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Move Apple linker args from rustc_target to rustc_codegen_ssa

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They are dependent on the deployment target and SDK version, but having
these in `rustc_target` makes it hard to introduce that dependency.
This commit is contained in:
Mads Marquart 2024-09-14 21:17:50 +02:00
parent f2becdff04
commit fb10eeb42b
2 changed files with 134 additions and 121 deletions
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133
compiler/rustc_codegen_ssa/src/back/link.rs
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@ -40,7 +40,7 @@ use rustc_target::spec::crt_objects::CrtObjects;
use rustc_target::spec::{
Cc, LinkOutputKind, LinkSelfContainedComponents, LinkSelfContainedDefault, LinkerFeatures,
LinkerFlavor, LinkerFlavorCli, Lld, PanicStrategy, RelocModel, RelroLevel, SanitizerSet,
SplitDebuginfo,
SplitDebuginfo, current_apple_deployment_target,
};
use tempfile::Builder as TempFileBuilder;
use tracing::{debug, info, warn};
@ -2405,6 +2405,8 @@ fn add_order_independent_options(
// Take care of the flavors and CLI options requesting the `lld` linker.
add_lld_args(cmd, sess, flavor, self_contained_components);
add_apple_link_args(cmd, sess, flavor);
let apple_sdk_root = add_apple_sdk(cmd, sess, flavor);
add_link_script(cmd, sess, tmpdir, crate_type);
@ -2957,6 +2959,135 @@ pub(crate) fn are_upstream_rust_objects_already_included(sess: &Session) -> bool
}
}
/// We need to communicate four things to the linker on Apple/Darwin targets:
/// - The architecture.
/// - The operating system (and that it's an Apple platform).
/// - The deployment target.
/// - The environment / ABI.
fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
if !sess.target.is_like_osx {
return;
}
let LinkerFlavor::Darwin(cc, _) = flavor else {
return;
};
// `sess.target.arch` (`target_arch`) is not detailed enough.
let llvm_arch = sess.target.llvm_target.split_once('-').expect("LLVM target must have arch").0;
let target_os = &*sess.target.os;
let target_abi = &*sess.target.abi;
// The architecture name to forward to the linker.
//
// Supported architecture names can be found in the source:
// https://github.com/apple-oss-distributions/ld64/blob/ld64-951.9/src/abstraction/MachOFileAbstraction.hpp#L578-L648
//
// Intentially verbose to ensure that the list always matches correctly
// with the list in the source above.
let ld64_arch = match llvm_arch {
"armv7k" => "armv7k",
"armv7s" => "armv7s",
"arm64" => "arm64",
"arm64e" => "arm64e",
"arm64_32" => "arm64_32",
// ld64 doesn't understand i686, so fall back to i386 instead.
//
// Same story when linking with cc, since that ends up invoking ld64.
"i386" | "i686" => "i386",
"x86_64" => "x86_64",
"x86_64h" => "x86_64h",
_ => bug!("unsupported architecture in Apple target: {}", sess.target.llvm_target),
};
if cc == Cc::No {
// From the man page for ld64 (`man ld`):
// > The linker accepts universal (multiple-architecture) input files,
// > but always creates a "thin" (single-architecture), standard
// > Mach-O output file. The architecture for the output file is
// > specified using the -arch option.
//
// The linker has heuristics to determine the desired architecture,
// but to be safe, and to avoid a warning, we set the architecture
// explicitly.
cmd.link_args(&["-arch", ld64_arch]);
// Man page says that ld64 supports the following platform names:
// > - macos
// > - ios
// > - tvos
// > - watchos
// > - bridgeos
// > - visionos
// > - xros
// > - mac-catalyst
// > - ios-simulator
// > - tvos-simulator
// > - watchos-simulator
// > - visionos-simulator
// > - xros-simulator
// > - driverkit
let platform_name = match (target_os, target_abi) {
(os, "") => os,
("ios", "macabi") => "mac-catalyst",
("ios", "sim") => "ios-simulator",
("tvos", "sim") => "tvos-simulator",
("watchos", "sim") => "watchos-simulator",
("visionos", "sim") => "visionos-simulator",
_ => bug!("invalid OS/ABI combination for Apple target: {target_os}, {target_abi}"),
};
let (major, minor, patch) = current_apple_deployment_target(&sess.target);
let min_version = format!("{major}.{minor}.{patch}");
// Lie about the SDK version, we don't know it here
let sdk_version = &*min_version;
// From the man page for ld64 (`man ld`):
// > This is set to indicate the platform, oldest supported version of
// > that platform that output is to be used on, and the SDK that the
// > output was built against.
//
// Like with `-arch`, the linker can figure out the platform versions
// itself from the binaries being linked, but to be safe, we specify
// the desired versions here explicitly.
cmd.link_args(&["-platform_version", platform_name, &*min_version, sdk_version]);
} else {
// cc == Cc::Yes
// We'd _like_ to use `-target` everywhere, since that can uniquely
// communicate all the required details, but that doesn't work on GCC,
// and since we don't know whether the `cc` compiler is Clang, GCC, or
// something else, we fall back to other options that also work on GCC
// when compiling for macOS.
//
// Targets other than macOS are ill-supported by GCC (it doesn't even
// support e.g. `-miphoneos-version-min`), so in those cases we can
// fairly safely use `-target`. See also the following, where it is
// made explicit that the recommendation by LLVM developers is to use
// `-target`: <https://github.com/llvm/llvm-project/issues/88271>
if target_os == "macos" {
// `-arch` communicates the architecture.
//
// CC forwards the `-arch` to the linker, so we use the same value
// here intentionally.
cmd.cc_args(&["-arch", ld64_arch]);
// The presence of `-mmacosx-version-min` makes CC default to
// macOS, and it sets the deployment target.
let (major, minor, patch) = current_apple_deployment_target(&sess.target);
// Intentionally pass this as a single argument, Clang doesn't
// seem to like it otherwise.
cmd.cc_arg(&format!("-mmacosx-version-min={major}.{minor}.{patch}"));
// macOS has no environment, so with these two, we've told CC the
// four desired parameters.
//
// We avoid `-m32`/`-m64`, as this is already encoded by `-arch`.
} else {
cmd.cc_args(&["-target", &sess.target.llvm_target]);
}
}
}
fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) -> Option<PathBuf> {
let arch = &sess.target.arch;
let os = &sess.target.os;