This commit adds an optimization to clang-scan-deps and clang's preprocessor that skips excluded preprocessor
blocks by bumping the lexer pointer, and not lexing the tokens until reaching appropriate #else/#endif directive.
The skip positions and lexer offsets are computed when the file is minimized, directly from the minimized tokens.
On an 18-core iMacPro with macOS Catalina Beta I got 10-15% speed-up from this optimization when running clang-scan-deps on
the compilation database for a recent LLVM and Clang (3511 files).
Differential Revision: https://reviews.llvm.org/D67127
llvm-svn: 371656
the dependency scanner on a single worker thread
This behavior can be controlled using the new `-reuse-filemanager` clang-scan-deps
option. By default the file manager is reused.
The added test/ClangScanDeps/symlink.cpp is able to pass with
the reused filemanager after the related FileEntryRef changes
landed earlier. The test test/ClangScanDeps/subframework_header_dir_symlink.m
still fails when the file manager is reused (I run the FileCheck with not to
make it PASS). I will address this in a follow-up patch that improves
the DirectoryEntry name modelling in the FileManager.
llvm-svn: 370420
This commit implements the fast dependency scanning mode in clang-scan-deps: the
preprocessing is done on files that are minimized using the dependency directives source minimizer.
A shared file system cache is used to ensure that the file system requests and source minimization
is performed only once. The cache assumes that the underlying filesystem won't change during the course
of the scan (or if it will, it will not affect the output), and it can't be evicted. This means that the
service and workers can be used for a single run of a dependency scanner, and can't be reused across multiple,
incremental runs. This is something that we'll most likely support in the future though.
Note that the driver still utilizes the underlying real filesystem.
This commit is also still missing the fast skipped PP block skipping optimization that I mentioned at EuroLLVM talk.
Additionally, the file manager is still not reused by the threads as well.
Differential Revision: https://reviews.llvm.org/D63907
llvm-svn: 368086
Alex Lorenz