101 lines
3.4 KiB
Rust
101 lines
3.4 KiB
Rust
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// compile-flags: -C debug-assertions
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// Check that we do *not* overflow on a number of edge cases.
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// (compare with test/run-fail/overflowing-{lsh,rsh}*.rs)
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// (Work around constant-evaluation)
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fn id<T>(x: T) -> T { x }
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fn main() {
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test_left_shift();
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test_right_shift();
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}
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fn test_left_shift() {
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// negative rhs can panic, but values in [0,N-1] are okay for iN
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macro_rules! tests {
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($iN:ty, $uN:ty, $max_rhs:expr, $expect_i:expr, $expect_u:expr) => { {
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let x = (1 as $iN) << id(0);
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assert_eq!(x, 1);
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let x = (1 as $uN) << id(0);
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assert_eq!(x, 1);
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let x = (1 as $iN) << id($max_rhs);
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assert_eq!(x, $expect_i);
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let x = (1 as $uN) << id($max_rhs);
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assert_eq!(x, $expect_u);
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// high-order bits on LHS are silently discarded without panic.
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let x = (3 as $iN) << id($max_rhs);
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assert_eq!(x, $expect_i);
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let x = (3 as $uN) << id($max_rhs);
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assert_eq!(x, $expect_u);
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} }
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}
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let x = 1_i8 << id(0);
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assert_eq!(x, 1);
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let x = 1_u8 << id(0);
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assert_eq!(x, 1);
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let x = 1_i8 << id(7);
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assert_eq!(x, std::i8::MIN);
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let x = 1_u8 << id(7);
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assert_eq!(x, 0x80);
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// high-order bits on LHS are silently discarded without panic.
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let x = 3_i8 << id(7);
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assert_eq!(x, std::i8::MIN);
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let x = 3_u8 << id(7);
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assert_eq!(x, 0x80);
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// above is (approximately) expanded from:
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tests!(i8, u8, 7, std::i8::MIN, 0x80_u8);
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tests!(i16, u16, 15, std::i16::MIN, 0x8000_u16);
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tests!(i32, u32, 31, std::i32::MIN, 0x8000_0000_u32);
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tests!(i64, u64, 63, std::i64::MIN, 0x8000_0000_0000_0000_u64);
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}
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fn test_right_shift() {
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// negative rhs can panic, but values in [0,N-1] are okay for iN
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macro_rules! tests {
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($iN:ty, $uN:ty, $max_rhs:expr,
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$signbit_i:expr, $highbit_i:expr, $highbit_u:expr) =>
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{ {
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let x = (1 as $iN) >> id(0);
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assert_eq!(x, 1);
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let x = (1 as $uN) >> id(0);
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assert_eq!(x, 1);
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let x = ($highbit_i) >> id($max_rhs-1);
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assert_eq!(x, 1);
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let x = ($highbit_u) >> id($max_rhs);
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assert_eq!(x, 1);
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// sign-bit is carried by arithmetic right shift
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let x = ($signbit_i) >> id($max_rhs);
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assert_eq!(x, -1);
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// low-order bits on LHS are silently discarded without panic.
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let x = ($highbit_i + 1) >> id($max_rhs-1);
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assert_eq!(x, 1);
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let x = ($highbit_u + 1) >> id($max_rhs);
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assert_eq!(x, 1);
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let x = ($signbit_i + 1) >> id($max_rhs);
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assert_eq!(x, -1);
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} }
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}
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tests!(i8, u8, 7, std::i8::MIN, 0x40_i8, 0x80_u8);
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tests!(i16, u16, 15, std::i16::MIN, 0x4000_u16, 0x8000_u16);
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tests!(i32, u32, 31, std::i32::MIN, 0x4000_0000_u32, 0x8000_0000_u32);
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tests!(i64, u64, 63, std::i64::MIN,
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0x4000_0000_0000_0000_u64, 0x8000_0000_0000_0000_u64);
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}
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