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Stabilize float::to_int_unchecked

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This renames and stabilizes unsafe floating point to integer casts, which are
intended to be the substitute for the currently unsound `as` behavior, once that
changes to safe-but-slower saturating casts.
This commit is contained in:
Mark Rousskov 2020-03-27 19:18:52 -04:00
parent 8ab82b87af
commit 56147219a5
6 changed files with 33 additions and 22 deletions
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13
src/libcore/convert/num.rs
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@ -13,9 +13,9 @@ mod private {
/// Typically doesn’t need to be used directly.
#[unstable(feature = "convert_float_to_int", issue = "67057")]
pub trait FloatToInt<Int>: private::Sealed + Sized {
#[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
#[unstable(feature = "convert_float_to_int", issue = "67057")]
#[doc(hidden)]
unsafe fn approx_unchecked(self) -> Int;
unsafe fn to_int_unchecked(self) -> Int;
}
macro_rules! impl_float_to_int {
@ -27,9 +27,16 @@ macro_rules! impl_float_to_int {
impl FloatToInt<$Int> for $Float {
#[doc(hidden)]
#[inline]
unsafe fn approx_unchecked(self) -> $Int {
unsafe fn to_int_unchecked(self) -> $Int {
#[cfg(bootstrap)]
{
crate::intrinsics::float_to_int_approx_unchecked(self)
}
#[cfg(not(bootstrap))]
{
crate::intrinsics::float_to_int_unchecked(self)
}
}
}
)+
}

8
src/libcore/intrinsics.rs
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@ -1582,8 +1582,16 @@ extern "rust-intrinsic" {
/// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range
/// (<https://github.com/rust-lang/rust/issues/10184>)
/// This is under stabilization at <https://github.com/rust-lang/rust/issues/67058>
#[cfg(bootstrap)]
pub fn float_to_int_approx_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int;
/// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range
/// (<https://github.com/rust-lang/rust/issues/10184>)
///
/// Stabilized as `f32::to_int_unchecked` and `f64::to_int_unchecked`.
#[cfg(not(bootstrap))]
pub fn float_to_int_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int;
/// Returns the number of bits set in an integer type `T`
///
/// The stabilized versions of this intrinsic are available on the integer

12
src/libcore/num/f32.rs
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@ -464,14 +464,12 @@ impl f32 {
/// assuming that the value is finite and fits in that type.
///
/// ```
/// #![feature(float_approx_unchecked_to)]
///
/// let value = 4.6_f32;
/// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
/// let rounded = unsafe { value.to_int_unchecked::<u16>() };
/// assert_eq!(rounded, 4);
///
/// let value = -128.9_f32;
/// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
/// let rounded = unsafe { value.to_int_unchecked::<i8>() };
/// assert_eq!(rounded, std::i8::MIN);
/// ```
///
@ -482,13 +480,13 @@ impl f32 {
/// * Not be `NaN`
/// * Not be infinite
/// * Be representable in the return type `Int`, after truncating off its fractional part
#[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
#[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
#[inline]
pub unsafe fn approx_unchecked_to<Int>(self) -> Int
pub unsafe fn to_int_unchecked<Int>(self) -> Int
where
Self: FloatToInt<Int>,
{
FloatToInt::<Int>::approx_unchecked(self)
FloatToInt::<Int>::to_int_unchecked(self)
}
/// Raw transmutation to `u32`.

12
src/libcore/num/f64.rs
View File

@ -478,14 +478,12 @@ impl f64 {
/// assuming that the value is finite and fits in that type.
///
/// ```
/// #![feature(float_approx_unchecked_to)]
///
/// let value = 4.6_f32;
/// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
/// let rounded = unsafe { value.to_int_unchecked::<u16>() };
/// assert_eq!(rounded, 4);
///
/// let value = -128.9_f32;
/// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
/// let rounded = unsafe { value.to_int_unchecked::<i8>() };
/// assert_eq!(rounded, std::i8::MIN);
/// ```
///
@ -496,13 +494,13 @@ impl f64 {
/// * Not be `NaN`
/// * Not be infinite
/// * Be representable in the return type `Int`, after truncating off its fractional part
#[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
#[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
#[inline]
pub unsafe fn approx_unchecked_to<Int>(self) -> Int
pub unsafe fn to_int_unchecked<Int>(self) -> Int
where
Self: FloatToInt<Int>,
{
FloatToInt::<Int>::approx_unchecked(self)
FloatToInt::<Int>::to_int_unchecked(self)
}
/// Raw transmutation to `u64`.

6
src/librustc_codegen_llvm/intrinsic.rs
View File

@ -544,13 +544,13 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
}
}
"float_to_int_approx_unchecked" => {
"float_to_int_unchecked" => {
if float_type_width(arg_tys[0]).is_none() {
span_invalid_monomorphization_error(
tcx.sess,
span,
&format!(
"invalid monomorphization of `float_to_int_approx_unchecked` \
"invalid monomorphization of `float_to_int_unchecked` \
intrinsic: expected basic float type, \
found `{}`",
arg_tys[0]
@ -571,7 +571,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
tcx.sess,
span,
&format!(
"invalid monomorphization of `float_to_int_approx_unchecked` \
"invalid monomorphization of `float_to_int_unchecked` \
intrinsic: expected basic integer type, \
found `{}`",
ret_ty

2
src/librustc_typeck/check/intrinsic.rs
View File

@ -275,7 +275,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
"fadd_fast" | "fsub_fast" | "fmul_fast" | "fdiv_fast" | "frem_fast" => {
(1, vec![param(0), param(0)], param(0))
}
"float_to_int_approx_unchecked" => (2, vec![param(0)], param(1)),
"float_to_int_unchecked" => (2, vec![param(0)], param(1)),
"assume" => (0, vec![tcx.types.bool], tcx.mk_unit()),
"likely" => (0, vec![tcx.types.bool], tcx.types.bool),