Avoid including FileManager.h from SourceManager.h

Most clients of SourceManager.h need to do things like turning source
locations into file & line number pairs, but this doesn't require
bringing in FileManager.h and LLVM's FS headers.

The main code change here is to sink SM::createFileID into the cpp file.
I reason that this is not performance critical because it doesn't happen
on the diagnostic path, it happens along the paths of macro expansion
(could be hot) and new includes (less hot).

Saves some includes:
    309 -    /usr/local/google/home/rnk/llvm-project/clang/include/clang/Basic/FileManager.h
    272 -    /usr/local/google/home/rnk/llvm-project/clang/include/clang/Basic/FileSystemOptions.h
    271 -    /usr/local/google/home/rnk/llvm-project/llvm/include/llvm/Support/VirtualFileSystem.h
    267 -    /usr/local/google/home/rnk/llvm-project/llvm/include/llvm/Support/FileSystem.h
    266 -    /usr/local/google/home/rnk/llvm-project/llvm/include/llvm/Support/Chrono.h

Differential Revision: https://reviews.llvm.org/D75406

Author: rnk

clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp

@@ -10,6 +10,7 @@
 #include "HeaderMapCollector.h"
 #include "PathConfig.h"
 #include "SymbolInfo.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/MacroInfo.h"

clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ExpandModularHeadersPPCallbacks.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Serialization/ASTReader.h"

clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.h

@@ -13,6 +13,13 @@
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/DenseSet.h"
 
+namespace llvm {
+namespace vfs {
+class OverlayFileSystem;
+class InMemoryFileSystem;
+} // namespace vfs
+} // namespace llvm
+
 namespace clang {
 class CompilerInstance;
 

clang-tools-extra/clangd/Format.cpp

@@ -8,6 +8,7 @@
 #include "Format.h"
 #include "Logger.h"
 #include "clang/Basic/SourceManager.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Format/Format.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/Core/Replacement.h"

clang-tools-extra/pp-trace/PPCallbacksTracker.cpp

@@ -14,6 +14,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "PPCallbacksTracker.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Lex/MacroArgs.h"
 #include "llvm/Support/raw_ostream.h"
 

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -52,14 +52,14 @@
 #include "clang/AST/DeclFriend.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
-#include "clang/AST/ParentMapContext.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/LambdaCapture.h"
 #include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/OpenMPClause.h"
 #include "clang/AST/OperationKinds.h"
+#include "clang/AST/ParentMapContext.h"
 #include "clang/AST/Stmt.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/StmtObjC.h"
@@ -72,6 +72,7 @@
 #include "clang/ASTMatchers/ASTMatchersMacros.h"
 #include "clang/Basic/AttrKinds.h"
 #include "clang/Basic/ExceptionSpecificationType.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceManager.h"

clang/include/clang/Basic/SourceManager.h

@@ -35,7 +35,6 @@
 #define LLVM_CLANG_BASIC_SOURCEMANAGER_H
 
 #include "clang/Basic/Diagnostic.h"
-#include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/BitVector.h"
@@ -60,6 +59,9 @@ namespace clang {
 
 class ASTReader;
 class ASTWriter;
+class FileManager;
+class FileEntry;
+class FileEntryRef;
 class LineTableInfo;
 class SourceManager;
 
@@ -830,24 +832,11 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// This translates NULL into standard input.
   FileID createFileID(const FileEntry *SourceFile, SourceLocation IncludePos,
                       SrcMgr::CharacteristicKind FileCharacter,
-                      int LoadedID = 0, unsigned LoadedOffset = 0) {
-    assert(SourceFile && "Null source file!");
-    const SrcMgr::ContentCache *IR =
-        getOrCreateContentCache(SourceFile, isSystem(FileCharacter));
-    assert(IR && "getOrCreateContentCache() cannot return NULL");
-    return createFileID(IR, SourceFile->getName(), IncludePos, FileCharacter,
-                        LoadedID, LoadedOffset);
-  }
+                      int LoadedID = 0, unsigned LoadedOffset = 0);
 
   FileID createFileID(FileEntryRef SourceFile, SourceLocation IncludePos,
                       SrcMgr::CharacteristicKind FileCharacter,
-                      int LoadedID = 0, unsigned LoadedOffset = 0) {
-    const SrcMgr::ContentCache *IR = getOrCreateContentCache(
-        &SourceFile.getFileEntry(), isSystem(FileCharacter));
-    assert(IR && "getOrCreateContentCache() cannot return NULL");
-    return createFileID(IR, SourceFile.getName(), IncludePos, FileCharacter,
-                        LoadedID, LoadedOffset);
-  }
+                      int LoadedID = 0, unsigned LoadedOffset = 0);
 
   /// Create a new FileID that represents the specified memory buffer.
   ///
@@ -856,12 +845,7 @@ class SourceManager : public RefCountedBase<SourceManager> {
   FileID createFileID(std::unique_ptr<llvm::MemoryBuffer> Buffer,
                       SrcMgr::CharacteristicKind FileCharacter = SrcMgr::C_User,
                       int LoadedID = 0, unsigned LoadedOffset = 0,
-                      SourceLocation IncludeLoc = SourceLocation()) {
-    StringRef Name = Buffer->getBufferIdentifier();
-    return createFileID(
-        createMemBufferContentCache(Buffer.release(), /*DoNotFree*/ false),
-        Name, IncludeLoc, FileCharacter, LoadedID, LoadedOffset);
-  }
+                      SourceLocation IncludeLoc = SourceLocation());
 
   enum UnownedTag { Unowned };
 
@@ -872,20 +856,12 @@ class SourceManager : public RefCountedBase<SourceManager> {
   FileID createFileID(UnownedTag, const llvm::MemoryBuffer *Buffer,
                       SrcMgr::CharacteristicKind FileCharacter = SrcMgr::C_User,
                       int LoadedID = 0, unsigned LoadedOffset = 0,
-                      SourceLocation IncludeLoc = SourceLocation()) {
-    return createFileID(createMemBufferContentCache(Buffer, /*DoNotFree*/ true),
-                        Buffer->getBufferIdentifier(), IncludeLoc,
-                        FileCharacter, LoadedID, LoadedOffset);
-  }
+                      SourceLocation IncludeLoc = SourceLocation());
 
   /// Get the FileID for \p SourceFile if it exists. Otherwise, create a
   /// new FileID for the \p SourceFile.
   FileID getOrCreateFileID(const FileEntry *SourceFile,
-                           SrcMgr::CharacteristicKind FileCharacter) {
-    FileID ID = translateFile(SourceFile);
-    return ID.isValid() ? ID : createFileID(SourceFile, SourceLocation(),
-                                            FileCharacter);
-  }
+                           SrcMgr::CharacteristicKind FileCharacter);
 
   /// Return a new SourceLocation that encodes the
   /// fact that a token from SpellingLoc should actually be referenced from
@@ -1025,17 +1001,7 @@ class SourceManager : public RefCountedBase<SourceManager> {
   }
 
   /// Returns the FileEntryRef for the provided FileID.
-  Optional<FileEntryRef> getFileEntryRefForID(FileID FID) const {
-    bool Invalid = false;
-    const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
-    if (Invalid || !Entry.isFile())
-      return None;
-
-    const SrcMgr::ContentCache *Content = Entry.getFile().getContentCache();
-    if (!Content || !Content->OrigEntry)
-      return None;
-    return FileEntryRef(Entry.getFile().getName(), *Content->OrigEntry);
-  }
+  Optional<FileEntryRef> getFileEntryRefForID(FileID FID) const;
 
   /// Returns the FileEntry record for the provided SLocEntry.
   const FileEntry *getFileEntryForSLocEntry(const SrcMgr::SLocEntry &sloc) const
@@ -1098,11 +1064,7 @@ class SourceManager : public RefCountedBase<SourceManager> {
   }
 
   /// Return the filename of the file containing a SourceLocation.
-  StringRef getFilename(SourceLocation SpellingLoc) const {
-    if (const FileEntry *F = getFileEntryForID(getFileID(SpellingLoc)))
-      return F->getName();
-    return StringRef();
-  }
+  StringRef getFilename(SourceLocation SpellingLoc) const;
 
   /// Return the source location corresponding to the first byte of
   /// the specified file.

clang/include/clang/Frontend/CompilerInstance.h

@@ -390,9 +390,7 @@ class CompilerInstance : public ModuleLoader {
   /// @name Virtual File System
   /// {
 
-  llvm::vfs::FileSystem &getVirtualFileSystem() const {
-    return getFileManager().getVirtualFileSystem();
-  }
+  llvm::vfs::FileSystem &getVirtualFileSystem() const;
 
   /// }
   /// @name File Manager

clang/include/clang/Frontend/VerifyDiagnosticConsumer.h

@@ -10,6 +10,7 @@
 #define LLVM_CLANG_FRONTEND_VERIFYDIAGNOSTICCONSUMER_H
 
 #include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/Preprocessor.h"

clang/include/clang/Lex/DirectoryLookup.h

@@ -14,13 +14,12 @@
 #define LLVM_CLANG_LEX_DIRECTORYLOOKUP_H
 
 #include "clang/Basic/LLVM.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/ModuleMap.h"
 
 namespace clang {
 class HeaderMap;
-class DirectoryEntry;
-class FileEntry;
 class HeaderSearch;
 class Module;