[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

llvm-svn: 336379

1 files changed, 25 insertions, 2 deletions

diff --git a/clang/lib/Lex/PPLexerChange.cpp b/clang/lib/Lex/PPLexerChange.cpp
index c7e0d2c7c28..352814d715f 100644
--- a/clang/lib/Lex/PPLexerChange.cpp
+++ b/clang/lib/Lex/PPLexerChange.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/HeaderSearch.h"
@@ -425,6 +426,8 @@ bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
     PragmaAssumeNonNullLoc = SourceLocation();
   }
 
+  bool LeavingPCHThroughHeader = false;
+
   // If this is a #include'd file, pop it off the include stack and continue
   // lexing the #includer file.
   if (!IncludeMacroStack.empty()) {
@@ -481,6 +484,12 @@ bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
       Result.setAnnotationValue(M);
     }
 
+    bool FoundPCHThroughHeader = false;
+    if (CurPPLexer && creatingPCHWithThroughHeader() &&
+        isPCHThroughHeader(
+            SourceMgr.getFileEntryForID(CurPPLexer->getFileID())))
+      FoundPCHThroughHeader = true;
+
     // We're done with the #included file.
     RemoveTopOfLexerStack();
 
@@ -500,8 +509,16 @@ bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
     if (ExitedFromPredefinesFile)
       replayPreambleConditionalStack();
 
-    // Client should lex another token unless we generated an EOM.
-    return LeavingSubmodule;
+    if (!isEndOfMacro && CurPPLexer && FoundPCHThroughHeader &&
+        (isInPrimaryFile() ||
+         CurPPLexer->getFileID() == getPredefinesFileID())) {
+      // Leaving the through header. Continue directly to end of main file
+      // processing.
+      LeavingPCHThroughHeader = true;
+    } else {
+      // Client should lex another token unless we generated an EOM.
+      return LeavingSubmodule;
+    }
   }
 
   // If this is the end of the main file, form an EOF token.
@@ -522,6 +539,12 @@ bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
         Result.setLocation(Result.getLocation().getLocWithOffset(-1));
     }
 
+    if (creatingPCHWithThroughHeader() && !LeavingPCHThroughHeader) {
+      // Reached the end of the compilation without finding the through header.
+      Diag(CurLexer->getFileLoc(), diag::err_pp_through_header_not_seen)
+          << PPOpts->PCHThroughHeader << 0;
+    }
+
     if (!isIncrementalProcessingEnabled())
       // We're done with lexing.
       CurLexer.reset();