bjoernager/rust
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allow mutating function args through &raw const

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This commit is contained in:
Lukas Markeffsky 2023-05-12 19:31:37 +02:00
parent 97ed808322
commit 9c418e5170
2 changed files with 50 additions and 5 deletions
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21
compiler/rustc_mir_transform/src/deduce_param_attrs.rs
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@ -8,7 +8,7 @@
use rustc_hir::def_id::LocalDefId;
use rustc_index::bit_set::BitSet;
use rustc_middle::mir::visit::{NonMutatingUseContext, PlaceContext, Visitor};
use rustc_middle::mir::{Body, Local, Location, Operand, Terminator, TerminatorKind, RETURN_PLACE};
use rustc_middle::mir::{Body, Location, Operand, Place, Terminator, TerminatorKind, RETURN_PLACE};
use rustc_middle::ty::{self, DeducedParamAttrs, Ty, TyCtxt};
use rustc_session::config::OptLevel;
@ -29,20 +29,31 @@ impl DeduceReadOnly {
}
impl<'tcx> Visitor<'tcx> for DeduceReadOnly {
fn visit_local(&mut self, local: Local, context: PlaceContext, _location: Location) {
fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) {
// We're only interested in arguments.
if local == RETURN_PLACE || local.index() > self.mutable_args.domain_size() {
if place.local == RETURN_PLACE || place.local.index() > self.mutable_args.domain_size() {
return;
}
match context {
let mark_as_mutable = match context {
PlaceContext::MutatingUse(..) => {
// This is a mutation, so mark it as such.
self.mutable_args.insert(local.index() - 1);
true
}
PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf) => {
// Whether mutating though a `&raw const` is allowed is still undecided, so we
// disable any sketchy `readonly` optimizations for now.
// But we only need to do this if the pointer would point into the argument.
!place.is_indirect()
}
PlaceContext::NonMutatingUse(..) | PlaceContext::NonUse(..) => {
// Not mutating, so it's fine.
false
}
};
if mark_as_mutable {
self.mutable_args.insert(place.local.index() - 1);
}
}