[clang][ifs] Clang Interface Stubs ToolChain plumbing.

Second Landing Attempt:

This patch enables end to end support for generating ELF interface stubs
directly from clang. Now the following:

clang -emit-interface-stubs -o libfoo.so a.cpp b.cpp c.cpp

will product an ELF binary with visible symbols populated. Visibility attributes
and -fvisibility can be used to control what gets populated.

* Adding ToolChain support for clang Driver IFS Merge Phase
* Implementing a default InterfaceStubs Merge clang Tool, used by ToolChain
* Adds support for the clang Driver to involve llvm-ifs on ifs files.
* Adds -emit-merged-ifs flag, to tell llvm-ifs to emit a merged ifs text file
  instead of the final object format (normally ELF)


Differential Revision: https://reviews.llvm.org/D63978

llvm-svn: 374061

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Driver/Action.cpp b/clang/lib/Driver/Action.cpp
index 47b03f6..0187cf9 100644
--- a/clang/lib/Driver/Action.cpp
+++ b/clang/lib/Driver/Action.cpp
@@ -31,6 +31,7 @@ const char *Action::getClassName(ActionClass AC) {
   case CompileJobClass: return "compiler";
   case BackendJobClass: return "backend";
   case AssembleJobClass: return "assembler";
+  case IfsMergeJobClass: return "interface-stub-merger";
   case LinkJobClass: return "linker";
   case LipoJobClass: return "lipo";
   case DsymutilJobClass: return "dsymutil";
@@ -357,6 +358,11 @@ void AssembleJobAction::anchor() {}
 AssembleJobAction::AssembleJobAction(Action *Input, types::ID OutputType)
     : JobAction(AssembleJobClass, Input, OutputType) {}
 
+void IfsMergeJobAction::anchor() {}
+
+IfsMergeJobAction::IfsMergeJobAction(ActionList &Inputs, types::ID Type)
+    : JobAction(IfsMergeJobClass, Inputs, Type) {}
+
 void LinkJobAction::anchor() {}
 
 LinkJobAction::LinkJobAction(ActionList &Inputs, types::ID Type)