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Rust demangling is another step after bfd demangling. Add a diagnosis to
identify mangled Rust symbols based on the hash that the Rust mangler appends
as the last path component, as well as other characteristics. Add a demangler
to reconstruct the original symbol.
Committer notes:
How I tested it:
Enabled COPR on Fedora 24 and then installed the 'rust-binary' package,
with it:
$ cat src/main.rs
fn main() {
println!("Hello, world!");
}
$ cat Cargo.toml
[package]
name = "hello_world"
version = "0.0.1"
authors = [ "Arnaldo Carvalho de Melo <acme@kernel.org>" ]
$ perf record cargo bench
Compiling hello_world v0.0.1 (file:///home/acme/projects/hello_world)
Running target/release/hello_world-d4b9dab4b2a47d75
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.096 MB perf.data (1457 samples) ]
$
Before this patch:
$ perf report --stdio --dsos librbml-e8edd0fd.so
# dso: librbml-e8edd0fd.so
#
# Total Lost Samples: 0
#
# Samples: 1K of event 'cycles:u'
# Event count (approx.): 979599126
#
# Overhead Command Symbol
# ........ ....... .............................................................................................................
#
1.78% rustc [.] rbml::reader::maybe_get_doc::hb9d387df6024b15b
1.50% rustc [.] _$LT$reader..DocsIterator$LT$$u27$a$GT$$u20$as$u20$std..iter..Iterator$GT$::next::hd9af9e60d79a35c8
1.20% rustc [.] rbml::reader::doc_at::hc88107fba445af31
0.46% rustc [.] _$LT$reader..TaggedDocsIterator$LT$$u27$a$GT$$u20$as$u20$std..iter..Iterator$GT$::next::h0cb40e696e4bb489
0.35% rustc [.] rbml::reader::Decoder::_next_int::h66eef7825a398bc3
0.29% rustc [.] rbml::reader::Decoder::_next_sub::h8e5266005580b836
0.15% rustc [.] rbml::reader::get_doc::h094521c645459139
0.14% rustc [.] _$LT$reader..Decoder$LT$$u27$doc$GT$$u20$as$u20$serialize..Decoder$GT$::read_u32::h0acea2fff9669327
0.07% rustc [.] rbml::reader::Decoder::next_doc::h6714d469c9dfaf91
0.07% rustc [.] _ZN4rbml6reader10doc_as_u6417h930b740aa94f1d3aE@plt
0.06% rustc [.] _fini
$
After:
$ perf report --stdio --dsos librbml-e8edd0fd.so
# dso: librbml-e8edd0fd.so
#
# Total Lost Samples: 0
#
# Samples: 1K of event 'cycles:u'
# Event count (approx.): 979599126
#
# Overhead Command Symbol
# ........ ....... .................................................................
#
1.78% rustc [.] rbml::reader::maybe_get_doc
1.50% rustc [.] <reader::DocsIterator<'a> as std::iter::Iterator>::next
1.20% rustc [.] rbml::reader::doc_at
0.46% rustc [.] <reader::TaggedDocsIterator<'a> as std::iter::Iterator>::next
0.35% rustc [.] rbml::reader::Decoder::_next_int
0.29% rustc [.] rbml::reader::Decoder::_next_sub
0.15% rustc [.] rbml::reader::get_doc
0.14% rustc [.] <reader::Decoder<'doc> as serialize::Decoder>::read_u32
0.07% rustc [.] rbml::reader::Decoder::next_doc
0.07% rustc [.] _ZN4rbml6reader10doc_as_u6417h930b740aa94f1d3aE@plt
0.06% rustc [.] _fini
$
Signed-off-by: David Tolnay <dtolnay@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5780B7FA.3030602@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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