Similar to how the alignment is already checked, this adds a check
for null pointer dereferences in debug mode. It is implemented similarly
to the alignment check as a MirPass.
This is related to a 2025H1 project goal for better UB checks in debug
mode: https://github.com/rust-lang/rust-project-goals/pull/177.
It's a function that does stuff with MIR and yet it weirdly has its own
module in `rustc_middle::util`. This commit moves it into
`rustc_middle::mir`, a more sensible home.
This also parameterize the "excluded pointee types" and exposes a
general method for inserting checks on pointers.
This is a preparation for adding a NullCheck that makes use of the same
code.
Lower index bounds checking to `PtrMetadata`, this time with the right fake borrow semantics 😸
Change `Rvalue::RawRef` to take a `RawRefKind` instead of just a `Mutability`. Then introduce `RawRefKind::FakeForPtrMetadata` and use that for lowering index bounds checking to a `PtrMetadata`. This new `RawRefKind::FakeForPtrMetadata` acts like a shallow fake borrow in borrowck, which mimics the semantics of the old `Rvalue::Len` operation we're replacing.
We can then use this `RawRefKind` instead of using a span desugaring hack in CTFE.
cc ``@scottmcm`` ``@RalfJung``
Use identifiers more in diagnostics code
This should make the diagnostics code slightly more correct when rendering idents in mixed crate edition situations. Kinda a no-op, but a cleanup regardless.
r? oli-obk or reassign
Incorporate `iter_nodes` into `graph::DirectedGraph`
This helper method iterates over all node IDs in the dense range `0..num_nodes`.
In practice, we have a lot of graph-algorithm code that already assumes that nodes are densely numbered, by using `num_nodes` to allocate per-node indexed data structures. So I don't think this is actually a substantial change to the de-facto semantics of `graph::DirectedGraph`.
---
Resolves a FIXME from #135481.
Get rid of `mir::Const::from_ty_const`
This function is strange, because it turns valtrees into `mir::Const::Value`, but the rest of the const variants stay as type system consts.
All of the callsites except for one in `instsimplify` (array length simplification of `ptr_metadata` call) just go through the valtree arm of the function, so it's easier to just create a `mir::Const` directly for those.
For the instsimplify case, if we have a type system const we should *keep* having a type system const, rather than turning it into a `mir::Const::Value`; it doesn't really matter in practice, though, bc `usize` has no padding, but it feels more principled.
This assumes that the set of valid node IDs is exactly `0..num_nodes`.
In practice, we have a lot of graph-algorithm code that already assumes that
nodes are densely numbered, by using `num_nodes` to allocate per-node indexed
data structures.
Add `#[optimize(none)]`
cc #54882
This extends the `optimize` attribute to add `none`, which corresponds to the LLVM `OptimizeNone` attribute.
Not sure if an MCP is required for this, happy to file one if so.
By removing all methods from this struct and treating it as a collection of
data fields, we make it easier for a future PR to store that data in a query
result, without having to move all of its methods into `rustc_middle`.
This dedicated type seemed like a good idea at the time, but if we want to
store this information in a query result then a plainer data type is more
convenient.
Using `SmallVec` here was fine when it was a module-private detail, but if we
want to pass these terms across query boundaries then it's not worth the extra
hassle.
Replacing a method call with direct field access is slightly simpler.
Using the name `counter_terms` is more consistent with other code that tries to
maintain a distinction between (physical) "counters" and "expressions".
This reflects the fact that we can't compute meaningful info for a function
that wasn't instrumented and therefore doesn't have `function_coverage_info`.
Making these separate types from `CovTerm` and `Expression` was historically
very helpful, but now that most of the counter-creation work is handled by
`node_flow` they are no longer needed.
- Move `make_bcb_counters` out of `CoverageCounters`
- Split out `make_node_counter_priority_list`
- Flatten `Transcriber` into the function `transcribe_counters`
Make MIR cleanup for functions with impossible predicates into a real MIR pass
It's a bit jarring to see the body of a function with an impossible-to-satisfy where clause suddenly go to a single `unreachable` terminator when looking at the MIR dump output in order, and I discovered it's because we manually replace the body outside of a MIR pass.
Let's make it into a fully flegded MIR pass so it's more clear what it's doing and when it's being applied.
Add an InstSimplify for repetitive array expressions
I noticed in https://github.com/rust-lang/rust/pull/135068#issuecomment-2569955426 that GVN's implementation of this same transform was quite profitable on the deep-vector benchmark. But of course GVN doesn't run in unoptimized builds, so this is my attempt to write a version of this transform that benefits the deep-vector case and is fast enough to run in InstSimplify.
The benchmark suite indicates that this is effective.
