https://github.com/rust-lang/rust http://git.dreamy.place/mirrors/rust/atom?h=1.63.0 2021-10-22T17:50:07+00:00 2021-10-22T17:50:07+00:00 Josh Stone jistone@redhat.com 2021-10-22T17:50:07+00:00 urn:sha1:e9f545b9a952f193dbe15730bcbe47784b6e7cde 2021-03-10T10:21:43+00:00 Simonas Kazlauskas git@kazlauskas.me 2021-03-07T23:59:10+00:00 urn:sha1:0517acd54353869b2fbfc50af61ea7bd1fd309e0 This removes all of the code we had in place to work-around LLVM's handling of forward progress. From this removal excluded is a workaround where we'd insert a `sideeffect` into clearly infinite loops such as `loop {}`. This code remains conditionally effective when the LLVM version is earlier than 12.0, which fixed the forward progress related miscompilations at their root. 2019-09-27T23:13:53+00:00 Xiang Fan sfanxiang@gmail.com 2019-09-27T23:13:53+00:00 urn:sha1:10c668190cb419b539a36214237382c6689f7daf 2019-09-27T20:45:08+00:00 Xiang Fan sfanxiang@gmail.com 2019-06-06T00:39:20+00:00 urn:sha1:f71e0daa29b232d8f689f77fecb84dcb87fce6da LLVM assumes that a thread will eventually cause side effect. This is not true in Rust if a loop or recursion does nothing in its body, causing undefined behavior even in common cases like `loop {}`. Inserting llvm.sideeffect fixes the undefined behavior. As a micro-optimization, only insert llvm.sideeffect when jumping back in blocks or calling a function. A patch for LLVM is expected to allow empty non-terminate code by default and fix this issue from LLVM side. https://github.com/rust-lang/rust/issues/28728