bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #133734 - scottmcm:lower-indexing-to-ptrmetadata, r=davidtwco,RalfJung

Browse source 
Bounds-check with PtrMetadata instead of Len in MIR

Rather than emitting `Len(*_n)` in array index bounds checks, emit `PtrMetadata(copy _n)` instead -- with some asterisks for arrays and `&mut` that need it to be done slightly differently.

We're getting pretty close to removing `Len` entirely, actually.  I think just one more PR after this (for slice drop shims).

r? mir
This commit is contained in:
bors 2024-12-14 22:43:39 +00:00
commit b57d93d8b9
100 changed files with 1451 additions and 1663 deletions
Download patch file Download diff file Expand all files Collapse all files

13
compiler/rustc_mir_transform/src/instsimplify.rs
View file

@ -47,7 +47,6 @@ impl<'tcx> crate::MirPass<'tcx> for InstSimplify {
}
ctx.simplify_bool_cmp(rvalue);
ctx.simplify_ref_deref(rvalue);
ctx.simplify_len(rvalue);
ctx.simplify_ptr_aggregate(rvalue);
ctx.simplify_cast(rvalue);
}
@ -132,18 +131,6 @@ impl<'tcx> InstSimplifyContext<'_, 'tcx> {
}
}
/// Transform `Len([_; N])` ==> `N`.
fn simplify_len(&self, rvalue: &mut Rvalue<'tcx>) {
if let Rvalue::Len(ref place) = *rvalue {
let place_ty = place.ty(self.local_decls, self.tcx).ty;
if let ty::Array(_, len) = *place_ty.kind() {
let const_ = Const::from_ty_const(len, self.tcx.types.usize, self.tcx);
let constant = ConstOperand { span: DUMMY_SP, const_, user_ty: None };
*rvalue = Rvalue::Use(Operand::Constant(Box::new(constant)));
}
}
}
/// Transform `Aggregate(RawPtr, [p, ()])` ==> `Cast(PtrToPtr, p)`.
fn simplify_ptr_aggregate(&self, rvalue: &mut Rvalue<'tcx>) {
if let Rvalue::Aggregate(box AggregateKind::RawPtr(pointee_ty, mutability), fields) = rvalue

8
compiler/rustc_mir_transform/src/validate.rs
View file

@ -1115,14 +1115,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}
UnOp::PtrMetadata => {
if !matches!(self.body.phase, MirPhase::Runtime(_)) {
// It would probably be fine to support this in earlier phases, but at
// the time of writing it's only ever introduced from intrinsic
// lowering or other runtime-phase optimization passes, so earlier
// things can just `bug!` on it.
self.fail(location, "PtrMetadata should be in runtime MIR only");
}
check_kinds!(
a,
"Cannot PtrMetadata non-pointer non-reference type {:?}",