diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/const_eval/machine.rs')
| -rw-r--r-- | compiler/rustc_const_eval/src/const_eval/machine.rs | 117 |
1 files changed, 57 insertions, 60 deletions
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs index fc2e6652a..e5acacd91 100644 --- a/compiler/rustc_const_eval/src/const_eval/machine.rs +++ b/compiler/rustc_const_eval/src/const_eval/machine.rs @@ -35,21 +35,7 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>> { // All `#[rustc_do_not_const_check]` functions should be hooked here. let def_id = instance.def_id(); - if Some(def_id) == self.tcx.lang_items().const_eval_select() { - // redirect to const_eval_select_ct - if let Some(const_eval_select) = self.tcx.lang_items().const_eval_select_ct() { - return Ok(Some( - ty::Instance::resolve( - *self.tcx, - ty::ParamEnv::reveal_all(), - const_eval_select, - instance.substs, - ) - .unwrap() - .unwrap(), - )); - } - } else if Some(def_id) == self.tcx.lang_items().panic_display() + if Some(def_id) == self.tcx.lang_items().panic_display() || Some(def_id) == self.tcx.lang_items().begin_panic_fn() { // &str or &&str @@ -89,10 +75,10 @@ pub struct CompileTimeInterpreter<'mir, 'tcx> { /// exhaustion error. /// /// Setting this to `0` disables the limit and allows the interpreter to run forever. - pub steps_remaining: usize, + pub(super) steps_remaining: usize, /// The virtual call stack. - pub(crate) stack: Vec<Frame<'mir, 'tcx, AllocId, ()>>, + pub(super) stack: Vec<Frame<'mir, 'tcx, AllocId, ()>>, /// We need to make sure consts never point to anything mutable, even recursively. That is /// relied on for pattern matching on consts with references. @@ -101,14 +87,22 @@ pub struct CompileTimeInterpreter<'mir, 'tcx> { /// * Pointers to allocations inside of statics can never leak outside, to a non-static global. /// This boolean here controls the second part. pub(super) can_access_statics: bool, + + /// Whether to check alignment during evaluation. + pub(super) check_alignment: bool, } impl<'mir, 'tcx> CompileTimeInterpreter<'mir, 'tcx> { - pub(crate) fn new(const_eval_limit: Limit, can_access_statics: bool) -> Self { + pub(crate) fn new( + const_eval_limit: Limit, + can_access_statics: bool, + check_alignment: bool, + ) -> Self { CompileTimeInterpreter { steps_remaining: const_eval_limit.0, stack: Vec::new(), can_access_statics, + check_alignment, } } } @@ -197,34 +191,35 @@ impl interpret::MayLeak for ! { } impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> { - fn guaranteed_eq(&mut self, a: Scalar, b: Scalar) -> InterpResult<'tcx, bool> { + /// See documentation on the `ptr_guaranteed_cmp` intrinsic. + fn guaranteed_cmp(&mut self, a: Scalar, b: Scalar) -> InterpResult<'tcx, u8> { Ok(match (a, b) { // Comparisons between integers are always known. - (Scalar::Int { .. }, Scalar::Int { .. }) => a == b, - // Equality with integers can never be known for sure. - (Scalar::Int { .. }, Scalar::Ptr(..)) | (Scalar::Ptr(..), Scalar::Int { .. }) => false, - // FIXME: return `true` for when both sides are the same pointer, *except* that - // some things (like functions and vtables) do not have stable addresses - // so we need to be careful around them (see e.g. #73722). - (Scalar::Ptr(..), Scalar::Ptr(..)) => false, - }) - } - - fn guaranteed_ne(&mut self, a: Scalar, b: Scalar) -> InterpResult<'tcx, bool> { - Ok(match (a, b) { - // Comparisons between integers are always known. - (Scalar::Int(_), Scalar::Int(_)) => a != b, + (Scalar::Int { .. }, Scalar::Int { .. }) => { + if a == b { + 1 + } else { + 0 + } + } // Comparisons of abstract pointers with null pointers are known if the pointer // is in bounds, because if they are in bounds, the pointer can't be null. // Inequality with integers other than null can never be known for sure. (Scalar::Int(int), ptr @ Scalar::Ptr(..)) - | (ptr @ Scalar::Ptr(..), Scalar::Int(int)) => { - int.is_null() && !self.scalar_may_be_null(ptr)? + | (ptr @ Scalar::Ptr(..), Scalar::Int(int)) + if int.is_null() && !self.scalar_may_be_null(ptr)? => + { + 0 } - // FIXME: return `true` for at least some comparisons where we can reliably + // Equality with integers can never be known for sure. + (Scalar::Int { .. }, Scalar::Ptr(..)) | (Scalar::Ptr(..), Scalar::Int { .. }) => 2, + // FIXME: return a `1` for when both sides are the same pointer, *except* that + // some things (like functions and vtables) do not have stable addresses + // so we need to be careful around them (see e.g. #73722). + // FIXME: return `0` for at least some comparisons where we can reliably // determine the result of runtime inequality tests at compile-time. // Examples include comparison of addresses in different static items. - (Scalar::Ptr(..), Scalar::Ptr(..)) => false, + (Scalar::Ptr(..), Scalar::Ptr(..)) => 2, }) } } @@ -236,6 +231,16 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, const PANIC_ON_ALLOC_FAIL: bool = false; // will be raised as a proper error + #[inline(always)] + fn enforce_alignment(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool { + ecx.machine.check_alignment + } + + #[inline(always)] + fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool { + ecx.tcx.sess.opts.unstable_opts.extra_const_ub_checks + } + fn load_mir( ecx: &InterpCx<'mir, 'tcx, Self>, instance: ty::InstanceDef<'tcx>, @@ -251,9 +256,10 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, ); throw_inval!(AlreadyReported(guar)); } else { + // `find_mir_or_eval_fn` checks that this is a const fn before even calling us, + // so this should be unreachable. let path = ecx.tcx.def_path_str(def.did); - Err(ConstEvalErrKind::NeedsRfc(format!("calling extern function `{}`", path)) - .into()) + bug!("trying to call extern function `{path}` at compile-time"); } } _ => Ok(ecx.tcx.instance_mir(instance)), @@ -321,22 +327,14 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, // CTFE-specific intrinsics. let Some(ret) = target else { - return Err(ConstEvalErrKind::NeedsRfc(format!( - "calling intrinsic `{}`", - intrinsic_name - )) - .into()); + throw_unsup_format!("intrinsic `{intrinsic_name}` is not supported at compile-time"); }; match intrinsic_name { - sym::ptr_guaranteed_eq | sym::ptr_guaranteed_ne => { - let a = ecx.read_immediate(&args[0])?.to_scalar()?; - let b = ecx.read_immediate(&args[1])?.to_scalar()?; - let cmp = if intrinsic_name == sym::ptr_guaranteed_eq { - ecx.guaranteed_eq(a, b)? - } else { - ecx.guaranteed_ne(a, b)? - }; - ecx.write_scalar(Scalar::from_bool(cmp), dest)?; + sym::ptr_guaranteed_cmp => { + let a = ecx.read_scalar(&args[0])?; + let b = ecx.read_scalar(&args[1])?; + let cmp = ecx.guaranteed_cmp(a, b)?; + ecx.write_scalar(Scalar::from_u8(cmp), dest)?; } sym::const_allocate => { let size = ecx.read_scalar(&args[0])?.to_machine_usize(ecx)?; @@ -382,11 +380,9 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, } } _ => { - return Err(ConstEvalErrKind::NeedsRfc(format!( - "calling intrinsic `{}`", - intrinsic_name - )) - .into()); + throw_unsup_format!( + "intrinsic `{intrinsic_name}` is not supported at compile-time" + ); } } @@ -429,7 +425,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, _left: &ImmTy<'tcx>, _right: &ImmTy<'tcx>, ) -> InterpResult<'tcx, (Scalar, bool, Ty<'tcx>)> { - Err(ConstEvalErrKind::NeedsRfc("pointer arithmetic or comparison".to_string()).into()) + throw_unsup_format!("pointer arithmetic or comparison is not supported at compile-time"); } fn before_terminator(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> { @@ -451,7 +447,8 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, _ecx: &mut InterpCx<'mir, 'tcx, Self>, _ptr: Pointer<AllocId>, ) -> InterpResult<'tcx> { - Err(ConstEvalErrKind::NeedsRfc("exposing pointers".to_string()).into()) + // This is only reachable with -Zunleash-the-miri-inside-of-you. + throw_unsup_format!("exposing pointers is not possible at compile-time") } #[inline(always)] |