Delete unreachable_unchecked hints

On my machine, benchmarks are 15% faster without these...

Author: dtolnay

src/lib.rs

@@ -258,16 +258,6 @@ macro_rules! impl_Unsigned {
  .try_into()
  .expect("branch is not hit for types that cannot fit 999 (u8)")
  {
- // SAFETY: All of the decimals fit in buf due to MAX_DEC_N
- // and the while condition ensures at least 4 more decimals.
- if offset < 4 {
- unsafe { hint::unreachable_unchecked() };
- }
- // SAFETY: The offset counts down from its initial buf.len()
- // without underflow due to the previous precondition.
- if offset > buf.len() {
- unsafe { hint::unreachable_unchecked() };
- }
  offset -= 4;
 
  // pull two pairs
@@ -286,16 +276,6 @@ macro_rules! impl_Unsigned {
 
  // Format per two digits from the lookup table.
  if remain > 9 {
- // SAFETY: All of the decimals fit in buf due to MAX_DEC_N
- // and the if condition ensures at least 2 more decimals.
- if offset < 2 {
- unsafe { hint::unreachable_unchecked() };
- }
- // SAFETY: The offset counts down from its initial buf.len()
- // without underflow due to the previous precondition.
- if offset > buf.len() {
- unsafe { hint::unreachable_unchecked() };
- }
  offset -= 2;
 
  let pair = (remain % 100) as usize;
@@ -306,16 +286,6 @@ macro_rules! impl_Unsigned {
 
  // Format the last remaining digit, if any.
  if remain != 0 || self == 0 {
- // SAFETY: All of the decimals fit in buf due to MAX_DEC_N
- // and the if condition ensures (at least) 1 more decimals.
- if offset < 1 {
- unsafe { hint::unreachable_unchecked() };
- }
- // SAFETY: The offset counts down from its initial buf.len()
- // without underflow due to the previous precondition.
- if offset > buf.len() {
- unsafe { hint::unreachable_unchecked() };
- }
  offset -= 1;
 
  // Either the compiler sees that remain < 10, or it prevents
@@ -368,16 +338,6 @@ impl Unsigned for u128 {
 
  // Format per four digits from the lookup table.
  while remain > 999 {
- // SAFETY: All of the decimals fit in buf due to u128::MAX_STR_LEN
- // and the while condition ensures at least 4 more decimals.
- if offset < 4 {
- unsafe { hint::unreachable_unchecked() };
- }
- // SAFETY: The offset counts down from its initial buf.len()
- // without underflow due to the previous precondition.
- if offset > buf.len() {
- unsafe { hint::unreachable_unchecked() };
- }
  offset -= 4;
 
  // pull two pairs
@@ -393,16 +353,6 @@ impl Unsigned for u128 {
 
  // Format per two digits from the lookup table.
  if remain > 9 {
- // SAFETY: All of the decimals fit in buf due to u128::MAX_STR_LEN
- // and the if condition ensures at least 2 more decimals.
- if offset < 2 {
- unsafe { hint::unreachable_unchecked() };
- }
- // SAFETY: The offset counts down from its initial buf.len()
- // without underflow due to the previous precondition.
- if offset > buf.len() {
- unsafe { hint::unreachable_unchecked() };
- }
  offset -= 2;
 
  let pair = (remain % 100) as usize;
@@ -413,16 +363,6 @@ impl Unsigned for u128 {
 
  // Format the last remaining digit, if any.
  if remain != 0 {
- // SAFETY: All of the decimals fit in buf due to u128::MAX_STR_LEN
- // and the if condition ensures (at least) 1 more decimals.
- if offset < 1 {
- unsafe { hint::unreachable_unchecked() };
- }
- // SAFETY: The offset counts down from its initial buf.len()
- // without underflow due to the previous precondition.
- if offset > buf.len() {
- unsafe { hint::unreachable_unchecked() };
- }
  offset -= 1;
 
  // Either the compiler sees that remain < 10, or it prevents