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//! `cargo xtask` automation.
//!
//! Please refer to <https://github.com/matklad/cargo-xtask/> for an explanation of the concept.
//!
//! Also see the docs in `asm.rs`.
use std::env::{self, current_dir};
use std::{
collections::BTreeMap,
fs::{self, File},
process::{self, Command},
};
fn rustc() -> Command {
let mut cmd = Command::new("rustc");
cmd.arg("+nightly");
cmd
}
fn assemble_really(target: &str, cfgs: &[&str], plugin_lto: bool) {
let mut cmd = rustc();
// Set the codegen target.
cmd.arg("--target").arg(target);
// Set all the `--cfg` directives for the target.
cmd.args(cfgs.iter().map(|cfg| format!("--cfg={}", cfg)));
// We want some level of debuginfo to allow unwinding through the functions.
cmd.arg("-g");
// We always optimize the assembly shims. There's not really any reason not to.
cmd.arg("-O");
// rustc will usually add frame pointers by default to aid with debugging, but that is a high
// overhead for the tiny assembly routines.
cmd.arg("-Cforce-frame-pointers=no");
// We don't want any system-specific paths to show up since we ship the result to other users.
// Add `--remap-path-prefix $(pwd)=.`.
let mut dir = current_dir().unwrap().as_os_str().to_os_string();
dir.push("=.");
cmd.arg("--remap-path-prefix").arg(dir);
// We let rustc build a single object file, not a staticlib, since the latter pulls in loads of
// code that will never be used (`compiler_builtins` and `core::fmt`, etc.). We build the static
// archive by hand after compiling.
cmd.arg("--emit=obj");
if plugin_lto {
// Make artifacts compatible with Linker-Plugin LTO (and incompatible with everything else).
cmd.arg("-Clinker-plugin-lto");
}
let file_stub = if plugin_lto {
format!("{}-lto", target)
} else {
target.to_string()
};
let obj_file = format!("bin/{}.o", file_stub);
// Pass output and input file.
cmd.arg("-o").arg(&obj_file);
cmd.arg("asm.rs");
println!("{:?}", cmd);
let status = cmd.status().unwrap();
assert!(status.success());
// Archive `target.o` -> `bin/target.a`.
let mut builder = ar::Builder::new(File::create(format!("bin/{}.a", file_stub)).unwrap());
// Use `append`, not `append_path`, to avoid adding any filesystem metadata (modification times,
// etc.).
let file = fs::read(&obj_file).unwrap();
builder
.append(
&ar::Header::new(obj_file.as_bytes().to_vec(), file.len() as u64),
&*file,
)
.unwrap();
fs::remove_file(&obj_file).unwrap();
}
fn assemble(target: &str, cfgs: &[&str]) {
assemble_really(target, cfgs, false);
assemble_really(target, cfgs, true);
}
// `--target` -> `--cfg` list (mirrors what `build.rs` does).
static TARGETS: &[(&str, &[&str])] = &[
("thumbv6m-none-eabi", &[]),
("thumbv7m-none-eabi", &["armv7m"]),
("thumbv7em-none-eabi", &["armv7m", "armv7em"]),
("thumbv7em-none-eabihf", &["armv7m", "armv7em", "has_fpu"]),
("thumbv8m.base-none-eabi", &["armv8m", "armv8m_base"]),
(
"thumbv8m.main-none-eabi",
&["armv7m", "armv8m", "armv8m_main"],
),
(
"thumbv8m.main-none-eabihf",
&["armv7m", "armv8m", "armv8m_main", "has_fpu"],
),
];
fn assemble_blobs() {
for (target, cfgs) in TARGETS {
println!("building artifacts for {}", target);
assemble(target, cfgs);
}
}
fn check_blobs() {
// Load each `.a` file in `bin` into memory.
let mut files_before = BTreeMap::new();
for entry in fs::read_dir("bin").unwrap() {
let entry = entry.unwrap();
if entry.path().extension().unwrap() == "a" {
files_before.insert(
entry
.path()
.file_name()
.unwrap()
.to_str()
.unwrap()
.to_string(),
fs::read(entry.path()).unwrap(),
);
}
}
assemble_blobs();
let mut files_after = BTreeMap::new();
for entry in fs::read_dir("bin").unwrap() {
let entry = entry.unwrap();
if entry.path().extension().unwrap() == "a" {
files_after.insert(
entry
.path()
.file_name()
.unwrap()
.to_str()
.unwrap()
.to_string(),
fs::read(entry.path()).unwrap(),
);
}
}
// Ensure they contain the same files.
let before = files_before.keys().collect::<Vec<_>>();
let after = files_after.keys().collect::<Vec<_>>();
assert_eq!(before, after);
for ((file, before), (_, after)) in files_before.iter().zip(files_after.iter()) {
if before != after {
panic!("{} differs between rebuilds", file);
}
}
println!("Blobs identical.");
}
fn main() {
let subcommand = env::args().skip(1).next();
match subcommand.as_deref() {
Some("assemble") => assemble_blobs(),
Some("check-blobs") => check_blobs(),
_ => {
eprintln!("usage: cargo xtask <subcommand>");
eprintln!();
eprintln!("subcommands:");
eprintln!(" assemble Reassemble the pre-built artifacts");
eprintln!(" check-blobs Check that the pre-built artifacts are up-to-date and reproducible");
process::exit(1);
}
}
}
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