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chore: Fixed incorrect use of cfg! macro and update build.rs to suppo…
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…rt arm target (#1458)


What I've done

    Fixed incorrect use of cfg! macro use the CARGO_CFG_TARGET_<OS/ARCH> macro instead of the original cfg! (target_<os/arch>) This is because The build script is compiled for the host architecture as a separate build phase, as that's where it runs. Since the cfg macro runs at compile time it'll always report the host configuration there.When cargo runs the build script it passes the configuration through environment variables, one of which is CARGO_CFG_TARGET_ARCH. Some dicussions can be found here

    update build.rs to support arm target support arm target. Like the Aarch64 target, we need to additionally install the cross-compilation toolchain and specify the linker in Cargo/config.toml. I can add this part of the work in next pull request if necessary.


Co-authored-by: Matt Mastracci <[email protected]>
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@chiichen @mmastrac
chiichen and mmastrac authored May 12, 2024
1 parent eb849c3 commit 4dd87b2
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Showing 2 changed files with 80 additions and 68 deletions.
139 changes: 71 additions & 68 deletions build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -137,20 +137,23 @@ fn build_v8(is_asan: bool) {
if need_gn_ninja_download() {
download_ninja_gn_binaries();
}

// `#[cfg(...)]` attributes don't work as expected from build.rs -- they refer to the configuration
// of the host system which the build.rs script will be running on. In short, `cfg!(target_<os/arch>)`
// is actually the host os/arch instead of target os/arch while cross compiling. Instead, Environment variables
// are the officially approach to get the target os/arch in build.rs.
let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
// On windows, rustc cannot link with a V8 debug build.
let mut gn_args = if is_debug() && !cfg!(target_os = "windows") {
let mut gn_args = if is_debug() && target_os != "windows" {
// Note: When building for Android aarch64-qemu, use release instead of debug.
vec!["is_debug=true".to_string()]
} else {
vec!["is_debug=false".to_string()]
};

if is_asan {
gn_args.push("is_asan=true".to_string());
}

if cfg!(not(feature = "use_custom_libcxx")) {
if env::var("CARGO_FEATURE_USE_CUSTOM_LIBCXX").is_err() {
gn_args.push("use_custom_libcxx=false".to_string());
}

Expand All @@ -172,7 +175,7 @@ fn build_v8(is_asan: bool) {
let clang_base_path = clang_download();
gn_args.push(format!("clang_base_path={:?}", clang_base_path));

if cfg!(target_os = "android") && cfg!(target_arch = "aarch64") {
if target_os == "android" && target_arch == "aarch64" {
gn_args.push("treat_warnings_as_errors=false".to_string());
}
}
Expand All @@ -194,45 +197,43 @@ fn build_v8(is_asan: bool) {
gn_args.push(arg.to_string());
}
}
// cross-compilation setup
if target_arch == "aarch64" {
gn_args.push(r#"target_cpu="arm64""#.to_string());
gn_args.push("use_sysroot=true".to_string());
maybe_install_sysroot("arm64");
maybe_install_sysroot("amd64");
}
if target_arch == "arm" {
gn_args.push(r#"target_cpu="arm""#.to_string());
gn_args.push(r#"v8_target_cpu="arm""#.to_string());
gn_args.push("use_sysroot=true".to_string());
maybe_install_sysroot("i386");
maybe_install_sysroot("arm");
}

let target_triple = env::var("TARGET").unwrap();
// check if the target triple describes a non-native environment
if target_triple != env::var("HOST").unwrap() {
// cross-compilation setup
if target_triple == "aarch64-unknown-linux-gnu"
|| target_triple == "aarch64-linux-android"
{
gn_args.push(r#"target_cpu="arm64""#.to_string());
gn_args.push("use_sysroot=true".to_string());
maybe_install_sysroot("arm64");
maybe_install_sysroot("amd64");
if target_triple != env::var("HOST").unwrap() && target_os == "android" {
let arch = if target_arch == "x86_64" {
"x64"
} else if target_arch == "aarch64" {
"arm64"
} else {
"unknown"
};
if target_arch == "x86_64" {
maybe_install_sysroot("amd64");
}
gn_args.push(format!(r#"v8_target_cpu="{}""#, arch).to_string());
gn_args.push(format!(r#"target_cpu="{}""#, arch).to_string());
gn_args.push(r#"target_os="android""#.to_string());
gn_args.push("treat_warnings_as_errors=false".to_string());
gn_args.push("use_sysroot=true".to_string());

let t_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
let t_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();

if t_os == "android" {
let arch = if t_arch == "x86_64" {
"x64"
} else if t_arch == "aarch64" {
"arm64"
} else {
"unknown"
};

if t_arch == "x86_64" {
maybe_install_sysroot("amd64");
}

gn_args.push(format!(r#"v8_target_cpu="{}""#, arch).to_string());
gn_args.push(format!(r#"target_cpu="{}""#, arch).to_string());
gn_args.push(r#"target_os="android""#.to_string());
gn_args.push("treat_warnings_as_errors=false".to_string());
gn_args.push("use_sysroot=true".to_string());

// NDK 23 and above removes libgcc entirely.
// https://github.com/rust-lang/rust/pull/85806
if !Path::new("./third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android24-clang++").exists() {
// NDK 23 and above removes libgcc entirely.
// https://github.com/rust-lang/rust/pull/85806
if !Path::new("./third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android24-clang++").exists() {
assert!(Command::new("curl")
.arg("-L")
.arg("-o").arg("./third_party/android-ndk-r26c-linux.zip")
Expand All @@ -253,21 +254,18 @@ fn build_v8(is_asan: bool) {
fs::rename("./third_party/android-ndk-r26c", "./third_party/android_ndk").unwrap();
fs::remove_file("./third_party/android-ndk-r26c-linux.zip").unwrap();
}

static CHROMIUM_URI: &str = "https://chromium.googlesource.com";

maybe_clone_repo(
"./third_party/android_platform",
&format!(
"{}/chromium/src/third_party/android_platform.git",
CHROMIUM_URI
),
);
maybe_clone_repo(
"./third_party/catapult",
&format!("{}/catapult.git", CHROMIUM_URI),
);
};
static CHROMIUM_URI: &str = "https://chromium.googlesource.com";
maybe_clone_repo(
"./third_party/android_platform",
&format!(
"{}/chromium/src/third_party/android_platform.git",
CHROMIUM_URI
),
);
maybe_clone_repo(
"./third_party/catapult",
&format!("{}/catapult.git", CHROMIUM_URI),
);
}

if target_triple.starts_with("i686-") {
Expand Down Expand Up @@ -321,7 +319,7 @@ fn maybe_install_sysroot(arch: &str) {
}
}

fn platform() -> String {
fn host_platform() -> String {
let os = if cfg!(target_os = "linux") {
"linux"
} else if cfg!(target_os = "macos") {
Expand All @@ -336,18 +334,19 @@ fn platform() -> String {
"amd64"
} else if cfg!(target_arch = "aarch64") {
"arm64"
} else if cfg!(target_arch = "arm") {
"arm"
} else {
"unknown"
};

format!("{os}-{arch}")
}

fn download_ninja_gn_binaries() {
let target_dir = build_dir();
let bin_dir = target_dir
.join("ninja_gn_binaries-20221218")
.join(platform());
.join(host_platform());
let gn = bin_dir.join("gn");
let ninja = bin_dir.join("ninja");
#[cfg(windows)]
Expand Down Expand Up @@ -379,9 +378,9 @@ fn static_lib_url() -> String {
env::var("RUSTY_V8_MIRROR").unwrap_or_else(|_| default_base.into());
let version = env::var("CARGO_PKG_VERSION").unwrap();
let target = env::var("TARGET").unwrap();

let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
// Note: we always use the release build on windows.
if cfg!(target_os = "windows") {
if target_os == "windows" {
return format!("{}/v{}/rusty_v8_release_{}.lib.gz", base, version, target);
}
// Use v8 in release mode unless $V8_FORCE_DEBUG=true
Expand All @@ -403,9 +402,11 @@ fn env_bool(key: &str) -> bool {
}

fn static_lib_name() -> &'static str {
match cfg!(target_os = "windows") {
true => "rusty_v8.lib",
false => "librusty_v8.a",
let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
if target_os == "windows" {
"rusty_v8.lib"
} else {
"librusty_v8.a"
}
}

Expand Down Expand Up @@ -616,8 +617,8 @@ fn copy_archive(url: &str, filename: &Path) {

fn print_link_flags() {
println!("cargo:rustc-link-lib=static=rusty_v8");

let should_dyn_link_libcxx = cfg!(not(feature = "use_custom_libcxx"))
let should_dyn_link_libcxx = env::var("CARGO_FEATURE_USE_CUSTOM_LIBCXX")
.is_err()
|| env::var("GN_ARGS").map_or(false, |gn_args| {
gn_args
.split_whitespace()
Expand Down Expand Up @@ -646,16 +647,18 @@ fn print_link_flags() {
}
}
}
let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();

if cfg!(target_os = "windows") {
if target_os == "windows" {
println!("cargo:rustc-link-lib=dylib=winmm");
println!("cargo:rustc-link-lib=dylib=dbghelp");
}

if cfg!(target_env = "msvc") {
if target_env == "msvc" {
// On Windows, including libcpmt[d]/msvcprt[d] explicitly links the C++
// standard library, which libc++ needs for exception_ptr internals.
if cfg!(target_feature = "crt-static") {
if env::var("CARGO_FEATURE_CRT_STATIC").is_ok() {
println!("cargo:rustc-link-lib=libcpmt");
} else {
println!("cargo:rustc-link-lib=dylib=msvcprt");
Expand Down
9 changes: 9 additions & 0 deletions rust-toolchain.toml
View file
Original file line number Diff line number Diff line change
@@ -1,3 +1,12 @@
[toolchain]
channel = "1.77.2"
components = ["rustfmt", "clippy"]
targets = [
"x86_64-apple-darwin",
"aarch64-apple-darwin",
"x86_64-unknown-linux-gnu",
"aarch64-unknown-linux-gnu",
"x86_64-pc-windows-msvc",
"aarch64-linux-android",
"x86_64-linux-android",
]

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