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Merge #4007

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4007: Reduce allocations when looking up proc macro decl r=edwin0cheng a=lnicola

`libserde_derive` has about 21K symbols on Linux. It's not much, but let's ~~not be wasteful~~ avoid the allocations anyway.

r? @edwin0cheng

Co-authored-by: Laurențiu Nicola <lnicola@dend.ro>
This commit is contained in:
bors[bot] 2020-04-17 08:32:20 +00:00 committed by GitHub
commit d426462b48
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1 changed files with 35 additions and 37 deletions
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72
crates/ra_proc_macro_srv/src/dylib.rs
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@ -16,55 +16,53 @@ fn invalid_data_err(e: impl Into<Box<dyn std::error::Error + Send + Sync>>) -> I
IoError::new(IoErrorKind::InvalidData, e)
}
fn get_symbols_from_lib(file: &Path) -> Result<Vec<String>, IoError> {
fn is_derive_registrar_symbol(symbol: &str) -> bool {
symbol.contains(NEW_REGISTRAR_SYMBOL)
}
fn find_registrar_symbol(file: &Path) -> Result<Option<String>, IoError> {
let buffer = std::fs::read(file)?;
let object = Object::parse(&buffer).map_err(invalid_data_err)?;
match object {
Object::Elf(elf) => {
let symbols = elf.dynstrtab.to_vec().map_err(invalid_data_err)?;
let names = symbols.iter().map(|s| s.to_string()).collect();
Ok(names)
let name =
symbols.iter().find(|s| is_derive_registrar_symbol(s)).map(|s| s.to_string());
Ok(name)
}
Object::PE(pe) => {
let symbol_names =
pe.exports.iter().flat_map(|s| s.name).map(|n| n.to_string()).collect();
Ok(symbol_names)
let name = pe
.exports
.iter()
.flat_map(|s| s.name)
.find(|s| is_derive_registrar_symbol(s))
.map(|s| s.to_string());
Ok(name)
}
Object::Mach(mach) => match mach {
Mach::Binary(binary) => {
let exports = binary.exports().map_err(invalid_data_err)?;
let names = exports
.into_iter()
.map(|s| {
// In macos doc:
// https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dlsym.3.html
// Unlike other dyld API's, the symbol name passed to dlsym() must NOT be
// prepended with an underscore.
if s.name.starts_with("_") {
s.name[1..].to_string()
} else {
s.name
}
})
.collect();
Ok(names)
}
Mach::Fat(_) => Ok(vec![]),
},
Object::Archive(_) | Object::Unknown(_) => Ok(vec![]),
Object::Mach(Mach::Binary(binary)) => {
let exports = binary.exports().map_err(invalid_data_err)?;
let name = exports
.iter()
.map(|s| {
// In macos doc:
// https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dlsym.3.html
// Unlike other dyld API's, the symbol name passed to dlsym() must NOT be
// prepended with an underscore.
if s.name.starts_with("_") {
&s.name[1..]
} else {
&s.name
}
})
.find(|s| is_derive_registrar_symbol(&s))
.map(|s| s.to_string());
Ok(name)
}
_ => Ok(None),
}
}
fn is_derive_registrar_symbol(symbol: &str) -> bool {
symbol.contains(NEW_REGISTRAR_SYMBOL)
}
fn find_registrar_symbol(file: &Path) -> Result<Option<String>, IoError> {
let symbols = get_symbols_from_lib(file)?;
Ok(symbols.into_iter().find(|s| is_derive_registrar_symbol(s)))
}
/// Loads dynamic library in platform dependent manner.
///
/// For unix, you have to use RTLD_DEEPBIND flag to escape problems described