[clang] Cherry-pick SLocEntry optimizations
#7594
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
) This commit removes the list of SLocEntry offsets to preload eagerly from PCM files. Commit introducing this functionality (258ae54) doesn't clarify why this would be more performant than the lazy approach used regularly. Currently, the only SLocEntry the reader is supposed to preload is the predefines buffer, but in my experience, it's not actually referenced in most modules, so the time spent deserializing its SLocEntry is wasted. This is especially noticeable in the dependency scanner, where this change brings 4.56% speedup on my benchmark.
In `SourceManager::getFileID()`, Clang performs binary search over its buffer of `SLocEntries`. For modules, this binary search fully deserializes the entire `SLocEntry` block for each visited entry. For some entries, that includes decompressing the associated buffer (e.g. the predefines buffer, macro expansion buffers, contents of volatile files), which shows up in profiles of the dependency scanner. This patch moves the binary search over loaded entries into `ASTReader`, which can perform cheaper partial deserialization during the binary search, reducing the wall time of dependency scans by ~3%. This also reduces the number of retired instructions by ~1.4% on regular (implicit) modules compilation. Note that this patch drops the optimizations based on the last lookup ID (pruning the search space and performing linear search before resorting to the full binary search). Instead, it reduces the search space by asking `ASTReader::GlobalSLocOffsetMap` for the containing `ModuleFile` and only does binary search over entries of single module file.
This fixes the following build failure on lldb-x86_64-debian:
/llvm-project/clang/lib/Serialization/ASTReader.cpp:1453:12: error: call to deleted constructor of 'llvm::Error'
return Err;
^~~
/llvm-project/llvm/include/llvm/Support/Error.h:189:3: note: 'Error' has been explicitly marked deleted here
Error(const Error &Other) = delete;
^
/llvm-project/llvm/include/llvm/Support/Error.h:496:18: note: passing argument to parameter 'Err' here
Expected(Error Err)
^
|
@swift-ci please test |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
No description provided.