Add an unused field of type Option<DefId> to ParamEnv struct.

This commit is contained in:
Bram van den Heuvel 2020-09-19 12:06:17 +02:00
parent 70148d7b31
commit ab83d372ed
3 changed files with 6 additions and 3 deletions

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@ -57,7 +57,7 @@ pub struct Obligation<'tcx, T> {
// `PredicateObligation` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(target_arch = "x86_64")]
static_assert_size!(PredicateObligation<'_>, 32);
static_assert_size!(PredicateObligation<'_>, 40);
pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;

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@ -1745,6 +1745,9 @@ pub struct ParamEnv<'tcx> {
///
/// Note: This is packed, use the reveal() method to access it.
packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, traits::Reveal, true>,
/// FIXME: This field is not used, but removing it causes a performance degradation. See #76913.
unused_field: Option<DefId>,
}
unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal {
@ -1825,7 +1828,7 @@ pub fn reveal_all() -> Self {
/// Construct a trait environment with the given set of predicates.
#[inline]
pub fn new(caller_bounds: &'tcx List<Predicate<'tcx>>, reveal: Reveal) -> Self {
ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal) }
ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal), unused_field: None }
}
pub fn with_user_facing(mut self) -> Self {

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@ -87,7 +87,7 @@ pub struct PendingPredicateObligation<'tcx> {
// `PendingPredicateObligation` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(target_arch = "x86_64")]
static_assert_size!(PendingPredicateObligation<'_>, 56);
static_assert_size!(PendingPredicateObligation<'_>, 64);
impl<'a, 'tcx> FulfillmentContext<'tcx> {
/// Creates a new fulfillment context.