[clang-cl, PCH] Implement support for MS-style PCH through headers

Implement support for MS-style PCH through headers.

This enables support for /Yc and /Yu where the through header is either
on the command line or included in the source. It replaces the current
support the requires the header also be specified with /FI.

This change adds a -cc1 option -pch-through-header that is used to either
start or stop compilation during PCH create or use.

When creating a PCH, the compilation ends after compilation of the through
header.

When using a PCH, tokens are skipped until after the through header is seen.

Patch By: mikerice
Differential Revision: https://reviews.llvm.org/D46652


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@336379 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 32 insertions, 0 deletions

diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index a6d5f264f9..4ec29fe8f3 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -720,6 +720,12 @@ private:
   /// The file ID for the preprocessor predefines.
   FileID PredefinesFileID;
 
+  /// The file ID for the PCH through header.
+  FileID PCHThroughHeaderFileID;
+
+  /// Whether tokens are being skipped until the through header is seen.
+  bool SkippingUntilPCHThroughHeader = false;
+
   /// \{
   /// Cache of macro expanders to reduce malloc traffic.
   enum { TokenLexerCacheSize = 8 };
@@ -1140,6 +1146,22 @@ public:
   /// all macro expansions, macro definitions, etc.
   void createPreprocessingRecord();
 
+  /// Returns true if the FileEntry is the PCH through header.
+  bool isPCHThroughHeader(const FileEntry *File);
+
+  /// True if creating a PCH with a through header.
+  bool creatingPCHWithThroughHeader();
+
+  /// True if using a PCH with a through header.
+  bool usingPCHWithThroughHeader();
+
+  /// Skip tokens until after the #include of the through header.
+  void SkipTokensUntilPCHThroughHeader();
+
+  /// Process directives while skipping until the through header is found.
+  void HandleSkippedThroughHeaderDirective(Token &Result,
+                                           SourceLocation HashLoc);
+
   /// Enter the specified FileID as the main source file,
   /// which implicitly adds the builtin defines etc.
   void EnterMainSourceFile();
@@ -2020,6 +2042,9 @@ private:
     PredefinesFileID = FID;
   }
 
+  /// Set the FileID for the PCH through header.
+  void setPCHThroughHeaderFileID(FileID FID);
+
   /// Returns true if we are lexing from a file and not a
   /// pragma or a macro.
   static bool IsFileLexer(const Lexer* L, const PreprocessorLexer* P) {
diff --git a/include/clang/Lex/PreprocessorOptions.h b/include/clang/Lex/PreprocessorOptions.h
index 8cf1fc6058..f4ec2f27c4 100644
--- a/include/clang/Lex/PreprocessorOptions.h
+++ b/include/clang/Lex/PreprocessorOptions.h
@@ -54,6 +54,13 @@ public:
   /// definitions and expansions.
   bool DetailedRecord = false;
 
+  /// If non-empty, the filename used in an #include directive in the primary
+  /// source file (or command-line preinclude) that is used to implement
+  /// MSVC-style precompiled headers. When creating a PCH, after the #include
+  /// of this header, the PCH generation stops. When using a PCH, tokens are
+  /// skipped until after an #include of this header is seen.
+  std::string PCHThroughHeader;
+
   /// The implicit PCH included at the start of the translation unit, or empty.
   std::string ImplicitPCHInclude;