Fix insertion of statements to be executed along return edge in inlining
Inlining creates additional statements to be executed along the return
edge: an assignment to the destination, storage end for temporaries.
Previously those statements where inserted directly into a call target,
but this is incorrect when the target has other predecessors.
Avoid the issue by creating a new dedicated block for those statements.
When the block happens to be redundant it will be removed by CFG
simplification that follows inlining.
Fixes#117355
Inlining creates additional statements to be executed along the return
edge: an assignment to the destination, storage end for temporaries.
Previously those statements where inserted directly into a call target,
but this is incorrect when the target has other predecessors.
Avoid the issue by creating a new dedicated block for those statements.
When the block happens to be redundant it will be removed by CFG
simplification that follows inlining.
Fixes#117355
Begin to abstract `rustc_type_ir` for rust-analyzer
This adds the "nightly" feature which is used by the compiler, and falls back to more simple implementations when that is not active.
r? `@lcnr` or `@jackh726`
Remove option_payload_ptr; redundant to offset_of
The `option_payload_ptr` intrinsic is no longer required as `offset_of` supports traversing enums (#114208). This PR removes it in order to dogfood offset_of (as suggested at https://github.com/rust-lang/rust/issues/106655#issuecomment-1790907626). However, it will not build until those changes reach beta (which I think is within the next 8 days?) so I've opened it as a draft.
Remove incorrect transformation from RemoveZsts
Partial removal of storage statements for a local is incorrect, so a decision to optimize cannot be make independently for each statement.
Avoid the issue by performing the transformation completely or not at all.
This method is trying to detect macro invocations, so that it can split a span
into two parts just after the `!` of the invocation.
Under some circumstances (probably involving nested macros), it gets confused
and produces a span that is larger than the original span, and possibly extends
outside its enclosing function and even into an adjacent file.
In extreme cases, that can result in malformed coverage mappings that cause
`llvm-cov` to fail. For now, we at least want to detect these egregious cases
and avoid them, so that coverage reports can still be produced.
Partial removal of storage statements for a local is incorrect, so a
decision to optimize cannot be make independently for each statement.
Avoid the issue by performing the transformation completely or not at
all.
generator layout: ignore fake borrows
fixes#117059
We emit fake shallow borrows in case the scrutinee place uses a `Deref` and there is a match guard. This is necessary to prevent the match guard from mutating the scrutinee: fab1054e17/compiler/rustc_mir_build/src/build/matches/mod.rs (L1250-L1265)
These fake borrows end up impacting the generator witness computation in `mir_generator_witnesses`, which causes the issue in #117059. This PR now completely ignores fake borrows during this computation. This is sound as thse are always removed after analysis and the actual computation of the generator layout happens afterwards.
Only the second commit impacts behavior, and could be backported by itself.
r? types
Update the alignment checks to match rust-lang/reference#1387
Previously, we had a special case to not check `Rvalue::AddressOf` in this pass because we weren't quite sure if pointers needed to be aligned in the Place passed to it: https://github.com/rust-lang/rust/pull/112026
Since https://github.com/rust-lang/reference/pull/1387 merged, this PR updates this pass to match. The behavior of the check is nearly unchanged, except we also avoid inserting a check for creating references. Most of the changes in this PR are cleanup and new tests.
Support enum variants in offset_of!
This MR implements support for navigating through enum variants in `offset_of!`, placing the enum variant name in the second argument to `offset_of!`. The RFC placed it in the first argument, but I think it interacts better with nested field access in the second, as you can then write things like
```rust
offset_of!(Type, field.Variant.field)
```
Alternatively, a syntactic distinction could be made between variants and fields (e.g. `field::Variant.field`) but I'm not convinced this would be helpful.
[RFC 3308 # Enum Support](https://rust-lang.github.io/rfcs/3308-offset_of.html#enum-support-offset_ofsomeenumstructvariant-field_on_variant)
Tracking Issue #106655.
Replace switch to unreachable by assume statements
`UnreachablePropagation` currently keeps some switch terminators alive in order to ensure codegen can infer the inequalities on the discriminants.
This PR proposes to encode those inequalities as `Assume` statements.
This allows to simplify MIR further by removing some useless terminators.
Historically, these errors existed so that the coverage debug code could dump
additional information before reporting a compiler bug. That debug code was
removed by #115962, so we can now simplify these methods by making them panic
when they detect a bug.
Enable cross-crate-inlining when MIR inlining is enabled
This would make https://github.com/rust-lang/rust/issues/117355 generally less obscure, and also seems like a good idea, even if for some reason someone wants MIR opts but no codegen opts.
See through aggregates in GVN
This PR is extracted from https://github.com/rust-lang/rust/pull/111344
The first 2 commit are cleanups to avoid repeated work. I propose to stop removing useless assignments as part of this pass, and let a later `SimplifyLocals` do it. This makes tests easier to read (among others).
The next 3 commits add a constant folding mechanism to the GVN pass, presented in https://github.com/rust-lang/rust/pull/116012. ~This pass is designed to only use global allocations, to avoid any risk of accidental modification of the stored state.~
The following commits implement opportunistic simplifications, in particular:
- projections of aggregates: `MyStruct { x: a }.x` gets replaced by `a`, works with enums too;
- projections of arrays: `[a, b][0]` becomes `a`;
- projections of repeat expressions: `[a; N][x]` becomes `a`;
- transform arrays of equal operands into a repeat rvalue.
Fixes https://github.com/rust-lang/miri/issues/3090
r? `@oli-obk`
Rollup of 5 pull requests
Successful merges:
- #115773 (tvOS simulator support on Apple Silicon for rustc)
- #117162 (Remove `cfg_match` from the prelude)
- #117311 (-Zunpretty help: add missing possible values)
- #117316 (Mark constructor of `BinaryHeap` as const fn)
- #117319 (explain why we don't inline when target features differ)
r? `@ghost`
`@rustbot` modify labels: rollup
Implement `gen` blocks in the 2024 edition
Coroutines tracking issue https://github.com/rust-lang/rust/issues/43122
`gen` block tracking issue https://github.com/rust-lang/rust/issues/117078
This PR implements `gen` blocks that implement `Iterator`. Most of the logic with `async` blocks is shared, and thus I renamed various types that were referring to `async` specifically.
An example usage of `gen` blocks is
```rust
fn foo() -> impl Iterator<Item = i32> {
gen {
yield 42;
for i in 5..18 {
if i.is_even() { continue }
yield i * 2;
}
}
}
```
The limitations (to be resolved) of the implementation are listed in the tracking issue
Only call `mir_const_qualif` if absolutely necessary
Pull the perf change out of https://github.com/rust-lang/rust/pull/113617
This should not have any impact on behaviour (if it does, we'll see an ICE)
Require target features to match exactly during inlining
In general it is not correct to inline a callee with a target features
that are subset of the callee. Require target features to match exactly
during inlining.
The exact match could be potentially relaxed, but this would require
identifying specific feature that are allowed to differ, those that need
to match, and those that can be present in caller but not in callee.
This resolves MIR part of #116573. For other concerns with respect to
the previous implementation also see areInlineCompatible in LLVM.
In general it is not correct to inline a callee with a target features
that are subset of the callee. Require target features to match exactly
during inlining.
The exact match could be potentially relaxed, but this would require
identifying specific feature that are allowed to differ, those that need
to match, and those that can be present in caller but not in callee.
This resolves MIR part of #116573. For other concerns with respect to
the previous implementation also see areInlineCompatible in LLVM.
Separate move path tracking between borrowck and drop elaboration.
The primary goal of this PR is to skip creating a `MovePathIndex` for path that do not need dropping in drop elaboration.
The 2 first commits are cleanups.
The next 2 commits displace `move` errors from move-path builder to borrowck. Move-path builder keeps the same logic, but does not carry error information any more.
The remaining commits allow to filter `MovePathIndex` creation according to types. This is used in drop elaboration, to avoid computing dataflow for paths that do not need dropping.
Implement jump threading MIR opt
This pass is an attempt to generalize `ConstGoto` and `SeparateConstSwitch` passes into a more complete jump threading pass.
This pass is rather heavy, as it performs a truncated backwards DFS on MIR starting from each `SwitchInt` terminator. This backwards DFS remains very limited, as it only walks through `Goto` terminators.
It is build to support constants and discriminants, and a propagating through a very limited set of operations.
The pass successfully manages to disentangle the `Some(x?)` use case and the DFA use case. It still needs a few tests before being ready.
coverage: Fix inconsistent handling of function signature spans
While doing some more cleanup of `spans`, I noticed a strange inconsistency in how function signatures are handled. Normally the function signature span is treated as though it were executable as part of the start of the function, but in some cases the signature span disappears entirely from coverage, for no obvious reason.
This is caused by the fact that spans created by `CoverageSpan::for_fn_sig` don't add the span to their `merged_spans` field (unlike normal statement/terminator spans). In cases where the span-processing code looks at those merged spans, it thinks the signature span is no longer visible and deletes it.
Adding the signature span to `merged_spans` resolves the inconsistency.
(Prior to #116409 this wouldn't have been possible, because there was no case in the old `CoverageStatement` enum representing a signature. Now that `merged_spans` is just a list of spans, that's no longer an obstacle.)
Implement rustc part of RFC 3127 trim-paths
This PR implements (or at least tries to) [RFC 3127 trim-paths](https://github.com/rust-lang/rust/issues/111540), the rustc part. That is `-Zremap-path-scope` with all of it's components/scopes.
`@rustbot` label: +F-trim-paths
Even though expression details are now stored in the info structure, we still
need to inject `ExpressionUsed` statements into MIR, because if one is missing
during codegen then we know that it was optimized out and we can remap all of
its associated code regions to zero.
Previously, mappings were attached to individual coverage statements in MIR.
That necessitated special handling in MIR optimizations to avoid deleting those
statements, since otherwise codegen would be unable to reassemble the original
list of mappings.
With this change, a function's list of mappings is now attached to its MIR
body, and survives intact even if individual statements are deleted by
optimizations.
Coverage codegen can now allocate arrays based on the number of
counters/expressions originally used by the instrumentor.
The existing query that inspects coverage statements is still used for
determining the number of counters passed to `llvm.instrprof.increment`. If
some high-numbered counters were removed by MIR optimizations, the instrumented
binary can potentially use less memory and disk space at runtime.
This allows coverage information to be attached to the function as a whole when
appropriate, instead of being smuggled through coverage statements in the
function's basic blocks.
As an example, this patch moves the `function_source_hash` value out of
individual `CoverageKind::Counter` statements and into the per-function info.
When synthesizing unused functions for coverage purposes, the absence of this
info is taken to indicate that a function was not eligible for coverage and
should not be synthesized.
Interacting with `basic_coverage_blocks` directly makes it easier to satisfy
the borrow checker when mutating `pending_dups` while reading other fields.
Format all the let-chains in compiler crates
Since rust-lang/rustfmt#5910 has landed, soon we will have support for formatting let-chains (as soon as rustfmt syncs and beta gets bumped).
This PR applies the changes [from master rustfmt to rust-lang/rust eagerly](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/out.20formatting.20of.20prs/near/374997516), so that the next beta bump does not have to deal with a 200+ file diff and can remain concerned with other things like `cfg(bootstrap)` -- #113637 was a pain to land, for example, because of let-else.
I will also add this commit to the ignore list after it has landed.
The commands that were run -- I'm not great at bash-foo, but this applies rustfmt to every compiler crate, and then reverts the two crates that should probably be formatted out-of-tree.
```
~/rustfmt $ ls -1d ~/rust/compiler/* | xargs -I@ cargo run --bin rustfmt -- `@/src/lib.rs` --config-path ~/rust --edition=2021 # format all of the compiler crates
~/rust $ git checkout HEAD -- compiler/rustc_codegen_{gcc,cranelift} # revert changes to cg-gcc and cg-clif
```
cc `@rust-lang/rustfmt`
r? `@WaffleLapkin` or `@Nilstrieb` who said they may be able to review this purely mechanical PR :>
cc `@Mark-Simulacrum` and `@petrochenkov,` who had some thoughts on the order of operations with big formatting changes in https://github.com/rust-lang/rust/pull/95262#issue-1178993801. I think the situation has changed since then, given that let-chains support exists on master rustfmt now, and I'm fairly confident that this formatting PR should land even if *bootstrap* rustfmt doesn't yet format let-chains in order to lessen the burden of the next beta bump.
const-eval: make misalignment a hard error
It's been a future-incompat error (showing up in cargo's reports) since https://github.com/rust-lang/rust/pull/104616, Rust 1.68, released in March. That should be long enough.
The question for the lang team is simply -- should we move ahead with this, making const-eval alignment failures a hard error? (It turns out some of them accidentally already were hard errors since #104616. But not all so this is still a breaking change. Crater found no regression.)
Having to keep passing in a graph reference was a holdover from when the graph
was partly mutated during traversal. As of #114354 that is no longer necessary,
so we can simplify the traversal code by storing a graph reference as a field
in `TraverseCoverageGraphWithLoops`.
The previous code was storing the worklist in a vector, and then selectively
adding items to the start or end of the vector. That's a perfect use-case for a
double-ended queue.
This change also reveals that the existing code was a bit confused about which
end of the worklist is the front or back. For now, items are always removed
from the front of the queue (instead of the back), and code that adds items to
the queue has been flipped, to preserve the existing behaviour.
Do not check for impossible predicates in const-prop lint.
The enclosing query already checks for them, and replaces the body with a single `unreachable` if they are indeed impossible.
Also consider call and yield as MIR SSA.
The SSA analysis on MIR only considered `Assign` statements as defining a SSA local.
This PR adds assignments as part of a `Call` or `Yield` terminator in that category.
This mainly allows to perform CopyProp on a call return place.
The only subtlety is in the dominance property: the assignment is only complete at the beginning of the target block.
coverage: Unbox and simplify `bcb_filtered_successors`
This is a small cleanup in the coverage instrumentor's graph-building code.
---
This function already has access to the MIR body, so instead of taking a reference to a terminator, it's simpler and easier to pass in a basic block index.
There is no need to box the returned iterator if we instead add appropriate lifetime captures, and make `short_circuit_preorder` generic over the type of iterator it expects.
We can also greatly simplify the function's implementation by observing that the only difference between its two cases is whether we take all of a BB's successors, or just the first one.
---
`@rustbot` label +A-code-coverage
This function already has access to the MIR body, so instead of taking a
reference to a terminator, it's simpler and easier to pass in a basic block
index.
There is no need to box the returned iterator if we instead add appropriate
lifetime captures, since `short_circuit_preorder` is now generic over the type
of iterator it expects.
We can also greatly simplify the function's implementation by observing that
the only difference between its two cases is whether we take all of a BB's
successors, or just the first one.
