Commits
Arnaldo Carvalho de Melo committed cb76371441d
perf llvm: Allow passing options to llc in addition to clang
The newly added 'llvm.opts' variable allows passing options directly to
llc, like needed to get sane DWARF in BPF ELF debug sections:
With:
[root@seventh perf]# cat ~/.perfconfig
[llvm]
dump-obj = true
clang-opt = -g
[root@seventh perf]#
We get:
[root@seventh perf]# perf trace -e tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
LLVM: dumping tools/perf/examples/bpf/hello.o
0.000 __bpf_stdout__:Hello, world
0.015 __bpf_stdout__:Hello, world
0.187 __bpf_stdout__:Hello, world
[root@seventh perf]# pahole tools/perf/examples/bpf/hello.o
struct clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c) {
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 0 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 4 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 8 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 12 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 16 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 20 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 24 4 */
/* size: 28, cachelines: 1, members: 7 */
/* last cacheline: 28 bytes */
};
[root@seventh perf]#
Adding these options to be passed to llvm's llc:
[root@seventh perf]# cat ~/.perfconfig
[llvm]
dump-obj = true
clang-opt = -g
opts = -mattr=dwarfris
[root@seventh perf]#
We get sane output:
[root@seventh perf]# perf trace -e tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
LLVM: dumping tools/perf/examples/bpf/hello.o
0.000 __bpf_stdout__:Hello, world
0.015 __bpf_stdout__:Hello, world
0.185 __bpf_stdout__:Hello, world
[root@seventh perf]# pahole tools/perf/examples/bpf/hello.o
struct bpf_map {
unsigned int type; /* 0 4 */
unsigned int key_size; /* 4 4 */
unsigned int value_size; /* 8 4 */
unsigned int max_entries; /* 12 4 */
unsigned int map_flags; /* 16 4 */
unsigned int inner_map_idx; /* 20 4 */
unsigned int numa_node; /* 24 4 */
/* size: 28, cachelines: 1, members: 7 */
/* last cacheline: 28 bytes */
};
[root@seventh perf]#
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>,
Cc: Yonghong Song <yhs@fb.com>
Link: https://lkml.kernel.org/n/tip-0lrwmrip4dru1651rm8xa7tq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>