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Rollup merge of #131544 - nbdd0121:asm_goto_safe_block, r=petrochenkov

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Make asm label blocks safe context

Tracking issue: https://github.com/rust-lang/rust/issues/119364

`asm!()` is forced to be wrapped inside unsafe. If there's no special treatment, the label blocks would also always be unsafe with no way of opting out. It was suggested that a simple fix is to make asm label blocks safe: https://github.com/rust-lang/rust/issues/119364#issuecomment-2316037703.

`@rustbot` labels: +A-inline-assembly +F-asm
This commit is contained in:
Matthias Krüger 2024-11-21 11:58:37 +01:00 • committed by GitHub
commit 395649558a
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4 changed files with 78 additions and 2 deletions
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39
compiler/rustc_mir_build/src/check_unsafety.rs
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@ -537,8 +537,45 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
self.requires_unsafe(expr.span, DerefOfRawPointer);
}
}
ExprKind::InlineAsm { .. } => {
ExprKind::InlineAsm(box InlineAsmExpr {
asm_macro: _,
ref operands,
template: _,
options: _,
line_spans: _,
}) => {
self.requires_unsafe(expr.span, UseOfInlineAssembly);
// For inline asm, do not use `walk_expr`, since we want to handle the label block
// specially.
for op in &**operands {
use rustc_middle::thir::InlineAsmOperand::*;
match op {
In { expr, reg: _ }
| Out { expr: Some(expr), reg: _, late: _ }
| InOut { expr, reg: _, late: _ } => self.visit_expr(&self.thir()[*expr]),
SplitInOut { in_expr, out_expr, reg: _, late: _ } => {
self.visit_expr(&self.thir()[*in_expr]);
if let Some(out_expr) = out_expr {
self.visit_expr(&self.thir()[*out_expr]);
}
}
Out { expr: None, reg: _, late: _ }
| Const { value: _, span: _ }
| SymFn { value: _, span: _ }
| SymStatic { def_id: _ } => {}
Label { block } => {
// Label blocks are safe context.
// `asm!()` is forced to be wrapped inside unsafe. If there's no special
// treatment, the label blocks would also always be unsafe with no way
// of opting out.
self.in_safety_context(SafetyContext::Safe, |this| {
visit::walk_block(this, &this.thir()[*block])
});
}
}
}
return;
}
ExprKind::Adt(box AdtExpr {
adt_def,