Use PlaceRef projection abstractions more consistently in rustc_mir
PlaceRef contains abstractions for dealing with the `projections` array. This PR uses these abstractions more consistently within the `rustc_mir` crate.
See associated issue: rust-lang/rust#80647.
r? `@RalfJung`
implement ptr::write without dedicated intrinsic
This makes `ptr::write` more consistent with `ptr::write_unaligned`, `ptr::read`, `ptr::read_unaligned`, all of which are implemented in terms of `copy_nonoverlapping`.
This means we can also remove `move_val_init` implementations in codegen and Miri, and its special handling in the borrow checker.
Also see [this Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/ptr.3A.3Aread.20vs.20ptr.3A.3Awrite).
Make CTFE able to check for UB...
... by not doing any optimizations on the `const fn` MIR used in CTFE. This means we duplicate all `const fn`'s MIR now, once for CTFE, once for runtime. This PR is for checking the perf effect, so we have some data when talking about https://github.com/rust-lang/const-eval/blob/master/rfcs/0000-const-ub.md
To do this, we now have two queries for obtaining mir: `optimized_mir` and `mir_for_ctfe`. It is now illegal to invoke `optimized_mir` to obtain the MIR of a const/static item's initializer, an array length, an inline const expression or an enum discriminant initializer. For `const fn`, both `optimized_mir` and `mir_for_ctfe` work, the former returning the MIR that LLVM should use if the function is called at runtime. Similarly it is illegal to invoke `mir_for_ctfe` on regular functions.
This is all checked via appropriate assertions and I don't think it is easy to get wrong, as there should be no `mir_for_ctfe` calls outside the const evaluator or metadata encoding. Almost all rustc devs should keep using `optimized_mir` (or `instance_mir` for that matter).
Add ABI argument for called function in `find_mir_or_eval_fn` and
`call_extra_fn`. Useful for comparing with expected ABI in interpreters.
Related to [miri/1631](https://github.com/rust-lang/miri/issues/1631)
MIR Inline is incompatible with coverage
Fixes: #80060
Fixed by disabling inlining if `-Zinstrument-coverage` is set.
The PR also adds additional use cases to the coverage test for doctests.
r? `@wesleywiser`
cc: `@tmandry`
Make `ExpnData` fields `krate` and `orig_id` private
These fields are only used by hygiene serialized, and should not be
accessed by anything outside of `rustc_span`.
Some Promotion Refactoring
Clean up promotion a bit:
* factor out some common code
* more exhaustive matches
This *should* not break anything... the only potentially-breaking change is that `BorrowKind::Shallow | BorrowKind::Unique` are now rejected for internal references.
r? ``@oli-obk``
Remap instrument-coverage line numbers in doctests
This uses the `SourceMap::doctest_offset_line` method to re-map line
numbers from doctests. Remapping columns is not yet done, and rustdoc
still does not output the correct filename when running doctests in a
workspace.
Part of #79417 although I dont consider that fixed until both filenames
and columns are mapped correctly.
r? `@richkadel`
I might jump on zulip the comming days. Still need to figure out how to properly write tests for this, and deal with other doctest issues in the meantime.
Always run intrinsics lowering pass
Move intrinsics lowering pass from the optimization phase (where it
would not run if -Zmir-opt-level=0), to the drop lowering phase where it
runs unconditionally.
The implementation of those intrinsics in code generation and
interpreter is unnecessary. Remove it.
Fixed conflict with drop elaboration and coverage
See
https://github.com/rust-lang/rust/issues/80045#issuecomment-745733339
Coverage statements are moved to the beginning of the BCB. This does
also affect what's counted before a panic, changing some results, but I
think these results may even be preferred? In any case, there are no
guarantees about what's counted when a panic occurs (by design).
r? `@tmandry`
FYI `@wesleywiser` `@ecstatic-morse`
Fix issue #78496
EarlyOtherwiseBranch finds MIR structures like:
```
bb0: {
...
_2 = discriminant(X)
...
switchInt(_2) -> [1_isize: bb1, otherwise: bb3]
}
bb1: {
...
_3 = discriminant(Y)
...
switchInt(_3) -> [1_isize: bb2, otherwise: bb3]
}
bb2: {...}
bb3: {...}
```
And transforms them into something like:
```
bb0: {
...
_2 = discriminant(X)
_3 = discriminant(Y)
_4 = Eq(_2, _3)
switchInt(_4) -> [true: bb4, otherwise: bb3]
}
bb2: {...} // unchanged
bb3: {...} // unchanged
bb4: {
switchInt(_2) -> [1_isize: bb2, otherwise: bb3]
}
```
But that is not always a safe thing to do -- sometimes the early `otherwise` branch is necessary so the later block could assume the value of `discriminant(X)`.
I am not totally sure what's the best way to detect that, but fixing #78496 should be easy -- we just check if `X` is a sub-expression of `Y`. A more precise test might be to check if `Y` contains a `Downcast(1)` of `X`, but I think this might be good enough.
Fix#78496
See
https://github.com/rust-lang/rust/issues/80045#issuecomment-745733339
Coverage statements are moved to the beginning of the BCB. This does
also affect what's counted before a panic, changing some results, but I
think these results may even be preferred? In any case, there are no
guarantees about what's counted when a panic occurs (by design).
Fixes reported bugs in Rust Coverage
Fixes: #79569Fixes: #79566Fixes: #79565
For the first issue (#79569), I got hit a `debug_assert!()` before
encountering the reported error message (because I have `debug = true`
enabled in my config.toml).
The assertion showed me that some `SwitchInt`s can have more than one
target pointing to the same `BasicBlock`.
I had thought that was invalid, but since it seems to be possible, I'm
allowing this now.
I added a new test for this.
----
In the last two cases above, both tests (intentionally) fail to compile,
but the `InstrumentCoverage` pass is invoked anyway.
The MIR starts with an `Unreachable` `BasicBlock`, which I hadn't
encountered before. (I had assumed the `InstrumentCoverage` pass
would only be invoked with MIRs from successful compilations.)
I don't have test infrastructure set up to test coverage on files that
fail to compile, so I didn't add a new test.
r? `@tmandry`
FYI: `@wesleywiser`
consider assignments of union field of ManuallyDrop type safe
Assigning to `Copy` union fields is safe because that assignment will never drop anything. However, with https://github.com/rust-lang/rust/pull/77547, unions may also have `ManuallyDrop` fields, and their assignments are currently still unsafe. That seems unnecessary though, as assigning `ManuallyDrop` does not drop anything either, and is thus safe even for union fields.
I assume this will at least require FCP.
[mir-opt] Allow debuginfo to be generated for a constant or a Place
Prior to this commit, debuginfo was always generated by mapping a name
to a Place. This has the side-effect that `SimplifyLocals` cannot remove
locals that are only used for debuginfo because their other uses have
been const-propagated.
To allow these locals to be removed, we now allow debuginfo to point to
a constant value. The `ConstProp` pass detects when debuginfo points to
a local with a known constant value and replaces it with the value. This
allows the later `SimplifyLocals` pass to remove the local.
Move intrinsics lowering pass from the optimization phase (where it
would not run if -Zmir-opt-level=0), to the drop lowering phase where it
runs unconditionally.
The implementation of those intrinsics in code generation and
interpreter is unnecessary. Remove it.
Adds checks for:
* `no_core` attribute
* explicitly-enabled `legacy` symbol mangling
* mir_opt_level > 1 (which enables inlining)
I removed code from the `Inline` MIR pass that forcibly disabled
inlining if `-Zinstrument-coverage` was set. The default `mir_opt_level`
does not enable inlining anyway. But if the level is explicitly set and
is greater than 1, I issue a warning.
The new warnings show up in tests, which is much better for diagnosing
potential option conflicts in these cases.
Remove an unused dependency that made `rustdoc` crash
Whilst struggling with https://github.com/rust-lang/rust/issues/79980 I discovered that this dependency was unused, and that made rustdoc crash. This PR removes it.
Fixes: #79569Fixes: #79566Fixes: #79565
For the first issue (#79569), I got hit a `debug_assert!()` before
encountering the reported error message (because I have `debug = true`
enabled in my config.toml).
The assertion showed me that some `SwitchInt`s can have more than one
target pointing to the same `BasicBlock`.
I had thought that was invalid, but since it seems to be possible, I'm
allowing this now.
I added a new test for this.
----
In the last two cases above, both tests (intentionally) fail to compile,
but the `InstrumentCoverage` pass is invoked anyway.
The MIR starts with an `Unreachable` `BasicBlock`, which I hadn't
encountered before. (I had assumed the `InstrumentCoverage` pass
would only be invoked with MIRs from successful compilations.)
I don't have test infrastructure set up to test coverage on files that
fail to compile, so I didn't add a new test.
Dogfood `str_split_once()`
Part of https://github.com/rust-lang/rust/issues/74773.
Beyond increased clarity, this fixes some instances of a common confusion with how `splitn(2)` behaves: the first element will always be `Some()`, regardless of the delimiter, and even if the value is empty.
Given this code:
```rust
fn main() {
let val = "...";
let mut iter = val.splitn(2, '=');
println!("Input: {:?}, first: {:?}, second: {:?}", val, iter.next(), iter.next());
}
```
We get:
```
Input: "no_delimiter", first: Some("no_delimiter"), second: None
Input: "k=v", first: Some("k"), second: Some("v")
Input: "=", first: Some(""), second: Some("")
```
Using `str_split_once()` makes more clear what happens when the delimiter is not found.
Fixes to Rust coverage
Fixes: #79725
Some macros can create a situation where `fn_sig_span` and `body_span`
map to different files.
New documentation on coverage tests incorrectly assumed multiple test
binaries could just be listed at the end of the `llvm-cov` command,
but it turns out each binary needs a `--object` prefix.
This PR fixes the bug and updates the documentation to correct that
issue. It also fixes a few other minor issues in internal implementation
comments, and adds documentation on getting coverage results for doc
tests.
Fixes: #79725
Some macros can create a situation where `fn_sig_span` and `body_span`
map to different files.
New documentation on coverage tests incorrectly assumed multiple test
binaries could just be listed at the end of the `llvm-cov` command,
but it turns out each binary needs a `--object` prefix.
This PR fixes the bug and updates the documentation to correct that
issue. It also fixes a few other minor issues in internal implementation
comments, and adds documentation on getting coverage results for doc
tests.
Prior to this commit, debuginfo was always generated by mapping a name
to a Place. This has the side-effect that `SimplifyLocals` cannot remove
locals that are only used for debuginfo because their other uses have
been const-propagated.
To allow these locals to be removed, we now allow debuginfo to point to
a constant value. The `ConstProp` pass detects when debuginfo points to
a local with a known constant value and replaces it with the value. This
allows the later `SimplifyLocals` pass to remove the local.
Added one more test (two files) showing coverage of generics and unused
functions across crates.
Created and referenced new Issues, as requested.
Added comments.
Added a note about the possible effects of compiler options on LLVM
coverage maps.
Fixes multiple issue with counters, with simplification
Includes a change to the implicit else span in ast_lowering, so coverage
of the implicit else no longer spans the `then` block.
Adds coverage for unused closures and async function bodies.
Fixes: #78542
Adding unreachable regions for known MIR missing from coverage map
Cleaned up PR commits, and removed link-dead-code requirement and tests
Coverage no longer depends on Issue #76038 (`-C link-dead-code` is
no longer needed or enforced, so MSVC can use the same tests as
Linux and MacOS now)
Restrict adding unreachable regions to covered files
Improved the code that adds coverage for uncalled functions (with MIR
but not-codegenned) to avoid generating coverage in files not already
included in the files with covered functions.
Resolved last known issue requiring --emit llvm-ir workaround
Fixed bugs in how unreachable code spans were added.
Allow using generic trait methods in `const fn`
Next step for https://github.com/rust-lang/rust/issues/67792, this now also allows code like the following:
```rust
struct S;
impl const PartialEq for S {
fn eq(&self, _: &S) -> bool {
true
}
}
const fn equals_self<T: PartialEq>(t: &T) -> bool {
*t == *t
}
pub const EQ: bool = equals_self(&S);
```
This works by threading const-ness of trait predicates through trait selection, in particular through `ParamCandidate`, and exposing it in the resulting `ImplSource`.
Since this change makes two bounds `T: Trait` and `T: ?const Trait` that only differ in their const-ness be treated like different bounds, candidate winnowing has been changed to drop the `?const` candidate in favor of the const candidate, to avoid ambiguities when both a const and a non-const bound is present.
Never inline naked functions
The `#[naked]` attribute disabled prologue / epilogue emission for the
function and it is responsibility of a developer to provide them. The
compiler is no position to inline such functions correctly.
Disable inlining of naked functions at LLVM and MIR level.
Closes#60919.
The `#[naked]` attribute disabled prologue / epilogue emission for the
function and it is responsibility of a developer to provide them. The
compiler is no position to inline such functions correctly.
Disable inlining of naked functions at LLVM and MIR level.
add optimization fuel checks to some mir passes
Fixes#77402
Inserts a bunch of calls to `consider_optimizing`. Note that `consider_optimizing` is the method that actually decrements the fuel count, so the point at which it's called is when the optimization takes place, from a fuel perspective. This means that where we call it has some thought behind it:
1. We probably don't want to decrement the fuel count before other simple checks, otherwise we count an optimization as being performed even if nothing was mutated (ie. it returned early).
2. In cases like `InstCombine`, where we gather optimizations in a pass and then mutate values, we probably would rather skip the gathering pass for performance reasons rather than skip the mutations afterwards.
Allow making `RUSTC_BOOTSTRAP` conditional on the crate name
Motivation: This came up in the [Zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Require.20users.20to.20confirm.20they.20know.20RUSTC_.E2.80.A6.20compiler-team.23350/near/208403962) for https://github.com/rust-lang/compiler-team/issues/350.
See also https://github.com/rust-lang/cargo/pull/6608#issuecomment-458546258; this implements https://github.com/rust-lang/cargo/issues/6627.
The goal is for this to eventually allow prohibiting setting `RUSTC_BOOTSTRAP` in build.rs (https://github.com/rust-lang/cargo/issues/7088).
## User-facing changes
- `RUSTC_BOOTSTRAP=1` still works; there is no current plan to remove this.
- Things like `RUSTC_BOOTSTRAP=0` no longer activate nightly features. In practice this shouldn't be a big deal, since `RUSTC_BOOTSTRAP` is the opposite of stable and everyone uses `RUSTC_BOOTSTRAP=1` anyway.
- `RUSTC_BOOTSTRAP=x` will enable nightly features only for crate `x`.
- `RUSTC_BOOTSTRAP=x,y` will enable nightly features only for crates `x` and `y`.
## Implementation changes
The main change is that `UnstableOptions::from_environment` now requires
an (optional) crate name. If the crate name is unknown (`None`), then the new feature is not available and you still have to use `RUSTC_BOOTSTRAP=1`. In practice this means the feature is only available for `--crate-name`, not for `#![crate_name]`; I'm interested in supporting the second but I'm not sure how.
Other major changes:
- Added `Session::is_nightly_build()`, which uses the `crate_name` of
the session
- Added `nightly_options::match_is_nightly_build`, a convenience method
for looking up `--crate-name` from CLI arguments.
`Session::is_nightly_build()`should be preferred where possible, since
it will take into account `#![crate_name]` (I think).
- Added `unstable_features` to `rustdoc::RenderOptions`
I'm not sure whether this counts as T-compiler or T-lang; _technically_ RUSTC_BOOTSTRAP is an implementation detail, but it's been used so much it seems like this counts as a language change too.
r? `@joshtriplett`
cc `@Mark-Simulacrum` `@hsivonen`
Normalize function type during validation
During inlining, the callee body is normalized and has types revealed,
but some of locals corresponding to the arguments might come from the
caller body which is not. As a result the caller body does not pass
validation without additional normalization.
Closes#78442.
Lower intrinsics calls: forget, size_of, unreachable, wrapping_*
This allows constant propagation to evaluate `size_of` and `wrapping_*`,
and unreachable propagation to propagate a call to `unreachable`.
The lowering is performed as a MIR optimization, rather than during MIR
building to preserve the special status of intrinsics with respect to
unsafety checks and promotion.
Currently enabled by default to determine the performance impact (no
significant impact expected). In practice only useful when combined with
inlining since intrinsics are rarely used directly (with exception of
`unreachable` and `discriminant_value` used by built-in derive macros).
Closes#32716.
This allows constant propagation to evaluate `size_of` and `wrapping_*`,
and unreachable propagation to propagate a call to `unreachable`.
The lowering is performed as a MIR optimization, rather than during MIR
building to preserve the special status of intrinsics with respect to
unsafety checks and promotion.
During inlining, the callee body is normalized and has types revealed,
but some of locals corresponding to the arguments might come from the
caller body which is not. As a result the caller body does not pass
validation without additional normalization.
The inliner looks if a sanitizer is enabled before considering
`no_sanitize` attribute as possible source of incompatibility.
The MIR inlining could happen in a crate with sanitizer disabled, but
code generation in a crate with sanitizer enabled, thus the attribute
would be incorrectly ignored.
To avoid the issue never inline functions with different `no_sanitize`
attributes.
Support inlining diverging function calls
The existing heuristic does penalize diverging calls to some degree, but since
it never inlined them previously it might need some further modifications.
Additionally introduce storage markers for all temporaries created by
the inliner. The temporary introduced for destination rebrorrow, didn't
use them previously.
Add flags customizing behaviour of MIR inlining
* `-Zinline-mir-threshold` to change the default threshold.
* `-Zinline-mir-hint-threshold` to change the threshold used by
functions with inline hint.
Having those as configurable flags makes it possible to experiment with with
different inlining thresholds and substantially increase test coverage of MIR
inlining when used with increased thresholds (for example, necessary to test
#78844).
Assert that a return place is not used for indexing during integration
The inliner integrates call destination place with callee return place
by remapping the local and adding extra projections as necessary.
If a call destination place contains any projections (which is already
possible) and a return place is used in an indexing projection (most
likely doesn't happen yet) the end result would be incorrect.
Add an assertion to ensure that potential issue won't go unnoticed in
the presence of more sophisticated copy propagation scheme.
* `-Zinline-mir-threshold` to change the default threshold.
* `-Zinline-mir-hint-threshold` to change the threshold used by
functions with inline hint.
Additionally introduce storage markers for all temporaries created by
the inliner. The temporary introduced for destination rebrorrow, didn't
use them previously.
When examining candidates for inlining, reject those that are determined
to be recursive either because of self-recursive calls or calls to any
instances already inlined.
inliner: Use substs_for_mir_body
Changes from 68965 extended the kind of instances that are being
inlined. For some of those, the `instance_mir` returns a MIR body that
is already expressed in terms of the types found in substitution array,
and doesn't need further substitution.
Use `substs_for_mir_body` to take that into account.
Resolves#78529.
Resolves#78560.
Rollup of 19 pull requests
Successful merges:
- #76097 (Stabilize hint::spin_loop)
- #76227 (Stabilize `Poll::is_ready` and `is_pending` as const)
- #78065 (make concurrency helper more pleasant to read)
- #78570 (Remove FIXME comment in print_type_sizes ui test suite)
- #78572 (Use SOCK_CLOEXEC and accept4() on more platforms.)
- #78658 (Add a tool to run `x.py` from any subdirectory)
- #78706 (Fix run-make tests running when LLVM is disabled)
- #78728 (Constantify `UnsafeCell::into_inner` and related)
- #78775 (Bump Rustfmt and RLS)
- #78788 (Correct unsigned equivalent of isize to be usize)
- #78811 (Make some std::io functions `const`)
- #78828 (use single char patterns for split() (clippy::single_char_pattern))
- #78841 (Small cleanup in `TypeFoldable` derive macro)
- #78842 (Honor the rustfmt setting in config.toml)
- #78843 (Less verbose debug logging from inlining integrator)
- #78852 (Convert a bunch of intra-doc links)
- #78860 (rustc_resolve: Use `#![feature(format_args_capture)]`)
- #78861 (typo and formatting)
- #78865 (Don't fire `CONST_ITEM_MUTATION` lint when borrowing a deref)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Don't fire `CONST_ITEM_MUTATION` lint when borrowing a deref
Fixes#78819
This extends the check for dereferences added in PR #77324
to cover mutable borrows, as well as direct writes. If we're operating
on a dereference of a `const` item, we shouldn't be firing the lint.
Less verbose debug logging from inlining integrator
The inlining integrator produces relatively verbose and uninteresting
logs. Move them from a debug log level to a trace level, so that they
can be easily isolated from others.
revert #75443, update mir validator
This PR reverts rust-lang#75443 to fix rust-lang#75992 and instead uses rust-lang#75419 to fix rust-lang#75313.
Adapts rust-lang#75419 to correctly deal with unevaluated constants as otherwise some `feature(const_evaluatable_checked)` tests would ICE.
Note that rust-lang#72793 was also fixed by rust-lang#75443, but as that issue only concerns `feature(type_alias_impl_trait)` I deleted that test case for now and would reopen that issue.
rust-lang#75443 may have also allowed some other code to now successfully compile which would make this revert a breaking change after 2 stable versions, but I hope that this is a purely theoretical concern.
See https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/generator.20upvars/near/214617274 for more reasoning about this.
r? `@nikomatsakis` `@eddyb` `@RalfJung`
Fixes#78819
This extends the check for dereferences added in PR #77324
to cover mutable borrows, as well as direct writes. If we're operating
on a dereference of a `const` item, we shouldn't be firing the lint.
The inlining integrator produces relatively verbose and uninteresting
logs. Move them from a debug log level to a trace level, so that they
can be easily isolated from others.
The main change is that `UnstableOptions::from_environment` now requires
an (optional) crate name. If the crate name is unknown (`None`), then the new feature is not available and you still have to use `RUSTC_BOOTSTRAP=1`. In practice this means the feature is only available for `--crate-name`, not for `#![crate_name]`; I'm interested in supporting the second but I'm not sure how.
Other major changes:
- Added `Session::is_nightly_build()`, which uses the `crate_name` of
the session
- Added `nightly_options::match_is_nightly_build`, a convenience method
for looking up `--crate-name` from CLI arguments.
`Session::is_nightly_build()`should be preferred where possible, since
it will take into account `#![crate_name]` (I think).
- Added `unstable_features` to `rustdoc::RenderOptions`
There is a user-facing change here: things like `RUSTC_BOOTSTRAP=0` no
longer active nightly features. In practice this shouldn't be a big
deal, since `RUSTC_BOOTSTRAP` is the opposite of stable and everyone
uses `RUSTC_BOOTSTRAP=1` anyway.
- Add tests
Check against `Cheat`, not whether nightly features are allowed.
Nightly features are always allowed on the nightly channel.
- Only call `is_nightly_build()` once within a function
- Use booleans consistently for rustc_incremental
Sessions can't be passed through threads, so `read_file` couldn't take a
session. To be consistent, also take a boolean in `write_file_header`.
The inliner integrates call destination place with callee return place
by remapping the local and adding extra projections as necessary.
If a call destination place contains any projections (which is already
possible) and a return place is used in an indexing projection (most
likely doesn't happen yet) the end result would be incorrect.
Add an assertion to ensure that potential issue won't go unnoticed in
the presence of more sophisticated copy propagation scheme.
inliner: Copy unevaluated constants only after successful inlining
Inliner copies the unevaluated constants from the callee body to the
caller at the point where decision to inline is yet to be made. The
constants will be unnecessary if inlining were to fail.
Organize the code moving items from callee to the caller together in one
place to avoid the issue.
Working expression optimization, and some improvements to branch-level source coverage
This replaces PR #78040 after reorganizing the original commits (by request) into a more logical sequence of major changes.
Most of the work is in the MIR `transform/coverage/` directory (originally, `transform/instrument_coverage.rs`).
Note this PR includes some significant additional debugging capabilities, to help myself and any future developer working on coverage improvements or issues.
In particular, there's a new Graphviz (.dot file) output for the coverage graph (the `BasicCoverageBlock` control flow graph) that provides ways to get some very good insight into the relationships between the MIR, the coverage graph BCBs, coverage spans, and counters. (There are also some cool debugging options, available via environment variable, to alter how some data in the graph appears.)
And the code for this Graphviz view is actually generic... it can be used by any implementation of the Rust `Graph` traits.
Finally (for now), I also now output information from `llvm-cov` that shows the actual counters and spans it found in the coverage map, and their counts (from the `--debug` flag). I found this to be enormously helpful in debugging some coverage issues, so I kept it in the test results as well for additional context.
`@tmandry` `@wesleywiser`
r? `@tmandry`
Here's an example of the new coverage graph:
* Within each `BasicCoverageBlock` (BCB), you can see each `CoverageSpan` and its contributing statements (MIR `Statement`s and/or `Terminator`s)
* Each `CoverageSpan` has a `Counter` or and `Expression`, and `Expression`s show their Add/Subtract operation with nested operations. (This can be changed to show the Counter and Expression IDs instead, or in addition to, the BCB.)
* The terminators of all MIR `BasicBlock`s in the BCB, including one final `Terminator`
* If an "edge counter" is required (because we need to count an edge between blocks, in some cases) the edge's Counter or Expression is shown next to its label. (Not shown in the example below.) (FYI, Edge Counters are converted into a new MIR `BasicBlock` with `Goto`)
<img width="1116" alt="Screen Shot 2020-10-17 at 12 23 29 AM" src="https://user-images.githubusercontent.com/3827298/96331095-616cb480-100f-11eb-8212-60f2d433e2d8.png">
r? `@tmandry`
FYI: `@wesleywiser`
Implementing the Graph traits for the BasicCoverageBlock
graph.
optimized replacement of counters with expressions plus new BCB graphviz
* Avoid adding coverage to unreachable blocks.
* Special case for Goto at the end of the body. Make it non-reportable.
Improved debugging and formatting options (from env)
Don't automatically add counters to BCBs without CoverageSpans. They may
still get counters but only if there are dependencies from
other BCBs that have spans, I think.
Make CodeRegions optional for Counters too. It is
possible to inject counters (`llvm.instrprof.increment` intrinsic calls
without corresponding code regions in the coverage map. An expression
can still uses these counter values.
Refactored instrument_coverage.rs -> instrument_coverage/mod.rs, and
then broke up the mod into multiple files.
Compiling with coverage, with the expression optimization, works on
the json5format crate and its dependencies.
Refactored debug features from mod.rs to debug.rs
Changes from 68965 extended the kind of instances that are being
inlined. For some of those, the `instance_mir` returns a MIR body that
is already expressed in terms of the types found in substitution array,
and doesn't need further substitution.
Use `substs_for_mir_body` to take that into account.
Inliner copies the unevaluated constants from the callee body to the
caller at the point where decision to inline is yet to be made. The
constants will be unnecessary if inlining were to fail.
Organize the code moving items from callee to the caller together in one
place to avoid the issue.
Corrected suggestion for generic parameters in `function_item_references` lint
This commit handles functions with generic type parameters like you pointed out as well as const generics. Also this is probably a minor thing, but the type alias you used in the example doesn't show up so the suggestion right now would be `size_of::<[u8; 16]> as fn() ->`. This is because the lint checker works with MIR instead of HIR. I don't think we can get the alias at that point, but let me know if I'm wrong and there's a way to fix this. Also I put you as the reviewer, but I'm not sure if you want to review it or if it makes more sense to ask one of the original reviewers of this lint.
closes#78571
Properly handle lint spans after MIR inlining
The first commit shows what happens when we apply mir inlining and then cause lints on the inlined MIR.
The second commit fixes that.
r? `@wesleywiser`
Retagging: do not retag 'raw reborrows'
When doing `&raw const (*raw_ptr).field`, we do not want any retagging; the original provenance should be fully preserved.
Fixes https://github.com/rust-lang/miri/issues/1608
Test added by https://github.com/rust-lang/miri/pull/1614
Not sure whom to ask for review on this... `@oli-obk` can you have a look? Or maybe highfive makes a good choice.^^
This lint was incorrectly suggesting casting a function to a pointer without
specifying generic type parameters or const generics. This would cause a
compiler error since the missing parameters couldn't be inferred. This commit
fixed the suggestion and added a few tests with generics.
The validator in visit_local asserts that local has a stroage when used,
but visit_local is never called so validation is ineffective.
Use super_statement and super_terminator to ensure that locals are visited.
Move "mutable thing in const" check from interning to validity
This moves the check for mutable things (such as `UnsafeCell` or `&mut`) in a`const` from interning to validity. That means we can give more targeted error messages (pointing out *where* the problem lies), and we can simplify interning a bit.
Also fix the interning mode used for promoteds in statics.
r? @oli-obk
When a function argument bound by `Pointer` is an associated type, we only
perform substitutions using the parameters from the callsite but don't attempt
to normalize since it may not succeed. A simplified version of the scenario that
triggered this error was added as a test case. Also fixed `Pointer::fmt` which
was being double-counted when called outside of macros and added a test case for
this.
Removed test for the unhandled case of calls to `fn f<T>(x: &T)` where `x` is a
function reference and is formatted as a pointer in `f`. This compiles since
`&T` implements `Pointer`, but is unlikely to occur in practice. Also tweaked
the lint's wording and modified tests accordingly.
The lint checks arguments in calls to `transmute` or functions that have
`Pointer` as a trait bound and displays a warning if the argument is a function
reference. Also checks for `std::fmt::Pointer::fmt` to handle formatting macros
although it doesn't depend on the exact expansion of the macro or formatting
internals. `std::fmt::Pointer` and `std::fmt::Pointer::fmt` were also added as
diagnostic items and symbols.
Working with MIR let's us exclude expressions like `&fn_name as &dyn Something`
and `(&fn_name)()`. Also added ABI, unsafety and whether a function is variadic
in the lint suggestion, included the `&` in the span of the lint and updated the
test.
Remove unused set-discriminant statements and assignments regardless of rvalue
* Represent use counts with u32
* Unify use count visitors
* Change RemoveStatements visitor into a function
* Remove unused set-discriminant statements
* Use exhaustive match to clarify what is being optimized
* Remove unused assignments regardless of rvalue kind
rustc_mir: track inlined callees in SourceScopeData.
We now record which MIR scopes are the roots of *other* (inlined) functions's scope trees, which allows us to generate the correct debuginfo in codegen, similar to what LLVM inlining generates.
This PR makes the `ui` test `backtrace-debuginfo` pass, if the MIR inliner is turned on by default.
Also, `#[track_caller]` is now correct in the face of MIR inlining (cc `@anp).`
Fixes#76997.
r? `@rust-lang/wg-mir-opt`
Update affected ui & incremental tests to use a user declared variable
bindings instead of temporaries. The former are preserved because of
debuginfo, the latter are not.
The simplify locals implementation uses two different visitors to update
the locals use counts. The DeclMarker calculates the initial use counts.
The StatementDeclMarker updates the use counts as statements are being
removed from the block.
Replace them with a single visitor that can operate in either mode,
ensuring consistency of behaviour.
Additionally use exhaustive match to clarify what is being optimized.
No functional changes intended.
replace `#[allow_internal_unstable]` with `#[rustc_allow_const_fn_unstable]` for `const fn`s
`#[allow_internal_unstable]` is currently used to side-step feature gate and stability checks.
While it was originally only meant to be used only on macros, its use was expanded to `const fn`s.
This pr adds stricter checks for the usage of `#[allow_internal_unstable]` (only on macros) and introduces the `#[rustc_allow_const_fn_unstable]` attribute for usage on `const fn`s.
This pr does not change any of the functionality associated with the use of `#[allow_internal_unstable]` on macros or the usage of `#[rustc_allow_const_fn_unstable]` (instead of `#[allow_internal_unstable]`) on `const fn`s (see https://github.com/rust-lang/rust/issues/69399#issuecomment-712911540).
Note: The check for `#[rustc_allow_const_fn_unstable]` currently only validates that the attribute is used on a function, because I don't know how I would check if the function is a `const fn` at the place of the check. I therefore openend this as a 'draft pull request'.
Closesrust-lang/rust#69399
r? @oli-obk
stop promoting union field accesses in 'const'
Turns out that promotion of union field accesses is the only difference between "promotion in `const`/`static` bodies" and "explicit promotion". So if we can remove this, we have finally achieved what I thought to already be the case -- that the bodies of `const`/`static` initializers behave the same as explicit promotion contexts.
The reason we do not want to promote union field accesses is that they can introduce UB, i.e., they can go wrong. We want to [minimize the ways promoteds can fail to evaluate](https://github.com/rust-lang/const-eval/issues/53). Also this change makes things more consistent overall, removing a special case that was added without much consideration (as far as I can tell).
Cc `@rust-lang/wg-const-eval`
Introduce a temporary for discriminant value in MatchBranchSimplification
The optimization introduces additional uses of the discriminant operand, but
does not ensure that it is still valid to evaluate it or that it still
evaluates to the same value.
Evaluate it once at original position, and store the result in a new temporary.
Follow up on #78151. The optimization remains disabled by default.
Closes#78239.
Fix const core::panic!(non_literal_str).
Invocations of `core::panic!(x)` where `x` is not a string literal expand to `panic!("{}", x)`, which is not understood by the const panic logic right now. This adds `panic_str` as a lang item, and modifies the const eval implementation to hook into this item as well.
This fixes the issue mentioned here: https://github.com/rust-lang/rust/issues/51999#issuecomment-687604248
r? `@RalfJung`
`@rustbot` modify labels: +A-const-eval
The optimization introduces additional uses of the discriminant operand, but
does not ensure that it is still valid to evaluate it or that it still
evaluates to the same value.
Evaluate it once at original position, and store the result in a new temporary.
This optimization can result in unsoundness, because it introduces
additional uses of a place holding the discriminant value without
ensuring that it is valid to do so.
normalize substs while inlining
fixes#68347 or more precisely, this fixes the same ICE in rust analyser as veloren is pinned to a specific nightly
and had an error with the current one.
I didn't look into creating an MVCE here as that seems fairly annoying, will spend a few minutes doing so rn. (failed)
r? `@eddyb` cc `@bjorn3`
instrument-coverage: try our best to not ICE
instrument-coverage was ICEing for me on some code, in particular code
that had devirtualized paths from standard library. Instrument coverage
probably has no bussiness dictating which paths are valid and which
aren't so just feed it everything and whatever and let tooling deal with
other stuff.
For example, with this commit we can generate coverage hitpoints for
these interesting paths:
* `/rustc/.../library/core/lib.rs` – non-devirtualized path for libcore
* `/home/.../src/library/core/lib.rs` – devirtualized version of above
* `<inline asm>`, `<anon>` and many similar synthetic paths
Even if those paths somehow get to the instrumentation pass, I'd much
rather get hits for these weird paths and hope some of them work (as
would be the case for devirtualized path to libcore), rather than have
compilation fail entirely.
instrument-coverage was ICEing for me on some code, in particular code
that had devirtualized paths from standard library. Instrument coverage
probably has no bussiness dictating which paths are valid and which
aren't so just feed it everything and whatever and let tooling deal with
other stuff.
For example, with this commit we can generate coverage hitpoints for
these interesting paths:
* `/rustc/.../library/core/lib.rs` – non-devirtualized path for libcore
* `/home/.../src/library/core/lib.rs` – devirtualized version of above
* `<inline asm>`, `<anon>` and many similar synthetic paths
Even if those paths somehow get to the instrumentation pass, I'd much
rather get hits for these weird paths and hope some of them work (as
would be the case for devirtualized path to libcore), rather than have
compilation fail entirely.
Create a single source scope for promoteds
A promoted inherits all scopes from the parent body. At the same time,
almost all statements and terminators inside the promoted body so far
refer only to one of those scopes: the outermost one.
Instead of inheriting all scopes, inherit only a single scope
corresponding to the location of the promoted, making sure that there
are no references to other scopes.
A promoted inherits all scopes from the parent body. At the same time,
almost all statements and terminators inside the promoted body so far
refer only to one of those scopes: the outermost one.
Instead of inheriting all scopes, inherit only a single scope
corresponding to the location of the promoted, making sure that there
are no references to other scopes.
Replace absolute paths with relative ones
Modern compilers allow reaching external crates
like std or core via relative paths in modules
outside of lib.rs and main.rs.
