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rust/compiler/rustc_serialize/tests/leb128.rs

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Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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#![feature(maybe_uninit_slice)]
#![feature(maybe_uninit_uninit_array)]
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use rustc_serialize::leb128::*;
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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use std::mem::MaybeUninit;
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macro_rules! impl_test_unsigned_leb128 {
Format the world
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($test_name:ident, $write_fn_name:ident, $read_fn_name:ident, $int_ty:ident) => {
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#[test]
fn $test_name() {
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
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// Test 256 evenly spaced values of integer range,
// integer max value, and some "random" numbers.
let mut values = Vec::new();
let increment = (1 as $int_ty) << ($int_ty::BITS - 8);
values.extend((0..256).map(|i| $int_ty::MIN + i * increment));
values.push($int_ty::MAX);
values.extend(
(-500..500).map(|i| (i as $int_ty).wrapping_mul(0x12345789ABCDEFu64 as $int_ty)),
);
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let mut stream = Vec::new();
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
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for &x in &values {
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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let mut buf = MaybeUninit::uninit_array();
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
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stream.extend($write_fn_name(&mut buf, x));
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}
let mut position = 0;
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
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for &expected in &values {
Format the world
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let (actual, bytes_read) = $read_fn_name(&stream[position..]);
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assert_eq!(expected, actual);
position += bytes_read;
}
assert_eq!(stream.len(), position);
}
Format the world
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};
libserialize: Unconfigure tests during normal build
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}
impl_test_unsigned_leb128!(test_u16_leb128, write_u16_leb128, read_u16_leb128, u16);
impl_test_unsigned_leb128!(test_u32_leb128, write_u32_leb128, read_u32_leb128, u32);
impl_test_unsigned_leb128!(test_u64_leb128, write_u64_leb128, read_u64_leb128, u64);
impl_test_unsigned_leb128!(test_u128_leb128, write_u128_leb128, read_u128_leb128, u128);
impl_test_unsigned_leb128!(test_usize_leb128, write_usize_leb128, read_usize_leb128, usize);
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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macro_rules! impl_test_signed_leb128 {
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
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($test_name:ident, $write_fn_name:ident, $read_fn_name:ident, $int_ty:ident) => {
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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#[test]
fn $test_name() {
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
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// Test 256 evenly spaced values of integer range,
// integer max value, and some "random" numbers.
let mut values = Vec::new();
let mut value = $int_ty::MIN;
let increment = (1 as $int_ty) << ($int_ty::BITS - 8);
for _ in 0..256 {
values.push(value);
// The addition in the last loop iteration overflows.
value = value.wrapping_add(increment);
}
values.push($int_ty::MAX);
values.extend(
(-500..500).map(|i| (i as $int_ty).wrapping_mul(0x12345789ABCDEFi64 as $int_ty)),
);
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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let mut stream = Vec::new();
for &x in &values {
let mut buf = MaybeUninit::uninit_array();
stream.extend($write_fn_name(&mut buf, x));
}
let mut position = 0;
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
2020-12-29 17:14:33 -06:00
for &expected in &values {
let (actual, bytes_read) = $read_fn_name(&stream[position..]);
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
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assert_eq!(expected, actual);
position += bytes_read;
}
assert_eq!(stream.len(), position);
}
};
libserialize: Unconfigure tests during normal build
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}
Serialize incr comp structures to file via fixed-size buffer Reduce a large memory spike that happens during serialization by writing the incr comp structures to file by way of a fixed-size buffer, rather than an unbounded vector. Effort was made to keep the instruction count close to that of the previous implementation. However, buffered writing to a file inherently has more overhead than writing to a vector, because each write may result in a handleable error. To reduce this overhead, arrangements are made so that each LEB128-encoded integer can be written to the buffer with only one capacity and error check. Higher-level optimizations in which entire composite structures can be written with one capacity and error check are possible, but would require much more work. The performance is mostly on par with the previous implementation, with small to moderate instruction count regressions. The memory reduction is significant, however, so it seems like a worth-while trade-off.
2020-12-06 19:30:55 -06:00
rustc_serialize: fix incorrect signed LEB128 decoding The signed LEB128 decoding function used a hardcoded constant of 64 instead of the number of bits in the type of integer being decoded, which resulted in incorrect results for some inputs. Fix this, make the decoding more consistent with the unsigned version, and increase the LEB128 encoding and decoding test coverage.
2020-12-29 17:14:33 -06:00
impl_test_signed_leb128!(test_i16_leb128, write_i16_leb128, read_i16_leb128, i16);
impl_test_signed_leb128!(test_i32_leb128, write_i32_leb128, read_i32_leb128, i32);
impl_test_signed_leb128!(test_i64_leb128, write_i64_leb128, read_i64_leb128, i64);
impl_test_signed_leb128!(test_i128_leb128, write_i128_leb128, read_i128_leb128, i128);
impl_test_signed_leb128!(test_isize_leb128, write_isize_leb128, read_isize_leb128, isize);
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