diff options
Diffstat (limited to 'compiler/rustc_transmute')
| -rw-r--r-- | compiler/rustc_transmute/src/layout/tree.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_transmute/src/lib.rs | 20 | ||||
| -rw-r--r-- | compiler/rustc_transmute/src/maybe_transmutable/mod.rs | 152 | ||||
| -rw-r--r-- | compiler/rustc_transmute/src/maybe_transmutable/tests.rs | 12 |
4 files changed, 99 insertions, 89 deletions
diff --git a/compiler/rustc_transmute/src/layout/tree.rs b/compiler/rustc_transmute/src/layout/tree.rs index ed9309b015d..6b718be7b15 100644 --- a/compiler/rustc_transmute/src/layout/tree.rs +++ b/compiler/rustc_transmute/src/layout/tree.rs @@ -188,14 +188,14 @@ pub(crate) mod rustc { /// The layout of the type is unspecified. Unspecified, /// This error will be surfaced elsewhere by rustc, so don't surface it. - Unknown, + UnknownLayout, TypeError(ErrorGuaranteed), } impl<'tcx> From<LayoutError<'tcx>> for Err { fn from(err: LayoutError<'tcx>) -> Self { match err { - LayoutError::Unknown(..) => Self::Unknown, + LayoutError::Unknown(..) => Self::UnknownLayout, err => unimplemented!("{:?}", err), } } diff --git a/compiler/rustc_transmute/src/lib.rs b/compiler/rustc_transmute/src/lib.rs index 7a8cbd50d45..34ad6bd8c69 100644 --- a/compiler/rustc_transmute/src/lib.rs +++ b/compiler/rustc_transmute/src/lib.rs @@ -19,10 +19,16 @@ pub struct Assume { pub validity: bool, } -/// Either we have an error, or we have an optional Condition that must hold. -pub type Answer<R> = Result<Option<Condition<R>>, Reason>; +/// Either we have an error, transmutation is allowed, or we have an optional +/// Condition that must hold. +#[derive(Debug, Hash, Eq, PartialEq, Clone)] +pub enum Answer<R> { + Yes, + No(Reason), + If(Condition<R>), +} -/// A condition which must hold for safe transmutation to be possible +/// A condition which must hold for safe transmutation to be possible. #[derive(Debug, Hash, Eq, PartialEq, Clone)] pub enum Condition<R> { /// `Src` is transmutable into `Dst`, if `src` is transmutable into `dst`. @@ -35,7 +41,7 @@ pub enum Condition<R> { IfAny(Vec<Condition<R>>), } -/// Answers: Why wasn't the source type transmutable into the destination type? +/// Answers "why wasn't the source type transmutable into the destination type?" #[derive(Debug, Hash, Eq, PartialEq, PartialOrd, Ord, Clone)] pub enum Reason { /// The layout of the source type is unspecified. @@ -52,6 +58,12 @@ pub enum Reason { DstHasStricterAlignment { src_min_align: usize, dst_min_align: usize }, /// Can't go from shared pointer to unique pointer DstIsMoreUnique, + /// Encountered a type error + TypeError, + /// The layout of src is unknown + SrcLayoutUnknown, + /// The layout of dst is unknown + DstLayoutUnknown, } #[cfg(feature = "rustc")] diff --git a/compiler/rustc_transmute/src/maybe_transmutable/mod.rs b/compiler/rustc_transmute/src/maybe_transmutable/mod.rs index 80e3489e99b..b223a90f751 100644 --- a/compiler/rustc_transmute/src/maybe_transmutable/mod.rs +++ b/compiler/rustc_transmute/src/maybe_transmutable/mod.rs @@ -33,6 +33,7 @@ where Self { src, dst, scope, assume, context } } + // FIXME(bryangarza): Delete this when all usages are removed pub(crate) fn map_layouts<F, M>( self, f: F, @@ -67,30 +68,26 @@ mod rustc { /// then computes an answer using those trees. #[instrument(level = "debug", skip(self), fields(src = ?self.src, dst = ?self.dst))] pub fn answer(self) -> Answer<<TyCtxt<'tcx> as QueryContext>::Ref> { - let query_or_answer = self.map_layouts(|src, dst, scope, &context| { - // Convert `src` and `dst` from their rustc representations, to `Tree`-based - // representations. If these conversions fail, conclude that the transmutation is - // unacceptable; the layouts of both the source and destination types must be - // well-defined. - let src = Tree::from_ty(src, context); - let dst = Tree::from_ty(dst, context); - - match (src, dst) { - // Answer `Ok(None)` here, because 'unknown layout' and type errors will already - // be reported by rustc. No need to spam the user with more errors. - (Err(Err::TypeError(_)), _) - | (_, Err(Err::TypeError(_))) - | (Err(Err::Unknown), _) - | (_, Err(Err::Unknown)) => Err(Ok(None)), - (Err(Err::Unspecified), _) => Err(Err(Reason::SrcIsUnspecified)), - (_, Err(Err::Unspecified)) => Err(Err(Reason::DstIsUnspecified)), - (Ok(src), Ok(dst)) => Ok((src, dst)), + let Self { src, dst, scope, assume, context } = self; + + // Convert `src` and `dst` from their rustc representations, to `Tree`-based + // representations. If these conversions fail, conclude that the transmutation is + // unacceptable; the layouts of both the source and destination types must be + // well-defined. + let src = Tree::from_ty(src, context); + let dst = Tree::from_ty(dst, context); + + match (src, dst) { + (Err(Err::TypeError(_)), _) | (_, Err(Err::TypeError(_))) => { + Answer::No(Reason::TypeError) + } + (Err(Err::UnknownLayout), _) => Answer::No(Reason::SrcLayoutUnknown), + (_, Err(Err::UnknownLayout)) => Answer::No(Reason::DstLayoutUnknown), + (Err(Err::Unspecified), _) => Answer::No(Reason::SrcIsUnspecified), + (_, Err(Err::Unspecified)) => Answer::No(Reason::DstIsUnspecified), + (Ok(src), Ok(dst)) => { + MaybeTransmutableQuery { src, dst, scope, assume, context }.answer() } - }); - - match query_or_answer { - Ok(query) => query.answer(), - Err(answer) => answer, } } } @@ -108,6 +105,7 @@ where #[instrument(level = "debug", skip(self), fields(src = ?self.src, dst = ?self.dst))] pub(crate) fn answer(self) -> Answer<<C as QueryContext>::Ref> { let assume_visibility = self.assume.safety; + // FIXME(bryangarza): Refactor this code to get rid of `map_layouts` let query_or_answer = self.map_layouts(|src, dst, scope, context| { // Remove all `Def` nodes from `src`, without checking their visibility. let src = src.prune(&|def| true); @@ -128,12 +126,13 @@ where // Convert `src` from a tree-based representation to an NFA-based representation. // If the conversion fails because `src` is uninhabited, conclude that the transmutation // is acceptable, because instances of the `src` type do not exist. - let src = Nfa::from_tree(src).map_err(|Uninhabited| Ok(None))?; + let src = Nfa::from_tree(src).map_err(|Uninhabited| Answer::Yes)?; // Convert `dst` from a tree-based representation to an NFA-based representation. // If the conversion fails because `src` is uninhabited, conclude that the transmutation // is unacceptable, because instances of the `dst` type do not exist. - let dst = Nfa::from_tree(dst).map_err(|Uninhabited| Err(Reason::DstIsPrivate))?; + let dst = + Nfa::from_tree(dst).map_err(|Uninhabited| Answer::No(Reason::DstIsPrivate))?; Ok((src, dst)) }); @@ -155,6 +154,7 @@ where #[inline(always)] #[instrument(level = "debug", skip(self), fields(src = ?self.src, dst = ?self.dst))] pub(crate) fn answer(self) -> Answer<<C as QueryContext>::Ref> { + // FIXME(bryangarza): Refactor this code to get rid of `map_layouts` let query_or_answer = self .map_layouts(|src, dst, scope, context| Ok((Dfa::from_nfa(src), Dfa::from_nfa(dst)))); @@ -226,13 +226,13 @@ where // So, if it's possible to transmute to a smaller Dst by truncating, and we can guarantee // that none of the actually-used data can introduce an invalid state for Dst's type, we // are able to safely transmute, even with truncation. - Ok(None) + Answer::Yes } else if src_state == self.src.accepting { // extension: `size_of(Src) >= size_of(Dst)` if let Some(dst_state_prime) = self.dst.byte_from(dst_state, Byte::Uninit) { self.answer_memo(cache, src_state, dst_state_prime) } else { - Err(Reason::DstIsTooBig) + Answer::No(Reason::DstIsTooBig) } } else { let src_quantifier = if self.assume.validity { @@ -265,7 +265,7 @@ where } else { // otherwise, we've exhausted our options. // the DFAs, from this point onwards, are bit-incompatible. - Err(Reason::DstIsBitIncompatible) + Answer::No(Reason::DstIsBitIncompatible) } }, ), @@ -282,8 +282,8 @@ where // the algoritm; only its performance. debug!(?bytes_answer); match bytes_answer { - Err(_) if !self.assume.validity => return bytes_answer, - Ok(None) if self.assume.validity => return bytes_answer, + Answer::No(_) if !self.assume.validity => return bytes_answer, + Answer::Yes if self.assume.validity => return bytes_answer, _ => {} }; @@ -299,11 +299,11 @@ where .into_iter() .map(|(&dst_ref, &dst_state_prime)| { if !src_ref.is_mutable() && dst_ref.is_mutable() { - Err(Reason::DstIsMoreUnique) + Answer::No(Reason::DstIsMoreUnique) } else if !self.assume.alignment && src_ref.min_align() < dst_ref.min_align() { - Err(Reason::DstHasStricterAlignment { + Answer::No(Reason::DstHasStricterAlignment { src_min_align: src_ref.min_align(), dst_min_align: dst_ref.min_align(), }) @@ -311,10 +311,10 @@ where // ...such that `src` is transmutable into `dst`, if // `src_ref` is transmutability into `dst_ref`. and( - Ok(Some(Condition::IfTransmutable { + Answer::If(Condition::IfTransmutable { src: src_ref, dst: dst_ref, - })), + }), self.answer_memo( cache, src_state_prime, @@ -346,65 +346,56 @@ fn and<R>(lhs: Answer<R>, rhs: Answer<R>) -> Answer<R> where R: PartialEq, { - // If both are errors, then we should return the more specific one - if lhs.is_err() && rhs.is_err() { - if lhs == Err(Reason::DstIsBitIncompatible) { - return rhs; - } else { - return lhs; - } - } - Ok(match (lhs?, rhs?) { + match (lhs, rhs) { + // If both are errors, then we should return the more specific one + (Answer::No(Reason::DstIsBitIncompatible), Answer::No(reason)) + | (Answer::No(reason), Answer::No(_)) + // If either is an error, return it + | (Answer::No(reason), _) | (_, Answer::No(reason)) => Answer::No(reason), // If only one side has a condition, pass it along - (None, other) | (other, None) => other, + | (Answer::Yes, other) | (other, Answer::Yes) => other, // If both sides have IfAll conditions, merge them - (Some(Condition::IfAll(mut lhs)), Some(Condition::IfAll(ref mut rhs))) => { + (Answer::If(Condition::IfAll(mut lhs)), Answer::If(Condition::IfAll(ref mut rhs))) => { lhs.append(rhs); - Some(Condition::IfAll(lhs)) + Answer::If(Condition::IfAll(lhs)) } // If only one side is an IfAll, add the other Condition to it - (Some(cond), Some(Condition::IfAll(mut conds))) - | (Some(Condition::IfAll(mut conds)), Some(cond)) => { + (Answer::If(cond), Answer::If(Condition::IfAll(mut conds))) + | (Answer::If(Condition::IfAll(mut conds)), Answer::If(cond)) => { conds.push(cond); - Some(Condition::IfAll(conds)) + Answer::If(Condition::IfAll(conds)) } // Otherwise, both lhs and rhs conditions can be combined in a parent IfAll - (Some(lhs), Some(rhs)) => Some(Condition::IfAll(vec![lhs, rhs])), - }) + (Answer::If(lhs), Answer::If(rhs)) => Answer::If(Condition::IfAll(vec![lhs, rhs])), + } } fn or<R>(lhs: Answer<R>, rhs: Answer<R>) -> Answer<R> where R: PartialEq, { - // If both are errors, then we should return the more specific one - if lhs.is_err() && rhs.is_err() { - if lhs == Err(Reason::DstIsBitIncompatible) { - return rhs; - } else { - return lhs; - } - } - // Otherwise, errors can be ignored for the rest of the pattern matching - let lhs = lhs.unwrap_or(None); - let rhs = rhs.unwrap_or(None); - Ok(match (lhs, rhs) { + match (lhs, rhs) { + // If both are errors, then we should return the more specific one + (Answer::No(Reason::DstIsBitIncompatible), Answer::No(reason)) + | (Answer::No(reason), Answer::No(_)) => Answer::No(reason), + // Otherwise, errors can be ignored for the rest of the pattern matching + (Answer::No(_), other) | (other, Answer::No(_)) => or(other, Answer::Yes), // If only one side has a condition, pass it along - (None, other) | (other, None) => other, + (Answer::Yes, other) | (other, Answer::Yes) => other, // If both sides have IfAny conditions, merge them - (Some(Condition::IfAny(mut lhs)), Some(Condition::IfAny(ref mut rhs))) => { + (Answer::If(Condition::IfAny(mut lhs)), Answer::If(Condition::IfAny(ref mut rhs))) => { lhs.append(rhs); - Some(Condition::IfAny(lhs)) + Answer::If(Condition::IfAny(lhs)) } // If only one side is an IfAny, add the other Condition to it - (Some(cond), Some(Condition::IfAny(mut conds))) - | (Some(Condition::IfAny(mut conds)), Some(cond)) => { + (Answer::If(cond), Answer::If(Condition::IfAny(mut conds))) + | (Answer::If(Condition::IfAny(mut conds)), Answer::If(cond)) => { conds.push(cond); - Some(Condition::IfAny(conds)) + Answer::If(Condition::IfAny(conds)) } // Otherwise, both lhs and rhs conditions can be combined in a parent IfAny - (Some(lhs), Some(rhs)) => Some(Condition::IfAny(vec![lhs, rhs])), - }) + (Answer::If(lhs), Answer::If(rhs)) => Answer::If(Condition::IfAny(vec![lhs, rhs])), + } } pub enum Quantifier { @@ -421,16 +412,21 @@ impl Quantifier { use std::ops::ControlFlow::{Break, Continue}; let (init, try_fold_f): (_, fn(_, _) -> _) = match self { - Self::ThereExists => (Err(Reason::DstIsBitIncompatible), |accum: Answer<R>, next| { - match or(accum, next) { - Ok(None) => Break(Ok(None)), + Self::ThereExists => { + (Answer::No(Reason::DstIsBitIncompatible), |accum: Answer<R>, next| { + match or(accum, next) { + Answer::Yes => Break(Answer::Yes), + maybe => Continue(maybe), + } + }) + } + Self::ForAll => (Answer::Yes, |accum: Answer<R>, next| { + let answer = and(accum, next); + match answer { + Answer::No(_) => Break(answer), maybe => Continue(maybe), } }), - Self::ForAll => (Ok(None), |accum: Answer<R>, next| match and(accum, next) { - Err(reason) => Break(Err(reason)), - maybe => Continue(maybe), - }), }; let (Continue(result) | Break(result)) = iter.into_iter().try_fold(init, try_fold_f); diff --git a/compiler/rustc_transmute/src/maybe_transmutable/tests.rs b/compiler/rustc_transmute/src/maybe_transmutable/tests.rs index df6a83df23f..e49bebf571d 100644 --- a/compiler/rustc_transmute/src/maybe_transmutable/tests.rs +++ b/compiler/rustc_transmute/src/maybe_transmutable/tests.rs @@ -4,6 +4,8 @@ use crate::{layout, Reason}; use itertools::Itertools; mod bool { + use crate::Answer; + use super::*; #[test] @@ -17,7 +19,7 @@ mod bool { UltraMinimal, ) .answer(); - assert_eq!(answer, Ok(None)); + assert_eq!(answer, Answer::Yes); } #[test] @@ -30,7 +32,7 @@ mod bool { UltraMinimal, ) .answer(); - assert_eq!(answer, Ok(None)); + assert_eq!(answer, Answer::Yes); } #[test] @@ -65,7 +67,7 @@ mod bool { if src_set.is_subset(&dst_set) { assert_eq!( - Ok(None), + Answer::Yes, MaybeTransmutableQuery::new( src_layout.clone(), dst_layout.clone(), @@ -80,7 +82,7 @@ mod bool { ); } else if !src_set.is_disjoint(&dst_set) { assert_eq!( - Ok(None), + Answer::Yes, MaybeTransmutableQuery::new( src_layout.clone(), dst_layout.clone(), @@ -95,7 +97,7 @@ mod bool { ); } else { assert_eq!( - Err(Reason::DstIsBitIncompatible), + Answer::No(Reason::DstIsBitIncompatible), MaybeTransmutableQuery::new( src_layout.clone(), dst_layout.clone(), |