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Replace offset with add in fmt/num.rs & remove some casts

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This commit is contained in:
Maybe Waffle 2022-08-21 02:18:16 +04:00
parent 495fa48790
commit 31b71816cd
1 changed files with 62 additions and 62 deletions
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124
library/core/src/fmt/num.rs
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@ -211,7 +211,7 @@ macro_rules! impl_Display {
fn $name(mut n: $u, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// 2^128 is about 3*10^38, so 39 gives an extra byte of space
let mut buf = [MaybeUninit::<u8>::uninit(); 39];
let mut curr = buf.len() as isize;
let mut curr = buf.len();
let buf_ptr = MaybeUninit::slice_as_mut_ptr(&mut buf);
let lut_ptr = DEC_DIGITS_LUT.as_ptr();
@ -228,7 +228,7 @@ macro_rules! impl_Display {
// eagerly decode 4 characters at a time
while n >= 10000 {
let rem = (n % 10000) as isize;
let rem = (n % 10000) as usize;
n /= 10000;
let d1 = (rem / 100) << 1;
@ -238,29 +238,29 @@ macro_rules! impl_Display {
// We are allowed to copy to `buf_ptr[curr..curr + 3]` here since
// otherwise `curr < 0`. But then `n` was originally at least `10000^10`
// which is `10^40 > 2^128 > n`.
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(curr), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d2), buf_ptr.add(curr + 2), 2);
}
// if we reach here numbers are <= 9999, so at most 4 chars long
let mut n = n as isize; // possibly reduce 64bit math
let mut n = n as usize; // possibly reduce 64bit math
// decode 2 more chars, if > 2 chars
if n >= 100 {
let d1 = (n % 100) << 1;
n /= 100;
curr -= 2;
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(curr), 2);
}
// decode last 1 or 2 chars
if n < 10 {
curr -= 1;
*buf_ptr.offset(curr) = (n as u8) + b'0';
*buf_ptr.add(curr) = (n as u8) + b'0';
} else {
let d1 = n << 1;
curr -= 2;
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(curr), 2);
}
}
@ -268,7 +268,7 @@ macro_rules! impl_Display {
// UTF-8 since `DEC_DIGITS_LUT` is
let buf_slice = unsafe {
str::from_utf8_unchecked(
slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize))
slice::from_raw_parts(buf_ptr.add(curr), buf.len() - curr))
};
f.pad_integral(is_nonnegative, "", buf_slice)
}
@ -339,18 +339,18 @@ macro_rules! impl_Exp {
// Since `curr` always decreases by the number of digits copied, this means
// that `curr >= 0`.
let mut buf = [MaybeUninit::<u8>::uninit(); 40];
let mut curr = buf.len() as isize; //index for buf
let mut curr = buf.len(); //index for buf
let buf_ptr = MaybeUninit::slice_as_mut_ptr(&mut buf);
let lut_ptr = DEC_DIGITS_LUT.as_ptr();
// decode 2 chars at a time
while n >= 100 {
let d1 = ((n % 100) as isize) << 1;
let d1 = ((n % 100) << 1) as usize;
curr -= 2;
// SAFETY: `d1 <= 198`, so we can copy from `lut_ptr[d1..d1 + 2]` since
// `DEC_DIGITS_LUT` has a length of 200.
unsafe {
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(curr), 2);
}
n /= 100;
exponent += 2;
@ -362,7 +362,7 @@ macro_rules! impl_Exp {
curr -= 1;
// SAFETY: Safe since `40 > curr >= 0` (see comment)
unsafe {
*buf_ptr.offset(curr) = (n as u8 % 10_u8) + b'0';
*buf_ptr.add(curr) = (n as u8 % 10_u8) + b'0';
}
n /= 10;
exponent += 1;
@ -372,7 +372,7 @@ macro_rules! impl_Exp {
curr -= 1;
// SAFETY: Safe since `40 > curr >= 0`
unsafe {
*buf_ptr.offset(curr) = b'.';
*buf_ptr.add(curr) = b'.';
}
}
@ -380,10 +380,10 @@ macro_rules! impl_Exp {
let buf_slice = unsafe {
// decode last character
curr -= 1;
*buf_ptr.offset(curr) = (n as u8) + b'0';
*buf_ptr.add(curr) = (n as u8) + b'0';
let len = buf.len() - curr as usize;
slice::from_raw_parts(buf_ptr.offset(curr), len)
slice::from_raw_parts(buf_ptr.add(curr), len)
};
// stores 'e' (or 'E') and the up to 2-digit exponent
@ -392,13 +392,13 @@ macro_rules! impl_Exp {
// SAFETY: In either case, `exp_buf` is written within bounds and `exp_ptr[..len]`
// is contained within `exp_buf` since `len <= 3`.
let exp_slice = unsafe {
*exp_ptr.offset(0) = if upper { b'E' } else { b'e' };
*exp_ptr.add(0) = if upper { b'E' } else { b'e' };
let len = if exponent < 10 {
*exp_ptr.offset(1) = (exponent as u8) + b'0';
*exp_ptr.add(1) = (exponent as u8) + b'0';
2
} else {
let off = exponent << 1;
ptr::copy_nonoverlapping(lut_ptr.offset(off), exp_ptr.offset(1), 2);
ptr::copy_nonoverlapping(lut_ptr.add(off), exp_ptr.add(1), 2);
3
};
slice::from_raw_parts(exp_ptr, len)
@ -479,7 +479,7 @@ mod imp {
impl_Exp!(i128, u128 as u128 via to_u128 named exp_u128);
/// Helper function for writing a u64 into `buf` going from last to first, with `curr`.
fn parse_u64_into<const N: usize>(mut n: u64, buf: &mut [MaybeUninit<u8>; N], curr: &mut isize) {
fn parse_u64_into<const N: usize>(mut n: u64, buf: &mut [MaybeUninit<u8>; N], curr: &mut usize) {
let buf_ptr = MaybeUninit::slice_as_mut_ptr(buf);
let lut_ptr = DEC_DIGITS_LUT.as_ptr();
assert!(*curr > 19);
@ -494,41 +494,41 @@ fn parse_u64_into<const N: usize>(mut n: u64, buf: &mut [MaybeUninit<u8>; N], cu
n /= 1e16 as u64;
// Some of these are nops but it looks more elegant this way.
let d1 = ((to_parse / 1e14 as u64) % 100) << 1;
let d2 = ((to_parse / 1e12 as u64) % 100) << 1;
let d3 = ((to_parse / 1e10 as u64) % 100) << 1;
let d4 = ((to_parse / 1e8 as u64) % 100) << 1;
let d5 = ((to_parse / 1e6 as u64) % 100) << 1;
let d6 = ((to_parse / 1e4 as u64) % 100) << 1;
let d7 = ((to_parse / 1e2 as u64) % 100) << 1;
let d8 = ((to_parse / 1e0 as u64) % 100) << 1;
let d1 = (((to_parse / 1e14 as u64) % 100) << 1) as usize;
let d2 = (((to_parse / 1e12 as u64) % 100) << 1) as usize;
let d3 = (((to_parse / 1e10 as u64) % 100) << 1) as usize;
let d4 = (((to_parse / 1e8 as u64) % 100) << 1) as usize;
let d5 = (((to_parse / 1e6 as u64) % 100) << 1) as usize;
let d6 = (((to_parse / 1e4 as u64) % 100) << 1) as usize;
let d7 = (((to_parse / 1e2 as u64) % 100) << 1) as usize;
let d8 = (((to_parse / 1e0 as u64) % 100) << 1) as usize;
*curr -= 16;
ptr::copy_nonoverlapping(lut_ptr.offset(d1 as isize), buf_ptr.offset(*curr + 0), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d2 as isize), buf_ptr.offset(*curr + 2), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d3 as isize), buf_ptr.offset(*curr + 4), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d4 as isize), buf_ptr.offset(*curr + 6), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d5 as isize), buf_ptr.offset(*curr + 8), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d6 as isize), buf_ptr.offset(*curr + 10), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d7 as isize), buf_ptr.offset(*curr + 12), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d8 as isize), buf_ptr.offset(*curr + 14), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(*curr + 0), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d2), buf_ptr.add(*curr + 2), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d3), buf_ptr.add(*curr + 4), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d4), buf_ptr.add(*curr + 6), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d5), buf_ptr.add(*curr + 8), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d6), buf_ptr.add(*curr + 10), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d7), buf_ptr.add(*curr + 12), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d8), buf_ptr.add(*curr + 14), 2);
}
if n >= 1e8 as u64 {
let to_parse = n % 1e8 as u64;
n /= 1e8 as u64;
// Some of these are nops but it looks more elegant this way.
let d1 = ((to_parse / 1e6 as u64) % 100) << 1;
let d2 = ((to_parse / 1e4 as u64) % 100) << 1;
let d3 = ((to_parse / 1e2 as u64) % 100) << 1;
let d4 = ((to_parse / 1e0 as u64) % 100) << 1;
let d1 = (((to_parse / 1e6 as u64) % 100) << 1) as usize;
let d2 = (((to_parse / 1e4 as u64) % 100) << 1) as usize;
let d3 = (((to_parse / 1e2 as u64) % 100) << 1) as usize;
let d4 = (((to_parse / 1e0 as u64) % 100) << 1) as usize;
*curr -= 8;
ptr::copy_nonoverlapping(lut_ptr.offset(d1 as isize), buf_ptr.offset(*curr + 0), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d2 as isize), buf_ptr.offset(*curr + 2), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d3 as isize), buf_ptr.offset(*curr + 4), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d4 as isize), buf_ptr.offset(*curr + 6), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(*curr + 0), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d2), buf_ptr.add(*curr + 2), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d3), buf_ptr.add(*curr + 4), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d4), buf_ptr.add(*curr + 6), 2);
}
// `n` < 1e8 < (1 << 32)
let mut n = n as u32;
@ -536,31 +536,31 @@ fn parse_u64_into<const N: usize>(mut n: u64, buf: &mut [MaybeUninit<u8>; N], cu
let to_parse = n % 1e4 as u32;
n /= 1e4 as u32;
let d1 = (to_parse / 100) << 1;
let d2 = (to_parse % 100) << 1;
let d1 = ((to_parse / 100) << 1) as usize;
let d2 = ((to_parse % 100) << 1) as usize;
*curr -= 4;
ptr::copy_nonoverlapping(lut_ptr.offset(d1 as isize), buf_ptr.offset(*curr + 0), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d2 as isize), buf_ptr.offset(*curr + 2), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(*curr + 0), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d2), buf_ptr.add(*curr + 2), 2);
}
// `n` < 1e4 < (1 << 16)
let mut n = n as u16;
if n >= 100 {
let d1 = (n % 100) << 1;
let d1 = ((n % 100) << 1) as usize;
n /= 100;
*curr -= 2;
ptr::copy_nonoverlapping(lut_ptr.offset(d1 as isize), buf_ptr.offset(*curr), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(*curr), 2);
}
// decode last 1 or 2 chars
if n < 10 {
*curr -= 1;
*buf_ptr.offset(*curr) = (n as u8) + b'0';
*buf_ptr.add(*curr) = (n as u8) + b'0';
} else {
let d1 = n << 1;
let d1 = (n << 1) as usize;
*curr -= 2;
ptr::copy_nonoverlapping(lut_ptr.offset(d1 as isize), buf_ptr.offset(*curr), 2);
ptr::copy_nonoverlapping(lut_ptr.add(d1), buf_ptr.add(*curr), 2);
}
}
}
@ -593,21 +593,21 @@ impl fmt::Display for i128 {
fn fmt_u128(n: u128, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// 2^128 is about 3*10^38, so 39 gives an extra byte of space
let mut buf = [MaybeUninit::<u8>::uninit(); 39];
let mut curr = buf.len() as isize;
let mut curr = buf.len();
let (n, rem) = udiv_1e19(n);
parse_u64_into(rem, &mut buf, &mut curr);
if n != 0 {
// 0 pad up to point
let target = (buf.len() - 19) as isize;
let target = buf.len() - 19;
// SAFETY: Guaranteed that we wrote at most 19 bytes, and there must be space
// remaining since it has length 39
unsafe {
ptr::write_bytes(
MaybeUninit::slice_as_mut_ptr(&mut buf).offset(target),
MaybeUninit::slice_as_mut_ptr(&mut buf).add(target),
b'0',
(curr - target) as usize,
curr - target,
);
}
curr = target;
@ -616,16 +616,16 @@ fn fmt_u128(n: u128, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::R
parse_u64_into(rem, &mut buf, &mut curr);
// Should this following branch be annotated with unlikely?
if n != 0 {
let target = (buf.len() - 38) as isize;
let target = buf.len() - 38;
// The raw `buf_ptr` pointer is only valid until `buf` is used the next time,
// buf `buf` is not used in this scope so we are good.
let buf_ptr = MaybeUninit::slice_as_mut_ptr(&mut buf);
// SAFETY: At this point we wrote at most 38 bytes, pad up to that point,
// There can only be at most 1 digit remaining.
unsafe {
ptr::write_bytes(buf_ptr.offset(target), b'0', (curr - target) as usize);
ptr::write_bytes(buf_ptr.add(target), b'0', curr - target);
curr = target - 1;
*buf_ptr.offset(curr) = (n as u8) + b'0';
*buf_ptr.add(curr) = (n as u8) + b'0';
}
}
}
@ -634,8 +634,8 @@ fn fmt_u128(n: u128, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::R
// UTF-8 since `DEC_DIGITS_LUT` is
let buf_slice = unsafe {
str::from_utf8_unchecked(slice::from_raw_parts(
MaybeUninit::slice_as_mut_ptr(&mut buf).offset(curr),
buf.len() - curr as usize,
MaybeUninit::slice_as_mut_ptr(&mut buf).add(curr),
buf.len() - curr,
))
};
f.pad_integral(is_nonnegative, "", buf_slice)