Mirrors/rust
1
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2026-04-27 18:57:42 +03:00
Code Issues Packages Projects Releases Wiki Activity

libm: Add basic tests for u256::shl

Browse Source 
Duplicate the shr test style to have a simple check for edge cases.
This commit is contained in:
Trevor Gross
2026-03-20 18:25:24 -04:00
parent 6ea1978117
commit 06ea8566a1
1 changed files with 167 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
library/compiler-builtins/libm/src/math/support/big/tests.rs
+167 -1
View File
@@ -1,7 +1,7 @@
extern crate std;
use std::eprintln;
use super::{HInt, MinInt, i256, u256};
use super::{DInt, HInt, MinInt, i256, u256};
use crate::support::{Int as _, NarrowingDiv};
const LOHI_SPLIT: u128 = 0xaaaaaaaaaaaaaaaaffffffffffffffff;
@@ -98,6 +98,172 @@ fn not_u256() {
assert_eq!(!u256::ZERO, u256::MAX);
}
#[test]
fn shl_u256() {
let only_high = [
1,
u16::MAX.into(),
u32::MAX.into(),
u64::MAX.into(),
u128::MAX,
];
let mut has_errors = false;
let mut add_error = |a, b, expected, actual| {
has_errors = true;
eprintln!(
"\
FAILURE: {} << {b}\n\
expected: {}\n\
actual: {}\
",
hexu(a),
hexu(expected),
hexu(actual),
);
};
for a in only_high {
for perturb in 0..10 {
let a = a.saturating_add(perturb);
for shift in 0..128 {
let res = u256::from_lo_hi(0, a) << shift;
let expected = u256::from_lo_hi(0, a << shift);
if res != expected {
add_error(a.widen(), shift, expected, res);
}
}
}
}
let check = [
(
u256::MAX,
1,
u256 {
lo: u128::MAX << 1,
hi: u128::MAX,
},
),
(
u256::MAX,
5,
u256 {
lo: u128::MAX << 5,
hi: u128::MAX,
},
),
(
u256::MAX,
63,
u256 {
lo: u128::MAX << 63,
hi: u128::MAX,
},
),
(
u256::MAX,
64,
u256 {
lo: (u64::MAX as u128) << 64,
hi: u128::MAX,
},
),
(
u256::MAX,
65,
u256 {
lo: (u64::MAX as u128) << 65,
hi: u128::MAX,
},
),
(
u256::MAX,
127,
u256 {
lo: 1 << 127,
hi: u128::MAX,
},
),
(
u256::MAX,
128,
u256 {
lo: 0,
hi: u128::MAX,
},
),
(
u256::MAX,
129,
u256 {
lo: 0,
hi: u128::MAX << 1,
},
),
(
u256::MAX,
191,
u256 {
lo: 0,
hi: u128::MAX << 63,
},
),
(
u256::MAX,
192,
u256 {
lo: 0,
hi: u128::MAX << 64,
},
),
(
u256::MAX,
193,
u256 {
lo: 0,
hi: u128::MAX << 65,
},
),
(
u256::MAX,
254,
u256 {
lo: 0,
hi: 0b11 << 126,
},
),
(
u256::MAX,
255,
u256 {
lo: 0,
hi: 1 << 127,
},
),
(
u256 {
hi: 0,
lo: LOHI_SPLIT,
},
64,
u256 {
lo: 0xffffffffffffffff0000000000000000,
hi: 0xaaaaaaaaaaaaaaaa,
},
),
];
for (input, shift, expected) in check {
let res = input << shift;
if res != expected {
add_error(input, shift, expected, res);
}
}
assert!(!has_errors);
}
#[test]
fn shr_u256() {
let only_low = [