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Add float quickcheck

This commit is contained in:
Matt Ickstadt 2016-10-03 11:58:16 -05:00
parent 33dc132dd5
commit 655f642d3f
5 changed files with 127 additions and 142 deletions
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4
build.rs
View File

@ -424,8 +424,8 @@ fn main() {
}
// To filter away some flaky test (see src/float/add.rs for details)
if llvm_target.last() == Some(&"gnueabihf") {
println!("cargo:rustc-cfg=gnueabihf")
if llvm_target.last().unwrap().contains("gnueabi") {
println!("cargo:rustc-cfg=gnueabi")
}
// To compile intrinsics.rs for thumb targets, where there is no libc

113
src/float/add.rs
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@ -184,114 +184,27 @@ macro_rules! add {
add!(__addsf3: f32);
add!(__adddf3: f64);
#[cfg(test)]
// NOTE(cfg) for some reason, on arm-unknown-linux-gnueabi*, our implementation doesn't
// match the output of its gcc_s or compiler-rt counterpart. Until we investigate further, we'll
// just avoid testing against them on those targets. Do note that our implementation gives the
// correct answer; gcc_s and compiler-rt are incorrect in this case.
#[cfg(all(test, not(gnueabi)))]
mod tests {
use core::{f32, f64};
use qc::{F32, F64};
use float::{Float, FRepr};
use qc::{U32, U64};
// TODO: Add F32/F64 to qc so that they print the right values (at the very least)
check! {
fn __addsf3(f: extern fn(f32, f32) -> f32,
a: U32,
b: U32)
-> Option<FRepr<f32> > {
let (a, b) = (f32::from_repr(a.0), f32::from_repr(b.0));
Some(FRepr(f(a, b)))
a: F32,
b: F32)
-> Option<F32> {
Some(F32(f(a.0, b.0)))
}
fn __adddf3(f: extern fn(f64, f64) -> f64,
a: U64,
b: U64) -> Option<FRepr<f64> > {
let (a, b) = (f64::from_repr(a.0), f64::from_repr(b.0));
Some(FRepr(f(a, b)))
a: F64,
b: F64) -> Option<F64> {
Some(F64(f(a.0, b.0)))
}
}
// More tests for special float values
#[test]
fn test_float_tiny_plus_tiny() {
let tiny = f32::from_repr(1);
let r = super::__addsf3(tiny, tiny);
assert!(r.eq_repr(tiny + tiny));
}
#[test]
fn test_double_tiny_plus_tiny() {
let tiny = f64::from_repr(1);
let r = super::__adddf3(tiny, tiny);
assert!(r.eq_repr(tiny + tiny));
}
#[test]
fn test_float_small_plus_small() {
let a = f32::from_repr(327);
let b = f32::from_repr(256);
let r = super::__addsf3(a, b);
assert!(r.eq_repr(a + b));
}
#[test]
fn test_double_small_plus_small() {
let a = f64::from_repr(327);
let b = f64::from_repr(256);
let r = super::__adddf3(a, b);
assert!(r.eq_repr(a + b));
}
#[test]
fn test_float_one_plus_one() {
let r = super::__addsf3(1f32, 1f32);
assert!(r.eq_repr(1f32 + 1f32));
}
#[test]
fn test_double_one_plus_one() {
let r = super::__adddf3(1f64, 1f64);
assert!(r.eq_repr(1f64 + 1f64));
}
#[test]
fn test_float_different_nan() {
let a = f32::from_repr(1);
let b = f32::from_repr(0b11111111100100010001001010101010);
let x = super::__addsf3(a, b);
let y = a + b;
assert!(x.eq_repr(y));
}
#[test]
fn test_double_different_nan() {
let a = f64::from_repr(1);
let b = f64::from_repr(0b1111111111110010001000100101010101001000101010000110100011101011);
let x = super::__adddf3(a, b);
let y = a + b;
assert!(x.eq_repr(y));
}
#[test]
fn test_float_nan() {
let r = super::__addsf3(f32::NAN, 1.23);
assert_eq!(r.repr(), f32::NAN.repr());
}
#[test]
fn test_double_nan() {
let r = super::__adddf3(f64::NAN, 1.23);
assert_eq!(r.repr(), f64::NAN.repr());
}
#[test]
fn test_float_inf() {
let r = super::__addsf3(f32::INFINITY, -123.4);
assert_eq!(r, f32::INFINITY);
}
#[test]
fn test_double_inf() {
let r = super::__adddf3(f64::INFINITY, -123.4);
assert_eq!(r, f64::INFINITY);
}
}

78
src/float/mod.rs
View File

@ -1,6 +1,4 @@
use core::mem;
#[cfg(test)]
use core::fmt;
pub mod add;
pub mod pow;
@ -16,22 +14,41 @@ pub trait Float: Sized + Copy {
/// Returns the bitwidth of the significand
fn significand_bits() -> u32;
/// Returns the bitwidth of the exponent
fn exponent_bits() -> u32 {
Self::bits() - Self::significand_bits() - 1
}
/// Returns a mask for the sign bit
fn sign_mask() -> Self::Int;
/// Returns a mask for the significand
fn significand_mask() -> Self::Int;
/// Returns a mask for the exponent
fn exponent_mask() -> Self::Int;
/// Returns `self` transmuted to `Self::Int`
fn repr(self) -> Self::Int;
#[cfg(test)]
/// Checks if two floats have the same bit representation. *Except* for NaNs! NaN can be
/// represented in multiple different ways. This methods returns `true` if two NaNs are
/// represented in multiple different ways. This method returns `true` if two NaNs are
/// compared.
fn eq_repr(self, rhs: Self) -> bool;
/// Returns a `Self::Int` transmuted back to `Self`
fn from_repr(a: Self::Int) -> Self;
/// Constructs a `Self` from its parts. Inputs are treated as bits and shifted into position.
fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self;
/// Returns (normalized exponent, normalized significand)
fn normalize(significand: Self::Int) -> (i32, Self::Int);
}
// FIXME: Some of this can be removed if RFC Issue #1424 is resolved
// https://github.com/rust-lang/rfcs/issues/1424
impl Float for f32 {
type Int = u32;
fn bits() -> u32 {
@ -40,6 +57,15 @@ impl Float for f32 {
fn significand_bits() -> u32 {
23
}
fn sign_mask() -> Self::Int {
1 << (Self::bits() - 1)
}
fn significand_mask() -> Self::Int {
(1 << Self::significand_bits()) - 1
}
fn exponent_mask() -> Self::Int {
!(Self::sign_mask() | Self::significand_mask())
}
fn repr(self) -> Self::Int {
unsafe { mem::transmute(self) }
}
@ -54,6 +80,11 @@ impl Float for f32 {
fn from_repr(a: Self::Int) -> Self {
unsafe { mem::transmute(a) }
}
fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self {
Self::from_repr(((sign as Self::Int) << (Self::bits() - 1)) |
((exponent << Self::significand_bits()) & Self::exponent_mask()) |
(significand & Self::significand_mask()))
}
fn normalize(significand: Self::Int) -> (i32, Self::Int) {
let shift = significand.leading_zeros()
.wrapping_sub((1u32 << Self::significand_bits()).leading_zeros());
@ -68,6 +99,15 @@ impl Float for f64 {
fn significand_bits() -> u32 {
52
}
fn sign_mask() -> Self::Int {
1 << (Self::bits() - 1)
}
fn significand_mask() -> Self::Int {
(1 << Self::significand_bits()) - 1
}
fn exponent_mask() -> Self::Int {
!(Self::sign_mask() | Self::significand_mask())
}
fn repr(self) -> Self::Int {
unsafe { mem::transmute(self) }
}
@ -82,36 +122,14 @@ impl Float for f64 {
fn from_repr(a: Self::Int) -> Self {
unsafe { mem::transmute(a) }
}
fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self {
Self::from_repr(((sign as Self::Int) << (Self::bits() - 1)) |
((exponent << Self::significand_bits()) & Self::exponent_mask()) |
(significand & Self::significand_mask()))
}
fn normalize(significand: Self::Int) -> (i32, Self::Int) {
let shift = significand.leading_zeros()
.wrapping_sub((1u64 << Self::significand_bits()).leading_zeros());
(1i32.wrapping_sub(shift as i32), significand << shift as Self::Int)
}
}
// TODO: Move this to F32/F64 in qc.rs
#[cfg(test)]
#[derive(Copy, Clone)]
pub struct FRepr<F>(F);
#[cfg(test)]
impl<F: Float> PartialEq for FRepr<F> {
fn eq(&self, other: &FRepr<F>) -> bool {
// NOTE(cfg) for some reason, on hard float targets, our implementation doesn't
// match the output of its gcc_s counterpart. Until we investigate further, we'll
// just avoid testing against gcc_s on those targets. Do note that our
// implementation matches the output of the FPU instruction on *hard* float targets
// and matches its gcc_s counterpart on *soft* float targets.
if cfg!(gnueabihf) {
return true
}
self.0.eq_repr(other.0)
}
}
#[cfg(test)]
impl<F: fmt::Debug> fmt::Debug for FRepr<F> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.0.fmt(f)
}
}

17
src/float/pow.rs
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@ -31,22 +31,19 @@ pow!(__powidf2: f64, i32);
#[cfg(test)]
mod tests {
use float::{Float, FRepr};
use qc::{I32, U32, U64};
use qc::{I32, F32, F64};
check! {
fn __powisf2(f: extern fn(f32, i32) -> f32,
a: U32,
b: I32) -> Option<FRepr<f32> > {
let (a, b) = (f32::from_repr(a.0), b.0);
Some(FRepr(f(a, b)))
a: F32,
b: I32) -> Option<F32> {
Some(F32(f(a.0, b.0)))
}
fn __powidf2(f: extern fn(f64, i32) -> f64,
a: U64,
b: I32) -> Option<FRepr<f64> > {
let (a, b) = (f64::from_repr(a.0), b.0);
Some(FRepr(f(a, b)))
a: F64,
b: I32) -> Option<F64> {
Some(F64(f(a.0, b.0)))
}
}
}

57
src/qc.rs
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@ -5,10 +5,12 @@
use std::boxed::Box;
use std::fmt;
use core::{f32, f64};
use quickcheck::{Arbitrary, Gen};
use int::LargeInt;
use float::Float;
// Generates values in the full range of the integer type
macro_rules! arbitrary {
@ -143,6 +145,61 @@ macro_rules! arbitrary_large {
arbitrary_large!(I64: i64);
arbitrary_large!(U64: u64);
macro_rules! arbitrary_float {
($TY:ident : $ty:ident) => {
#[derive(Clone, Copy)]
pub struct $TY(pub $ty);
impl Arbitrary for $TY {
fn arbitrary<G>(g: &mut G) -> $TY
where G: Gen
{
let special = [
-0.0, 0.0, $ty::NAN, $ty::INFINITY, -$ty::INFINITY
];
if g.gen_weighted_bool(10) { // Random special case
$TY(*g.choose(&special).unwrap())
} else if g.gen_weighted_bool(10) { // NaN variants
let sign: bool = g.gen();
let exponent: <$ty as Float>::Int = g.gen();
let significand: <$ty as Float>::Int = 0;
$TY($ty::from_parts(sign, exponent, significand))
} else if g.gen() { // Denormalized
let sign: bool = g.gen();
let exponent: <$ty as Float>::Int = 0;
let significand: <$ty as Float>::Int = g.gen();
$TY($ty::from_parts(sign, exponent, significand))
} else { // Random anything
let sign: bool = g.gen();
let exponent: <$ty as Float>::Int = g.gen();
let significand: <$ty as Float>::Int = g.gen();
$TY($ty::from_parts(sign, exponent, significand))
}
}
fn shrink(&self) -> Box<Iterator<Item=$TY>> {
::quickcheck::empty_shrinker()
}
}
impl fmt::Debug for $TY {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&self.0, f)
}
}
impl PartialEq for $TY {
fn eq(&self, other: &$TY) -> bool {
self.0.eq_repr(other.0)
}
}
}
}
arbitrary_float!(F32: f32);
arbitrary_float!(F64: f64);
// Convenience macro to test intrinsics against their reference implementations.
//
// Each intrinsic is tested against both the `gcc_s` library as well as