Much of the size of PCH/PCM files comes from stored SourceLocations.
These are encoded using (almost) their raw value, VBR-encoded. Absolute
SourceLocations can be relatively large numbers, so this commonly takes
20-30 bits per location.
We can reduce this by exploiting redundancy: many "nearby" SourceLocations are
stored differing only slightly and can be delta-encoded.
Randam-access loading of AST nodes constrains how long these sequences
can be, but we can do it at least within a node that always gets
deserialized as an atomic unit.
TypeLoc is implemented in this patch as it's a relatively small change
that shows most of the API.
This saves ~3.5% of PCH size, I have local changes applying this technique
further that save another 3%, I think it's possible to get to 10% total.
Differential Revision: https://reviews.llvm.org/D125403
It was possible to re-add a module to a shared in-memory module cache
when search paths are changed. This can eventually cause a crash if the
original module is referenced after this occurs.
1. Module A depends on B
2. B exists in two paths C and D
3. First run only has C on the search path, finds A and B and loads
them
4. Second run adds D to the front of the search path. A is loaded and
contains a reference to the already compiled module from C. But
searching finds the module from D instead, causing a mismatch
5. B and the modules that depend on it are considered out of date and
thus rebuilt
6. The recompiled module A is added to the in-memory cache, freeing
the previously inserted one
This can never occur from a regular clang process, but is very easy to
do through the API - whether through the use of a shared case or just
running multiple compilations from a single `CompilerInstance`. Update
the compilation to return early if a module is already finalized so that
the pre-condition in the in-memory module cache holds.
Resolves rdar://78180255
Differential Revision: https://reviews.llvm.org/D105328
This moves Bitcode/Bitstream*, Bitcode/BitCodes.h to Bitstream/.
This is needed to avoid a circular dependency when using the bitstream
code for parsing optimization remarks.
Since Bitcode uses Core for the IR part:
libLLVMRemarks -> Bitcode -> Core
and Core uses libLLVMRemarks to generate remarks (see
IR/RemarkStreamer.cpp):
Core -> libLLVMRemarks
we need to separate the Bitstream and Bitcode part.
For clang-doc, it seems that it doesn't need the whole bitcode layer, so
I updated the CMake to only use the bitstream part.
Differential Revision: https://reviews.llvm.org/D63899
llvm-svn: 365091
Change MemoryBufferCache to InMemoryModuleCache, moving it from Basic to
Serialization. Another patch will start using it to manage module build
more explicitly, but this is split out because it's mostly mechanical.
Because of the move to Serialization we can no longer abuse the
Preprocessor to forward it to the ASTReader. Besides the rename and
file move, that means Preprocessor::Preprocessor has one fewer parameter
and ASTReader::ASTReader has one more.
llvm-svn: 355777
Sam McCall