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

goussepi · goussepi · commit 533a893fa126 · 2016-07-13T14:21:11.000Z
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
diff --git a/clang/include/clang/Driver/CC1Options.td b/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
diff --git a/clang/include/clang/Frontend/FrontendOptions.h b/clang/include/clang/Frontend/FrontendOptions.h
@@ -154,6 +154,8 @@ class FrontendOptions {
                                            ///< 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 @@ class FrontendOptions {
     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
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/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);
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/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));
 
diff --git a/clang/test/PCH/Inputs/pragma-once2-pch.h b/clang/test/PCH/Inputs/pragma-once2-pch.h
@@ -0,0 +1 @@
+#include "pragma-once2.h"
diff --git a/clang/test/PCH/Inputs/pragma-once2.h b/clang/test/PCH/Inputs/pragma-once2.h
@@ -0,0 +1,3 @@
+#pragma once
+
+inline void f() {}
diff --git a/clang/test/PCH/include-timestamp.cpp b/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

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+#pragma once`
	`2`	`+`
	`3`	`+inline void f() {}`