[clang] 3e47883 - Recover performance loss after PagedVector introduction (#67972)

[via cfe-commits]

Author: Giulio Eulisse
Date: 2024-09-05T10:16:51+02:00
New Revision: 3e4788377bb29ed389b46521fcba0d06aa985bcf

URL: https://github.com/llvm/llvm-project/commit/3e4788377bb29ed389b46521fcba0d06aa985bcf
DIFF: https://github.com/llvm/llvm-project/commit/3e4788377bb29ed389b46521fcba0d06aa985bcf.diff

LOG: Recover performance loss after PagedVector introduction (#67972)

Added: 
    

Modified: 
    clang/include/clang/Basic/SourceManager.h
    llvm/include/llvm/ADT/PagedVector.h

Removed: 
    


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diff  --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index d3ccc7ef81c079..e0f1ea435d54e4 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -724,7 +724,7 @@ class SourceManager : public RefCountedBase<SourceManager> {
   ///
   /// Negative FileIDs are indexes into this table. To get from ID to an index,
   /// use (-ID - 2).
-  llvm::PagedVector<SrcMgr::SLocEntry> LoadedSLocEntryTable;
+  llvm::PagedVector<SrcMgr::SLocEntry, 32> LoadedSLocEntryTable;
 
   /// For each allocation in LoadedSLocEntryTable, we keep the first FileID.
   /// We assume exactly one allocation per AST file, and use that to determine

diff  --git a/llvm/include/llvm/ADT/PagedVector.h b/llvm/include/llvm/ADT/PagedVector.h
index 3fcca6d82cb33a..52ecd0bb0ba118 100644
--- a/llvm/include/llvm/ADT/PagedVector.h
+++ b/llvm/include/llvm/ADT/PagedVector.h
@@ -84,7 +84,7 @@ template <typename T, size_t PageSize = 1024 / sizeof(T)> class PagedVector {
     assert(Index / PageSize < PageToDataPtrs.size());
     T *&PagePtr = PageToDataPtrs[Index / PageSize];
     // If the page was not yet allocated, allocate it.
-    if (!PagePtr) {
+    if (LLVM_UNLIKELY(!PagePtr)) {
       PagePtr = Allocator.getPointer()->template Allocate<T>(PageSize);
       // We need to invoke the default constructor on all the elements of the
       // page.