`hir::BorrowKind::Raw` borrows and casting a reference to a raw
pointer no longer do a reborrow followed by a cast. Instead we
dereference and take the address.
Remove uniform array move MIR passes
This PR fixes a number of bugs caused by limitations of this pass
* Projections from constant indexes weren't being canonicalized
* Constant indexes from the start weren't being canonicalized (they could have different min_lengths)
* It didn't apply to non-moves
This PR makes the following changes to support removing this pass:
* ConstantIndex of arrays are now generated in a canonical form (from the start, min_length is the actual length).
* Subslices are now split when generating move paths and when checking subslices have been moved.
Additionally
* The parent move path of a projection from an array element is now calculated correctly
closes#66502
These passes were buggy, MIR building is now responsible for
canonicalizing `ConstantIndex` projections and `MoveData` is responsible
for splitting `Subslice` projections.
We now only propagate a scalar pair if the Rvalue is a tuple with two
scalars. This for example avoids propagating a (u8, u8) value when
Rvalue has type `((), u8, u8)` (see the regression test). While this is
a correct thing to do, implementation is tricky and will be done later.
Fixes#66971Fixes#66339Fixes#67019
rustc: hide HirId's fmt::Debug output from -Z span_free_formats.
This replaces the only occurrences of `HirId {...}` from tests with paths, i.e.:
```rust
[closure@HirId { owner: DefIndex(4), local_id: 15 } q:&i32, t:&T]
```
becomes, after this PR:
```rust
[closure@foo<T>::{{closure}}#0 q:&i32, t:&T]
```
r? @oli-obk cc @michaelwoerister
Handle statics in MIR as const pointers
This is the first PR towards the goal of removing `PlaceBase::Static`. In this PR:
* Statics are lowered to dereferencing a const pointer.
* The temporaries holding such pointers are tracked in MIR, for the most part this is only used for diagnostics. There are two exceptions:
* The borrow checker has some checks for thread-locals that directly use this data.
* Const checking will suppress "cannot dereference raw pointer" diagnostics for pointers to `static mut`/`extern static`. This is to maintain the current behaviour (12 tests fail otherwise).
The following are left to future PRs (I think that @spastorino will be working on the first 3):
* Applying the same treatments to promoted statics.
* Removing `PlaceBase::Static`.
* Replacing `PlaceBase` with `Local`.
* Moving the ever growing collection of metadata that we have for diagnostics in MIR passes somewhere more appropriate.
r? @oli-obk
This optimization depends on inlining for the identity
conversions introduced by the lowering of the `?`.
To take advantage of `SimplifyArmIdentity`, `-Z mir-opt-level=2`
is required because that triggers the inlining MIR optimization.
Split ConstValue into two enums
Hello,
Issue #59210 appeared abandoned, so I gave it a go.
Some further cleanup and refactoring may be mandated.
I did not test beyond `x.py check`, since my home computer dies compiling librustc.
Fixes#59210
An expression like `x[1][{ x = y; 2}]` would perform the bounds check
for the inner index operation before evaluating the outer index. This
would allow out of bounds memory accesses.
[mir-opt] Handle return place in ConstProp and improve SimplifyLocals pass
Temporarily rebased on top of #66074. The top 2 commits are new.
r? @oli-obk
[mir-opt] Implement pass to remove branches on uninhabited variants
Based on discussion [here](https://github.com/rust-lang/rust/pull/64890#discussion_r333612125), this is a pass to eliminate dead code that is caused by branching on an enum with uninhabited variants.
r? @oli-obk
Fix `-Zunpretty=mir-cfg` to render multiple items
`-Zunpretty=mir-cfg` outputs DOT to stdout for all items being compiled. However, it puts all of these items in separate `digraph`s, which means the result of redirecting that output to a file is not valid. Most dot renderers (I have tried `dot` and `xdot`) cannot render the output.
This PR checks to see if `write_mir_graphviz` will process multiple items, and writes them each as a `subgraph` in a single, top-level `digraph`. As a result, DOT can be viewed without manually editing the output file. The output is unchanged when printing a single item (e.g.`-Zunpretty=mir-cfg=item_name`).
Here's the output of `xdot` for a rust file containing three items:
The borders are a result of the nonstandard–but well-supported–[`cluster` prefix](https://graphviz.gitlab.io/_pages/doc/info/lang.html) (search for "Subgraphs and Clusters"). They will not appear if your renderer does not support this extension, but the graph will still render properly.
Passes LLVM codegen and Emscripten link-time flags for exception
handling if and only if the panic strategy is `unwind`. Sets the
default panic strategy for Emscripten targets to `unwind`. Re-enables
tests that depend on unwinding support for Emscripten, including
`should_panic` tests.
The `ConstProp` can cause many locals to be initialized to a constant
value and then never read from. `ConstProp` can also evaluate ZSTs into
constant values. Previously, many of these would be removed by other
parts of the MIR optimization pipeline. However, evaluating ZSTs
(especially `()`) into constant values defeated those parts of the
optimizer and so in a2e3ed5c05, I added a
hack to `ConstProp` that skips evaluating ZSTs to avoid that regression.
This commit changes `SimplifyLocals` so that it doesn't consider writes
of const values to a local to be a use of that local. In doing so,
`SimplifyLocals` is able to remove otherwise unused locals left behind
by other optimization passes (`ConstProp` in particular).
- Compatible with Emscripten 1.38.46-upstream or later upstream.
- Refactors the Emscripten target spec to share code with other wasm
targets.
- Replaces the old incorrect wasm32 C call ABI with the correct one,
preserving the old one as wasm32_bindgen_compat for wasm-bindgen
compatibility.
- Updates the varargs ABI used by Emscripten and deletes the old one.
- Removes the obsolete wasm32-experimental-emscripten target.
- Uses EMCC_CFLAGS on CI to avoid the timeout problems with #63649.
