coverage bug fixes and optimization support
Adjusted LLVM codegen for code compiled with `-Zinstrument-coverage` to
address multiple, somewhat related issues.
Fixed a significant flaw in prior coverage solution: Every counter
generated a new counter variable, but there should have only been one
counter variable per function. This appears to have bloated .profraw
files significantly. (For a small program, it increased the size by
about 40%. I have not tested large programs, but there is anecdotal
evidence that profraw files were way too large. This is a good fix,
regardless, but hopefully it also addresses related issues.
Fixes: #82144
Invalid LLVM coverage data produced when compiled with -C opt-level=1
Existing tests now work up to at least `opt-level=3`. This required a
detailed analysis of the LLVM IR, comparisons with Clang C++ LLVM IR
when compiled with coverage, and a lot of trial and error with codegen
adjustments.
The biggest hurdle was figuring out how to continue to support coverage
results for unused functions and generics. Rust's coverage results have
three advantages over Clang's coverage results:
1. Rust's coverage map does not include any overlapping code regions,
making coverage counting unambiguous.
2. Rust generates coverage results (showing zero counts) for all unused
functions, including generics. (Clang does not generate coverage for
uninstantiated template functions.)
3. Rust's unused functions produce minimal stubbed functions in LLVM IR,
sufficient for including in the coverage results; while Clang must
generate the complete LLVM IR for each unused function, even though
it will never be called.
This PR removes the previous hack of attempting to inject coverage into
some other existing function instance, and generates dedicated instances
for each unused function. This change, and a few other adjustments
(similar to what is required for `-C link-dead-code`, but with lower
impact), makes it possible to support LLVM optimizations.
Fixes: #79651
Coverage report: "Unexecuted instantiation:..." for a generic function
from multiple crates
Fixed by removing the aforementioned hack. Some "Unexecuted
instantiation" notices are unavoidable, as explained in the
`used_crate.rs` test, but `-Zinstrument-coverage` has new options to
back off support for either unused generics, or all unused functions,
which avoids the notice, at the cost of less coverage of unused
functions.
Fixes: #82875
Invalid LLVM coverage data produced with crate brotli_decompressor
Fixed by disabling the LLVM function attribute that forces inlining, if
`-Z instrument-coverage` is enabled. This attribute is applied to
Rust functions with `#[inline(always)], and in some cases, the forced
inlining breaks coverage instrumentation and reports.
FYI: `@wesleywiser`
r? `@tmandry`
Add documentation for rustdoc-gui tests
I think a bit of documentation doesn't hurt in this case considering how "out of the ordinary" this is.
r? ``@jyn514``
Remove Option::{unwrap_none, expect_none}.
This removes `Option::unwrap_none` and `Option::expect_none` since we're not going to stabilize them, see https://github.com/rust-lang/rust/issues/62633.
Closes#62633
Fixes#80691
When we evaluate a trait predicate, we convert an
`EvaluatedToOk` result to `EvaluatedToOkModuloRegions` if we erased any
regions. We cache the result under a region-erased 'freshened'
predicate, so `EvaluatedToOk` may not be correct for other predicates
that have the same cache key.
2229 migration: Don't try resolve regions before writeback
In the analysis use `resolve_vars_if_possible` instead of `fully_resolve`,
because we might not have performed regionck yet.
Fixes: #83176
r? `@nikomatsakis`
implement `feature(const_generics_defaults)`
Implements const generics defaults `struct Example<const N: usize=3>`, as well as a query for getting the default of a given const-parameter's def id. There are some remaining FIXME's but they were specified as not blocking for merging this PR. This also puts the defaults behind the unstable feature gate `#![feature(const_generics_defaults)]`.
~~This currently creates a field which is always false on `GenericParamDefKind` for future use when
consts are permitted to have defaults. I'm not sure if this is exactly what is best for adding default parameters, but I mimicked the style of type defaults, so hopefully this is ok.~~
r? `@lcnr`
Allow not emitting `uwtable` on Android
`uwtable` is marked as required on Android, so it can't be disabled via `-C force-unwind-tables=no`. However, I found that the reason it's marked as required was to resolve a [backtrace issue in Gecko](https://github.com/rust-lang/rust/issues/49867), and I haven't find any other reasons that make it required ([yet](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/Unwind.20tables.20are.20strictly.20required.20on.20Windows.20and.20Android)). Therefore, I assume it's safe to turn it off if a (nice) backtrace is not needed, and submit this PR to allow `-C force-unwind-tables=no` when targeting Android.
Note that I haven't tested this change on Android as I don't have an Android environment for testing.
Only enable assert_dep_graph when query-dep-graph is enabled.
This is a debugging option. The only effect should be on rustc tests.
r? ``@michaelwoerister``
Sidebar trait items order
We were actually sorting `Symbol` and not `String`, creating a completely invalid sort result. I added a test to prevent regressions.
r? ``@jyn514``
Rename `source` to `span` and `span` to `source`
- Rename `clean::Item.source` to `span`
- Rename `clean::Span::span()` to `clean::Span::inner()`
- Rename `rustdoc_json_types::Item.source` to `span`
- rustdoc-json: Rename `Import.span` to `Import.source`
*See also the [discussion on Zulip][z] (this is a bit more than discussed in
that conversation, but all the changes are related).*
r? `@jyn514`
[z]: https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/get.20span.20of.20file.20from.20name/near/229603729
This currently creates a field which is always false on GenericParamDefKind for future use when
consts are permitted to have defaults
Update const_generics:default locations
Previously just ignored them, now actually do something about them.
Fix using type check instead of value
Add parsing
This adds all the necessary changes to lower const-generics defaults from parsing.
Change P<Expr> to AnonConst
This matches the arguments passed to instantiations of const generics, and makes it specific to
just anonymous constants.
Attempt to fix lowering bugs
Use TrustedRandomAccess for in-place iterators where possible
This can speed up in-place iterators containing simple casts and transmutes from `Copy` types to any type of same size. `!Copy` types can't be optimized since `TrustedRandomAccess` isn't implemented for those iterators.
```
name on.b ns/iter o1.b ns/iter diff ns/iter diff % speedup
vec::bench_transmute 20 (40000 MB/s) 12 (66666 MB/s) -8 -40.00% x 1.67
```
This saves us both the Freeze/Unpin queries, and avoids placing
noalias attributes, which have a compile-time impact on LLVM
even in optnone builds (due to always_inline functions).
Such structures may contain self-references, in which case the
same location may be accessible through a pointer that is not
based-on the noalias pointer.
This is still grey area as far as language semantics are concerned,
but checking for !Unpin as an indicator for self-referential
sturctures seems like a good approach for the meantime.
Perform 'deep recollection' in test helper macros
Currently, the print helper macro performs 'recollection' by doing
`token_stream.into_iter().collect()`. However, this will not affect
nonterminals that occur nested inside delimited groups, since the
wrapping delimited group will be left untouched.
This commit adds 'deep recollection', which recursively recollects every
delimited group in the token stream. As with normal recollection, we
only print out something if deep recollection results in a different
stringified token stream.
This is useful for catching bugs where we update the AST of a
nonterminal (which affects pretty-printing), but do not update the
attatched `TokenStream`
