A modified version of compiler-builtins for zynq, with fast memcpy implementation adapted from newlib.
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use std::env;
fn main() {
let target = env::var("TARGET").unwrap();
let cwd = env::current_dir().unwrap();
println!("cargo:compiler-rt={}", cwd.join("compiler-rt").display());
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// Activate libm's unstable features to make full use of Nightly.
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2 years ago
// Emscripten's runtime includes all the builtins
if target.contains("emscripten") {
// OpenBSD provides compiler_rt by default, use it instead of rebuilding it from source
if target.contains("openbsd") {
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// Forcibly enable memory intrinsics on wasm32 & SGX as we don't have a libc to
// provide them.
if (target.contains("wasm32") && !target.contains("wasi"))
|| (target.contains("sgx") && target.contains("fortanix"))
// 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<_>>();
// 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
// build anything and we rely on the upstream implementation of compiler-rt
// functions
if !cfg!(feature = "mangled-names") && cfg!(feature = "c") {
// Don't use a C compiler for these targets:
// * wasm32 - clang 8 for wasm is somewhat hard to come by and it's
// unlikely that the C is really that much better than our own Rust.
// * nvptx - everything is bitcode, not compatible with mixed C/Rust
// * riscv - the rust-lang/rust distribution container doesn't have a C
// compiler nor is cc-rs ready for compilation to riscv (at this
// time). This can probably be removed in the future
if !target.contains("wasm32") && !target.contains("nvptx") && !target.starts_with("riscv") {
#[cfg(feature = "c")]
c::compile(&llvm_target, &target);
// To compile intrinsics.rs for thumb targets, where there is no libc
if llvm_target[0].starts_with("thumb") {
// compiler-rt `cfg`s away some intrinsics for thumbv6m and thumbv8m.base because
// these targets do not have full Thumb-2 support but only original Thumb-1.
// We have to cfg our code accordingly.
if llvm_target[0] == "thumbv6m" || llvm_target[0] == "thumbv8m.base" {
// Only emit the ARM Linux atomic emulation on pre-ARMv6 architectures.
if llvm_target[0] == "armv4t" || llvm_target[0] == "armv5te" {
#[cfg(feature = "c")]
mod c {
extern crate cc;
use std::collections::BTreeMap;
use std::env;
use std::path::PathBuf;
struct Sources {
map: BTreeMap<&'static str, &'static str>,
impl Sources {
fn new() -> Sources {
Sources {
map: BTreeMap::new(),
fn extend(&mut self, sources: &[(&'static str, &'static str)]) {
// NOTE Some intrinsics have both a generic implementation (e.g.
// `floatdidf.c`) and an arch optimized implementation
// (`x86_64/floatdidf.c`). In those cases, we keep the arch optimized
// implementation and discard the generic implementation. If we don't
// and keep both implementations, the linker will yell at us about
// duplicate symbols!
for (symbol, src) in sources {
if src.contains("/") {
// Arch-optimized implementation (preferred)
self.map.insert(symbol, src);
} else {
// Generic implementation
if !self.map.contains_key(symbol) {
self.map.insert(symbol, src);
fn remove(&mut self, symbols: &[&str]) {
for symbol in symbols {
/// 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();
let mut consider_float_intrinsics = true;
let cfg = &mut cc::Build::new();
// AArch64 GCCs exit with an error condition when they encounter any kind of floating point
// code if the `nofp` and/or `nosimd` compiler flags have been set.
// 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 let Ok(cflags_value) = env::var(cflags_key) {
if cflags_value.contains("+nofp") || cflags_value.contains("+nosimd") {
consider_float_intrinsics = false;
if target_env == "msvc" {
// Don't pull in extra libraries on MSVC
// Emulate C99 and C++11's __func__ for MSVC prior to 2013 CTP
cfg.define("__func__", Some("__FUNCTION__"));
} else {
// Turn off various features of gcc and such, mostly copying
// compiler-rt's build system already
// Avoid the following warning appearing once **per file**:
// clang: warning: optimization flag '-fomit-frame-pointer' is not supported for target 'armv7' [-Wignored-optimization-argument]
// Note that compiler-rt's build system also checks
// `check_cxx_compiler_flag(-fomit-frame-pointer COMPILER_RT_HAS_FOMIT_FRAME_POINTER_FLAG)`
// in https://github.com/rust-lang/compiler-rt/blob/c8fbcb3/cmake/config-ix.cmake#L19.
cfg.define("VISIBILITY_HIDDEN", None);
let mut sources = Sources::new();
("__absvdi2", "absvdi2.c"),
("__absvsi2", "absvsi2.c"),
("__addvdi3", "addvdi3.c"),
("__addvsi3", "addvsi3.c"),
("apple_versioning", "apple_versioning.c"),
("__clzdi2", "clzdi2.c"),
("__clzsi2", "clzsi2.c"),
("__cmpdi2", "cmpdi2.c"),
("__ctzdi2", "ctzdi2.c"),
("__ctzsi2", "ctzsi2.c"),
("__int_util", "int_util.c"),
("__mulvdi3", "mulvdi3.c"),
("__mulvsi3", "mulvsi3.c"),
("__negdi2", "negdi2.c"),
("__negvdi2", "negvdi2.c"),
("__negvsi2", "negvsi2.c"),
("__paritydi2", "paritydi2.c"),
("__paritysi2", "paritysi2.c"),
("__popcountdi2", "popcountdi2.c"),
("__popcountsi2", "popcountsi2.c"),
("__subvdi3", "subvdi3.c"),
("__subvsi3", "subvsi3.c"),
("__ucmpdi2", "ucmpdi2.c"),
if consider_float_intrinsics {
("__divdc3", "divdc3.c"),
("__divsc3", "divsc3.c"),
("__divxc3", "divxc3.c"),
("__extendhfsf2", "extendhfsf2.c"),
("__muldc3", "muldc3.c"),
("__mulsc3", "mulsc3.c"),
("__mulxc3", "mulxc3.c"),
("__negdf2", "negdf2.c"),
("__negsf2", "negsf2.c"),
("__powixf2", "powixf2.c"),
("__truncdfhf2", "truncdfhf2.c"),
("__truncdfsf2", "truncdfsf2.c"),
("__truncsfhf2", "truncsfhf2.c"),
// When compiling in rustbuild (the rust-lang/rust repo) this library
// also needs to satisfy intrinsics that jemalloc or C in general may
// need, so include a few more that aren't typically needed by
// LLVM/Rust.
if cfg!(feature = "rustbuild") {
sources.extend(&[("__ffsdi2", "ffsdi2.c")]);
// On iOS and 32-bit OSX these are all just empty intrinsics, no need to
// include them.
if target_os != "ios" && (target_vendor != "apple" || target_arch != "x86") {
("__absvti2", "absvti2.c"),
("__addvti3", "addvti3.c"),
("__clzti2", "clzti2.c"),
("__cmpti2", "cmpti2.c"),
("__ctzti2", "ctzti2.c"),
("__ffsti2", "ffsti2.c"),
("__mulvti3", "mulvti3.c"),
("__negti2", "negti2.c"),
("__parityti2", "parityti2.c"),
("__popcountti2", "popcountti2.c"),
("__subvti3", "subvti3.c"),
("__ucmpti2", "ucmpti2.c"),
if consider_float_intrinsics {
sources.extend(&[("__negvti2", "negvti2.c")]);
if target_vendor == "apple" {
("atomic_flag_clear", "atomic_flag_clear.c"),
("atomic_flag_clear_explicit", "atomic_flag_clear_explicit.c"),
("atomic_flag_test_and_set", "atomic_flag_test_and_set.c"),
("atomic_signal_fence", "atomic_signal_fence.c"),
("atomic_thread_fence", "atomic_thread_fence.c"),
if target_env == "msvc" {
if target_arch == "x86_64" {
("__floatdisf", "x86_64/floatdisf.c"),
("__floatdixf", "x86_64/floatdixf.c"),
} else {
// None of these seem to be used on x86_64 windows, and they've all
// got the wrong ABI anyway, so we want to avoid them.
if target_os != "windows" {
if target_arch == "x86_64" {
("__floatdisf", "x86_64/floatdisf.c"),
("__floatdixf", "x86_64/floatdixf.c"),
("__floatundidf", "x86_64/floatundidf.S"),
("__floatundisf", "x86_64/floatundisf.S"),
("__floatundixf", "x86_64/floatundixf.S"),
if target_arch == "x86" {
("__ashldi3", "i386/ashldi3.S"),
("__ashrdi3", "i386/ashrdi3.S"),
("__divdi3", "i386/divdi3.S"),
("__floatdidf", "i386/floatdidf.S"),
("__floatdisf", "i386/floatdisf.S"),
("__floatdixf", "i386/floatdixf.S"),
("__floatundidf", "i386/floatundidf.S"),
("__floatundisf", "i386/floatundisf.S"),
("__floatundixf", "i386/floatundixf.S"),
("__lshrdi3", "i386/lshrdi3.S"),
("__moddi3", "i386/moddi3.S"),
("__muldi3", "i386/muldi3.S"),
("__udivdi3", "i386/udivdi3.S"),
("__umoddi3", "i386/umoddi3.S"),
if target_arch == "arm" && target_os != "ios" && target_env != "msvc" {
("__aeabi_div0", "arm/aeabi_div0.c"),
("__aeabi_drsub", "arm/aeabi_drsub.c"),
("__aeabi_frsub", "arm/aeabi_frsub.c"),
("__bswapdi2", "arm/bswapdi2.S"),
("__bswapsi2", "arm/bswapsi2.S"),
("__clzdi2", "arm/clzdi2.S"),
("__clzsi2", "arm/clzsi2.S"),
("__divmodsi4", "arm/divmodsi4.S"),
("__divsi3", "arm/divsi3.S"),
("__modsi3", "arm/modsi3.S"),
("__switch16", "arm/switch16.S"),
("__switch32", "arm/switch32.S"),
("__switch8", "arm/switch8.S"),
("__switchu8", "arm/switchu8.S"),
("__sync_synchronize", "arm/sync_synchronize.S"),
("__udivmodsi4", "arm/udivmodsi4.S"),
("__udivsi3", "arm/udivsi3.S"),
("__umodsi3", "arm/umodsi3.S"),
if target_os == "freebsd" {
sources.extend(&[("__clear_cache", "clear_cache.c")]);
// First of all aeabi_cdcmp and aeabi_cfcmp are never called by LLVM.
// Second are little-endian only, so build fail on big-endian targets.
// Temporally workaround: exclude these files for big-endian targets.
if !llvm_target[0].starts_with("thumbeb") && !llvm_target[0].starts_with("armeb") {
("__aeabi_cdcmp", "arm/aeabi_cdcmp.S"),
("__aeabi_cdcmpeq_check_nan", "arm/aeabi_cdcmpeq_check_nan.c"),
("__aeabi_cfcmp", "arm/aeabi_cfcmp.S"),
("__aeabi_cfcmpeq_check_nan", "arm/aeabi_cfcmpeq_check_nan.c"),
if llvm_target[0] == "armv7" {
("__sync_fetch_and_add_4", "arm/sync_fetch_and_add_4.S"),
("__sync_fetch_and_add_8", "arm/sync_fetch_and_add_8.S"),
("__sync_fetch_and_and_4", "arm/sync_fetch_and_and_4.S"),
("__sync_fetch_and_and_8", "arm/sync_fetch_and_and_8.S"),
("__sync_fetch_and_max_4", "arm/sync_fetch_and_max_4.S"),
("__sync_fetch_and_max_8", "arm/sync_fetch_and_max_8.S"),
("__sync_fetch_and_min_4", "arm/sync_fetch_and_min_4.S"),
("__sync_fetch_and_min_8", "arm/sync_fetch_and_min_8.S"),
("__sync_fetch_and_nand_4", "arm/sync_fetch_and_nand_4.S"),
("__sync_fetch_and_nand_8", "arm/sync_fetch_and_nand_8.S"),
("__sync_fetch_and_or_4", "arm/sync_fetch_and_or_4.S"),
("__sync_fetch_and_or_8", "arm/sync_fetch_and_or_8.S"),
("__sync_fetch_and_sub_4", "arm/sync_fetch_and_sub_4.S"),
("__sync_fetch_and_sub_8", "arm/sync_fetch_and_sub_8.S"),
("__sync_fetch_and_umax_4", "arm/sync_fetch_and_umax_4.S"),
("__sync_fetch_and_umax_8", "arm/sync_fetch_and_umax_8.S"),
("__sync_fetch_and_umin_4", "arm/sync_fetch_and_umin_4.S"),
("__sync_fetch_and_umin_8", "arm/sync_fetch_and_umin_8.S"),
("__sync_fetch_and_xor_4", "arm/sync_fetch_and_xor_4.S"),
("__sync_fetch_and_xor_8", "arm/sync_fetch_and_xor_8.S"),
if llvm_target.last().unwrap().ends_with("eabihf") {
if !llvm_target[0].starts_with("thumbv7em")
&& !llvm_target[0].starts_with("thumbv8m.main")
// The FPU option chosen for these architectures in cc-rs, ie:
// -mfpu=fpv4-sp-d16 for thumbv7em
// -mfpu=fpv5-sp-d16 for thumbv8m.main
// do not support double precision floating points conversions so the files
// that include such instructions are not included for these targets.
("__fixdfsivfp", "arm/fixdfsivfp.S"),
("__fixunsdfsivfp", "arm/fixunsdfsivfp.S"),
("__floatsidfvfp", "arm/floatsidfvfp.S"),
("__floatunssidfvfp", "arm/floatunssidfvfp.S"),
("__fixsfsivfp", "arm/fixsfsivfp.S"),
("__fixunssfsivfp", "arm/fixunssfsivfp.S"),
("__floatsisfvfp", "arm/floatsisfvfp.S"),
("__floatunssisfvfp", "arm/floatunssisfvfp.S"),
("__floatunssisfvfp", "arm/floatunssisfvfp.S"),
("__restore_vfp_d8_d15_regs", "arm/restore_vfp_d8_d15_regs.S"),
("__save_vfp_d8_d15_regs", "arm/save_vfp_d8_d15_regs.S"),
("__negdf2vfp", "arm/negdf2vfp.S"),
("__negsf2vfp", "arm/negsf2vfp.S"),
if target_arch == "aarch64" && consider_float_intrinsics {
("__comparetf2", "comparetf2.c"),
("__extenddftf2", "extenddftf2.c"),
("__extendsftf2", "extendsftf2.c"),
("__fixtfdi", "fixtfdi.c"),
("__fixtfsi", "fixtfsi.c"),
("__fixtfti", "fixtfti.c"),
("__fixunstfdi", "fixunstfdi.c"),
("__fixunstfsi", "fixunstfsi.c"),
("__fixunstfti", "fixunstfti.c"),
("__floatditf", "floatditf.c"),
("__floatsitf", "floatsitf.c"),
("__floatunditf", "floatunditf.c"),
("__floatunsitf", "floatunsitf.c"),
("__trunctfdf2", "trunctfdf2.c"),
("__trunctfsf2", "trunctfsf2.c"),
if target_os != "windows" {
sources.extend(&[("__multc3", "multc3.c")]);
// Remove the assembly implementations that won't compile for the target
if llvm_target[0] == "thumbv6m" || llvm_target[0] == "thumbv8m.base" {
let mut to_remove = Vec::new();
for (k, v) in sources.map.iter() {
if v.ends_with(".S") {
// But use some generic implementations where possible
sources.extend(&[("__clzdi2", "clzdi2.c"), ("__clzsi2", "clzsi2.c")])
if llvm_target[0] == "thumbv7m" || llvm_target[0] == "thumbv7em" {
sources.remove(&["__aeabi_cdcmp", "__aeabi_cfcmp"]);
// When compiling the C code we require the user to tell us where the
// source code is, and this is largely done so when we're compiling as
// part of rust-lang/rust we can use the same llvm-project repository as
// rust-lang/rust.
let root = match env::var_os("RUST_COMPILER_RT_ROOT") {
Some(s) => PathBuf::from(s),
None => panic!("RUST_COMPILER_RT_ROOT is not set"),
if !root.exists() {
panic!("RUST_COMPILER_RT_ROOT={} does not exist", root.display());
// Support deterministic builds by remapping the __FILE__ prefix if the
// compiler supports it. This fixes the nondeterminism caused by the
// use of that macro in lib/builtins/int_util.h in compiler-rt.
cfg.flag_if_supported(&format!("-ffile-prefix-map={}=.", root.display()));
let src_dir = root.join("lib/builtins");
for (sym, src) in sources.map.iter() {
let src = src_dir.join(src);
println!("cargo:rerun-if-changed={}", src.display());
println!("cargo:rustc-cfg={}=\"optimized-c\"", sym);