2e832047c6
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.
(cherry picked from commit 69b71e4410)
45 lines
1.2 KiB
Rust
45 lines
1.2 KiB
Rust
//@ revisions: align16 align1024
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//@ compile-flags: -C no-prepopulate-passes -Z mir-opt-level=0
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//@ [align16] compile-flags: -Zmin-function-alignment=16
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//@ [align1024] compile-flags: -Zmin-function-alignment=1024
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#![crate_type = "lib"]
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// FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
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#![feature(rustc_attrs)]
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#![feature(fn_align)]
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// functions without explicit alignment use the global minimum
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//
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// CHECK-LABEL: @no_explicit_align
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// align16: align 16
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// align1024: align 1024
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#[no_mangle]
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pub fn no_explicit_align() {}
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// CHECK-LABEL: @lower_align
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// align16: align 16
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// align1024: align 1024
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#[no_mangle]
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#[rustc_align(8)]
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pub fn lower_align() {}
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// the higher value of min-function-alignment and the align attribute wins out
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//
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// CHECK-LABEL: @higher_align
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// align16: align 32
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// align1024: align 1024
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#[no_mangle]
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#[rustc_align(32)]
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pub fn higher_align() {}
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// cold functions follow the same rules as other functions
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//
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// in GCC, the `-falign-functions` does not apply to cold functions, but
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// `-Zmin-function-alignment` applies to all functions.
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//
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// CHECK-LABEL: @no_explicit_align_cold
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// align16: align 16
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// align1024: align 1024
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#[no_mangle]
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#[cold]
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pub fn no_explicit_align_cold() {}
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