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).
The strategy that we use for now to support template instantiation is to check the impl declaration as if it were a generic, but to defer all checking of the impl definition until we see a use in which all template parameters have arguments. At that point, we clone the impl definition and type-check the whole thing, with constant values set on the template parameters corresponding to the given arguments.
No caching of template instantiations is performed yet; each time we form a reference to a template instantiation, we instantiate it afresh. We also don't implement the name lookup rule from #949 yet; lookups during template instantiation look only in the actual type and not in the constraint.
Depends on #2699
This is intended to be used for template instantiation, but for now takes no stance as to what it's cloning.
This is tested by parsing and cloning all of our test files, and checking that the result of converting each AST to proto is the same as the result of cloning and then converting each AST to proto.
Right now //explorer/fuzzing:explorer_fuzzer takes my machine 80s to run, just because of the corpus size. The corpus is actually pretty small compared to the toolchain fuzzer, so reducing the corpus size doesn't feel quite right.
This adds support for sharding fuzz tests, and with 8 shards each is closer to 10s. This should put it closer to the noise of other explorer tests in terms of runtime.
Unfortunately I'm not seeing a sharding flag in the llvm library, which seems fair. However, that's why I'm working around it by creating separate test targets per shard, then a suite to merge them back together. The use of `shard_count` for this is idiomatic for bazel rules; I'm using it so that switching implementations should be low-impact if that's ever needed.
Co-authored-by: Adrien Leravat <Pixep@users.noreply.github.com>
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>
We fundamentally have cyclic references between declarations,
statements, expressions, and patterns, and there's no meaningful
layering between them. Combine them into a single build target.
Components such as paren_contents, static_scope, and library_name that
are defined without reference to specific AST nodes are kept as separate
BUILD targets.
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
Richard Smith
pk19604014