I'm partly doing this because the current setup would be difficult to share with the toolchain. e.g., ProtoToCarbon isn't explorer-specific, but the only way to run it via CLI is the explorer's fuzzverter. I want a separate tool.
This change:
- Adds a //common/fuzzing:proto_to_carbon tool.
- The rest of fuzzverter is now just //explorer/fuzzing:ast_to_proto.
- The change simplifies overall handling and removes a LLVM CLI dependency.
- Stops allowing unknown fields in the proto.
- This has mostly led to forgetting to remove fuzzer inputs that were for removed features.
- Moves more non-explorer-specific bits to //common/fuzzing.
- Cleans up remaining pieces in //explorer/fuzzing
- Merges the //explorer/fuzzing proto tests, which deduplicates AstToString copies.
- These tests also had duplicate dependencies, etc -- and all complete in ~6s.
- Updates and fixes regen_corpus which was previously broken by other changes.
- Updates the README to reflect changes.
- Removes obsolete proto-fuzzer build configuration (AFAICT this is no longer needed).
This is intended to address currently flaky timeouts that are likely caused by the size of the prelude. I'm addressing a performance bottleneck in AnalyzeProgram with trace output. Trying to omit prelude traces reduces most trace output significantly, and I think it'll scale better as the prelude size increases.
The basic mechanics here are:
- In order to consistently track whether tracing is on, I've added a TraceStream class, explorer/interpreter/trace_stream.h.
- The AST now has a num_prelude_declarations field, so that it's provided where the boundary is.
- In order to mark where we try to skip prelude output, I've added calls to set_in_prelude in type_checker.
- In exec_program, I just use num_prelude_declarations directly to skip over.
- Everywhere checks TraceStream::is_enabled before printing, similar to the std::optional check that was previously used.
This does add some timing output in order to better diagnose where slowness is coming from, when tracing. It also adds "verbose" targets to make it easier to get the trace output.
So for example, here's a timing for zero.carbon:
```
Timings:
- Parse: 13ms
- AddPrelude: 25ms
- AnalyzeProgram: 116ms
- ExecProgram: 12ms
```
If I make a small change to just not set skipping_prelude (essentially getting back to current output):
```
- Parse: 13ms
- AddPrelude: 25ms
- AnalyzeProgram: 2359ms
- ExecProgram: 57ms
```
Thus in this trivial example, I'm eliminating about 95% of the execution time.
Note this approach could still be refined in a few ways:
- We could add a flag to allow overriding in_prelude. It should be a small amount of work after this change. But it's a little consistent with how parser_debug works, that it won't print prelude output by default (unless there's an error).
- Execution could skip messages involving initialization of globals declared in the prelude. This is a little noisy right now, but I don't think it's significant for performance because ExecProgram is tiny.
- Once files are more separated, we should be able to change the num_prelude_declarations/set_in_prelude approach.
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Support for global variables is still missing; they're a bit more tricky because they use a pattern to introduce their name.
Prior to this change, explorer heavily relied on name comparisons to determine whether two declarations declare the same entity. Some of those instances are fixed in this PR, but more remain to be fixed, and some TODOs are added for some harder-to-fix instances.
This is to help with frequent build breakages cased by proto changes.
Fuzzer corpus can be periodically auto-regenerated.
Crashing samples from the fuzzer are better 'preserved' in the form of fail_xx.carbon tests.
I'm doing this to avoid macro name conflicts, following https://google.github.io/styleguide/cppguide.html#Preprocessor_Macros: "If you do export a macro from a header, it must have a globally unique name. To achieve this, it must be named with a prefix consisting of your project's namespace name (but upper case)."
Commands run:
```
sed -i 's/\(DCHECK\|CHECK\|FATAL\|MAKE_UNIQUE_NAME\|MAKE_UNIQUE_NAME_IMPL\|RAW_EXITING_STREAM\|RETURN_IF_ERROR\|RETURN_IF_ERROR_IMPL\|ASSIGN_OR_RETURN\|ASSIGN_OR_RETURN_IMPL\|DIAGNOSTIC_KIND\|RETURN_IF_STACK_LIMITED\)(/CARBON_\1(/g' $(git ls-files *.cpp *.h *.lpp *.ypp *.def ':!third_party')
sed -i 's/#undef DIAGNOSTIC_KIND/#undef CARBON_DIAGNOSTIC_KIND/' toolchain/diagnostics/diagnostic_registry.def
```
Note this isn't *quite* everything, but it's intended to be a large pass at everything:
```
╚╡git grep '#define ' *.cpp *.h *.lpp *.ypp *.def ':!third_party' | grep -v '#define CARBON' | grep -v _H_
explorer/syntax/lexer.lpp: #define YY_USER_ACTION \
explorer/syntax/lexer.lpp: #define SIMPLE_TOKEN(name) \
explorer/syntax/lexer.lpp: #define ARG_TOKEN(name, arg) \
explorer/syntax/parse_and_lex_context.h:#define YY_DECL \
migrate_cpp/cpp_refactoring/var_decl.cpp:#define ABSTRACT_TYPE(Class, Base)
migrate_cpp/cpp_refactoring/var_decl.cpp:#define TYPE(Class, Base) \
```
We may in particular want to do a pass to clean up #ifdef guards and make them be CARBON_ rooted.
The logic is using bazel Runfiles API per Jon's suggestion.
One of the scenarios used by the fuzzing framework is to place the binary and its runfiles into a folder, resulting in a directory layout like this:
[temp dir]
fuzzer
fuzzer.runfiles/
Tested:
bazel test -c opt explorer/fuzzing:explorer_fuzzer
bazel build -c opt explorer/fuzzing:explorer_fuzzer + run the binary from various locations
Jon Ross-Perkins
pk19604014