[llvm-branch-commits] [llvm] release/19.x: [loongarch][DAG][FREEZE] Fix crash when FREEZE a half(f16) type on loongarch (#107791) (PR #109093)

[Trevor Gross via llvm-branch-commits]

tgross35 wrote:

> Currently, Rust's compiler-builtins has marked fp16 as available for loongarch64, but in fact, the functionality is broken. Even with this patch, it is not optimal. Subjectively, I hope these patches can be backported to LLVM 19 to avoid ABI incompatibility issues across multiple versions. If we don’t break anything unrelated to fp16, it won’t be a bad thing to work on fixing fp16, as it was already broken to begin with. Thanks.

If you are referring to https://github.com/rust-lang/compiler-builtins/blob/bb18ce58c2b5fec081a5dd3553aa960a36b8de5c/configure.rs#L51-L91, we only disable f16/f128 on platforms where LLVM 19 actually has a crash or produces code that can't be linked. Quite a few of the targets that aren't disabled there have some form of ABI issue - so we just build the symbols but don't actually test with them.

(the config for what gets tested is at https://github.com/rust-lang/rust/blob/2bd1e894efde3b6be857ad345914a3b1cea51def/library/std/build.rs#L81-L186)


https://github.com/llvm/llvm-project/pull/109093