Two ARM64-specific compiler optimization bugs, in GCC 15/16 and Rust, hit curl(mastodon.social)
35 pointsby torutofu4 hours ago3 comments
  • vlovich1233 hours ago
    Not actually confirmed as compiler bugs yet.

    Here’s a similar bug where OpenSSL’s inline asm was wrong and probably only GCC was smart enough to try to exploit the bug:

    https://github.com/openssl/openssl/pull/23233

    Same for rust - could be UB in quiche that is getting exposed.

    • account422 hours ago
      Can't even find an upstream compiler bug report not to mention a confirmation/patch. Doesn't look like the compiler output was analyzed at all either, they are just going by "-O3 results in valgrind warnings, -O2 doesn't".

      It's not like compiler bugs are unheard of but they are rare enough that the base assumption should be that the bug is in your own code.

  • edoceo4 hours ago
    The social post links to this bug https://github.com/curl/curl/issues/23237
  • rurban2 hours ago
    Looks like a valid new optimization to me, which only fails on valgrind, which is a bit too strict with uninitialized values. In openssl's strlcpy. They'll deal with that.