Wno-redundant-decls
      $
    
    And here is how tools/perf/util/setup.py checks if the used clang has
    options that the distro specific python extension building compiler
    defaults:
    
      if cc_is_clang:
          from distutils.sysconfig import get_config_vars
          vars = get_config_vars()
          for var in ('CFLAGS', 'OPT'):
              vars[var] = sub("-specs=[^ ]+", "", vars[var])
              if not clang_has_option("-mcet"):
                  vars[var] = sub("-mcet", "", vars[var])
              if not clang_has_option("-fcf-protection"):
                  vars[var] = sub("-fcf-protection", "", vars[var])
              if not clang_has_option("-fstack-clash-protection"):
                  vars[var] = sub("-fstack-clash-protection", "", vars[var])
              if not clang_has_option("-fstack-protector-strong"):
                  vars[var] = sub("-fstack-protector-strong", "", vars[var])
    
    So "-fcf-protection=full" is used, clang-9 has this option and thus it
    was kept, the perf python extension was built with it and the build
    completed successfully.
    
    Link: https://github.com/ClangBuiltLinux/linux/issues/903
    Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
    Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Igor Lubashev <ilubashe@akamai.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: clang-built-linux@googlegroups.com
    Link: http://lore.kernel.org/lkml/20200309085618.14307-1-ilie.halip@gmail.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index aa344a163eaf..8a065a6f9713 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -2,11 +2,13 @@ from os import getenv
 from subprocess import Popen, PIPE
 from re import sub
 
+cc = getenv("CC")
+cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline()
+
 def clang_has_option(option):
-    return [o for o in Popen(['clang', option], stderr=PIPE).stderr.readlines() if b"unknown argument" in o] == [ ]
+    return [o for o in Popen([cc, option], stderr=PIPE).stderr.readlines() if b"unknown argument" in o] == [ ]
 
-cc = getenv("CC")
-if cc == "clang":
+if cc_is_clang:
     from distutils.sysconfig import get_config_vars
     vars = get_config_vars()
     for var in ('CFLAGS', 'OPT'):
@@ -40,7 +42,7 @@ class install_lib(_install_lib):
 cflags = getenv('CFLAGS', '').split()
 # switch off several checks (need to be at the end of cflags list)
 cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
-if cc != "clang":
+if not cc_is_clang:
     cflags += ['-Wno-cast-function-type' ]
 
 src_perf  = getenv('srctree') + '/tools/perf'