69b71e4410
From `#[align]` -> `#[rustc_align]`. Attributes starting with `rustc`
are always perma-unstable and feature-gated by `feature(rustc_attrs)`.
See regression RUST-143834.
For the underlying problem where even introducing new feature-gated
unstable built-in attributes can break user code such as
```rs
macro_rules! align {
() => {
/* .. */
};
}
pub(crate) use align; // `use` here becomes ambiguous
```
refer to RUST-134963.
Since the `#[align]` attribute is still feature-gated by
`feature(fn_align)`, we can rename it as a mitigation. Note that
`#[rustc_align]` will obviously mean that current unstable user code
using `feature(fn_aling)` will need additionally `feature(rustc_attrs)`,
but this is a short-term mitigation to buy time, and is expected to be
changed to a better name with less collision potential.
See
<https://rust-lang.zulipchat.com/#narrow/channel/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202025-07-17/near/529290371>
where mitigation options were considered.
48 lines
1.5 KiB
Rust
48 lines
1.5 KiB
Rust
//@ revisions: align16 align1024
|
|
//@ compile-flags: -C no-prepopulate-passes -Z mir-opt-level=0 -Clink-dead-code
|
|
//@ [align16] compile-flags: -Zmin-function-alignment=16
|
|
//@ [align1024] compile-flags: -Zmin-function-alignment=1024
|
|
//@ ignore-wasm32 aligning functions is not currently supported on wasm (#143368)
|
|
|
|
#![crate_type = "lib"]
|
|
// FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
|
|
#![feature(rustc_attrs)]
|
|
#![feature(fn_align)]
|
|
|
|
// Functions without explicit alignment use the global minimum.
|
|
//
|
|
// NOTE: this function deliberately has zero (0) attributes! That is to make sure that
|
|
// `-Zmin-function-alignment` is applied regardless of whether attributes are used.
|
|
//
|
|
// CHECK-LABEL: no_explicit_align
|
|
// align16: align 16
|
|
// align1024: align 1024
|
|
pub fn no_explicit_align() {}
|
|
|
|
// CHECK-LABEL: @lower_align
|
|
// align16: align 16
|
|
// align1024: align 1024
|
|
#[no_mangle]
|
|
#[rustc_align(8)]
|
|
pub fn lower_align() {}
|
|
|
|
// the higher value of min-function-alignment and the align attribute wins out
|
|
//
|
|
// CHECK-LABEL: @higher_align
|
|
// align16: align 32
|
|
// align1024: align 1024
|
|
#[no_mangle]
|
|
#[rustc_align(32)]
|
|
pub fn higher_align() {}
|
|
|
|
// cold functions follow the same rules as other functions
|
|
//
|
|
// in GCC, the `-falign-functions` does not apply to cold functions, but
|
|
// `-Zmin-function-alignment` applies to all functions.
|
|
//
|
|
// CHECK-LABEL: @no_explicit_align_cold
|
|
// align16: align 16
|
|
// align1024: align 1024
|
|
#[no_mangle]
|
|
#[cold]
|
|
pub fn no_explicit_align_cold() {}
|