bjoernager/rust
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Auto merge of #122629 - RalfJung:assert-unsafe-precondition, r=saethlin

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refactor check_{lang,library}_ub: use a single intrinsic

This enacts the plan I laid out [here](https://github.com/rust-lang/rust/pull/122282#issuecomment-1996917998): use a single intrinsic, called `ub_checks` (in aniticpation of https://github.com/rust-lang/compiler-team/issues/725), that just exposes the value of `debug_assertions` (consistently implemented in both codegen and the interpreter). Put the language vs library UB logic into the library.

This makes it easier to do something like https://github.com/rust-lang/rust/pull/122282 in the future: that just slightly alters the semantics of `ub_checks` (making it more approximating when crates built with different flags are mixed), but it no longer affects whether these checks can happen in Miri or compile-time.

The first commit just moves things around; I don't think these macros and functions belong into `intrinsics.rs` as they are not intrinsics.

r? `@saethlin`
This commit is contained in:
bors 2024-03-23 21:11:00 +00:00
commit 2f090c30dd
48 changed files with 313 additions and 291 deletions
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12
compiler/rustc_const_eval/src/interpret/step.rs
View file

@ -258,17 +258,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let val = layout.offset_of_subfield(self, fields.iter()).bytes();
Scalar::from_target_usize(val, self)
}
mir::NullOp::UbCheck(kind) => {
// We want to enable checks for library UB, because the interpreter doesn't
// know about those on its own.
// But we want to disable checks for language UB, because the interpreter
// has its own better checks for that.
let should_check = match kind {
mir::UbKind::LibraryUb => self.tcx.sess.opts.debug_assertions,
mir::UbKind::LanguageUb => false,
};
Scalar::from_bool(should_check)
}
mir::NullOp::UbChecks => Scalar::from_bool(self.tcx.sess.opts.debug_assertions),
};
self.write_scalar(val, &dest)?;
}

2
compiler/rustc_const_eval/src/transform/check_consts/check.rs
View file

@ -558,7 +558,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
Rvalue::Cast(_, _, _) => {}
Rvalue::NullaryOp(
NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(_) | NullOp::UbCheck(_),
NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(_) | NullOp::UbChecks,
_,
) => {}
Rvalue::ShallowInitBox(_, _) => {}

2
compiler/rustc_const_eval/src/transform/validate.rs
View file

@ -1168,7 +1168,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
Rvalue::Repeat(_, _)
| Rvalue::ThreadLocalRef(_)
| Rvalue::AddressOf(_, _)
| Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::UbCheck(_), _)
| Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::UbChecks, _)
| Rvalue::Discriminant(_) => {}
}
self.super_rvalue(rvalue, location);