Apply `weak` attributes to all intrinsics by Amjad50 · Pull Request #598 · rust-lang/compiler-builtins

Amjad50 · 2024-04-29T14:07:59Z

Removed the weak-intrinsics feature, so that all functions will have the weak linkage attribute.

But this caused issues for memset (maybe other mem functions are related), so added a special feature for those mem-weak-intrinsics.

mem functions won't have the weak attribute unless this feature is enabled.

This also fixed the bug in rust-lang/rust#124042.

Before this commit, generated code will be

pub extern "C" fn <name>(...) -> ... {
        // code...
}
pub mod <name> {
    #[linkage = "weak"]
    #[no_mangle]
    pub extern "C" fn <name>(...) -> ... {
        super::<name>(...)
    }
}

The issue is that there is 2 weak linkage, the first one is not required. Along refactoring weak attributes, this was fixed.

Amanieu

This may also be a good opportunity to cleanup the mod wrappers around the no_mangle version of each intrinsic. Specifically:

There is no need for these modules to be pub. Same with the function inside them. #[no_mangle] will ensure the symbol is exported.
The whole module should be #[cfg(not(feature = "mangled-names")]. The functions themselves can then be #[no_mangle] unconditionally.

Removed the `weak-intrinsics` feature, so that all functions will have the `weak` linkage attribute. Also this fixed the bug in rust-lang/rust#124042. Before this commit, generated code will be ```rust pub extern "C" fn <name>(...) -> ... { // code... } pub mod <name> { #[linkage = "weak"] #[no_mangle] pub extern "C" fn <name>(...) -> ... { super::<name>(...) } } ``` The issue is that there is 2 `weak` linkage, the first one is not required. Along refactoring `weak` attributes, this was fixed.

`weak` is only used with `no_mangle`

Don't generate the whole function if we are not going to use `no_mangle`, there is no point

Amjad50 · 2024-05-03T12:11:18Z

Thanks @Amanieu , can a new version be released?

Amanieu · 2024-05-04T19:20:33Z

Done

The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These cause a compilation error (reproduce with `ENABLE_GCC_CODEGEN=1 src/ci/docker/run.sh x86_64-gnu-llvm-17`), so enable `no-f16-f128` for now.

The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc.

- rust-lang/compiler-builtins#598 - rust-lang/compiler-builtins#601

The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc.

Update compiler_builtins to 0.1.112 The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc.

…anieu Update compiler_builtins to 0.1.113 The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc.

The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc. Also disable it for LLVM targets that don't support it.

After <rust-lang#598>, arm-android was failing to complete in CI because it was hanging on some tests. This issue appears to have been caused by symbols related to atomics, e.g. `__sync_val_compare_and_swap_4`, to have become weak. It turns out that these symbols were always strong before, even though Android was always setting the `weak-intrinsics` feature. So, making them weak presumably caused the system implementation to get linked, which appears buggy. Resolve this by making `__sync_*` symbols weak on Android. (this includes a recursion limit increase, our macros are getting big). Link: rust-lang#641

The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc. Also disable it for LLVM targets that don't support it.

…ss35 Update compiler_builtins to 0.1.114 The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc.

The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc. Also disable it for LLVM targets that don't support it.

Update compiler_builtins to 0.1.114 The `weak-intrinsics` feature was removed from compiler_builtins in rust-lang/compiler-builtins#598, so dropped the `compiler-builtins-weak-intrinsics` feature from alloc/std/sysroot. In rust-lang/compiler-builtins#593, some builtins for f16/f128 were added. These don't work for all compiler backends, so add a `compiler-builtins-no-f16-f128` feature and disable it for cranelift and gcc.