1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
use std::env;
fn defined(var: &str) -> bool {
env::var_os(var).is_some()
}
fn target_arch() -> String {
let target = env::var("TARGET").unwrap();
let target_components: Vec<&str> = target.split("-").collect();
target_components[0].to_string()
}
fn target_os() -> String {
let target = env::var("TARGET").unwrap();
let target_components: Vec<&str> = target.split("-").collect();
target_components[2].to_string()
}
fn is_windows() -> bool {
target_os() == "windows"
}
fn is_x86_64() -> bool {
target_arch() == "x86_64"
}
fn is_armv7() -> bool {
target_arch() == "armv7"
}
fn new_build() -> cc::Build {
let mut build = cc::Build::new();
if !is_windows() {
build.flag("-std=c11");
}
build
}
fn main() -> Result<(), Box<dyn std::error::Error>> {
// "c_avx512' is a no-op for non-x86_64 targets. It also participates in
// dynamic CPU feature detection, so it's generally safe to enable.
// However, it probably won't build in some older environments without
// AVX-512 support in the C compiler, and it's disabled by default for that
// reason.
if defined("CARGO_FEATURE_C_AVX512") && is_x86_64() {
let mut build = new_build();
build.file("c/blake3_avx512.c");
if is_windows() {
// Note that a lot of versions of MSVC don't support /arch:AVX512,
// and they'll discard it with a warning, hopefully leading to a
// build error.
build.flag("/arch:AVX512");
} else {
build.flag("-mavx512f");
build.flag("-mavx512vl");
}
build.compile("blake3_avx512");
}
if defined("CARGO_FEATURE_C_NEON") {
let mut build = new_build();
// Note that blake3_neon.c normally depends on the blake3_portable.c
// for the single-instance compression function, but we expose
// portable.rs over FFI instead. See c_neon.rs.
build.file("c/blake3_neon.c");
// ARMv7 platforms that support NEON generally need the following
// flags. AArch64 supports NEON by default and does not support -mpfu.
if is_armv7() {
build.flag("-mfpu=neon-vfpv4");
build.flag("-mfloat-abi=hard");
}
build.compile("blake3_neon");
}
// The `cc` crate does not automatically emit rerun-if directives for the
// environment variables it supports, in particular for $CC. We expect to
// do a lot of benchmarking across different compilers, so we explicitly
// add the variables that we're likely to need.
println!("cargo:rerun-if-env-changed=CC");
println!("cargo:rerun-if-env-changed=CFLAGS");
// Ditto for source files, though these shouldn't change as often.
for file in std::fs::read_dir("c")? {
println!(
"cargo:rerun-if-changed={}",
file?.path().to_str().expect("utf-8")
);
}
Ok(())
}