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Merge pull request #652 from tgross35/control-f16-f128-feature
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@Amanieu
Amanieu authored Aug 4, 2024
2 parents 9dcc46a + c6f95d7 commit 1211d02
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Showing 17 changed files with 263 additions and 237 deletions.
164 changes: 122 additions & 42 deletions build.rs
View file
Original file line number Diff line number Diff line change
@@ -1,56 +1,97 @@
use std::{collections::BTreeMap, env, path::PathBuf, sync::atomic::Ordering};

#[allow(dead_code)]
struct Target {
triple: String,
os: String,
arch: String,
vendor: String,
env: String,
pointer_width: u8,
little_endian: bool,
features: Vec<String>,
}

impl Target {
fn from_env() -> Self {
let little_endian = match env::var("CARGO_CFG_TARGET_ENDIAN").unwrap().as_str() {
"little" => true,
"big" => false,
x => panic!("unknown endian {x}"),
};

Self {
triple: env::var("TARGET").unwrap(),
os: env::var("CARGO_CFG_TARGET_OS").unwrap(),
arch: env::var("CARGO_CFG_TARGET_ARCH").unwrap(),
vendor: env::var("CARGO_CFG_TARGET_VENDOR").unwrap(),
env: env::var("CARGO_CFG_TARGET_ENV").unwrap(),
pointer_width: env::var("CARGO_CFG_TARGET_POINTER_WIDTH")
.unwrap()
.parse()
.unwrap(),
little_endian,
features: env::var("CARGO_CFG_TARGET_FEATURE")
.unwrap_or_default()
.split(",")
.map(ToOwned::to_owned)
.collect(),
}
}
}

fn main() {
println!("cargo:rerun-if-changed=build.rs");
configure_check_cfg();

let target = env::var("TARGET").unwrap();
let target = Target::from_env();
let cwd = env::current_dir().unwrap();

configure_check_cfg();
configure_f16_f128(&target);

println!("cargo:compiler-rt={}", cwd.join("compiler-rt").display());

// Activate libm's unstable features to make full use of Nightly.
println!("cargo::rustc-check-cfg=cfg(feature, values(\"unstable\"))");
println!("cargo:rustc-cfg=feature=\"unstable\"");

// Emscripten's runtime includes all the builtins
if target.contains("emscripten") {
if target.env == "emscripten" {
return;
}

// OpenBSD provides compiler_rt by default, use it instead of rebuilding it from source
if target.contains("openbsd") {
if target.os == "openbsd" {
println!("cargo:rustc-link-search=native=/usr/lib");
println!("cargo:rustc-link-lib=compiler_rt");
return;
}

// Forcibly enable memory intrinsics on wasm & SGX as we don't have a libc to
// provide them.
if (target.contains("wasm") && !target.contains("wasi"))
|| (target.contains("sgx") && target.contains("fortanix"))
|| target.contains("-none")
|| target.contains("nvptx")
|| target.contains("uefi")
|| target.contains("xous")
if (target.triple.contains("wasm") && !target.triple.contains("wasi"))
|| (target.triple.contains("sgx") && target.triple.contains("fortanix"))
|| target.triple.contains("-none")
|| target.triple.contains("nvptx")
|| target.triple.contains("uefi")
|| target.triple.contains("xous")
{
println!("cargo:rustc-cfg=feature=\"mem\"");
}

// These targets have hardware unaligned access support.
println!("cargo::rustc-check-cfg=cfg(feature, values(\"mem-unaligned\"))");
if target.contains("x86_64")
|| target.contains("i686")
|| target.contains("aarch64")
|| target.contains("bpf")
if target.arch.contains("x86_64")
|| target.arch.contains("i686")
|| target.arch.contains("aarch64")
|| target.arch.contains("bpf")
{
println!("cargo:rustc-cfg=feature=\"mem-unaligned\"");
}

// NOTE we are going to assume that llvm-target, what determines our codegen option, matches the
// target triple. This is usually correct for our built-in targets but can break in presence of
// custom targets, which can have arbitrary names.
let llvm_target = target.split('-').collect::<Vec<_>>();
let llvm_target = target.triple.split('-').collect::<Vec<_>>();

// Build missing intrinsics from compiler-rt C source code. If we're
// mangling names though we assume that we're also in test mode so we don't
Expand All @@ -60,7 +101,7 @@ fn main() {
// Don't use a C compiler for these targets:
//
// * nvptx - everything is bitcode, not compatible with mixed C/Rust
if !target.contains("nvptx") {
if !target.arch.contains("nvptx") {
#[cfg(feature = "c")]
c::compile(&llvm_target, &target);
}
Expand All @@ -86,7 +127,7 @@ fn main() {
println!("cargo::rustc-check-cfg=cfg(kernel_user_helpers)");
if llvm_target[0] == "armv4t"
|| llvm_target[0] == "armv5te"
|| target == "arm-linux-androideabi"
|| target.triple == "arm-linux-androideabi"
{
println!("cargo:rustc-cfg=kernel_user_helpers")
}
Expand Down Expand Up @@ -219,6 +260,47 @@ fn configure_check_cfg() {
println!("cargo::rustc-check-cfg=cfg(assert_no_panic)");
}

/// Configure whether or not `f16` and `f128` support should be enabled.
fn configure_f16_f128(target: &Target) {
// Set whether or not `f16` and `f128` are supported at a basic level by LLVM. This only means
// that the backend will not crash when using these types. This does not mean that the
// backend does the right thing, or that the platform doesn't have ABI bugs.
//
// We do this here rather than in `rust-lang/rust` because configuring via cargo features is
// not straightforward.
//
// Original source of this list:
// <https://github.com/rust-lang/compiler-builtins/pull/652#issuecomment-2266151350>
let (f16_ok, f128_ok) = match target.arch.as_str() {
// `f16` and `f128` both crash <https://github.com/llvm/llvm-project/issues/94434>
"arm64ec" => (false, false),
// `f16` crashes <https://github.com/llvm/llvm-project/issues/50374>
"s390x" => (false, true),
// `f128` crashes <https://github.com/llvm/llvm-project/issues/96432>
"mips64" | "mips64r6" => (true, false),
// `f128` crashes <https://github.com/llvm/llvm-project/issues/101545>
"powerpc64" if &target.os == "aix" => (true, false),
// `f128` crashes <https://github.com/llvm/llvm-project/issues/41838>
"sparc" | "sparcv9" => (true, false),
// Most everything else works as of LLVM 19
_ => (true, true),
};

// If the feature is set, disable these types.
let disable_both = env::var_os("CARGO_FEATURE_NO_F16_F128").is_some();

println!("cargo::rustc-check-cfg=cfg(f16_enabled)");
println!("cargo::rustc-check-cfg=cfg(f128_enabled)");

if f16_ok && !disable_both {
println!("cargo::rustc-cfg=f16_enabled");
}

if f128_ok && !disable_both {
println!("cargo::rustc-cfg=f128_enabled");
}
}

#[cfg(feature = "c")]
mod c {
use std::collections::{BTreeMap, HashSet};
Expand All @@ -227,6 +309,8 @@ mod c {
use std::io::Write;
use std::path::{Path, PathBuf};

use super::Target;

struct Sources {
// SYMBOL -> PATH TO SOURCE
map: BTreeMap<&'static str, &'static str>,
Expand Down Expand Up @@ -267,11 +351,7 @@ mod c {
}

/// Compile intrinsics from the compiler-rt C source code
pub fn compile(llvm_target: &[&str], target: &String) {
let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
let target_vendor = env::var("CARGO_CFG_TARGET_VENDOR").unwrap();
pub fn compile(llvm_target: &[&str], target: &Target) {
let mut consider_float_intrinsics = true;
let cfg = &mut cc::Build::new();

Expand All @@ -280,8 +360,8 @@ mod c {
//
// Therefore, evaluate if those flags are present and set a boolean that causes any
// compiler-rt intrinsics that contain floating point source to be excluded for this target.
if target_arch == "aarch64" {
let cflags_key = String::from("CFLAGS_") + &(target.to_owned().replace("-", "_"));
if target.arch == "aarch64" {
let cflags_key = String::from("CFLAGS_") + &(target.triple.replace("-", "_"));
if let Ok(cflags_value) = env::var(cflags_key) {
if cflags_value.contains("+nofp") || cflags_value.contains("+nosimd") {
consider_float_intrinsics = false;
Expand All @@ -299,7 +379,7 @@ mod c {

cfg.warnings(false);

if target_env == "msvc" {
if target.env == "msvc" {
// Don't pull in extra libraries on MSVC
cfg.flag("/Zl");

Expand Down Expand Up @@ -328,7 +408,7 @@ mod c {
// at odds with compiling with `-ffreestanding`, as the header
// may be incompatible or not present. Create a minimal stub
// header to use instead.
if target_os == "uefi" {
if target.os == "uefi" {
let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
let include_dir = out_dir.join("include");
if !include_dir.exists() {
Expand Down Expand Up @@ -373,7 +453,7 @@ mod c {

// On iOS and 32-bit OSX these are all just empty intrinsics, no need to
// include them.
if target_vendor != "apple" || target_arch != "x86" {
if target.vendor != "apple" || target.arch != "x86" {
sources.extend(&[
("__absvti2", "absvti2.c"),
("__addvti3", "addvti3.c"),
Expand All @@ -392,7 +472,7 @@ mod c {
}
}

if target_vendor == "apple" {
if target.vendor == "apple" {
sources.extend(&[
("atomic_flag_clear", "atomic_flag_clear.c"),
("atomic_flag_clear_explicit", "atomic_flag_clear_explicit.c"),
Expand All @@ -406,8 +486,8 @@ mod c {
]);
}

if target_env != "msvc" {
if target_arch == "x86" {
if target.env != "msvc" {
if target.arch == "x86" {
sources.extend(&[
("__ashldi3", "i386/ashldi3.S"),
("__ashrdi3", "i386/ashrdi3.S"),
Expand All @@ -421,7 +501,7 @@ mod c {
}
}

if target_arch == "arm" && target_vendor != "apple" && target_env != "msvc" {
if target.arch == "arm" && target.vendor != "apple" && target.env != "msvc" {
sources.extend(&[
("__aeabi_div0", "arm/aeabi_div0.c"),
("__aeabi_drsub", "arm/aeabi_drsub.c"),
Expand All @@ -441,7 +521,7 @@ mod c {
("__umodsi3", "arm/umodsi3.S"),
]);

if target_os == "freebsd" {
if target.os == "freebsd" {
sources.extend(&[("__clear_cache", "clear_cache.c")]);
}

Expand Down Expand Up @@ -513,7 +593,7 @@ mod c {
]);
}

if (target_arch == "aarch64" || target_arch == "arm64ec") && consider_float_intrinsics {
if (target.arch == "aarch64" || target.arch == "arm64ec") && consider_float_intrinsics {
sources.extend(&[
("__comparetf2", "comparetf2.c"),
("__floatditf", "floatditf.c"),
Expand All @@ -526,16 +606,16 @@ mod c {
("__fe_raise_inexact", "fp_mode.c"),
]);

if target_os != "windows" {
if target.os != "windows" {
sources.extend(&[("__multc3", "multc3.c")]);
}
}

if target_arch == "mips" || target_arch == "riscv32" || target_arch == "riscv64" {
if target.arch == "mips" || target.arch == "riscv32" || target.arch == "riscv64" {
sources.extend(&[("__bswapsi2", "bswapsi2.c")]);
}

if target_arch == "mips64" {
if target.arch == "mips64" {
sources.extend(&[
("__netf2", "comparetf2.c"),
("__floatsitf", "floatsitf.c"),
Expand All @@ -544,7 +624,7 @@ mod c {
]);
}

if target_arch == "loongarch64" {
if target.arch == "loongarch64" {
sources.extend(&[
("__netf2", "comparetf2.c"),
("__floatsitf", "floatsitf.c"),
Expand All @@ -554,7 +634,7 @@ mod c {
}

// Remove the assembly implementations that won't compile for the target
if llvm_target[0] == "thumbv6m" || llvm_target[0] == "thumbv8m.base" || target_os == "uefi"
if llvm_target[0] == "thumbv6m" || llvm_target[0] == "thumbv8m.base" || target.os == "uefi"
{
let mut to_remove = Vec::new();
for (k, v) in sources.map.iter() {
Expand All @@ -570,7 +650,7 @@ mod c {
}

// Android uses emulated TLS so we need a runtime support function.
if target_os == "android" {
if target.os == "android" {
sources.extend(&[("__emutls_get_address", "emutls.c")]);

// Work around a bug in the NDK headers (fixed in
Expand All @@ -580,7 +660,7 @@ mod c {
}

// OpenHarmony also uses emulated TLS.
if target_env == "ohos" {
if target.env == "ohos" {
sources.extend(&[("__emutls_get_address", "emutls.c")]);
}

Expand All @@ -607,7 +687,7 @@ mod c {
// sets of flags to the same source file.
// Note: Out-of-line aarch64 atomics are not supported by the msvc toolchain (#430).
let src_dir = root.join("lib/builtins");
if target_arch == "aarch64" && target_env != "msvc" {
if target.arch == "aarch64" && target.env != "msvc" {
// See below for why we're building these as separate libraries.
build_aarch64_out_of_line_atomics_libraries(&src_dir, cfg);

Expand Down
2 changes: 1 addition & 1 deletion src/float/add.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -204,7 +204,7 @@ intrinsics! {
}

#[ppc_alias = __addkf3]
#[cfg(not(feature = "no-f16-f128"))]
#[cfg(f128_enabled)]
pub extern "C" fn __addtf3(a: f128, b: f128) -> f128 {
add(a, b)
}
Expand Down
2 changes: 1 addition & 1 deletion src/float/cmp.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -172,7 +172,7 @@ intrinsics! {
}
}

#[cfg(not(feature = "no-f16-f128",))]
#[cfg(f128_enabled)]
intrinsics! {
#[avr_skip]
#[ppc_alias = __lekf2]
Expand Down
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