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Auto merge of #85600 - 12101111:rustbuild-libunwind, r=petrochenkov
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build llvm libunwind.a in rustbuild

This PR move the building of llvm-libunwind from build script of libunwind to rustbuild, so user don't need a C compiler and recompile this C/C++ library when using build-std, and user can use codegen flags `link-self-contained` and cargo flag `build-std-features` to control the behavior of libunwind linking.
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@bors
bors committed Aug 28, 2021
2 parents 42a2a53 + 9a53d59 commit 926f069
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Showing 6 changed files with 212 additions and 157 deletions.
146 changes: 10 additions & 136 deletions library/unwind/build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,36 +4,18 @@ fn main() {
println!("cargo:rerun-if-changed=build.rs");
let target = env::var("TARGET").expect("TARGET was not set");

if cfg!(target_os = "linux") && cfg!(feature = "system-llvm-libunwind") {
// linking for Linux is handled in lib.rs
return;
}

if cfg!(feature = "llvm-libunwind")
&& ((target.contains("linux") && !target.contains("musl")) || target.contains("fuchsia"))
{
// Build the unwinding from libunwind C/C++ source code.
llvm_libunwind::compile();
} else if target.contains("x86_64-fortanix-unknown-sgx") {
llvm_libunwind::compile();
} else if target.contains("linux") {
// linking for Linux is handled in lib.rs
if target.contains("musl") {
llvm_libunwind::compile();
} else if target.contains("android") {
let build = cc::Build::new();
if target.contains("android") {
let build = cc::Build::new();

// Since ndk r23 beta 3 `libgcc` was replaced with `libunwind` thus
// check if we have `libunwind` available and if so use it. Otherwise
// fall back to `libgcc` to support older ndk versions.
let has_unwind =
build.is_flag_supported("-lunwind").expect("Unable to invoke compiler");
// Since ndk r23 beta 3 `libgcc` was replaced with `libunwind` thus
// check if we have `libunwind` available and if so use it. Otherwise
// fall back to `libgcc` to support older ndk versions.
let has_unwind = build.is_flag_supported("-lunwind").expect("Unable to invoke compiler");

if has_unwind {
println!("cargo:rustc-link-lib=unwind");
} else {
println!("cargo:rustc-link-lib=gcc");
}
if has_unwind {
println!("cargo:rustc-link-lib=unwind");
} else {
println!("cargo:rustc-link-lib=gcc");
}
} else if target.contains("freebsd") {
println!("cargo:rustc-link-lib=gcc_s");
Expand Down Expand Up @@ -63,111 +45,3 @@ fn main() {
// redox is handled in lib.rs
}
}

mod llvm_libunwind {
use std::env;
use std::path::Path;

/// Compile the libunwind C/C++ source code.
pub fn compile() {
let target = env::var("TARGET").expect("TARGET was not set");
let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
let mut cc_cfg = cc::Build::new();
let mut cpp_cfg = cc::Build::new();
let root = Path::new("../../src/llvm-project/libunwind");

cpp_cfg.cpp(true);
cpp_cfg.cpp_set_stdlib(None);
cpp_cfg.flag("-nostdinc++");
cpp_cfg.flag("-fno-exceptions");
cpp_cfg.flag("-fno-rtti");
cpp_cfg.flag_if_supported("-fvisibility-global-new-delete-hidden");

// Don't set this for clang
// By default, Clang builds C code in GNU C17 mode.
// By default, Clang builds C++ code according to the C++98 standard,
// with many C++11 features accepted as extensions.
if cpp_cfg.get_compiler().is_like_gnu() {
cpp_cfg.flag("-std=c++11");
cc_cfg.flag("-std=c99");
}

if target.contains("x86_64-fortanix-unknown-sgx") || target_env == "musl" {
// use the same GCC C compiler command to compile C++ code so we do not need to setup the
// C++ compiler env variables on the builders.
// Don't set this for clang++, as clang++ is able to compile this without libc++.
if cpp_cfg.get_compiler().is_like_gnu() {
cpp_cfg.cpp(false);
}
}

for cfg in [&mut cc_cfg, &mut cpp_cfg].iter_mut() {
cfg.warnings(false);
cfg.flag("-fstrict-aliasing");
cfg.flag("-funwind-tables");
cfg.flag("-fvisibility=hidden");
cfg.define("_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS", None);
cfg.include(root.join("include"));
cfg.cargo_metadata(false);

if target.contains("x86_64-fortanix-unknown-sgx") {
cfg.static_flag(true);
cfg.opt_level(3);
cfg.flag("-fno-stack-protector");
cfg.flag("-ffreestanding");
cfg.flag("-fexceptions");

// easiest way to undefine since no API available in cc::Build to undefine
cfg.flag("-U_FORTIFY_SOURCE");
cfg.define("_FORTIFY_SOURCE", "0");
cfg.define("RUST_SGX", "1");
cfg.define("__NO_STRING_INLINES", None);
cfg.define("__NO_MATH_INLINES", None);
cfg.define("_LIBUNWIND_IS_BAREMETAL", None);
cfg.define("__LIBUNWIND_IS_NATIVE_ONLY", None);
cfg.define("NDEBUG", None);
}
}

let mut c_sources = vec![
"Unwind-sjlj.c",
"UnwindLevel1-gcc-ext.c",
"UnwindLevel1.c",
"UnwindRegistersRestore.S",
"UnwindRegistersSave.S",
];

let cpp_sources = vec!["Unwind-EHABI.cpp", "Unwind-seh.cpp", "libunwind.cpp"];
let cpp_len = cpp_sources.len();

if target.contains("x86_64-fortanix-unknown-sgx") {
c_sources.push("UnwindRustSgx.c");
}

for src in c_sources {
cc_cfg.file(root.join("src").join(src).canonicalize().unwrap());
}

for src in cpp_sources {
cpp_cfg.file(root.join("src").join(src).canonicalize().unwrap());
}

let out_dir = env::var("OUT_DIR").unwrap();
println!("cargo:rustc-link-search=native={}", &out_dir);

cpp_cfg.compile("unwind-cpp");

let mut count = 0;
for entry in std::fs::read_dir(&out_dir).unwrap() {
let obj = entry.unwrap().path().canonicalize().unwrap();
if let Some(ext) = obj.extension() {
if ext == "o" {
cc_cfg.object(&obj);
count += 1;
}
}
}
assert_eq!(cpp_len, count, "Can't get object files from {:?}", &out_dir);
cc_cfg.compile("unwind");
}
}
12 changes: 7 additions & 5 deletions library/unwind/src/lib.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
#![no_std]
#![unstable(feature = "panic_unwind", issue = "32837")]
#![feature(link_cfg)]
#![feature(native_link_modifiers)]
#![feature(native_link_modifiers_bundle)]
#![feature(nll)]
#![feature(staged_api)]
#![feature(static_nobundle)]
Expand Down Expand Up @@ -42,14 +44,14 @@ cfg_if::cfg_if! {
if #[cfg(all(feature = "llvm-libunwind", feature = "system-llvm-libunwind"))] {
compile_error!("`llvm-libunwind` and `system-llvm-libunwind` cannot be enabled at the same time");
} else if #[cfg(feature = "llvm-libunwind")] {
#[link(name = "unwind", kind = "static")]
#[link(name = "unwind", kind = "static", modifiers = "-bundle")]
extern "C" {}
} else if #[cfg(feature = "system-llvm-libunwind")] {
#[link(name = "unwind", kind = "static-nobundle", cfg(target_feature = "crt-static"))]
#[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
#[link(name = "unwind", cfg(not(target_feature = "crt-static")))]
extern "C" {}
} else {
#[link(name = "unwind", kind = "static", cfg(target_feature = "crt-static"))]
#[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
#[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
extern "C" {}
}
Expand Down Expand Up @@ -77,10 +79,10 @@ extern "C" {}
extern "C" {}

#[cfg(target_os = "redox")]
#[link(name = "gcc_eh", kind = "static-nobundle", cfg(target_feature = "crt-static"))]
#[link(name = "gcc_eh", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
#[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
extern "C" {}

#[cfg(all(target_vendor = "fortanix", target_env = "sgx"))]
#[link(name = "unwind", kind = "static")]
#[link(name = "unwind", kind = "static", modifiers = "-bundle")]
extern "C" {}
35 changes: 22 additions & 13 deletions library/unwind/src/libunwind.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -77,9 +77,18 @@ pub enum _Unwind_Context {}

pub type _Unwind_Exception_Cleanup_Fn =
extern "C" fn(unwind_code: _Unwind_Reason_Code, exception: *mut _Unwind_Exception);

// FIXME: The `#[link]` attributes on `extern "C"` block marks those symbols declared in
// the block are reexported in dylib build of libstd. This is needed when build rustc with
// feature `llvm-libunwind', as no other cdylib will provided those _Unwind_* symbols.
// However the `link` attribute is duplicated multiple times and does not just export symbol,
// a better way to manually export symbol would be another attribute like `#[export]`.
// See the logic in function rustc_codegen_ssa::src::back::exported_symbols, module
// rustc_codegen_ssa::src::back::symbol_export, rustc_middle::middle::exported_symbols
// and RFC 2841
#[cfg_attr(
all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static")
link(name = "unwind", kind = "static", modifiers = "-bundle")
)]
extern "C-unwind" {
pub fn _Unwind_Resume(exception: *mut _Unwind_Exception) -> !;
Expand All @@ -106,9 +115,10 @@ if #[cfg(any(target_os = "ios", target_os = "netbsd", not(target_arch = "arm")))
}
pub use _Unwind_Action::*;

#[cfg_attr(all(feature = "llvm-libunwind",
any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static"))]
#[cfg_attr(
all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static", modifiers = "-bundle")
)]
extern "C" {
pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word;
pub fn _Unwind_SetGR(ctx: *mut _Unwind_Context, reg_index: c_int, value: _Unwind_Word);
Expand Down Expand Up @@ -163,9 +173,10 @@ if #[cfg(any(target_os = "ios", target_os = "netbsd", not(target_arch = "arm")))
pub const UNWIND_SP_REG: c_int = 13;
pub const UNWIND_IP_REG: c_int = 15;

#[cfg_attr(all(feature = "llvm-libunwind",
any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static"))]
#[cfg_attr(
all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static", modifiers = "-bundle")
)]
extern "C" {
fn _Unwind_VRS_Get(ctx: *mut _Unwind_Context,
regclass: _Unwind_VRS_RegClass,
Expand Down Expand Up @@ -228,9 +239,10 @@ if #[cfg(any(target_os = "ios", target_os = "netbsd", not(target_arch = "arm")))
cfg_if::cfg_if! {
if #[cfg(not(all(target_os = "ios", target_arch = "arm")))] {
// Not 32-bit iOS
#[cfg_attr(all(feature = "llvm-libunwind",
any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static"))]
#[cfg_attr(
all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static", modifiers = "-bundle")
)]
extern "C-unwind" {
pub fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
}
Expand All @@ -241,9 +253,6 @@ if #[cfg(not(all(target_os = "ios", target_arch = "arm")))] {
}
} else {
// 32-bit iOS uses SjLj and does not provide _Unwind_Backtrace()
#[cfg_attr(all(feature = "llvm-libunwind",
any(target_os = "fuchsia", target_os = "linux")),
link(name = "unwind", kind = "static"))]
extern "C-unwind" {
pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
}
Expand Down
14 changes: 13 additions & 1 deletion src/bootstrap/compile.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ use serde::Deserialize;
use crate::builder::Cargo;
use crate::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
use crate::cache::{Interned, INTERNER};
use crate::config::TargetSelection;
use crate::config::{LlvmLibunwind, TargetSelection};
use crate::dist;
use crate::native;
use crate::tool::SourceType;
Expand Down Expand Up @@ -234,6 +234,18 @@ fn copy_self_contained_objects(
}
}

if target.contains("musl")
|| target.contains("x86_64-fortanix-unknown-sgx")
|| builder.config.llvm_libunwind == LlvmLibunwind::InTree
&& (target.contains("linux") || target.contains("fuchsia"))
{
let libunwind_path = builder.ensure(native::Libunwind { target });
let libunwind_source = libunwind_path.join("libunwind.a");
let libunwind_target = libdir_self_contained.join("libunwind.a");
builder.copy(&libunwind_source, &libunwind_target);
target_deps.push((libunwind_target, DependencyType::TargetSelfContained));
}

target_deps
}

Expand Down
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