Add a frontend option -chained-pch and don't pass an active PCH reader to the PCH writer if it is not set, preventing creation of chained PCH files. Since the reader is so far unused, effectively no functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107936 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 12 insertions, 1 deletions

diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 8e813fbfd2..51695a0848 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -347,6 +347,8 @@ def rewrite_macros : Flag<"-rewrite-macros">,
 
 def relocatable_pch : Flag<"-relocatable-pch">,
   HelpText<"Whether to build a relocatable precompiled header">;
+def chained_pch : Flag<"-chained-pch">,
+  HelpText<"Whether to chain the new precompiled header to the old one.">;
 def print_stats : Flag<"-print-stats">,
   HelpText<"Print performance metrics and statistics">;
 def ftime_report : Flag<"-ftime-report">,
diff --git a/include/clang/Frontend/FrontendOptions.h b/include/clang/Frontend/FrontendOptions.h
index 0f4538976d..4010ea6dd7 100644
--- a/include/clang/Frontend/FrontendOptions.h
+++ b/include/clang/Frontend/FrontendOptions.h
@@ -62,6 +62,9 @@ public:
   unsigned RelocatablePCH : 1;             ///< When generating PCH files,
                                            /// instruct the PCH writer to create
                                            /// relocatable PCH files.
+  unsigned ChainedPCH : 1;                 ///< When generating PCH files,
+                                           /// instruct the PCH writer to create
+                                           /// chained PCH files.
   unsigned ShowHelp : 1;                   ///< Show the -help text.
   unsigned ShowMacrosInCodeCompletion : 1; ///< Show macros in code completion
                                            /// results.
@@ -114,6 +117,7 @@ public:
     ProgramAction = frontend::ParseSyntaxOnly;
     ActionName = "";
     RelocatablePCH = 0;
+    ChainedPCH = 0;
     ShowHelp = 0;
     ShowMacrosInCodeCompletion = 0;
     ShowCodePatternsInCodeCompletion = 0;
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 2520341255..239283a0cc 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -353,6 +353,8 @@ static void FrontendOptsToArgs(const FrontendOptions &Opts,
     Res.push_back("-disable-free");
   if (Opts.RelocatablePCH)
     Res.push_back("-relocatable-pch");
+  if (Opts.ChainedPCH)
+    Res.push_back("-chained-pch");
   if (Opts.ShowHelp)
     Res.push_back("-help");
   if (Opts.ShowMacrosInCodeCompletion)
@@ -1032,6 +1034,7 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   Opts.OutputFile = Args.getLastArgValue(OPT_o);
   Opts.Plugins = Args.getAllArgValues(OPT_load);
   Opts.RelocatablePCH = Args.hasArg(OPT_relocatable_pch);
+  Opts.ChainedPCH = Args.hasArg(OPT_chained_pch);
   Opts.ShowHelp = Args.hasArg(OPT_help);
   Opts.ShowMacrosInCodeCompletion = Args.hasArg(OPT_code_completion_macros);
   Opts.ShowCodePatternsInCodeCompletion
diff --git a/lib/Frontend/FrontendActions.cpp b/lib/Frontend/FrontendActions.cpp
index 400d35361c..694cadcd13 100644
--- a/lib/Frontend/FrontendActions.cpp
+++ b/lib/Frontend/FrontendActions.cpp
@@ -82,7 +82,9 @@ ASTConsumer *GeneratePCHAction::CreateASTConsumer(CompilerInstance &CI,
 
   if (CI.getFrontendOpts().RelocatablePCH)
     return CreatePCHGenerator(CI.getPreprocessor(), OS,
-                              CI.getPCHReader(), Sysroot.c_str());
+                              CI.getInvocation().getFrontendOpts().ChainedPCH ?
+			          CI.getPCHReader() : 0,
+                              Sysroot.c_str());
 
   return CreatePCHGenerator(CI.getPreprocessor(), OS, CI.getPCHReader());
 }