When building in Bazel actions, notably building runtimes, using
absolute paths makes the results non-hermetic and generally less
cache-friendly.
This restructures the code to only form an absolute path as part of the
`bazel run` change of working directory. It also tries to make the API
for doing this a bit more clear by taking the `exe_path` and
transforming it internally.
To support this, this PR also generalizes the `RemovingDir` to support
relative paths. While these can be tricky -- the working directory needs
to not change while they exist -- that isn't a reason to fully exclude
them and they're useful for implementing relative-path runtimes, etc.
We had a long discussion of this, so trying to document what seems to be
the conclusion... and also clean up the exceptions that I could find.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
This changes to an `Error` return to let the driver do the "error: "
prefix, except for one case with `help` that needs more work to change
(I'm not planning on picking up that TODO). It also changes
capitalization, backtick use, and a few minor punctuation things to try
to better match the diagnostic style.
This also adds `Error` matchers so that the changes to command line
testing are clearer.
The big addition here is a very, very rough and very early skeleton of a
source code generator framework. This builds upon the lexers identifier
synthesis logic, improving on its framework and wiring it up with the
most rudimentary of source file generation. This is just enough to
roughly replicate my "big API file" source code benchmarks.
The source generation works *very* hard to both vary the structure and
content of the source as much as possible while ensuring the same
*total* amount of each construct is in use, from bytes in identifiers to
line breaks, parameters, etc. This lets us generate randomly structure
inputs that should consistently take the exact same amount of total work
to compile.
The complex identifier synthesis logic from the lexer's benchmark is
moved over here and the lexer uses APIs in the source generator for
identifiers. The other source synthesis in the lexer's benchmark isn't
yet moved over, but should likely be slowly absorbed here as it can be
refactored into a more principled and re-usable form. Some bits may stay
of course if they're just too lexer-specific.
Next, this adds a simple end-to-end compile benchmark for the driver
that directly and much more clearly reproduces all the measurements I've
done manually up until now. It should also be easy to extend to more
patterns over time as we add support to the source generator to produce
those patterns.
Last but not least, I've added a tiny CLI to the source generator so
that you can generate source code manually. This is especially nice for
generating demo source code to actually run through the driver or look
at in an editor. The CLI can also generate C++ source code which lets us
do some minimal comparative benchmarking between Carbon and C++/Clang.
There are huge number of TODOs in the source generation framework. This
is going to be a large ongoing effort I suspect.
There are also a bunch of rough edges I've left to try and get this out
for review sooner. I've left TODOs for refactorings that really need to
be done here, but hoping these can maybe be follow-ups. If not, please
flag and I'll try to layer them on here.
Sample compile benchmark output, nicely showing where we are w.r.t. our
goal speeds (2x behind on lex and check, 5x on parse) at least on a
recent AMD server CPU:
```
------------------------------------------------------------------------------------------------------
Benchmark Time CPU Iterations Lines
------------------------------------------------------------------------------------------------------
BM_CompileAPIFileDenseDecls<Phase::Lex>/256 29420 ns 29419 ns 22860 6.62847M/s
BM_CompileAPIFileDenseDecls<Phase::Lex>/1024 146130 ns 146128 ns 4840 6.69959M/s
BM_CompileAPIFileDenseDecls<Phase::Lex>/4096 601584 ns 601577 ns 1020 6.69573M/s
BM_CompileAPIFileDenseDecls<Phase::Lex>/16384 2547578 ns 2547313 ns 280 6.404M/s
BM_CompileAPIFileDenseDecls<Phase::Lex>/65536 10816591 ns 10816389 ns 80 6.05193M/s
BM_CompileAPIFileDenseDecls<Phase::Lex>/262144 52191320 ns 52189828 ns 20 5.02261M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 101706 ns 101698 ns 6900 1.91745M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 512161 ns 512162 ns 1380 1.9115M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 2078426 ns 2078430 ns 340 1.938M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 8795786 ns 8795583 ns 100 1.85468M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 35073596 ns 35072973 ns 20 1.86639M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 151100688 ns 151097370 ns 20 1.73483M/s
BM_CompileAPIFileDenseDecls<Phase::Check>/256 957059 ns 957049 ns 740 203.751k/s
BM_CompileAPIFileDenseDecls<Phase::Check>/1024 1956134 ns 1955985 ns 360 500.515k/s
BM_CompileAPIFileDenseDecls<Phase::Check>/4096 5797864 ns 5797417 ns 120 694.792k/s
BM_CompileAPIFileDenseDecls<Phase::Check>/16384 21219608 ns 21217584 ns 40 768.843k/s
BM_CompileAPIFileDenseDecls<Phase::Check>/65536 96311116 ns 96302334 ns 20 679.734k/s
BM_CompileAPIFileDenseDecls<Phase::Check>/262144 371637963 ns 371609964 ns 20 705.387k/s
```
Lest someone think this is *bad*, the fact that we're already within 2x
of our rather audacious goals makes me quite happy. =D
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Chandler Carruth
Thomas Köppe
Jon Ross-PerkinsandDana Jansens
