[clang] 590b1e3 - [clang][modules] Only serialize info for locally-included headers (#113718)

[via cfe-commits]

Author: Jan Svoboda
Date: 2024-10-25T15:00:07-07:00
New Revision: 590b1e31546572b62040066f90a35893a1b64f29

URL: https://github.com/llvm/llvm-project/commit/590b1e31546572b62040066f90a35893a1b64f29
DIFF: https://github.com/llvm/llvm-project/commit/590b1e31546572b62040066f90a35893a1b64f29.diff

LOG: [clang][modules] Only serialize info for locally-included headers (#113718)

I noticed that some PCM files contain `HeaderFileInfo` for headers only
included in a dependent PCM file, which is wasteful.

This patch changes the logic to only write headers that are included
locally. This makes the PCM files smaller and saves some superfluous
deserialization of `HeaderFileInfo` triggered by
`Preprocessor::alreadyIncluded()`.

Added: 
    

Modified: 
    clang/include/clang/Lex/Preprocessor.h
    clang/lib/Lex/HeaderSearch.cpp
    clang/lib/Serialization/ASTWriter.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index f3f4de044fc41a..38a527d2324ffe 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -1490,7 +1490,7 @@ class Preprocessor {
   /// Mark the file as included.
   /// Returns true if this is the first time the file was included.
   bool markIncluded(FileEntryRef File) {
-    HeaderInfo.getFileInfo(File);
+    HeaderInfo.getFileInfo(File).IsLocallyIncluded = true;
     return IncludedFiles.insert(File).second;
   }
 

diff  --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 8826ab449df493..052be1395161d4 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1582,7 +1582,6 @@ bool HeaderSearch::ShouldEnterIncludeFile(Preprocessor &PP,
     }
   }
 
-  FileInfo.IsLocallyIncluded = true;
   IsFirstIncludeOfFile = PP.markIncluded(File);
   return true;
 }

diff  --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index b576822fa704c8..c09a41f4d1403c 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2163,8 +2163,8 @@ void ASTWriter::WriteHeaderSearch(const HeaderSearch &HS) {
       continue; // We have no information on this being a header file.
     if (!HFI->isCompilingModuleHeader && HFI->isModuleHeader)
       continue; // Header file info is tracked by the owning module file.
-    if (!HFI->isCompilingModuleHeader && !PP->alreadyIncluded(*File))
-      continue; // Non-modular header not included is not needed.
+    if (!HFI->isCompilingModuleHeader && !HFI->IsLocallyIncluded)
+      continue; // Header file info is tracked by the including module file.
 
     // Massage the file path into an appropriate form.
     StringRef Filename = File->getName();
@@ -2176,7 +2176,7 @@ void ASTWriter::WriteHeaderSearch(const HeaderSearch &HS) {
       SavedStrings.push_back(Filename.data());
     }
 
-    bool Included = PP->alreadyIncluded(*File);
+    bool Included = HFI->IsLocallyIncluded || PP->alreadyIncluded(*File);
 
     HeaderFileInfoTrait::key_type Key = {
       Filename, File->getSize(), getTimestampForOutput(*File)