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

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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
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25
compiler/rustc_const_eval/src/check_consts/check.rs
View file

@ -573,12 +573,27 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
) => {}
Rvalue::ShallowInitBox(_, _) => {}
Rvalue::UnaryOp(_, operand) => {
Rvalue::UnaryOp(op, operand) => {
let ty = operand.ty(self.body, self.tcx);
if is_int_bool_float_or_char(ty) {
// Int, bool, float, and char operations are fine.
} else {
span_bug!(self.span, "non-primitive type in `Rvalue::UnaryOp`: {:?}", ty);
match op {
UnOp::Not | UnOp::Neg => {
if is_int_bool_float_or_char(ty) {
// Int, bool, float, and char operations are fine.
} else {
span_bug!(
self.span,
"non-primitive type in `Rvalue::UnaryOp{op:?}`: {ty:?}",
);
}
}
UnOp::PtrMetadata => {
if !ty.is_ref() && !ty.is_unsafe_ptr() {
span_bug!(
self.span,
"non-pointer type in `Rvalue::UnaryOp({op:?})`: {ty:?}",
);
}
}
}
}

13
compiler/rustc_const_eval/src/interpret/step.rs
View file

@ -9,6 +9,7 @@ use rustc_middle::ty::layout::FnAbiOf;
use rustc_middle::ty::{self, Instance, Ty};
use rustc_middle::{bug, mir, span_bug};
use rustc_span::source_map::Spanned;
use rustc_span::{DesugaringKind, Span};
use rustc_target::callconv::FnAbi;
use tracing::{info, instrument, trace};
@ -80,7 +81,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
use rustc_middle::mir::StatementKind::*;
match &stmt.kind {
Assign(box (place, rvalue)) => self.eval_rvalue_into_place(rvalue, *place)?,
Assign(box (place, rvalue)) => {
self.eval_rvalue_into_place(rvalue, *place, stmt.source_info.span)?
}
SetDiscriminant { place, variant_index } => {
let dest = self.eval_place(**place)?;
@ -159,6 +162,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
&mut self,
rvalue: &mir::Rvalue<'tcx>,
place: mir::Place<'tcx>,
span: Span,
) -> InterpResult<'tcx> {
let dest = self.eval_place(place)?;
// FIXME: ensure some kind of non-aliasing between LHS and RHS?
@ -250,8 +254,13 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
let src = self.eval_place(place)?;
let place = self.force_allocation(&src)?;
let mut val = ImmTy::from_immediate(place.to_ref(self), dest.layout);
if !place_base_raw {
if !place_base_raw
&& span.desugaring_kind() != Some(DesugaringKind::IndexBoundsCheckReborrow)
{
// If this was not already raw, it needs retagging.
// As a special hack, we exclude the desugared `PtrMetadata(&raw const *_n)`
// from indexing. (Really we should not do any retag on `&raw` but that does not
// currently work with Stacked Borrows.)
val = M::retag_ptr_value(self, mir::RetagKind::Raw, &val)?;
}
self.write_immediate(*val, &dest)?;