If a keyword or a sized type literal (eg, `f2`) is used in a context
where we are confident that we are expecting an identifier -- either
before a `:` in a binding pattern or after a `.` in a member access or
designator -- then recover as if a raw identifier was used.
This appears to be a particular stumbling block for coding agents, so
seems worth paying special attention to.
Add a mechanism to the tokenized buffer to track additional tokens
synthesized for error recovery so that we can keep the lexed token
sequence immutable and still satisfy the invariants throughout the rest
of the toolchain for recovery tokens. Thanks to chandlerc for suggesting
this approach!
This fixes various violations of C++'s One Definition Rule, where we
accidentally gave the same static data member multiple definitions in
different translation units. Clang happens to emit such definitions with
weak linkage, which allows us to get away with this without link errors,
but it's still formally incorrect.
Also switch keyword order around for a handful of instances of
`constexpr inline`, per agreement in open discussion.
This happens to reduce the size of a `-c dbg` toolchain binary by 7.2
MiB, presumably by making more of our symbols and especially debug info
discardable.
This switches `DCHECK` and `FATAL` as well.
The goal is to reduce the code size impact of these assertions so that
we can keep more of them enabled. Currently, the largest cost I see from
`CHECK` is not the actual check or the cold code itself, but actually
the failure to inline trivial functions due to the presence of the cold
code. This means that our goal isn't to reduce apparent code size in the
final binary but the LLVM IR cost assessed for these routines in the
inliner, which closely correlates with code size but is a bit different.
As discussed in #4283, experimentation shows that a single function call
with a minimal number of arguments is the lowest cost model for these.
This is easily achieved with a format-string API that internally uses
`llvm::formatv`. This PR is essentially the `CHECK` version of #4283.
However, the check macros are substantially harder to make work with
both format strings and streaming because they also take a condition.
Also, unexpectedly, I was very successful at devising a regular
expression based automated rewrite from the streaming to the format
string form with only low 10s of manual fixes. This includes compacting
strings broken up across lines, etc. Given how well that went, I've
prepared this PR which just directly switches to the format string API
and migrate everything to use it.
One nice side-effect is that the format string approach ends up greatly
simplifying the implementation here as well.
This is ... *shockingly* effective. Parsing speeds up by more than 3%
with just this change. And checking speeds up by **8%** with this change
alone:
```
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 86.3µs ± 1% 82.9µs ± 1% -3.94% (p=0.000 n=17+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 431µs ± 1% 415µs ± 1% -3.76% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 1.77ms ± 1% 1.71ms ± 1% -3.18% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 7.44ms ± 1% 7.17ms ± 2% -3.56% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 30.7ms ± 1% 29.7ms ± 1% -3.15% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 131ms ± 1% 127ms ± 1% -2.81% (p=0.000 n=18+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/256 878µs ± 2% 800µs ± 1% -8.91% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/1024 1.88ms ± 2% 1.72ms ± 1% -8.56% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/4096 5.78ms ± 2% 5.28ms ± 1% -8.70% (p=0.000 n=20+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/16384 21.9ms ± 1% 20.1ms ± 1% -8.02% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/65536 90.4ms ± 2% 83.1ms ± 1% -8.04% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/262144 381ms ± 2% 352ms ± 1% -7.79% (p=0.000 n=19+19)
```
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Playing with the macro suggestion on #4028, replace DeclKind with some
templating that asserts the in-use token is an introducer token. This
allows type-safe usage of Lex::TokenKind, reducing the benefit of a
separate enum while improving stdout (since now this will ostream as the
keyword name).
Just spotted these while looking at warnings that seem to fire on our
code are probably are things we'd fix if we saw them. None of these seem
important FWIW.
Also removes a redundant flag that is part of `-Wall`.
I have a follow-up for the high-value warning I spotted that motivated
me to look at all of this. But it's noisy so kept it as a separate PR.
Change syntax for package declaration to put the `impl` keyword at the
start and remove the `api` keyword.
To support this, rearrange processing of package, library, and import
declarations to use the general modifier handling support in declaration
parsing rather than special-case logic.
There is an ambiguity in `impl package.Foo as Bar`, which we resolve by
treating `package` as an introducer after a modifier only if it's not
followed by `.`.
We already do this with things like llvm::DenseMapInfo, I don't know why
I was doing this with format_provider. But this should be more
consistent, and slightly better for not entering another library's
namespace.
I was suggesting this because `FloatingPoint` is pretty long. `int` and
`float` should be familiar abbreviations. `unsigned` should be familiar
to developers too, but `UnsignedInt` still feels usefully clearer for
the additional chars.
This gets to a lifetime subtlety, particularly with things like the
sorting diagnostic consumer that delay output. In order to reduce the
chance of accidental references, disallow StringRef in the diagnostics.
For example:
```
./toolchain/diagnostics/diagnostic_emitter.h:162:5: error: static_assert failed due to requirement '!std::is_same_v<llvm::StringRef, llvm::StringRef>' "Use std::string or llvm::StringLiteral for diagnostic lifetimes."
static_assert(
^
toolchain/check/convert.cpp:477:11: note: in instantiation of member function 'Carbon::Internal::DiagnosticBase<std::string, std::string, llvm::StringRef>::DiagnosticBase' requested here
CARBON_DIAGNOSTIC(StructInitMissingFieldInConversion, Error,
^
./toolchain/diagnostics/diagnostic_emitter.h:47:7: note: expanded from macro 'CARBON_DIAGNOSTIC'
::Carbon::Internal::DiagnosticBase<__VA_ARGS__>( \
^
```
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Per [#toolchain
discussion](https://discord.com/channels/655572317891461132/655578254970716160/1176632520834560211)
We'd at one point been trying to put `[[nodiscard]]` everywhere, but
then we stopped because it had felt verbose without finding many issues
(plus, people plain forgot to add it). Some history in #888.
Since newer code gets added without it, we now have code like:
```
auto GetLineInfo(Line line) -> LineInfo&;
[[nodiscard]] auto GetLineInfo(Line line) const -> const LineInfo&;
auto AddLine(LineInfo info) -> Line;
auto GetTokenInfo(Token token) -> TokenInfo&;
[[nodiscard]] auto GetTokenInfo(Token token) const -> const TokenInfo&;
auto AddToken(TokenInfo info) -> Token;
[[nodiscard]] auto GetTokenPrintWidths(Token token) const -> PrintWidths;
```
Here, the lack of `[[nodiscard]]` doesn't mean anything: for example,
`GetLineInfo` should not have its result discarded if it's called. But
the mix could be confusing for readers.
As a resolution, remove the attribute. `[[nodiscard]]` should be treated
like other attributes going forward, which essentially means "avoid in
general, add a comment to explain why the attribute is needed" rather
than use-as-default.
When originally switching to the table dispatch approach we discussed
that it'd be nice to disentangle the monolithic symbol lexing routine
with this as we'll typically have fairly precise dispatch. This is
especially true for grouping symbols, which in Carbon are all
constructively one-character (at this point).
I think this provides a substantial improvement to the clarity of the
code by disentangling the different paths. It also allowed a bunch of
simplifications / clarifications to exactly what the behavior with
closing invalid groups actually involves currently.
This was initially motivated by code organization improvements, and any
performance wins were speculative. However, when benchmarking it
surfaced a problem that hadn't been clear -- we're generating too many
distinct functions here, and the table-based dispatch slows down in the
face of that.
So this PR also includes a fix for that, removing the template-generated
fan-out of dispatch functions for distinct symbols. Instead, we have
a dedicated table to translate one character into the token kinds. This
seems to work quite well, avoiding the huge branch-y structure and just
do fairly cheap table translation & dispatch for all one-character
symbols. Building the table requires the token kinds to be default
constructable, so this also enables that and arranges for the zero-value
kind to be the error kind.
Combined, this is a modest speedup for *non* grouping symbols (3-4%,
a bit noisy). And in some cases it is a huge speedup for grouping
symbols (>10%).
Raw benchmark data with 20 runs before/after -- despite the # of runs,
the grouping symbols benchmarks were frustratingly noisy in non-uniform
ways that couldn't fully be accounted for here. Still, this seems like
an overall improvement.
```
BM_RandomSource 7.98ms ± 2% 7.73ms ± 3% -3.12% (p=0.000 n=18+19)
BM_GroupingSymbols/1/0/0 5.90ms ± 2% 5.82ms ± 4% -1.38% (p=0.001 n=20+20)
BM_GroupingSymbols/2/0/0 5.21ms ± 2% 5.15ms ± 2% -1.14% (p=0.002 n=20+18)
BM_GroupingSymbols/3/0/0 4.42ms ± 2% 4.34ms ± 2% -1.87% (p=0.000 n=19+18)
BM_GroupingSymbols/4/0/0 4.29ms ± 2% 4.38ms ± 5% ~ (p=0.297 n=17+20)
BM_GroupingSymbols/8/0/0 5.09ms ±10% 5.10ms ± 7% ~ (p=0.919 n=18+20)
BM_GroupingSymbols/16/0/0 6.35ms ± 8% 6.29ms ± 6% ~ (p=0.201 n=20+20)
BM_GroupingSymbols/32/0/0 9.88ms ± 2% 9.83ms ± 1% ~ (p=0.167 n=18+20)
BM_GroupingSymbols/0/1/0 5.12ms ± 2% 5.01ms ± 2% -2.14% (p=0.000 n=20+19)
BM_GroupingSymbols/0/2/0 4.01ms ± 2% 3.93ms ± 4% -2.03% (p=0.000 n=20+19)
BM_GroupingSymbols/0/3/0 2.92ms ± 3% 2.81ms ± 2% -3.87% (p=0.000 n=20+19)
BM_GroupingSymbols/0/4/0 2.61ms ± 3% 2.47ms ± 2% -5.30% (p=0.000 n=20+18)
BM_GroupingSymbols/0/8/0 1.77ms ± 3% 1.61ms ± 2% -8.91% (p=0.000 n=18+19)
BM_GroupingSymbols/0/16/0 1.41ms ± 3% 1.16ms ± 4% -17.66% (p=0.000 n=20+20)
BM_GroupingSymbols/0/32/0 1.10ms ± 2% 0.92ms ± 3% -16.36% (p=0.000 n=20+17)
BM_GroupingSymbols/0/0/1 5.09ms ± 2% 5.03ms ± 3% -1.11% (p=0.001 n=20+18)
BM_GroupingSymbols/0/0/2 4.01ms ± 2% 3.91ms ± 2% -2.67% (p=0.000 n=20+18)
BM_GroupingSymbols/0/0/3 2.93ms ± 3% 2.81ms ± 2% -4.23% (p=0.000 n=20+19)
BM_GroupingSymbols/0/0/4 2.59ms ± 2% 2.48ms ± 3% -4.48% (p=0.000 n=20+19)
BM_GroupingSymbols/0/0/8 1.75ms ± 1% 1.62ms ± 3% -7.65% (p=0.000 n=17+19)
BM_GroupingSymbols/0/0/16 1.40ms ± 2% 1.15ms ± 3% -17.67% (p=0.000 n=19+20)
BM_GroupingSymbols/0/0/32 1.10ms ± 2% 0.92ms ± 3% -15.91% (p=0.000 n=20+19)
BM_GroupingSymbols/32/1/0 9.62ms ± 2% 9.65ms ± 2% ~ (p=0.654 n=18+20)
BM_GroupingSymbols/32/2/0 9.41ms ± 2% 9.37ms ± 2% ~ (p=0.095 n=20+19)
BM_GroupingSymbols/32/3/0 9.13ms ± 2% 9.13ms ± 3% ~ (p=0.687 n=19+20)
BM_GroupingSymbols/32/4/0 8.93ms ± 1% 8.87ms ± 2% -0.69% (p=0.010 n=20+18)
BM_GroupingSymbols/32/8/0 8.15ms ± 2% 8.14ms ± 3% ~ (p=0.729 n=19+19)
BM_GroupingSymbols/32/16/0 7.04ms ± 3% 6.92ms ± 1% -1.71% (p=0.000 n=20+18)
BM_GroupingSymbols/32/32/0 5.48ms ± 2% 5.38ms ± 3% -1.81% (p=0.000 n=20+20)
BM_GroupingSymbols/32/32/1 5.39ms ± 2% 5.29ms ± 2% -1.87% (p=0.000 n=19+19)
BM_GroupingSymbols/32/32/2 5.34ms ± 2% 5.21ms ± 1% -2.45% (p=0.000 n=20+18)
BM_GroupingSymbols/32/32/3 5.27ms ± 3% 5.16ms ± 2% -2.18% (p=0.000 n=20+19)
BM_GroupingSymbols/32/32/4 5.21ms ± 2% 5.10ms ± 3% -2.11% (p=0.000 n=19+20)
BM_GroupingSymbols/32/32/8 4.98ms ± 2% 4.83ms ± 2% -2.85% (p=0.000 n=19+19)
BM_GroupingSymbols/32/32/16 4.55ms ± 2% 4.45ms ± 2% -2.25% (p=0.000 n=18+20)
BM_GroupingSymbols/32/32/32 3.95ms ± 2% 3.84ms ± 2% -2.98% (p=0.000 n=19+20)
```
The big change is to make the lexer helpers have internal linkage,
making all of them easy to inline into single call sites.
Looking at the profile showed several other cases of unfortunate
out-of-line functions. Two were due to the code size produced for checks
-- those are switched to `DCHECK`s to remove that code from optimized
builds. The loss of coverage seems minor.
A last one was closing open groups. This was a surprising routine to be
hot, but it the paths to discover "nothing to do here" were intertwined
into the code. This PR extracts this common trace into a separate
function that delegates to the looping recovery path. This lets the hot
path inline easily.
At this point, for a large lexing benchmark I'm using, 50% of the time
is in the identifier hash table at this point. The remaining
improvements are to actually make some of the hot routines like symbol
lexing and comment lexing faster.
Continuing with #3070. Just a dir and file rename (only prefix change is
lexer_file_test). Everything in the lex dir should be marked as a move.
Note, I think this closes#3070. There may still be further cleanup
later, but the organizational changes suggested there are being
completed.
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Richard Smith
Jon Ross-Perkins