The size of a.pcm produced by an RV64 clang running natively is 67416
bytes, causing this test to fail. Bump up the maximum size. The test
still retains its original intent as far as I can see, as it's really
trying to ensure that compressing kicks in and reduces the
multi-megabyte input.
In D152070 we added many new intrinsic types required for the RISC-V
Vector Extension.
This was crashing when loading the AST as those types are intrinsically
added to the AST (they don't come from the disk).
The total number required now by clang exceeds 400 so increasing the
value to 500 solves the problem. This value was already increased in
D92715 but I assume this has some impact on the on-disk format.
Also add a static assert to avoid this happening again in the future.
Differential Revision: https://reviews.llvm.org/D153111
Extend SM_SLOC_BUFFER_BLOB_COMPRESSED to allow zstd, which is much faster
(compression/decompression) than zlib with a similar compression ratio.
An alternative is to add a value beside SM_SLOC_BUFFER_BLOB_COMPRESSED, but
reusing SM_SLOC_BUFFER_BLOB_COMPRESSED slightly simplifies the implementation
and leads to better diagnostics when a slightly older Clang consumes zstd
compressed blob.
Compressing AST takes a small portion of WriteAST, so we can pick a higher
compression level.
Compiling a relatively large .pcm (absl endian) with -fmodules-embed-all-files,
zstd level 9 has comparable performance with zlib-chromium level 6 (default),
but provides smaller output (5809156 => 5796016). Higher zstd levels will make
"Compress AST" notably slower and do not provide significant more size saving.
```
2.219345 Total ExecuteCompiler
0.746799 Total Frontend
0.736862 Total Source
0.339434 Total ReadAST
0.165452 Total WriteAST
0.043045 Total Compress AST
0.008236 Total ParseClass
0.00633 Total InstantiateClass
0.001887 Total isPotentialConstantExpr
0.001808 Total InstantiateFunction
0.001535 Total EvaluateForOverflow
0.000986 Total EvaluateAsRValue
0.000536 Total EvaluateAsBooleanCondition
0.000308 Total EvaluateAsConstantExpr
0.000156 Total EvaluateAsInt
3.4e-05 Total EvaluateKnownConstInt
8e-06 Total EvaluateAsInitializer
0 Total PerformPendingInstantiations
```
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D137885
