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Rollup merge of rust-lang#100200 - petrochenkov:zgccld2, r=lqd,Mark-S…
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…imulacrum

Change implementation of `-Z gcc-ld` and `lld-wrapper` again

This PR partially reverts rust-lang#97375 and uses the strategy described in rust-lang#97402 (comment) instead, thus fixes rust-lang#97755.
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matthiaskrgr authored Sep 2, 2022
2 parents e5b9ec8 + 6b68921 commit 9ec4dc6
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Showing 5 changed files with 48 additions and 33 deletions.
32 changes: 18 additions & 14 deletions compiler/rustc_codegen_ssa/src/back/link.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2876,20 +2876,24 @@ fn add_gcc_ld_path(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
if let LinkerFlavor::Gcc = flavor {
match ld_impl {
LdImpl::Lld => {
let tools_path = sess.get_tools_search_paths(false);
let gcc_ld_dir = tools_path
.into_iter()
.map(|p| p.join("gcc-ld"))
.find(|p| {
p.join(if sess.host.is_like_windows { "ld.exe" } else { "ld" }).exists()
})
.unwrap_or_else(|| sess.fatal("rust-lld (as ld) not found"));
cmd.arg({
let mut arg = OsString::from("-B");
arg.push(gcc_ld_dir);
arg
});
cmd.arg(format!("-Wl,-rustc-lld-flavor={}", sess.target.lld_flavor.as_str()));
// Implement the "self-contained" part of -Zgcc-ld
// by adding rustc distribution directories to the tool search path.
for path in sess.get_tools_search_paths(false) {
cmd.arg({
let mut arg = OsString::from("-B");
arg.push(path.join("gcc-ld"));
arg
});
}
// Implement the "linker flavor" part of -Zgcc-ld
// by asking cc to use some kind of lld.
cmd.arg("-fuse-ld=lld");
if sess.target.lld_flavor != LldFlavor::Ld {
// Tell clang to use a non-default LLD flavor.
// Gcc doesn't understand the target option, but we currently assume
// that gcc is not used for Apple and Wasm targets (#97402).
cmd.arg(format!("--target={}", sess.target.llvm_target));
}
}
}
} else {
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4 changes: 3 additions & 1 deletion src/bootstrap/compile.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1281,7 +1281,9 @@ impl Step for Assemble {
compiler: build_compiler,
target: target_compiler.host,
});
builder.copy(&lld_wrapper_exe, &gcc_ld_dir.join(exe("ld", target_compiler.host)));
for name in crate::LLD_FILE_NAMES {
builder.copy(&lld_wrapper_exe, &gcc_ld_dir.join(exe(name, target_compiler.host)));
}
}

if builder.config.rust_codegen_backends.contains(&INTERNER.intern_str("llvm")) {
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7 changes: 5 additions & 2 deletions src/bootstrap/dist.rs
Original file line number Diff line number Diff line change
Expand Up @@ -423,8 +423,11 @@ impl Step for Rustc {
let gcc_lld_src_dir = src_dir.join("gcc-ld");
let gcc_lld_dst_dir = dst_dir.join("gcc-ld");
t!(fs::create_dir(&gcc_lld_dst_dir));
let exe_name = exe("ld", compiler.host);
builder.copy(&gcc_lld_src_dir.join(&exe_name), &gcc_lld_dst_dir.join(&exe_name));
for name in crate::LLD_FILE_NAMES {
let exe_name = exe(name, compiler.host);
builder
.copy(&gcc_lld_src_dir.join(&exe_name), &gcc_lld_dst_dir.join(&exe_name));
}
}

// Man pages
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3 changes: 3 additions & 0 deletions src/bootstrap/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -187,6 +187,9 @@ const LLVM_TOOLS: &[&str] = &[
"opt", // used to optimize LLVM bytecode
];

/// LLD file names for all flavors.
const LLD_FILE_NAMES: &[&str] = &["ld.lld", "ld64.lld", "lld-link", "wasm-ld"];

pub const VERSION: usize = 2;

/// Extra --check-cfg to add when building
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35 changes: 19 additions & 16 deletions src/tools/lld-wrapper/src/main.rs
Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,8 @@
//! make gcc/clang pass `-flavor <flavor>` as the first two arguments in the linker invocation
//! and since Windows does not support symbolic links for files this wrapper is used in place of a
//! symbolic link. It execs `../rust-lld -flavor <flavor>` by propagating the flavor argument
//! passed to the wrapper as the first two arguments. On Windows it spawns a `..\rust-lld.exe`
//! child process.
//! obtained from the wrapper's name as the first two arguments.
//! On Windows it spawns a `..\rust-lld.exe` child process.

use std::fmt::Display;
use std::path::{Path, PathBuf};
Expand Down Expand Up @@ -53,29 +53,32 @@ fn get_rust_lld_path(current_exe_path: &Path) -> PathBuf {
rust_lld_path
}

/// Extract LLD flavor name from the lld-wrapper executable name.
fn get_lld_flavor(current_exe_path: &Path) -> Result<&'static str, String> {
let stem = current_exe_path.file_stem();
Ok(match stem.and_then(|s| s.to_str()) {
Some("ld.lld") => "gnu",
Some("ld64.lld") => "darwin",
Some("lld-link") => "link",
Some("wasm-ld") => "wasm",
_ => return Err(format!("{:?}", stem)),
})
}

/// Returns the command for invoking rust-lld with the correct flavor.
/// LLD only accepts the flavor argument at the first two arguments, so move it there.
/// LLD only accepts the flavor argument at the first two arguments, so pass it there.
///
/// Exits on error.
fn get_rust_lld_command(current_exe_path: &Path) -> process::Command {
let rust_lld_path = get_rust_lld_path(current_exe_path);
let mut command = process::Command::new(rust_lld_path);

let mut flavor = None;
let args = env::args_os()
.skip(1)
.filter(|arg| match arg.to_str().and_then(|s| s.strip_prefix("-rustc-lld-flavor=")) {
Some(suffix) => {
flavor = Some(suffix.to_string());
false
}
None => true,
})
.collect::<Vec<_>>();
let flavor =
get_lld_flavor(current_exe_path).unwrap_or_exit_with("executable has unexpected name");

command.arg("-flavor");
command.arg(flavor.unwrap_or_exit_with("-rustc-lld-flavor=<flavor> is not passed"));
command.args(args);
command.arg(flavor);
command.args(env::args_os().skip(1));
command
}

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