Enable configuration files in clang

Clang is inherently a cross compiler and can generate code for any target
enabled during build. It however requires to specify many parameters in the
invocation, which could be hardcoded during configuration process in the
case of single-target compiler. The purpose of configuration files is to
make specifying clang arguments easier.

A configuration file is a collection of driver options, which are inserted
into command line before other options specified in the clang invocation.
It groups related options together and allows specifying them in simpler,
more flexible and less error prone way than just listing the options
somewhere in build scripts. Configuration file may be thought as a "macro"
that names an option set and is expanded when the driver is called.

Use of configuration files is described in `UserManual.rst`.

Differential Revision: https://reviews.llvm.org/D24933


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321621 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 59 insertions, 8 deletions

diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index 41b5e42b44..45cdf82d36 100644
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -112,6 +112,18 @@ def err_drv_invalid_argument_to_fdebug_prefix_map : Error<
   "invalid argument '%0' to -fdebug-prefix-map">;
 def err_drv_malformed_sanitizer_blacklist : Error<
   "malformed sanitizer blacklist: '%0'">;
+def err_drv_duplicate_config : Error<
+  "no more than one option '--config' is allowed">;
+def err_drv_config_file_not_exist : Error<
+  "configuration file '%0' does not exist">;
+def err_drv_config_file_not_found : Error<
+  "configuration file '%0' cannot be found">;
+def note_drv_config_file_searched_in : Note<
+  "was searched for in the directory: %0">;
+def err_drv_cannot_read_config_file : Error<
+  "cannot read configuration file '%0'">;
+def err_drv_nested_config_file: Error<
+  "option '--config' is not allowed inside configuration file">;
 
 def err_target_unsupported_arch
   : Error<"the target architecture '%0' is not supported by the target '%1'">;
diff --git a/include/clang/Config/config.h.cmake b/include/clang/Config/config.h.cmake
index daac9b7b45..5f420195e8 100644
--- a/include/clang/Config/config.h.cmake
+++ b/include/clang/Config/config.h.cmake
@@ -35,6 +35,10 @@
 /* Directories clang will search for headers */
 #define C_INCLUDE_DIRS "${C_INCLUDE_DIRS}"
 
+/* Directories clang will search for configuration files */
+#cmakedefine CLANG_CONFIG_FILE_SYSTEM_DIR "${CLANG_CONFIG_FILE_SYSTEM_DIR}"
+#cmakedefine CLANG_CONFIG_FILE_USER_DIR "${CLANG_CONFIG_FILE_USER_DIR}"
+
 /* Default <path> to all compiler invocations for --sysroot=<path>. */
 #define DEFAULT_SYSROOT "${DEFAULT_SYSROOT}"
 
diff --git a/include/clang/Driver/Driver.h b/include/clang/Driver/Driver.h
index a3662872a9..0713430983 100644
--- a/include/clang/Driver/Driver.h
+++ b/include/clang/Driver/Driver.h
@@ -19,6 +19,8 @@
 #include "clang/Driver/Util.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/Support/StringSaver.h"
 
 #include <list>
 #include <map>
@@ -26,14 +28,6 @@
 
 namespace llvm {
 class Triple;
-
-namespace opt {
-  class Arg;
-  class ArgList;
-  class DerivedArgList;
-  class InputArgList;
-  class OptTable;
-}
 }
 
 namespace clang {
@@ -138,6 +132,12 @@ public:
   /// The path to the compiler resource directory.
   std::string ResourceDir;
 
+  /// System directory for config files.
+  std::string SystemConfigDir;
+
+  /// User directory for config files.
+  std::string UserConfigDir;
+
   /// A prefix directory used to emulate a limited subset of GCC's '-Bprefix'
   /// functionality.
   /// FIXME: This type of customization should be removed in favor of the
@@ -208,6 +208,21 @@ private:
   /// Name to use when invoking gcc/g++.
   std::string CCCGenericGCCName;
 
+  /// Name of configuration file if used.
+  std::string ConfigFile;
+
+  /// Allocator for string saver.
+  llvm::BumpPtrAllocator Alloc;
+
+  /// Object that stores strings read from configuration file.
+  llvm::StringSaver Saver;
+
+  /// Arguments originated from configuration file.
+  std::unique_ptr<llvm::opt::InputArgList> CfgOptions;
+
+  /// Arguments originated from command line.
+  std::unique_ptr<llvm::opt::InputArgList> CLOptions;
+
   /// Whether to check that input files exist when constructing compilation
   /// jobs.
   unsigned CheckInputsExist : 1;
@@ -277,6 +292,8 @@ public:
   /// Name to use when invoking gcc/g++.
   const std::string &getCCCGenericGCCName() const { return CCCGenericGCCName; }
 
+  const std::string &getConfigFile() const { return ConfigFile; }
+
   const llvm::opt::OptTable &getOpts() const { return *Opts; }
 
   const DiagnosticsEngine &getDiags() const { return Diags; }
@@ -493,6 +510,18 @@ public:
   LTOKind getLTOMode() const { return LTOMode; }
 
 private:
+
+  /// Tries to load options from configuration file.
+  ///
+  /// \returns true if error occurred.
+  bool loadConfigFile();
+
+  /// Read options from the specified file.
+  ///
+  /// \param [in] FileName File to read.
+  /// \returns true, if error occurred while reading.
+  bool readConfigFile(StringRef FileName);
+
   /// Set the driver mode (cl, gcc, etc) from an option string of the form
   /// --driver-mode=<mode>.
   void setDriverModeFromOption(StringRef Opt);
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 7dc6632e82..3ee834e685 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -519,6 +519,12 @@ def cl_fp32_correctly_rounded_divide_sqrt : Flag<["-"], "cl-fp32-correctly-round
 def client__name : JoinedOrSeparate<["-"], "client_name">;
 def combine : Flag<["-", "--"], "combine">, Flags<[DriverOption, Unsupported]>;
 def compatibility__version : JoinedOrSeparate<["-"], "compatibility_version">;
+def config : Separate<["--"], "config">, Flags<[DriverOption]>,
+  HelpText<"Specifies configuration file">;
+def config_system_dir_EQ : Joined<["--"], "config-system-dir=">, Flags<[DriverOption, HelpHidden]>,
+  HelpText<"System directory for configuration files">;
+def config_user_dir_EQ : Joined<["--"], "config-user-dir=">, Flags<[DriverOption, HelpHidden]>,
+  HelpText<"User directory for configuration files">;
 def coverage : Flag<["-", "--"], "coverage">, Flags<[CoreOption]>;
 def cpp_precomp : Flag<["-"], "cpp-precomp">, Group<clang_ignored_f_Group>;
 def current__version : JoinedOrSeparate<["-"], "current_version">;