Introduce module file extensions to piggy-back data onto module files.

Introduce the notion of a module file extension, which introduces
additional information into a module file at the time it is built that
can then be queried when the module file is read. Module file
extensions are identified by a block name (which must be unique to the
extension) and can write any bitstream records into their own
extension block within the module file. When a module file is loaded,
any extension blocks are matched up with module file extension
readers, that are per-module-file and are given access to the input
bitstream.

Note that module file extensions can only be introduced by
programmatic clients that have access to the CompilerInvocation. There
is only one such extension at the moment, which is used for testing
the module file extension harness. As a future direction, one could
imagine allowing the plugin mechanism to introduce new module file
extensions.

llvm-svn: 251955

1 files changed, 52 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 0c1c4eaefa9..468cc5746ce 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -7,6 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "TestModuleFileExtension.h"
 #include "clang/Frontend/CompilerInvocation.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/Version.h"
@@ -19,6 +20,7 @@
 #include "clang/Frontend/Utils.h"
 #include "clang/Lex/HeaderSearchOptions.h"
 #include "clang/Serialization/ASTReader.h"
+#include "clang/Serialization/ModuleFileExtension.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
@@ -832,6 +834,30 @@ static void ParseFileSystemArgs(FileSystemOptions &Opts, ArgList &Args) {
   Opts.WorkingDir = Args.getLastArgValue(OPT_working_directory);
 }
 
+/// Parse the argument to the -ftest-module-file-extension
+/// command-line argument.
+///
+/// \returns true on error, false on success.
+static bool parseTestModuleFileExtensionArg(StringRef Arg,
+                                            std::string &BlockName,
+                                            unsigned &MajorVersion,
+                                            unsigned &MinorVersion,
+                                            bool &Hashed,
+                                            std::string &UserInfo) {
+  SmallVector<StringRef, 5> Args;
+  Arg.split(Args, ':', 5);
+  if (Args.size() < 5)
+    return true;
+
+  BlockName = Args[0];
+  if (Args[1].getAsInteger(10, MajorVersion)) return true;
+  if (Args[2].getAsInteger(10, MinorVersion)) return true;
+  if (Args[3].getAsInteger(2, Hashed)) return true;
+  if (Args.size() > 4)
+    UserInfo = Args[4];
+  return false;
+}
+
 static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
                                    DiagnosticsEngine &Diags) {
   using namespace options;
@@ -924,6 +950,26 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
       if (A->getValue(0) == Opts.AddPluginActions[i])
         Opts.AddPluginArgs[i].emplace_back(A->getValue(1));
 
+  for (const std::string &Arg :
+         Args.getAllArgValues(OPT_ftest_module_file_extension_EQ)) {
+    std::string BlockName;
+    unsigned MajorVersion;
+    unsigned MinorVersion;
+    bool Hashed;
+    std::string UserInfo;
+    if (parseTestModuleFileExtensionArg(Arg, BlockName, MajorVersion,
+                                        MinorVersion, Hashed, UserInfo)) {
+      Diags.Report(diag::err_test_module_file_extension_format) << Arg;
+
+      continue;
+    }
+
+    // Add the testing module file extension.
+    Opts.ModuleFileExtensions.push_back(
+      new TestModuleFileExtension(BlockName, MajorVersion, MinorVersion,
+                                  Hashed, UserInfo));
+  }
+
   if (const Arg *A = Args.getLastArg(OPT_code_completion_at)) {
     Opts.CodeCompletionAt =
       ParsedSourceLocation::FromString(A->getValue());
@@ -2076,6 +2122,12 @@ std::string CompilerInvocation::getModuleHash() const {
   // Extend the signature with the user build path.
   code = hash_combine(code, hsOpts.ModuleUserBuildPath);
 
+  // Extend the signature with the module file extensions.
+  const FrontendOptions &frontendOpts = getFrontendOpts();
+  for (auto ext : frontendOpts.ModuleFileExtensions) {
+    code = ext->hashExtension(code);
+  }
+
   // Darwin-specific hack: if we have a sysroot, use the contents and
   // modification time of
   //   $sysroot/System/Library/CoreServices/SystemVersion.plist