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build.rs
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build.rs
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use std::env;
use std::ffi::{OsStr, OsString};
use std::fmt::Display;
use std::path::{Path, PathBuf};
use std::process::{Command, Stdio};
const OPTIONAL_COMPONENTS: &[&str] = &[
"x86",
"arm",
"aarch64",
"amdgpu",
"avr",
"m68k",
"mips",
"powerpc",
"systemz",
"jsbackend",
"webassembly",
"msp430",
"sparc",
"nvptx",
"hexagon",
"riscv",
"bpf",
];
const REQUIRED_COMPONENTS: &[&str] =
&["ipo", "bitreader", "bitwriter", "linker", "asmparser", "lto", "coverage", "instrumentation"];
fn detect_llvm_link() -> (&'static str, &'static str) {
// Force the link mode we want, preferring static by default, but
// possibly overridden by `configure --enable-llvm-link-shared`.
if tracked_env_var_os("LLVM_LINK_SHARED").is_some() {
("dylib", "--link-shared")
} else {
("static", "--link-static")
}
}
// Because Cargo adds the compiler's dylib path to our library search path, llvm-config may
// break: the dylib path for the compiler, as of this writing, contains a copy of the LLVM
// shared library, which means that when our freshly built llvm-config goes to load it's
// associated LLVM, it actually loads the compiler's LLVM. In particular when building the first
// compiler (i.e., in stage 0) that's a problem, as the compiler's LLVM is likely different from
// the one we want to use. As such, we restore the environment to what bootstrap saw. This isn't
// perfect -- we might actually want to see something from Cargo's added library paths -- but
// for now it works.
fn restore_library_path() {
let key = tracked_env_var_os("REAL_LIBRARY_PATH_VAR").expect("REAL_LIBRARY_PATH_VAR");
if let Some(env) = tracked_env_var_os("REAL_LIBRARY_PATH") {
env::set_var(&key, &env);
} else {
env::remove_var(&key);
}
}
/// Reads an environment variable and adds it to dependencies.
/// Supposed to be used for all variables except those set for build scripts by cargo
/// <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts>
fn tracked_env_var_os<K: AsRef<OsStr> + Display>(key: K) -> Option<OsString> {
println!("cargo:rerun-if-env-changed={}", key);
env::var_os(key)
}
fn rerun_if_changed_anything_in_dir(dir: &Path) {
let mut stack = dir
.read_dir()
.unwrap()
.map(|e| e.unwrap())
.filter(|e| &*e.file_name() != ".git")
.collect::<Vec<_>>();
while let Some(entry) = stack.pop() {
let path = entry.path();
if entry.file_type().unwrap().is_dir() {
stack.extend(path.read_dir().unwrap().map(|e| e.unwrap()));
} else {
println!("cargo:rerun-if-changed={}", path.display());
}
}
}
#[track_caller]
fn output(cmd: &mut Command) -> String {
let output = match cmd.stderr(Stdio::inherit()).output() {
Ok(status) => status,
Err(e) => {
println!("\n\nfailed to execute command: {:?}\nerror: {}\n\n", cmd, e);
std::process::exit(1);
}
};
if !output.status.success() {
panic!(
"command did not execute successfully: {:?}\n\
expected success, got: {}",
cmd, output.status
);
}
String::from_utf8(output.stdout).unwrap()
}
fn main() {
for component in REQUIRED_COMPONENTS.iter().chain(OPTIONAL_COMPONENTS.iter()) {
println!("cargo:rustc-check-cfg=values(llvm_component,\"{}\")", component);
}
if tracked_env_var_os("RUST_CHECK").is_some() {
// If we're just running `check`, there's no need for LLVM to be built.
return;
}
restore_library_path();
let target = env::var("TARGET").expect("TARGET was not set");
let llvm_config =
tracked_env_var_os("LLVM_CONFIG").map(|x| Some(PathBuf::from(x))).unwrap_or_else(|| {
if let Some(dir) = tracked_env_var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
let to_test = dir
.parent()
.unwrap()
.parent()
.unwrap()
.join(&target)
.join("llvm/bin/llvm-config");
if Command::new(&to_test).output().is_ok() {
return Some(to_test);
}
}
None
});
if let Some(llvm_config) = &llvm_config {
println!("cargo:rerun-if-changed={}", llvm_config.display());
}
let llvm_config = llvm_config.unwrap_or_else(|| PathBuf::from("llvm-config"));
// Test whether we're cross-compiling LLVM. This is a pretty rare case
// currently where we're producing an LLVM for a different platform than
// what this build script is currently running on.
//
// In that case, there's no guarantee that we can actually run the target,
// so the build system works around this by giving us the LLVM_CONFIG for
// the host platform. This only really works if the host LLVM and target
// LLVM are compiled the same way, but for us that's typically the case.
//
// We *want* detect this cross compiling situation by asking llvm-config
// what its host-target is. If that's not the TARGET, then we're cross
// compiling. Unfortunately `llvm-config` seems either be buggy, or we're
// misconfiguring it, because the `i686-pc-windows-gnu` build of LLVM will
// report itself with a `--host-target` of `x86_64-pc-windows-gnu`. This
// tricks us into thinking we're doing a cross build when we aren't, so
// havoc ensues.
//
// In any case, if we're cross compiling, this generally just means that we
// can't trust all the output of llvm-config because it might be targeted
// for the host rather than the target. As a result a bunch of blocks below
// are gated on `if !is_crossed`
let target = env::var("TARGET").expect("TARGET was not set");
let host = env::var("HOST").expect("HOST was not set");
let is_crossed = target != host;
let components = output(Command::new(&llvm_config).arg("--components"));
let mut components = components.split_whitespace().collect::<Vec<_>>();
components.retain(|c| OPTIONAL_COMPONENTS.contains(c) || REQUIRED_COMPONENTS.contains(c));
for component in REQUIRED_COMPONENTS {
if !components.contains(component) {
panic!("require llvm component {} but wasn't found", component);
}
}
for component in components.iter() {
println!("cargo:rustc-cfg=llvm_component=\"{}\"", component);
}
// Link in our own LLVM shims, compiled with the same flags as LLVM
let mut cmd = Command::new(&llvm_config);
cmd.arg("--cxxflags");
let cxxflags = output(&mut cmd);
let mut cfg = cc::Build::new();
cfg.warnings(false);
for flag in cxxflags.split_whitespace() {
// Ignore flags like `-m64` when we're doing a cross build
if is_crossed && flag.starts_with("-m") {
continue;
}
if flag.starts_with("-flto") {
continue;
}
// -Wdate-time is not supported by the netbsd cross compiler
if is_crossed && target.contains("netbsd") && flag.contains("date-time") {
continue;
}
// Include path contains host directory, replace it with target
if is_crossed && flag.starts_with("-I") {
cfg.flag(&flag.replace(&host, &target));
continue;
}
cfg.flag(flag);
}
for component in &components {
let mut flag = String::from("LLVM_COMPONENT_");
flag.push_str(&component.to_uppercase());
cfg.define(&flag, None);
}
if tracked_env_var_os("LLVM_RUSTLLVM").is_some() {
cfg.define("LLVM_RUSTLLVM", None);
}
if tracked_env_var_os("LLVM_NDEBUG").is_some() {
cfg.define("NDEBUG", None);
cfg.debug(false);
}
rerun_if_changed_anything_in_dir(Path::new("llvm-wrapper"));
cfg.file("llvm-wrapper/PassWrapper.cpp")
.file("llvm-wrapper/RustWrapper.cpp")
.file("llvm-wrapper/ArchiveWrapper.cpp")
.file("llvm-wrapper/CoverageMappingWrapper.cpp")
.file("llvm-wrapper/Linker.cpp")
.cpp(true)
.cpp_link_stdlib(None) // we handle this below
.compile("llvm-wrapper");
let (llvm_kind, llvm_link_arg) = detect_llvm_link();
// Link in all LLVM libraries, if we're using the "wrong" llvm-config then
// we don't pick up system libs because unfortunately they're for the host
// of llvm-config, not the target that we're attempting to link.
let mut cmd = Command::new(&llvm_config);
cmd.arg(llvm_link_arg).arg("--libs");
if !is_crossed {
cmd.arg("--system-libs");
} else if target.contains("windows-gnu") {
println!("cargo:rustc-link-lib=shell32");
println!("cargo:rustc-link-lib=uuid");
} else if target.contains("netbsd") || target.contains("haiku") || target.contains("darwin") {
println!("cargo:rustc-link-lib=z");
} else if target.starts_with("arm")
|| target.starts_with("mips-")
|| target.starts_with("mipsel-")
|| target.starts_with("powerpc-")
{
// 32-bit targets need to link libatomic.
println!("cargo:rustc-link-lib=atomic");
}
cmd.args(&components);
for lib in output(&mut cmd).split_whitespace() {
let name = if let Some(stripped) = lib.strip_prefix("-l") {
stripped
} else if let Some(stripped) = lib.strip_prefix('-') {
stripped
} else if Path::new(lib).exists() {
// On MSVC llvm-config will print the full name to libraries, but
// we're only interested in the name part
let name = Path::new(lib).file_name().unwrap().to_str().unwrap();
name.trim_end_matches(".lib")
} else if lib.ends_with(".lib") {
// Some MSVC libraries just come up with `.lib` tacked on, so chop
// that off
lib.trim_end_matches(".lib")
} else {
continue;
};
// Don't need or want this library, but LLVM's CMake build system
// doesn't provide a way to disable it, so filter it here even though we
// may or may not have built it. We don't reference anything from this
// library and it otherwise may just pull in extra dependencies on
// libedit which we don't want
if name == "LLVMLineEditor" {
continue;
}
let kind = if name.starts_with("LLVM") { llvm_kind } else { "dylib" };
println!("cargo:rustc-link-lib={}={}", kind, name);
}
// LLVM ldflags
//
// If we're a cross-compile of LLVM then unfortunately we can't trust these
// ldflags (largely where all the LLVM libs are located). Currently just
// hack around this by replacing the host triple with the target and pray
// that those -L directories are the same!
let mut cmd = Command::new(&llvm_config);
cmd.arg(llvm_link_arg).arg("--ldflags");
for lib in output(&mut cmd).split_whitespace() {
if is_crossed {
if let Some(stripped) = lib.strip_prefix("-LIBPATH:") {
println!("cargo:rustc-link-search=native={}", stripped.replace(&host, &target));
} else if let Some(stripped) = lib.strip_prefix("-L") {
println!("cargo:rustc-link-search=native={}", stripped.replace(&host, &target));
}
} else if let Some(stripped) = lib.strip_prefix("-LIBPATH:") {
println!("cargo:rustc-link-search=native={}", stripped);
} else if let Some(stripped) = lib.strip_prefix("-l") {
println!("cargo:rustc-link-lib={}", stripped);
} else if let Some(stripped) = lib.strip_prefix("-L") {
println!("cargo:rustc-link-search=native={}", stripped);
}
}
// Some LLVM linker flags (-L and -l) may be needed even when linking
// rustc_llvm, for example when using static libc++, we may need to
// manually specify the library search path and -ldl -lpthread as link
// dependencies.
let llvm_linker_flags = tracked_env_var_os("LLVM_LINKER_FLAGS");
if let Some(s) = llvm_linker_flags {
for lib in s.into_string().unwrap().split_whitespace() {
if let Some(stripped) = lib.strip_prefix("-l") {
println!("cargo:rustc-link-lib={}", stripped);
} else if let Some(stripped) = lib.strip_prefix("-L") {
println!("cargo:rustc-link-search=native={}", stripped);
}
}
}
let llvm_static_stdcpp = tracked_env_var_os("LLVM_STATIC_STDCPP");
let llvm_use_libcxx = tracked_env_var_os("LLVM_USE_LIBCXX");
let stdcppname = if target.contains("openbsd") {
if target.contains("sparc64") { "estdc++" } else { "c++" }
} else if target.contains("darwin")
|| target.contains("freebsd")
|| target.contains("windows-gnullvm")
{
"c++"
} else if target.contains("netbsd") && llvm_static_stdcpp.is_some() {
// NetBSD uses a separate library when relocation is required
"stdc++_pic"
} else if llvm_use_libcxx.is_some() {
"c++"
} else {
"stdc++"
};
// RISC-V GCC erroneously requires libatomic for sub-word
// atomic operations. Some BSD uses Clang as its system
// compiler and provides no libatomic in its base system so
// does not want this.
if target.starts_with("riscv") && !target.contains("freebsd") && !target.contains("openbsd") {
println!("cargo:rustc-link-lib=atomic");
}
// C++ runtime library
if !target.contains("msvc") {
if let Some(s) = llvm_static_stdcpp {
assert!(!cxxflags.contains("stdlib=libc++"));
let path = PathBuf::from(s);
println!("cargo:rustc-link-search=native={}", path.parent().unwrap().display());
if target.contains("windows") {
println!("cargo:rustc-link-lib=static:-bundle={}", stdcppname);
} else {
println!("cargo:rustc-link-lib=static={}", stdcppname);
}
} else if cxxflags.contains("stdlib=libc++") {
println!("cargo:rustc-link-lib=c++");
} else {
println!("cargo:rustc-link-lib={}", stdcppname);
}
}
// Libstdc++ depends on pthread which Rust doesn't link on MinGW
// since nothing else requires it.
if target.ends_with("windows-gnu") {
println!("cargo:rustc-link-lib=static:-bundle=pthread");
}
}