aa3b1261b1
All deprecation warnings have been converted to errors. This includes the warning for multiple cfgs on one item. We'll leave that as an error for some period of time to ensure that all uses are updated before the behavior changes from "or" to "and".
65 lines
1.8 KiB
Rust
65 lines
1.8 KiB
Rust
// Copyright 2012-2014 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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#![feature(asm)]
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#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
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unsafe fn next_power_of_2(n: u32) -> u32 {
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let mut tmp = n;
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asm!("dec $0" : "+rm"(tmp) :: "cc");
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let mut shift = 1u;
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while shift <= 16 {
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asm!(
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"shr %cl, $2
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or $2, $0
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shl $$1, $1"
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: "+&rm"(tmp), "+{ecx}"(shift) : "r"(tmp) : "cc"
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);
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}
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asm!("inc $0" : "+rm"(tmp) :: "cc");
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return tmp;
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}
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#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
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pub fn main() {
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unsafe {
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assert_eq!(64, next_power_of_2(37));
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assert_eq!(2147483648, next_power_of_2(2147483647));
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}
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let mut y: int = 5;
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let x: int;
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unsafe {
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// Treat the output as initialization.
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asm!(
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"shl $2, $1
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add $3, $1
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mov $1, $0"
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: "=r"(x), "+r"(y) : "i"(3u), "ir"(7u) : "cc"
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);
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}
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assert_eq!(x, 47);
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assert_eq!(y, 47);
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let mut x = x + 1;
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assert_eq!(x, 48);
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unsafe {
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// Assignment to mutable.
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// Early clobber "&":
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// Forbids the use of a single register by both operands.
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asm!("shr $$2, $1; add $1, $0" : "+&r"(x) : "r"(x) : "cc");
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}
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assert_eq!(x, 60);
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}
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#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
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pub fn main() {}
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