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  1. RHEL
  2. RHEL-54023

Jump threading MIR opt unsoundly uses bitpattern equality for floats

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: Critical Critical
    • rhel-10.0.beta
    • rhel-10.0.beta
    • rust
    • None
    • rust-1.79.0-3.el10
    • Yes
    • None
    • 1
    • rhel-sst-pt-llvm-rust-go
    • ssg_platform_tools
    • 1
    • False
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    • No
    • SST LLVM/Rust/Go Sprint 8
    • Unspecified Release Note Type - Unknown
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      Upstream:

      Jump threading was enabled in Rust 1.78, but this bug with floating point comparisons was only discovered 2 weeks ago. It was deemed important enough by the upstream compiler team to justify the 1.80.1 point release, and I think we should strongly consider it for RHEL's upcoming 1.79 builds as well.

      The minimized reproducer prints "ok" in debug mode and "bug" in release mode (rustc -O).

      fn main() {
    let tmp = if true { -0.0 } else { 1.0 };
    if tmp == 0.0 {
        println!("ok");
    } else {
        println!("bug")
    }
}

              jistone@redhat.com Josh Stone
              jistone@redhat.com Josh Stone
              Josh Stone Josh Stone
              Jesus Checa Hidalgo Jesus Checa Hidalgo
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                Created:
                Updated: