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Rollup merge of #127935 - tgross35:binary_asm_labels-x86-only, r=estebank,Urgau

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Change `binary_asm_labels` to only fire on x86 and x86_64

In <https://github.com/rust-lang/rust/pull/126922>, the `binary_asm_labels` lint was added which flags labels such as `0:` and `1:`. Before that change, LLVM was giving a confusing error on x86/x86_64 because of an incorrect interpretation.

However, targets other than x86 and x86_64 never had the error message and have not been a problem. This means that the lint was causing code that previously worked to start failing (e.g. `compiler_builtins`), rather than only providing a more clear messages where there has always been an error.

Adjust the lint to only fire on x86 and x86_64 assembly to avoid this regression.

Also update the help message.

Fixes: https://github.com/rust-lang/rust/issues/127821
This commit is contained in:
Trevor Gross 2024-07-19 03:27:50 -05:00 committed by GitHub
commit 6bdf9bd276
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5 changed files with 77 additions and 26 deletions
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5
compiler/rustc_lint/messages.ftl
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@ -403,8 +403,9 @@ lint_inner_macro_attribute_unstable = inner macro attributes are unstable
lint_invalid_asm_label_binary = avoid using labels containing only the digits `0` and `1` in inline assembly
.label = use a different label that doesn't start with `0` or `1`
.note = an LLVM bug makes these labels ambiguous with a binary literal number
.note = see <https://bugs.llvm.org/show_bug.cgi?id=36144> for more information
.help = start numbering with `2` instead
.note1 = an LLVM bug makes these labels ambiguous with a binary literal number on x86
.note2 = see <https://github.com/llvm/llvm-project/issues/99547> for more information
lint_invalid_asm_label_format_arg = avoid using named labels in inline assembly
.help = only local labels of the form `<number>:` should be used in inline asm

57
compiler/rustc_lint/src/builtin.rs
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@ -66,6 +66,7 @@ use rustc_span::source_map::Spanned;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, InnerSpan, Span};
use rustc_target::abi::Abi;
use rustc_target::asm::InlineAsmArch;
use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
use rustc_trait_selection::traits::{self, misc::type_allowed_to_implement_copy};
@ -2739,8 +2740,9 @@ declare_lint! {
///
/// ### Example
///
/// ```rust,compile_fail
/// # #![feature(asm_experimental_arch)]
/// ```rust,ignore (fails on non-x86_64)
/// #![cfg(target_arch = "x86_64")]
///
/// use std::arch::asm;
///
/// fn main() {
@ -2750,19 +2752,32 @@ declare_lint! {
/// }
/// ```
///
/// {{produces}}
/// This will produce:
///
/// ```text
/// error: avoid using labels containing only the digits `0` and `1` in inline assembly
/// --> <source>:7:15
/// |
/// 7 | asm!("0: jmp 0b");
/// | ^ use a different label that doesn't start with `0` or `1`
/// |
/// = help: start numbering with `2` instead
/// = note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
/// = note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
/// = note: `#[deny(binary_asm_labels)]` on by default
/// ```
///
/// ### Explanation
///
/// A [LLVM bug] causes this code to fail to compile because it interprets the `0b` as a binary
/// literal instead of a reference to the previous local label `0`. Note that even though the
/// bug is marked as fixed, it only fixes a specific usage of intel syntax within standalone
/// files, not inline assembly. To work around this bug, don't use labels that could be
/// confused with a binary literal.
/// An [LLVM bug] causes this code to fail to compile because it interprets the `0b` as a binary
/// literal instead of a reference to the previous local label `0`. To work around this bug,
/// don't use labels that could be confused with a binary literal.
///
/// This behavior is platform-specific to x86 and x86-64.
///
/// See the explanation in [Rust By Example] for more details.
///
/// [LLVM bug]: https://bugs.llvm.org/show_bug.cgi?id=36144
/// [LLVM bug]: https://github.com/llvm/llvm-project/issues/99547
/// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels
pub BINARY_ASM_LABELS,
Deny,
@ -2908,16 +2923,22 @@ impl<'tcx> LateLintPass<'tcx> for AsmLabels {
InvalidAsmLabel::FormatArg { missing_precise_span },
);
}
AsmLabelKind::Binary => {
// the binary asm issue only occurs when using intel syntax
if !options.contains(InlineAsmOptions::ATT_SYNTAX) {
cx.emit_span_lint(
BINARY_ASM_LABELS,
span,
InvalidAsmLabel::Binary { missing_precise_span, span },
)
}
// the binary asm issue only occurs when using intel syntax on x86 targets
AsmLabelKind::Binary
if !options.contains(InlineAsmOptions::ATT_SYNTAX)
&& matches!(
cx.tcx.sess.asm_arch,
Some(InlineAsmArch::X86 | InlineAsmArch::X86_64) | None
) =>
{
cx.emit_span_lint(
BINARY_ASM_LABELS,
span,
InvalidAsmLabel::Binary { missing_precise_span, span },
)
}
// No lint on anything other than x86
AsmLabelKind::Binary => (),
};
}
}

4
compiler/rustc_lint/src/lints.rs
View File

@ -2074,7 +2074,9 @@ pub enum InvalidAsmLabel {
missing_precise_span: bool,
},
#[diag(lint_invalid_asm_label_binary)]
#[note]
#[help]
#[note(lint_note1)]
#[note(lint_note2)]
Binary {
#[note(lint_invalid_asm_label_no_span)]
missing_precise_span: bool,

20
tests/ui/asm/binary_asm_labels.stderr
View File

@ -4,7 +4,9 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
LL | asm!("0: jmp 0b");
| ^ use a different label that doesn't start with `0` or `1`
|
= note: an LLVM bug makes these labels ambiguous with a binary literal number
= help: start numbering with `2` instead
= note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
= note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
= note: `#[deny(binary_asm_labels)]` on by default
error: avoid using labels containing only the digits `0` and `1` in inline assembly
@ -13,7 +15,9 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
LL | asm!("1: jmp 1b");
| ^ use a different label that doesn't start with `0` or `1`
|
= note: an LLVM bug makes these labels ambiguous with a binary literal number
= help: start numbering with `2` instead
= note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
= note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
error: avoid using labels containing only the digits `0` and `1` in inline assembly
--> $DIR/binary_asm_labels.rs:13:15
@ -21,7 +25,9 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
LL | asm!("10: jmp 10b");
| ^^ use a different label that doesn't start with `0` or `1`
|
= note: an LLVM bug makes these labels ambiguous with a binary literal number
= help: start numbering with `2` instead
= note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
= note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
error: avoid using labels containing only the digits `0` and `1` in inline assembly
--> $DIR/binary_asm_labels.rs:14:15
@ -29,7 +35,9 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
LL | asm!("01: jmp 01b");
| ^^ use a different label that doesn't start with `0` or `1`
|
= note: an LLVM bug makes these labels ambiguous with a binary literal number
= help: start numbering with `2` instead
= note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
= note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
error: avoid using labels containing only the digits `0` and `1` in inline assembly
--> $DIR/binary_asm_labels.rs:15:15
@ -37,7 +45,9 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
LL | asm!("1001101: jmp 1001101b");
| ^^^^^^^ use a different label that doesn't start with `0` or `1`
|
= note: an LLVM bug makes these labels ambiguous with a binary literal number
= help: start numbering with `2` instead
= note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
= note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
error: aborting due to 5 previous errors

17
tests/ui/asm/binary_asm_labels_allowed.rs Normal file
View File

@ -0,0 +1,17 @@
//@ build-pass
//@ only-aarch64
// The `binary_asm_labels` lint should only be raised on `x86`. Make sure it
// doesn't get raised on other platforms.
use std::arch::asm;
fn main() {
unsafe {
asm!("0: bl 0b");
asm!("1: bl 1b");
asm!("10: bl 10b");
asm!("01: bl 01b");
asm!("1001101: bl 1001101b");
}
}