0525bb7669
Adds an `assume` intrinsic that gets translated to llvm.assume. It is used on a boolean expression and allows the optimizer to assume that the expression is true. This implements #18051.
26 lines
673 B
Rust
26 lines
673 B
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
|
|
// file at the top-level directory of this distribution and at
|
|
// http://rust-lang.org/COPYRIGHT.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
|
|
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
|
|
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
|
|
// option. This file may not be copied, modified, or distributed
|
|
// except according to those terms.
|
|
|
|
use std::intrinsics::assume;
|
|
|
|
unsafe fn f(x: i32) -> i32 {
|
|
assume(x == 34);
|
|
match x {
|
|
34 => 42,
|
|
_ => 30
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
let x = unsafe { f(34) };
|
|
assert_eq!(x, 42);
|
|
}
|
|
|