[PCH] Add a fno-pch-timestamp option to cc1 to disable inclusion of timestamps in PCH files.

This is to allow distributed build systems, that do not preserve time stamps, to use PCH files.

Second and last part of the patch proposed at:

Differential Revision: http://reviews.llvm.org/D20867

llvm-svn: 275267

clang/include/clang/Driver/CC1Options.td

@@ -509,6 +509,8 @@ def find_pch_source_EQ : Joined<["-"], "find-pch-source=">,
   HelpText<"When building a pch, try to find the input file in include "
            "directories, as if it had been included by the argument passed "
            "to this flag.">;
+def fno_pch_timestamp : Flag<["-"], "fno-pch-timestamp">,
+  HelpText<"Disable inclusion of timestamp in precompiled headers">;
   
 //===----------------------------------------------------------------------===//
 // Language Options

clang/include/clang/Frontend/FrontendOptions.h

@@ -154,6 +154,8 @@ public:
                                            ///< implicit module build.
   unsigned ModulesEmbedAllFiles : 1;       ///< Whether we should embed all used
                                            ///< files into the PCM file.
+  unsigned IncludeTimestamps : 1;          ///< Whether timestamps should be
+                                           ///< written to the produced PCH file.
 
   CodeCompleteOptions CodeCompleteOpts;
 
@@ -278,8 +280,8 @@ public:
     SkipFunctionBodies(false), UseGlobalModuleIndex(true),
     GenerateGlobalModuleIndex(true), ASTDumpDecls(false), ASTDumpLookups(false),
     BuildingImplicitModule(false), ModulesEmbedAllFiles(false),
-    ARCMTAction(ARCMT_None), ObjCMTAction(ObjCMT_None),
-    ProgramAction(frontend::ParseSyntaxOnly)
+    IncludeTimestamps(true), ARCMTAction(ARCMT_None),
+    ObjCMTAction(ObjCMT_None), ProgramAction(frontend::ParseSyntaxOnly)
   {}
 
   /// getInputKindForExtension - Return the appropriate input kind for a file

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1197,6 +1197,7 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   Opts.ModuleFiles = Args.getAllArgValues(OPT_fmodule_file);
   Opts.ModulesEmbedFiles = Args.getAllArgValues(OPT_fmodules_embed_file_EQ);
   Opts.ModulesEmbedAllFiles = Args.hasArg(OPT_fmodules_embed_all_files);
+  Opts.IncludeTimestamps = !Args.hasArg(OPT_fno_pch_timestamp);
 
   Opts.CodeCompleteOpts.IncludeMacros
     = Args.hasArg(OPT_code_completion_macros);

clang/lib/Frontend/FrontendActions.cpp

@@ -92,7 +92,10 @@ GeneratePCHAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
   std::vector<std::unique_ptr<ASTConsumer>> Consumers;
   Consumers.push_back(llvm::make_unique<PCHGenerator>(
                         CI.getPreprocessor(), OutputFile, nullptr, Sysroot,
-                        Buffer, CI.getFrontendOpts().ModuleFileExtensions));
+                        Buffer, CI.getFrontendOpts().ModuleFileExtensions,
+                        /*AllowASTWithErrors*/false,
+                        /*IncludeTimestamps*/
+                          +CI.getFrontendOpts().IncludeTimestamps));
   Consumers.push_back(CI.getPCHContainerWriter().CreatePCHContainerGenerator(
       CI, InFile, OutputFile, OS, Buffer));
 

clang/test/PCH/Inputs/pragma-once2-pch.h

@@ -0,0 +1 @@
+#include "pragma-once2.h"

clang/test/PCH/Inputs/pragma-once2.h

@@ -0,0 +1,3 @@
+#pragma once
+
+inline void f() {}

clang/test/PCH/include-timestamp.cpp

@@ -0,0 +1,27 @@
+// Test that the timestamp is not included in the produced pch file with
+// -fno-pch-timestamp.
+
+// Check timestamp is included by default.
+// RUN: %clang_cc1 -x c++-header -emit-pch -o %t %S/Inputs/pragma-once2-pch.h
+// RUN: touch -m -a -t 201008011501 %S/Inputs/pragma-once2.h
+// RUN: not %clang_cc1 -include-pch %t %s 2>&1 | FileCheck -check-prefix=CHECK-TIMESTAMP %s
+
+// Check bitcode output as well.
+// RUN: llvm-bcanalyzer -dump %t | FileCheck -check-prefix=CHECK-BITCODE-TIMESTAMP-ON %s
+
+// Check timestamp inclusion is disabled by -fno-pch-timestamp.
+// RUN: %clang_cc1 -x c++-header -emit-pch -o %t %S/Inputs/pragma-once2-pch.h -fno-pch-timestamp
+// RUN: touch -m -a -t 201008011502 %S/Inputs/pragma-once2.h
+// RUN: %clang_cc1 -include-pch %t %s 2>&1
+
+// Check bitcode output as well.
+// RUN: llvm-bcanalyzer -dump %t | FileCheck -check-prefix=CHECK-BITCODE-TIMESTAMP-OFF %s
+
+#include "Inputs/pragma-once2.h"
+
+void g() { f(); }
+
+// CHECK-BITCODE-TIMESTAMP-ON: <INPUT_FILE abbrevid={{.*}} op0={{.*}} op1={{.*}} op2={{[^0]}}
+// CHECK-BITCODE-TIMESTAMP-OFF: <INPUT_FILE abbrevid={{.*}} op0={{.*}} op1={{.*}} op2={{[0]}}
+
+// CHECK-TIMESTAMP: fatal error: file {{.*}} has been modified since the precompiled header {{.*}} was built