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Use more rustc_codegen_ssa::back::link for linking
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@bjorn3
bjorn3 committed Apr 20, 2019
1 parent 8b3b6f0 commit 5d3fbdd
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Showing 3 changed files with 4 additions and 284 deletions.
3 changes: 2 additions & 1 deletion src/link.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ use tempfile::Builder as TempFileBuilder;
use rustc::session::config::{self, CrateType, DebugInfo, RUST_CGU_EXT};
use rustc::session::search_paths::PathKind;
use rustc::session::Session;
use rustc_codegen_ssa::METADATA_FILENAME;
use rustc_codegen_ssa::back::command::Command;
use rustc_codegen_ssa::back::link::*;
use rustc_codegen_ssa::back::linker::*;
Expand Down Expand Up @@ -48,7 +49,7 @@ pub(crate) fn link_rlib(sess: &Session, res: &CodegenResults, output_name: PathB
builder
.append(
&ar::Header::new(
crate::metadata::METADATA_FILENAME.as_bytes().to_vec(),
METADATA_FILENAME.as_bytes().to_vec(),
res.metadata.raw_data.len() as u64,
),
::std::io::Cursor::new(res.metadata.raw_data.clone()),
Expand Down
282 changes: 1 addition & 281 deletions src/link_copied.rs
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Original file line number Diff line number Diff line change
@@ -1,21 +1,14 @@
//! All functions here are copied from https://github.com/rust-lang/rust/blob/942864a000efd74b73e36bda5606b2cdb55ecf39/src/librustc_codegen_llvm/back/link.rs
use std::fmt;
use std::fs;
use std::io;
use std::iter;
use std::path::{Path, PathBuf};
use std::process::{Output, Stdio};

use log::info;

use rustc::middle::cstore::{NativeLibrary, NativeLibraryKind};
use rustc::middle::dependency_format::Linkage;
use rustc::session::config::{self, OutputType, RUST_CGU_EXT};
use rustc::session::search_paths::PathKind;
use rustc::session::Session;
use rustc::util::common::time;
use rustc_codegen_ssa::back::command::Command;
use rustc_codegen_ssa::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION};
use rustc_codegen_ssa::back::linker::*;
use rustc_codegen_ssa::back::link::*;
use rustc_data_structures::fx::FxHashSet;
Expand All @@ -25,11 +18,6 @@ use syntax::attr;
use crate::prelude::*;

use crate::archive::{ArchiveBuilder, ArchiveConfig};
use crate::metadata::METADATA_FILENAME;


// cg_clif doesn't have bytecode, so this is just a dummy
const RLIB_BYTECODE_EXTENSION: &str = ".cg_clif_bytecode_dummy";

fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
sess.target_filesearch(PathKind::Native).search_path_dirs()
Expand All @@ -46,147 +34,6 @@ fn archive_config<'a>(sess: &'a Session,
}
}

pub fn exec_linker(sess: &Session, cmd: &mut Command, out_filename: &Path, tmpdir: &Path)
-> io::Result<Output>
{
// When attempting to spawn the linker we run a risk of blowing out the
// size limits for spawning a new process with respect to the arguments
// we pass on the command line.
//
// Here we attempt to handle errors from the OS saying "your list of
// arguments is too big" by reinvoking the linker again with an `@`-file
// that contains all the arguments. The theory is that this is then
// accepted on all linkers and the linker will read all its options out of
// there instead of looking at the command line.
if !cmd.very_likely_to_exceed_some_spawn_limit() {
match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() {
Ok(child) => {
let output = child.wait_with_output();
flush_linked_file(&output, out_filename)?;
return output;
}
Err(ref e) if command_line_too_big(e) => {
info!("command line to linker was too big: {}", e);
}
Err(e) => return Err(e)
}
}

info!("falling back to passing arguments to linker via an @-file");
let mut cmd2 = cmd.clone();
let mut args = String::new();
for arg in cmd2.take_args() {
args.push_str(&Escape {
arg: arg.to_str().unwrap(),
is_like_msvc: sess.target.target.options.is_like_msvc,
}.to_string());
args.push_str("\n");
}
let file = tmpdir.join("linker-arguments");
let bytes = if sess.target.target.options.is_like_msvc {
let mut out = Vec::with_capacity((1 + args.len()) * 2);
// start the stream with a UTF-16 BOM
for c in iter::once(0xFEFF).chain(args.encode_utf16()) {
// encode in little endian
out.push(c as u8);
out.push((c >> 8) as u8);
}
out
} else {
args.into_bytes()
};
fs::write(&file, &bytes)?;
cmd2.arg(format!("@{}", file.display()));
info!("invoking linker {:?}", cmd2);
let output = cmd2.output();
flush_linked_file(&output, out_filename)?;
return output;

#[cfg(unix)]
fn flush_linked_file(_: &io::Result<Output>, _: &Path) -> io::Result<()> {
Ok(())
}

#[cfg(windows)]
fn flush_linked_file(command_output: &io::Result<Output>, out_filename: &Path)
-> io::Result<()>
{
// On Windows, under high I/O load, output buffers are sometimes not flushed,
// even long after process exit, causing nasty, non-reproducible output bugs.
//
// File::sync_all() calls FlushFileBuffers() down the line, which solves the problem.
//
// А full writeup of the original Chrome bug can be found at
// randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp

if let &Ok(ref out) = command_output {
if out.status.success() {
if let Ok(of) = fs::OpenOptions::new().write(true).open(out_filename) {
of.sync_all()?;
}
}
}

Ok(())
}

#[cfg(unix)]
fn command_line_too_big(err: &io::Error) -> bool {
err.raw_os_error() == Some(::libc::E2BIG)
}

#[cfg(windows)]
fn command_line_too_big(err: &io::Error) -> bool {
const ERROR_FILENAME_EXCED_RANGE: i32 = 206;
err.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE)
}

struct Escape<'a> {
arg: &'a str,
is_like_msvc: bool,
}

impl<'a> fmt::Display for Escape<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if self.is_like_msvc {
// This is "documented" at
// https://msdn.microsoft.com/en-us/library/4xdcbak7.aspx
//
// Unfortunately there's not a great specification of the
// syntax I could find online (at least) but some local
// testing showed that this seemed sufficient-ish to catch
// at least a few edge cases.
write!(f, "\"")?;
for c in self.arg.chars() {
match c {
'"' => write!(f, "\\{}", c)?,
c => write!(f, "{}", c)?,
}
}
write!(f, "\"")?;
} else {
// This is documented at https://linux.die.net/man/1/ld, namely:
//
// > Options in file are separated by whitespace. A whitespace
// > character may be included in an option by surrounding the
// > entire option in either single or double quotes. Any
// > character (including a backslash) may be included by
// > prefixing the character to be included with a backslash.
//
// We put an argument on each line, so all we need to do is
// ensure the line is interpreted as one whole argument.
for c in self.arg.chars() {
match c {
'\\' | ' ' => write!(f, "\\{}", c)?,
c => write!(f, "{}", c)?,
}
}
}
Ok(())
}
}
}

// # Rust Crate linking
//
// Rust crates are not considered at all when creating an rlib output. All
Expand Down Expand Up @@ -505,130 +352,3 @@ pub fn add_upstream_rust_crates(cmd: &mut dyn Linker,
parent.unwrap_or(Path::new("")));
}
}

// # Native library linking
//
// User-supplied library search paths (-L on the command line). These are
// the same paths used to find Rust crates, so some of them may have been
// added already by the previous crate linking code. This only allows them
// to be found at compile time so it is still entirely up to outside
// forces to make sure that library can be found at runtime.
//
// Also note that the native libraries linked here are only the ones located
// in the current crate. Upstream crates with native library dependencies
// may have their native library pulled in above.
pub fn add_local_native_libraries(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults) {
let filesearch = sess.target_filesearch(PathKind::All);
for search_path in filesearch.search_paths() {
match search_path.kind {
PathKind::Framework => { cmd.framework_path(&search_path.dir); }
_ => { cmd.include_path(&fix_windows_verbatim_for_gcc(&search_path.dir)); }
}
}

let relevant_libs = codegen_results.crate_info.used_libraries.iter().filter(|l| {
relevant_lib(sess, l)
});

let search_path = archive_search_paths(sess);
for lib in relevant_libs {
let name = match lib.name {
Some(ref l) => l,
None => continue,
};
match lib.kind {
NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&name.as_str()),
NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&name.as_str(),
&search_path)
}
}
}

// Link in all of our upstream crates' native dependencies. Remember that
// all of these upstream native dependencies are all non-static
// dependencies. We've got two cases then:
//
// 1. The upstream crate is an rlib. In this case we *must* link in the
// native dependency because the rlib is just an archive.
//
// 2. The upstream crate is a dylib. In order to use the dylib, we have to
// have the dependency present on the system somewhere. Thus, we don't
// gain a whole lot from not linking in the dynamic dependency to this
// crate as well.
//
// The use case for this is a little subtle. In theory the native
// dependencies of a crate are purely an implementation detail of the crate
// itself, but the problem arises with generic and inlined functions. If a
// generic function calls a native function, then the generic function must
// be instantiated in the target crate, meaning that the native symbol must
// also be resolved in the target crate.
pub fn add_upstream_native_libraries(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults,
crate_type: config::CrateType) {
// Be sure to use a topological sorting of crates because there may be
// interdependencies between native libraries. When passing -nodefaultlibs,
// for example, almost all native libraries depend on libc, so we have to
// make sure that's all the way at the right (liblibc is near the base of
// the dependency chain).
//
// This passes RequireStatic, but the actual requirement doesn't matter,
// we're just getting an ordering of crate numbers, we're not worried about
// the paths.
let formats = sess.dependency_formats.borrow();
let data = formats.get(&crate_type).unwrap();

let crates = &codegen_results.crate_info.used_crates_static;
for &(cnum, _) in crates {
for lib in codegen_results.crate_info.native_libraries[&cnum].iter() {
let name = match lib.name {
Some(ref l) => l,
None => continue,
};
if !relevant_lib(sess, &lib) {
continue
}
match lib.kind {
NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
NativeLibraryKind::NativeStaticNobundle => {
// 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.as_str())
}
},
// ignore statically included native libraries here as we've
// already included them when we included the rust library
// previously
NativeLibraryKind::NativeStatic => {}
}
}
}
}

fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
match lib.cfg {
Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),
None => true,
}
}

fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
match sess.lto() {
Lto::Fat => true,
Lto::Thin => {
// If we defer LTO to the linker, we haven't run LTO ourselves, so
// any upstream object files have not been copied yet.
!sess.opts.cg.linker_plugin_lto.enabled()
}
Lto::No |
Lto::ThinLocal => false,
}
}
3 changes: 1 addition & 2 deletions src/metadata.rs
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Original file line number Diff line number Diff line change
@@ -1,11 +1,10 @@
use rustc::middle::cstore::MetadataLoader;
use rustc_codegen_ssa::METADATA_FILENAME;
use rustc_data_structures::owning_ref::{self, OwningRef};
use rustc_data_structures::rustc_erase_owner;
use std::fs::File;
use std::path::Path;

pub const METADATA_FILENAME: &str = "rust.metadata.bin";

pub struct CraneliftMetadataLoader;

impl MetadataLoader for CraneliftMetadataLoader {
Expand Down

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