39 lines
1.1 KiB
Rust
39 lines
1.1 KiB
Rust
// NOTE: Exposing the bug encoded in this test is sensitive to
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// LLVM optimization choices. See additional note below for an
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// example.
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#[link(name = "bad")]
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extern "C" {
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pub fn c_read_value(a: u32, b: u32, c: u32) -> u16;
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}
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fn main() {
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const C1: usize = 0x327b23c6;
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const C2: usize = C1 & 0xFFFF;
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let r1: usize = 0x0;
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let r2: usize = C1;
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let r3: usize = 0x0;
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let value: u16 = unsafe { c_read_value(r1 as u32, r2 as u32, r3 as u32) };
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// NOTE: as an example of the sensitivity of this test to optimization choices,
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// uncommenting this block of code makes the bug go away on pnkfelix's machine.
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// (But observing via `dbg!` doesn't hide the bug. At least sometimes.)
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/*
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println!("{}", value);
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println!("{}", value as usize);
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println!("{}", usize::from(value));
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println!("{}", (value as usize) & 0xFFFF);
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*/
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let d1 = value;
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let d2 = value as usize;
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let d3 = usize::from(value);
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let d4 = (value as usize) & 0xFFFF;
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let d = (&d1, &d2, &d3, &d4);
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let d_ = (d1, d2, d3, d4);
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assert_eq!(((&(C2 as u16), &C2, &C2, &C2), (C2 as u16, C2, C2, C2)), (d, d_));
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}
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