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Implement RFC 2951: Native link modifiers
This commit implements both the native linking modifiers infrastructure
as well as an initial attempt at the individual modifiers from the RFC.
It also introduces a feature flag for the general syntax along with
individual feature flags for each modifier.
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luqmana committed May 5, 2021
1 parent bacf770 commit db555e1
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Showing 38 changed files with 829 additions and 170 deletions.
39 changes: 39 additions & 0 deletions compiler/rustc_ast_passes/src/feature_gate.rs
Expand Up @@ -326,6 +326,45 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
);
}
}

// Check for unstable modifiers on `#[link(..)]` attribute
if self.sess.check_name(attr, sym::link) {
for nested_meta in attr.meta_item_list().unwrap_or_default() {
if nested_meta.has_name(sym::modifiers) {
gate_feature_post!(
self,
native_link_modifiers,
nested_meta.span(),
"native link modifiers are experimental"
);

if let Some(modifiers) = nested_meta.value_str() {
for modifier in modifiers.as_str().split(',') {
if let Some(modifier) = modifier.strip_prefix(&['+', '-'][..]) {
macro_rules! gate_modifier { ($($name:literal => $feature:ident)*) => {
$(if modifier == $name {
let msg = concat!("`#[link(modifiers=\"", $name, "\")]` is unstable");
gate_feature_post!(
self,
$feature,
nested_meta.name_value_literal_span().unwrap(),
msg
);
})*
}}

gate_modifier!(
"bundle" => native_link_modifiers_bundle
"verbatim" => native_link_modifiers_verbatim
"whole-archive" => native_link_modifiers_whole_archive
"as-needed" => native_link_modifiers_as_needed
);
}
}
}
}
}
}
}

fn visit_item(&mut self, i: &'a ast::Item) {
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_codegen_cranelift/src/archive.rs
Expand Up @@ -85,8 +85,8 @@ impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
));
}

fn add_native_library(&mut self, name: rustc_span::symbol::Symbol) {
let location = find_library(name, &self.lib_search_paths, self.sess);
fn add_native_library(&mut self, name: rustc_span::symbol::Symbol, verbatim: bool) {
let location = find_library(name, verbatim, &self.lib_search_paths, self.sess);
self.add_archive(location.clone(), |_| false).unwrap_or_else(|e| {
panic!("failed to add native library {}: {}", location.to_string_lossy(), e);
});
Expand Down
5 changes: 3 additions & 2 deletions compiler/rustc_codegen_llvm/src/back/archive.rs
Expand Up @@ -100,8 +100,9 @@ impl<'a> ArchiveBuilder<'a> for LlvmArchiveBuilder<'a> {

/// Adds all of the contents of a native library to this archive. This will
/// search in the relevant locations for a library named `name`.
fn add_native_library(&mut self, name: Symbol) {
let location = find_library(name, &self.config.lib_search_paths, self.config.sess);
fn add_native_library(&mut self, name: Symbol, verbatim: bool) {
let location =
find_library(name, verbatim, &self.config.lib_search_paths, self.config.sess);
self.add_archive(&location, |_| false).unwrap_or_else(|e| {
self.config.sess.fatal(&format!(
"failed to add native library {}: {}",
Expand Down
16 changes: 12 additions & 4 deletions compiler/rustc_codegen_ssa/src/back/archive.rs
Expand Up @@ -4,11 +4,19 @@ use rustc_span::symbol::Symbol;
use std::io;
use std::path::{Path, PathBuf};

pub fn find_library(name: Symbol, search_paths: &[PathBuf], sess: &Session) -> PathBuf {
pub fn find_library(
name: Symbol,
verbatim: bool,
search_paths: &[PathBuf],
sess: &Session,
) -> PathBuf {
// On Windows, static libraries sometimes show up as libfoo.a and other
// times show up as foo.lib
let oslibname =
format!("{}{}{}", sess.target.staticlib_prefix, name, sess.target.staticlib_suffix);
let oslibname = if verbatim {
name.to_string()
} else {
format!("{}{}{}", sess.target.staticlib_prefix, name, sess.target.staticlib_suffix)
};
let unixlibname = format!("lib{}.a", name);

for path in search_paths {
Expand Down Expand Up @@ -45,7 +53,7 @@ pub trait ArchiveBuilder<'a> {
lto: bool,
skip_objects: bool,
) -> io::Result<()>;
fn add_native_library(&mut self, name: Symbol);
fn add_native_library(&mut self, name: Symbol, verbatim: bool);
fn update_symbols(&mut self);

fn build(self);
Expand Down
73 changes: 47 additions & 26 deletions compiler/rustc_codegen_ssa/src/back/link.rs
Expand Up @@ -329,15 +329,15 @@ fn link_rlib<'a, B: ArchiveBuilder<'a>>(
// metadata of the rlib we're generating somehow.
for lib in codegen_results.crate_info.used_libraries.iter() {
match lib.kind {
NativeLibKind::StaticBundle => {}
NativeLibKind::StaticNoBundle
| NativeLibKind::Dylib
| NativeLibKind::Framework
NativeLibKind::Static { bundle: None | Some(true), .. } => {}
NativeLibKind::Static { bundle: Some(false), .. }
| NativeLibKind::Dylib { .. }
| NativeLibKind::Framework { .. }
| NativeLibKind::RawDylib
| NativeLibKind::Unspecified => continue,
}
if let Some(name) = lib.name {
ab.add_native_library(name);
ab.add_native_library(name, lib.verbatim.unwrap_or(false));
}
}

Expand Down Expand Up @@ -430,9 +430,10 @@ fn link_staticlib<'a, B: ArchiveBuilder<'a>>(
// Clearly this is not sufficient for a general purpose feature, and
// we'd want to read from the library's metadata to determine which
// object files come from where and selectively skip them.
let skip_object_files = native_libs
.iter()
.any(|lib| lib.kind == NativeLibKind::StaticBundle && !relevant_lib(sess, lib));
let skip_object_files = native_libs.iter().any(|lib| {
matches!(lib.kind, NativeLibKind::Static { bundle: None | Some(true), .. })
&& !relevant_lib(sess, lib)
});
ab.add_rlib(
path,
&name.as_str(),
Expand Down Expand Up @@ -931,7 +932,7 @@ fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) {
let path = find_sanitizer_runtime(&sess, &filename);
let rpath = path.to_str().expect("non-utf8 component in path");
linker.args(&["-Wl,-rpath", "-Xlinker", rpath]);
linker.link_dylib(Symbol::intern(&filename));
linker.link_dylib(Symbol::intern(&filename), false, true);
} else {
let filename = format!("librustc{}_rt.{}.a", channel, name);
let path = find_sanitizer_runtime(&sess, &filename).join(&filename);
Expand Down Expand Up @@ -1080,21 +1081,25 @@ fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLib]) {
.filter_map(|lib| {
let name = lib.name?;
match lib.kind {
NativeLibKind::StaticNoBundle
| NativeLibKind::Dylib
NativeLibKind::Static { bundle: Some(false), .. }
| NativeLibKind::Dylib { .. }
| NativeLibKind::Unspecified => {
let verbatim = lib.verbatim.unwrap_or(false);
if sess.target.is_like_msvc {
Some(format!("{}.lib", name))
Some(format!("{}{}", name, if verbatim { "" } else { ".lib" }))
} else if sess.target.linker_is_gnu {
Some(format!("-l{}{}", if verbatim { ":" } else { "" }, name))
} else {
Some(format!("-l{}", name))
}
}
NativeLibKind::Framework => {
NativeLibKind::Framework { .. } => {
// ld-only syntax, since there are no frameworks in MSVC
Some(format!("-framework {}", name))
}
// These are included, no need to print them
NativeLibKind::StaticBundle | NativeLibKind::RawDylib => None,
NativeLibKind::Static { bundle: None | Some(true), .. }
| NativeLibKind::RawDylib => None,
}
})
.collect();
Expand Down Expand Up @@ -1812,11 +1817,20 @@ fn add_local_native_libraries(
Some(l) => l,
None => continue,
};
let verbatim = lib.verbatim.unwrap_or(false);
match lib.kind {
NativeLibKind::Dylib | NativeLibKind::Unspecified => cmd.link_dylib(name),
NativeLibKind::Framework => cmd.link_framework(name),
NativeLibKind::StaticNoBundle => cmd.link_staticlib(name),
NativeLibKind::StaticBundle => cmd.link_whole_staticlib(name, &search_path),
NativeLibKind::Dylib { as_needed } => {
cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
}
NativeLibKind::Unspecified => cmd.link_dylib(name, verbatim, true),
NativeLibKind::Framework { as_needed } => {
cmd.link_framework(name, as_needed.unwrap_or(true))
}
NativeLibKind::Static { bundle: None | Some(true), .. }
| NativeLibKind::Static { whole_archive: Some(true), .. } => {
cmd.link_whole_staticlib(name, verbatim, &search_path);
}
NativeLibKind::Static { .. } => cmd.link_staticlib(name, verbatim),
NativeLibKind::RawDylib => {
// FIXME(#58713): Proper handling for raw dylibs.
bug!("raw_dylib feature not yet implemented");
Expand Down Expand Up @@ -2000,9 +2014,10 @@ fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(
// there's a static library that's not relevant we skip all object
// files.
let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
let skip_native = native_libs
.iter()
.any(|lib| lib.kind == NativeLibKind::StaticBundle && !relevant_lib(sess, lib));
let skip_native = native_libs.iter().any(|lib| {
matches!(lib.kind, NativeLibKind::Static { bundle: None | Some(true), .. })
&& !relevant_lib(sess, lib)
});

if (!are_upstream_rust_objects_already_included(sess)
|| ignored_for_lto(sess, &codegen_results.crate_info, cnum))
Expand Down Expand Up @@ -2144,22 +2159,28 @@ fn add_upstream_native_libraries(
if !relevant_lib(sess, &lib) {
continue;
}
let verbatim = lib.verbatim.unwrap_or(false);
match lib.kind {
NativeLibKind::Dylib | NativeLibKind::Unspecified => cmd.link_dylib(name),
NativeLibKind::Framework => cmd.link_framework(name),
NativeLibKind::StaticNoBundle => {
NativeLibKind::Dylib { as_needed } => {
cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
}
NativeLibKind::Unspecified => cmd.link_dylib(name, verbatim, true),
NativeLibKind::Framework { as_needed } => {
cmd.link_framework(name, as_needed.unwrap_or(true))
}
NativeLibKind::Static { bundle: Some(false), .. } => {
// Link "static-nobundle" native libs only if the crate they originate from
// is being linked statically to the current crate. If it's linked dynamically
// or is an rlib already included via some other dylib crate, the symbols from
// native libs will have already been included in that dylib.
if data[cnum.as_usize() - 1] == Linkage::Static {
cmd.link_staticlib(name)
cmd.link_staticlib(name, verbatim)
}
}
// ignore statically included native libraries here as we've
// already included them when we included the rust library
// previously
NativeLibKind::StaticBundle => {}
NativeLibKind::Static { bundle: None | Some(true), .. } => {}
NativeLibKind::RawDylib => {
// FIXME(#58713): Proper handling for raw dylibs.
bug!("raw_dylib feature not yet implemented");
Expand Down

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