Undefined external symbols from compiler_builtins #124042
Comments
rustbot
added
the
needs-triage
Noratrieb
added
A-linkage
|
Thanks for letting me know. The changes in |
export all symbols as `weak` for non `windows`/`apple` targets.
Additionally fixes an issue when creating `weak` instrinsics:
Before this commit, generated code will be
```rust
#[linkage = "weak"]
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, and this is the cause for the bug in rust-lang/rust#124042.
Along with the remval of the `weak-intrinsics` feature, we fixed this issue as well.
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. 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.
|
So after looking around and trying to fix the issue, the main issue is from Added a quick small fix here, Kingcom/armips#242, but not sure if the maintainer is around anymore |
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.
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.
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.
|
So, the PR in Though, there appear to be another issue. When running armips with the library from latest nightly, it gives an error that Looking at the call void @llvm.memset.p0.i64(ptr noundef nonnull align 4 dereferenceable(80) %iq, i8 0, i64 80, i1 false)which is converted into There is a way to fix this, which is to add I'm not sure if that is the correct behavior of llvm or not. since the target in the example has This is a static library, so maybe its assuming |
|
memcpy, memmove and memset are expected to be present by LLVM. They are either provided by libc (if any) or compiler-builtins (on no_std targets) Compiler-builtins has a hard coded set of no_std targets. For any other you have to explicitly use |
|
Thanks @bjorn3, so I guess this is expected behavior. I think then this ticket can be closed, the fix is to use the newer |
|
Can confirm this is fixed by using the new armips and adding |
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.
I have a project where I'm experimenting with introducing Rust code into an existing codebase by compiling it into a static library for a custom target and linking it using armips. This process no longer works on the latest nightly because armips complains about undefined external symbols such as
_rnvntcse1eqnti5u6g_17compiler_builtins4math5atan2.A minimal example is at https://github.com/fenhl/rust-builtins-min which can be tested by running
python build.pyafter installing armips (scoop install extras/armipson Windows, see https://github.com/Kingcom/armips for binaries and build instructions for other platforms).I ran
cargo-bisect-rustcon the original project where I ran into this (not the minimal example, hence the different script in the command line) and it points to #123719 as the commit that introduced the regression.cargo-bisect-rustcoutputsearched nightlies: from nightly-2022-06-21 to nightly-2024-04-16
regressed nightly: nightly-2024-04-15
searched commit range: 0bf471f...0d8b334
regressed commit: 29b1207
bisected with cargo-bisect-rustc v0.6.8
Host triple: x86_64-pc-windows-msvc
Reproduce with:
cargo bisect-rustc --start=2022-06-21 -c rust-src --script python -- .\cargo-bisect-rustc-test.pyThe text was updated successfully, but these errors were encountered: