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Auto merge of #112307 - lcnr:operand-ref, r=compiler-errors

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mir opt + codegen: handle subtyping

fixes #107205

the same issue was caused in multiple places:
- mir opts: both copy and destination propagation
- codegen: assigning operands to locals (which also propagates values)

I changed codegen to always update the type in the operands used for locals which should guard against any new occurrences of this bug going forward. I don't know how to make mir optimizations more resilient here. Hopefully the added tests will be enough to detect any trivially wrong optimizations going forward.
This commit is contained in:
bors 2023-06-28 00:41:37 +00:00
commit bb95b7dcd6
12 changed files with 207 additions and 39 deletions
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30
compiler/rustc_mir_transform/src/shim.rs
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@ -32,13 +32,15 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<'
let mut result = match instance {
ty::InstanceDef::Item(..) => bug!("item {:?} passed to make_shim", instance),
ty::InstanceDef::VTableShim(def_id) => {
build_call_shim(tcx, instance, Some(Adjustment::Deref), CallKind::Direct(def_id))
let adjustment = Adjustment::Deref { source: DerefSource::MutPtr };
build_call_shim(tcx, instance, Some(adjustment), CallKind::Direct(def_id))
}
ty::InstanceDef::FnPtrShim(def_id, ty) => {
let trait_ = tcx.trait_of_item(def_id).unwrap();
let adjustment = match tcx.fn_trait_kind_from_def_id(trait_) {
Some(ty::ClosureKind::FnOnce) => Adjustment::Identity,
Some(ty::ClosureKind::FnMut | ty::ClosureKind::Fn) => Adjustment::Deref,
Some(ty::ClosureKind::Fn) => Adjustment::Deref { source: DerefSource::ImmRef },
Some(ty::ClosureKind::FnMut) => Adjustment::Deref { source: DerefSource::MutRef },
None => bug!("fn pointer {:?} is not an fn", ty),
};
@ -107,16 +109,26 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<'
result
}
#[derive(Copy, Clone, Debug, PartialEq)]
enum DerefSource {
/// `fn shim(&self) { inner(*self )}`.
ImmRef,
/// `fn shim(&mut self) { inner(*self )}`.
MutRef,
/// `fn shim(*mut self) { inner(*self )}`.
MutPtr,
}
#[derive(Copy, Clone, Debug, PartialEq)]
enum Adjustment {
/// Pass the receiver as-is.
Identity,
/// We get passed `&[mut] self` and call the target with `*self`.
/// We get passed a reference or a raw pointer to `self` and call the target with `*self`.
///
/// This either copies `self` (if `Self: Copy`, eg. for function items), or moves out of it
/// (for `VTableShim`, which effectively is passed `&own Self`).
Deref,
Deref { source: DerefSource },
/// We get passed `self: Self` and call the target with `&mut self`.
///
@ -667,8 +679,12 @@ fn build_call_shim<'tcx>(
let self_arg = &mut inputs_and_output[0];
*self_arg = match rcvr_adjustment.unwrap() {
Adjustment::Identity => fnty,
Adjustment::Deref => tcx.mk_imm_ptr(fnty),
Adjustment::RefMut => tcx.mk_mut_ptr(fnty),
Adjustment::Deref { source } => match source {
DerefSource::ImmRef => tcx.mk_imm_ref(tcx.lifetimes.re_erased, fnty),
DerefSource::MutRef => tcx.mk_mut_ref(tcx.lifetimes.re_erased, fnty),
DerefSource::MutPtr => tcx.mk_mut_ptr(fnty),
},
Adjustment::RefMut => bug!("`RefMut` is never used with indirect calls: {instance:?}"),
};
sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output);
}
@ -699,7 +715,7 @@ fn build_call_shim<'tcx>(
let rcvr = rcvr_adjustment.map(|rcvr_adjustment| match rcvr_adjustment {
Adjustment::Identity => Operand::Move(rcvr_place()),
Adjustment::Deref => Operand::Move(tcx.mk_place_deref(rcvr_place())),
Adjustment::Deref { source: _ } => Operand::Move(tcx.mk_place_deref(rcvr_place())),
Adjustment::RefMut => {
// let rcvr = &mut rcvr;
let ref_rcvr = local_decls.push(