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Rollup merge of #143355 - hkBst:cleanup-shift-double-bitmask, r=Mark-Simulacrum

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wrapping shift: remove first bitmask and table

```rust
        #[inline(always)]
        pub const fn wrapping_shl(self, rhs: u32) -> Self {
            // SAFETY: the masking by the bitsize of the type ensures that we do not shift
            // out of bounds
            unsafe {
                self.unchecked_shl(rhs & (Self::BITS - 1))
            }
        }
```
already does the bitmask, so it seems unnecessary here.

More context: internals.rust-lang.org/t/wrapping-shift-operator-code-doing-bitmasking-twice/23167
This commit is contained in:
Samuel Tardieu 2025-07-16 17:06:38 +02:00 • committed by GitHub
commit 37aba8388e
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1 changed files with 6 additions and 42 deletions
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48
library/core/src/num/wrapping.rs
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@ -94,9 +94,9 @@ macro_rules! sh_impl_signed {
#[inline]
fn shl(self, other: $f) -> Wrapping<$t> {
if other < 0 {
Wrapping(self.0.wrapping_shr((-other & self::shift_max::$t as $f) as u32))
Wrapping(self.0.wrapping_shr(-other as u32))
} else {
Wrapping(self.0.wrapping_shl((other & self::shift_max::$t as $f) as u32))
Wrapping(self.0.wrapping_shl(other as u32))
}
}
}
@ -119,9 +119,9 @@ macro_rules! sh_impl_signed {
#[inline]
fn shr(self, other: $f) -> Wrapping<$t> {
if other < 0 {
Wrapping(self.0.wrapping_shl((-other & self::shift_max::$t as $f) as u32))
Wrapping(self.0.wrapping_shl(-other as u32))
} else {
Wrapping(self.0.wrapping_shr((other & self::shift_max::$t as $f) as u32))
Wrapping(self.0.wrapping_shr(other as u32))
}
}
}
@ -147,7 +147,7 @@ macro_rules! sh_impl_unsigned {
#[inline]
fn shl(self, other: $f) -> Wrapping<$t> {
Wrapping(self.0.wrapping_shl((other & self::shift_max::$t as $f) as u32))
Wrapping(self.0.wrapping_shl(other as u32))
}
}
forward_ref_binop! { impl Shl, shl for Wrapping<$t>, $f,
@ -168,7 +168,7 @@ macro_rules! sh_impl_unsigned {
#[inline]
fn shr(self, other: $f) -> Wrapping<$t> {
Wrapping(self.0.wrapping_shr((other & self::shift_max::$t as $f) as u32))
Wrapping(self.0.wrapping_shr(other as u32))
}
}
forward_ref_binop! { impl Shr, shr for Wrapping<$t>, $f,
@ -1052,39 +1052,3 @@ macro_rules! wrapping_int_impl_unsigned {
}
wrapping_int_impl_unsigned! { usize u8 u16 u32 u64 u128 }
mod shift_max {
#![allow(non_upper_case_globals)]
#[cfg(target_pointer_width = "16")]
mod platform {
pub(crate) const usize: u32 = super::u16;
pub(crate) const isize: u32 = super::i16;
}
#[cfg(target_pointer_width = "32")]
mod platform {
pub(crate) const usize: u32 = super::u32;
pub(crate) const isize: u32 = super::i32;
}
#[cfg(target_pointer_width = "64")]
mod platform {
pub(crate) const usize: u32 = super::u64;
pub(crate) const isize: u32 = super::i64;
}
pub(super) const i8: u32 = (1 << 3) - 1;
pub(super) const i16: u32 = (1 << 4) - 1;
pub(super) const i32: u32 = (1 << 5) - 1;
pub(super) const i64: u32 = (1 << 6) - 1;
pub(super) const i128: u32 = (1 << 7) - 1;
pub(super) use self::platform::isize;
pub(super) const u8: u32 = i8;
pub(super) const u16: u32 = i16;
pub(super) const u32: u32 = i32;
pub(super) const u64: u32 = i64;
pub(super) const u128: u32 = i128;
pub(super) use self::platform::usize;
}