bjoernager/rust
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Introduce ConstAllocation.

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Currently some `Allocation`s are interned, some are not, and it's very
hard to tell at a use point which is which.

This commit introduces `ConstAllocation` for the known-interned ones,
which makes the division much clearer. `ConstAllocation::inner()` is
used to get the underlying `Allocation`.

In some places it's natural to use an `Allocation`, in some it's natural
to use a `ConstAllocation`, and in some places there's no clear choice.
I've tried to make things look as nice as possible, while generally
favouring `ConstAllocation`, which is the type that embodies more
information. This does require quite a few calls to `inner()`.

The commit also tweaks how `PartialOrd` works for `Interned`. The
previous code was too clever by half, building on `T: Ord` to make the
code shorter. That caused problems with deriving `PartialOrd` and `Ord`
for `ConstAllocation`, so I changed it to build on `T: PartialOrd`,
which is slightly more verbose but much more standard and avoided the
problems.
This commit is contained in:
Nicholas Nethercote 2022-03-02 07:15:04 +11:00
parent c38b8a8c62
commit 4852291417
30 changed files with 166 additions and 119 deletions
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6
compiler/rustc_codegen_ssa/src/traits/consts.rs
View file

@ -1,6 +1,6 @@
use super::BackendTypes;
use crate::mir::place::PlaceRef;
use rustc_middle::mir::interpret::{Allocation, Scalar};
use rustc_middle::mir::interpret::{ConstAllocation, Scalar};
use rustc_middle::ty::layout::TyAndLayout;
use rustc_span::Symbol;
use rustc_target::abi::{self, Size};
@ -26,13 +26,13 @@ pub trait ConstMethods<'tcx>: BackendTypes {
fn const_to_opt_uint(&self, v: Self::Value) -> Option<u64>;
fn const_to_opt_u128(&self, v: Self::Value, sign_ext: bool) -> Option<u128>;
fn const_data_from_alloc(&self, alloc: &Allocation) -> Self::Value;
fn const_data_from_alloc(&self, alloc: ConstAllocation<'tcx>) -> Self::Value;
fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: Self::Type) -> Self::Value;
fn from_const_alloc(
&self,
layout: TyAndLayout<'tcx>,
alloc: &Allocation,
alloc: ConstAllocation<'tcx>,
offset: Size,
) -> PlaceRef<'tcx, Self::Value>;