wasmer/lib/clif-backend/src/libcalls.rs
2019-01-10 23:00:05 -05:00

84 lines
2.1 KiB
Rust

use std::{f32, f64};
// F32
pub extern "C" fn ceilf32(x: f32) -> f32 {
x.ceil()
}
pub extern "C" fn floorf32(x: f32) -> f32 {
x.floor()
}
pub extern "C" fn truncf32(x: f32) -> f32 {
x.trunc()
}
/// `f32.round()` doesn't have the correct behavior. Ideally, we'd use
/// "https://doc.rust-lang.org/std/intrinsics/fn.nearbyintf32.html" for this,
/// but support for stable compilers is necessary, so we must implement
/// this ourselves.
/// This is ported from "https://github.com/rust-lang/rust/issues/55107#issuecomment-431247454"
pub extern "C" fn nearbyintf32(x: f32) -> f32 {
#[inline]
fn copysign(x: f32, y: f32) -> f32 {
let bitmask = y.to_bits() & (1 << 31);
f32::from_bits(x.to_bits() | bitmask)
}
if x.is_nan() {
f32::from_bits(x.to_bits() | (1 << 22))
} else {
let k = f32::EPSILON.recip();
let a = x.abs();
if a < k {
copysign((a + k) - k, x)
} else {
x
}
}
}
// F64
pub extern "C" fn ceilf64(x: f64) -> f64 {
x.ceil()
}
pub extern "C" fn floorf64(x: f64) -> f64 {
x.floor()
}
pub extern "C" fn truncf64(x: f64) -> f64 {
x.trunc()
}
/// `f64.round()` doesn't have the correct behavior. Ideally, we'd use
/// "https://doc.rust-lang.org/std/intrinsics/fn.nearbyintf64.html" for this,
/// but support for stable compilers is necessary, so we must implement
/// this ourselves.
/// This is ported from "https://github.com/rust-lang/rust/issues/55007#issuecomment-431247454"
pub extern "C" fn nearbyintf64(x: f64) -> f64 {
#[inline]
fn copysign(x: f64, y: f64) -> f64 {
let bitmask = y.to_bits() & (1 << 63);
f64::from_bits(x.to_bits() | bitmask)
}
if x.is_nan() {
f64::from_bits(x.to_bits() | (1 << 51))
} else {
let k = f64::EPSILON.recip();
let a = x.abs();
if a < k {
copysign((a + k) - k, x)
} else {
x
}
}
}
/// A declaration for the stack probe function in Rust's standard library, for
/// catching callstack overflow.
extern "C" {
pub fn __rust_probestack();
}