Introduce -fembed-bitcode driver option

Summary:
This is the clang driver part of the change to embedded bitcode. This
includes:
1. -fembed-bitcode option which breaks down the compilation into two
stages. The first stage emits optimized bitcode and the second stage
compiles bitcode into object file.
2. -fembed-bitcode-marker option which doesn't really break down to
two stages to speedup the compilation flow.
3. pass the correct linker flag to darwin linker if tool chains supports
embedded bitcode.

Reviewers: rsmith, thakis

Subscribers: thakis, cfe-commits

Differential Revision: http://reviews.llvm.org/D17390

llvm-svn: 262282

4 files changed, 23 insertions, 1 deletions

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 4b232006660..c6e6eaf47cc 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -134,7 +134,9 @@ def err_drv_omp_host_ir_file_not_found : Error<
   "The provided host compiler IR file '%0' is required to generate code for OpenMP target regions but cannot be found.">;
 def err_drv_omp_host_target_not_supported : Error<
   "The target '%0' is not a supported OpenMP host target.">;
-  
+def err_drv_bitcode_unsupported_on_toolchain : Error<
+  "-fembed-bitcode is not supported on versions of iOS prior to 6.0">;
+
 def warn_O4_is_O3 : Warning<"-O4 is equivalent to -O3">, InGroup<Deprecated>;
 def warn_drv_lto_libpath : Warning<"libLTO.dylib relative to clang installed dir not found; using 'ld' default search path instead">,
   InGroup<LibLTO>;
diff --git a/clang/include/clang/Driver/Driver.h b/clang/include/clang/Driver/Driver.h
index b6580456f41..ccf23e04696 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -83,6 +83,12 @@ class Driver {
     SaveTempsObj
   } SaveTemps;
 
+  enum BitcodeEmbedMode {
+    EmbedNone,
+    EmbedMarker,
+    EmbedBitcode
+  } BitcodeEmbed;
+
   /// LTO mode selected via -f(no-)?lto(=.*)? options.
   LTOKind LTOMode;
 
@@ -262,6 +268,9 @@ public:
   bool isSaveTempsEnabled() const { return SaveTemps != SaveTempsNone; }
   bool isSaveTempsObj() const { return SaveTemps == SaveTempsObj; }
 
+  bool embedBitcodeEnabled() const { return BitcodeEmbed == EmbedBitcode; }
+  bool embedBitcodeMarkerOnly() const { return BitcodeEmbed == EmbedMarker; }
+
   /// @}
   /// @name Primary Functionality
   /// @{
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 8a22abcfdca..e05808eb513 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -437,6 +437,12 @@ def fno_autolink : Flag <["-"], "fno-autolink">, Group<f_Group>,
   Flags<[DriverOption, CC1Option]>,
   HelpText<"Disable generation of linker directives for automatic library linking">;
 
+def fembed_bitcode : Flag<["-"], "fembed-bitcode">, Group<f_Group>,
+  Flags<[CC1Option, CC1AsOption]>,
+  HelpText<"Embed LLVM IR bitcode as data">;
+def fembed_bitcode_marker : Flag<["-"], "fembed-bitcode-marker">,
+  Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Embed placeholder LLVM IR data as a marker">;
 def fgnu_inline_asm : Flag<["-"], "fgnu-inline-asm">, Group<f_Group>, Flags<[DriverOption]>;
 def fno_gnu_inline_asm : Flag<["-"], "fno-gnu-inline-asm">, Group<f_Group>,
   Flags<[DriverOption, CC1Option]>,
diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index da0c40e8ad6..e093f633167 100644
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -319,6 +319,11 @@ public:
     return false;
   }
 
+  /// SupportsEmbeddedBitcode - Does this tool chain support embedded bitcode.
+  virtual bool SupportsEmbeddedBitcode() const {
+    return false;
+  }
+
   /// getThreadModel() - Which thread model does this target use?
   virtual std::string getThreadModel() const { return "posix"; }