Rollup merge of #80042 - sivadeilra:cold_bits, r=oli-obk
Split a func into cold/hot parts, reducing binary size I noticed that the Size::bits function is called in many places, and is inlined into them. On x86_64-pc-windows-msvc, this function is inlined 527 times, and compiled separately (non-inlined) 3 times. Each of those inlined calls contains code that panics. This commit moves the `panic!` call into a separate function and marks that function with `#[cold]`. This reduces binary size by 24 KB. Not much, but it's something. Changes like this often reduce pressure on instruction-caches, since it reduces the amount of code that is inlined into hot code paths. Or more precisely, it removes cold code from hot cache lines.
This commit is contained in:
commit
56504a00f2
|
@ -271,22 +271,38 @@ impl ToJson for Endian {
|
|||
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Encodable, Decodable)]
|
||||
#[derive(HashStable_Generic)]
|
||||
pub struct Size {
|
||||
// The top 3 bits are ALWAYS zero.
|
||||
raw: u64,
|
||||
}
|
||||
|
||||
impl Size {
|
||||
pub const ZERO: Size = Size { raw: 0 };
|
||||
|
||||
#[inline]
|
||||
/// Rounds `bits` up to the next-higher byte boundary, if `bits` is
|
||||
/// is not aligned.
|
||||
pub fn from_bits(bits: impl TryInto<u64>) -> Size {
|
||||
let bits = bits.try_into().ok().unwrap();
|
||||
|
||||
#[cold]
|
||||
fn overflow(bits: u64) -> ! {
|
||||
panic!("Size::from_bits({}) has overflowed", bits);
|
||||
}
|
||||
|
||||
// This is the largest value of `bits` that does not cause overflow
|
||||
// during rounding, and guarantees that the resulting number of bytes
|
||||
// cannot cause overflow when multiplied by 8.
|
||||
if bits > 0xffff_ffff_ffff_fff8 {
|
||||
overflow(bits);
|
||||
}
|
||||
|
||||
// Avoid potential overflow from `bits + 7`.
|
||||
Size::from_bytes(bits / 8 + ((bits % 8) + 7) / 8)
|
||||
Size { raw: bits / 8 + ((bits % 8) + 7) / 8 }
|
||||
}
|
||||
|
||||
#[inline]
|
||||
pub fn from_bytes(bytes: impl TryInto<u64>) -> Size {
|
||||
Size { raw: bytes.try_into().ok().unwrap() }
|
||||
let bytes: u64 = bytes.try_into().ok().unwrap();
|
||||
Size { raw: bytes }
|
||||
}
|
||||
|
||||
#[inline]
|
||||
|
@ -301,9 +317,7 @@ impl Size {
|
|||
|
||||
#[inline]
|
||||
pub fn bits(self) -> u64 {
|
||||
self.bytes().checked_mul(8).unwrap_or_else(|| {
|
||||
panic!("Size::bits: {} bytes in bits doesn't fit in u64", self.bytes())
|
||||
})
|
||||
self.raw << 3
|
||||
}
|
||||
|
||||
#[inline]
|
||||
|
|
Loading…
Reference in New Issue