diff options
Diffstat (limited to '')
| -rw-r--r-- | compiler/rustc_serialize/src/leb128.rs | 21 | ||||
| -rw-r--r-- | compiler/rustc_serialize/src/opaque.rs | 36 |
2 files changed, 27 insertions, 30 deletions
diff --git a/compiler/rustc_serialize/src/leb128.rs b/compiler/rustc_serialize/src/leb128.rs index 08b3c0542..7dad9aa01 100644 --- a/compiler/rustc_serialize/src/leb128.rs +++ b/compiler/rustc_serialize/src/leb128.rs @@ -1,22 +1,19 @@ -#![macro_use] - -macro_rules! max_leb128_len { - ($int_ty:ty) => { - // The longest LEB128 encoding for an integer uses 7 bits per byte. - (std::mem::size_of::<$int_ty>() * 8 + 6) / 7 - }; +/// Returns the length of the longest LEB128 encoding for `T`, assuming `T` is an integer type +pub const fn max_leb128_len<T>() -> usize { + // The longest LEB128 encoding for an integer uses 7 bits per byte. + (std::mem::size_of::<T>() * 8 + 6) / 7 } -// Returns the longest LEB128 encoding of all supported integer types. -pub const fn max_leb128_len() -> usize { - max_leb128_len!(u128) +/// Returns the length of the longest LEB128 encoding of all supported integer types. +pub const fn largest_max_leb128_len() -> usize { + max_leb128_len::<u128>() } macro_rules! impl_write_unsigned_leb128 { ($fn_name:ident, $int_ty:ty) => { #[inline] pub fn $fn_name( - out: &mut [::std::mem::MaybeUninit<u8>; max_leb128_len!($int_ty)], + out: &mut [::std::mem::MaybeUninit<u8>; max_leb128_len::<$int_ty>()], mut value: $int_ty, ) -> &[u8] { let mut i = 0; @@ -90,7 +87,7 @@ macro_rules! impl_write_signed_leb128 { ($fn_name:ident, $int_ty:ty) => { #[inline] pub fn $fn_name( - out: &mut [::std::mem::MaybeUninit<u8>; max_leb128_len!($int_ty)], + out: &mut [::std::mem::MaybeUninit<u8>; max_leb128_len::<$int_ty>()], mut value: $int_ty, ) -> &[u8] { let mut i = 0; diff --git a/compiler/rustc_serialize/src/opaque.rs b/compiler/rustc_serialize/src/opaque.rs index f35cc08f4..0afeb86fc 100644 --- a/compiler/rustc_serialize/src/opaque.rs +++ b/compiler/rustc_serialize/src/opaque.rs @@ -1,4 +1,4 @@ -use crate::leb128::{self, max_leb128_len}; +use crate::leb128::{self, largest_max_leb128_len}; use crate::serialize::{Decodable, Decoder, Encodable, Encoder}; use std::convert::TryInto; use std::fs::File; @@ -32,7 +32,7 @@ impl MemEncoder { macro_rules! write_leb128 { ($enc:expr, $value:expr, $int_ty:ty, $fun:ident) => {{ - const MAX_ENCODED_LEN: usize = max_leb128_len!($int_ty); + const MAX_ENCODED_LEN: usize = $crate::leb128::max_leb128_len::<$int_ty>(); let old_len = $enc.data.len(); if MAX_ENCODED_LEN > $enc.data.capacity() - old_len { @@ -155,19 +155,19 @@ impl Encoder for MemEncoder { pub type FileEncodeResult = Result<usize, io::Error>; -// `FileEncoder` encodes data to file via fixed-size buffer. -// -// When encoding large amounts of data to a file, using `FileEncoder` may be -// preferred over using `MemEncoder` to encode to a `Vec`, and then writing the -// `Vec` to file, as the latter uses as much memory as there is encoded data, -// while the former uses the fixed amount of memory allocated to the buffer. -// `FileEncoder` also has the advantage of not needing to reallocate as data -// is appended to it, but the disadvantage of requiring more error handling, -// which has some runtime overhead. +/// `FileEncoder` encodes data to file via fixed-size buffer. +/// +/// When encoding large amounts of data to a file, using `FileEncoder` may be +/// preferred over using `MemEncoder` to encode to a `Vec`, and then writing the +/// `Vec` to file, as the latter uses as much memory as there is encoded data, +/// while the former uses the fixed amount of memory allocated to the buffer. +/// `FileEncoder` also has the advantage of not needing to reallocate as data +/// is appended to it, but the disadvantage of requiring more error handling, +/// which has some runtime overhead. pub struct FileEncoder { - // The input buffer. For adequate performance, we need more control over - // buffering than `BufWriter` offers. If `BufWriter` ever offers a raw - // buffer access API, we can use it, and remove `buf` and `buffered`. + /// The input buffer. For adequate performance, we need more control over + /// buffering than `BufWriter` offers. If `BufWriter` ever offers a raw + /// buffer access API, we can use it, and remove `buf` and `buffered`. buf: Box<[MaybeUninit<u8>]>, buffered: usize, flushed: usize, @@ -186,12 +186,12 @@ impl FileEncoder { pub fn with_capacity<P: AsRef<Path>>(path: P, capacity: usize) -> io::Result<Self> { // Require capacity at least as large as the largest LEB128 encoding // here, so that we don't have to check or handle this on every write. - assert!(capacity >= max_leb128_len()); + assert!(capacity >= largest_max_leb128_len()); // Require capacity small enough such that some capacity checks can be // done using guaranteed non-overflowing add rather than sub, which // shaves an instruction off those code paths (on x86 at least). - assert!(capacity <= usize::MAX - max_leb128_len()); + assert!(capacity <= usize::MAX - largest_max_leb128_len()); // Create the file for reading and writing, because some encoders do both // (e.g. the metadata encoder when -Zmeta-stats is enabled) @@ -411,7 +411,7 @@ impl Drop for FileEncoder { macro_rules! file_encoder_write_leb128 { ($enc:expr, $value:expr, $int_ty:ty, $fun:ident) => {{ - const MAX_ENCODED_LEN: usize = max_leb128_len!($int_ty); + const MAX_ENCODED_LEN: usize = $crate::leb128::max_leb128_len::<$int_ty>(); // We ensure this during `FileEncoder` construction. debug_assert!($enc.capacity() >= MAX_ENCODED_LEN); @@ -711,7 +711,7 @@ impl<'a> Decodable<MemDecoder<'a>> for Vec<u8> { } } -// An integer that will always encode to 8 bytes. +/// An integer that will always encode to 8 bytes. pub struct IntEncodedWithFixedSize(pub u64); impl IntEncodedWithFixedSize { |