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fn main() {
let mut builder = cc::Build::new();
if !builder.get_compiler().is_like_clang() {
// if the default/configured cc is not clang, try to call clang manually
builder.compiler("clang");
}
builder.warnings_into_errors(true);
builder.flag("-flto=thin");
build_ll(builder.clone());
build_c(builder);
}
fn build_ll(mut builder: cc::Build) {
// the ll files are written bare, let the compiler override module annotations and don't warn
// about it
builder.flag("-Wno-override-module");
builder.file("src/poison/freeze.ll").compile("freeze");
}
fn build_c(mut builder: cc::Build) {
builder.opt_level(3);
// TODO control flags with generics
builder.flag("-fassociative-math");
builder.flag("-freciprocal-math");
builder.flag("-fno-signed-zeros");
builder.flag("-fno-trapping-math");
builder.flag("-ffp-contract=fast");
// -fapprox-func isn't currently available in the clang driver (fixed with
// https://reviews.llvm.org/D106191 but need an updated version), but it is in clang itself.
// This means it can be toggled using the `-Xclang <arg>` option.
//
// The clang version on docs.rs doesn't recognize -fapprox-func even with -Xclang :shrug:
// We could attempt to check flag support using cc's flag_if_supported, but this is a compound
// flag which doesn't seem to mix well with the is_supported api checks. Instead, do the dumb
// thing and don't enable this flag when compiling on docs.rs. That way, normal users should at
// least get a slightly informative error if they have an incompatible clang
match std::env::var("DOCS_RS") {
Err(std::env::VarError::NotPresent) => {
builder.flag("-Xclang").flag("-fapprox-func");
}
Ok(_) => {}
Err(err) => panic!("{}", err),
}
builder.flag("-fno-math-errno");
// poison_unsafe must be compiled without finite-math-only
// see its docs for details
poison_unsafe(builder.clone());
builder.flag("-ffinite-math-only");
poison_safe(builder);
}
fn poison_unsafe(mut builder: cc::Build) {
builder
.file("src/math/poison_unsafe.c")
.compile("poison_unsafe")
}
fn poison_safe(mut builder: cc::Build) {
builder
.file("src/math/poison_safe.c")
.compile("poison_safe")
}