1 files changed, 69 insertions, 8 deletions

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index cdf4a579f43..40cada744d0 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -292,10 +292,6 @@ phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
              (PhaseArg = DAL.getLastArg(options::OPT_emit_ast))) {
     FinalPhase = phases::Compile;
 
-  // clang interface stubs
-  } else if ((PhaseArg = DAL.getLastArg(options::OPT_emit_interface_stubs))) {
-    FinalPhase = phases::IfsMerge;
-
   // -S only runs up to the backend.
   } else if ((PhaseArg = DAL.getLastArg(options::OPT_S))) {
     FinalPhase = phases::Backend;
@@ -3502,6 +3498,68 @@ void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
     Actions.push_back(
         C.MakeAction<IfsMergeJobAction>(MergerInputs, types::TY_Image));
 
+  if (Arg *A = Args.getLastArg(options::OPT_emit_interface_stubs)) {
+    llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> PhaseList;
+    if (Args.hasArg(options::OPT_c)) {
+      llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> CompilePhaseList;
+      types::getCompilationPhases(types::TY_IFS_CPP, CompilePhaseList);
+      llvm::copy_if(PhaseList, std::back_inserter(CompilePhaseList),
+                    [&](phases::ID Phase) { return Phase <= phases::Compile; });
+    } else {
+      types::getCompilationPhases(types::TY_IFS_CPP, PhaseList);
+    }
+
+    ActionList MergerInputs;
+
+    for (auto &I : Inputs) {
+      types::ID InputType = I.first;
+      const Arg *InputArg = I.second;
+
+      // Currently clang and the llvm assembler do not support generating symbol
+      // stubs from assembly, so we skip the input on asm files. For ifs files
+      // we rely on the normal pipeline setup in the pipeline setup code above.
+      if (InputType == types::TY_IFS || InputType == types::TY_PP_Asm ||
+          InputType == types::TY_Asm)
+        continue;
+
+      Action *Current = C.MakeAction<InputAction>(*InputArg, InputType);
+
+      for (auto Phase : PhaseList) {
+        switch (Phase) {
+        default:
+          llvm_unreachable(
+              "IFS Pipeline can only consist of Compile followed by IfsMerge.");
+        case phases::Compile: {
+          // Only IfsMerge (llvm-ifs) can handle .o files by looking for ifs
+          // files where the .o file is located. The compile action can not
+          // handle this.
+          if (InputType == types::TY_Object)
+            break;
+
+          Current = C.MakeAction<CompileJobAction>(Current, types::TY_IFS_CPP);
+          break;
+        }
+        case phases::IfsMerge: {
+          assert(Phase == PhaseList.back() &&
+                 "merging must be final compilation step.");
+          MergerInputs.push_back(Current);
+          Current = nullptr;
+          break;
+        }
+        }
+      }
+
+      // If we ended with something, add to the output list.
+      if (Current)
+        Actions.push_back(Current);
+    }
+
+    // Add an interface stubs merge action if necessary.
+    if (!MergerInputs.empty())
+      Actions.push_back(
+          C.MakeAction<IfsMergeJobAction>(MergerInputs, types::TY_Image));
+  }
+
   // If --print-supported-cpus, -mcpu=? or -mtune=? is specified, build a custom
   // Compile phase that prints out supported cpu models and quits.
   if (Arg *A = Args.getLastArg(options::OPT_print_supported_cpus)) {
@@ -3603,8 +3661,6 @@ Action *Driver::ConstructPhaseAction(
       return C.MakeAction<CompileJobAction>(Input, types::TY_ModuleFile);
     if (Args.hasArg(options::OPT_verify_pch))
       return C.MakeAction<VerifyPCHJobAction>(Input, types::TY_Nothing);
-    if (Args.hasArg(options::OPT_emit_interface_stubs))
-      return C.MakeAction<CompileJobAction>(Input, types::TY_IFS_CPP);
     return C.MakeAction<CompileJobAction>(Input, types::TY_LLVM_BC);
   }
   case phases::Backend: {
@@ -3633,11 +3689,16 @@ void Driver::BuildJobs(Compilation &C) const {
   Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o);
 
   // It is an error to provide a -o option if we are making multiple output
-  // files.
+  // files. There is one exception, IfsMergeJob: when generating interface stubs
+  // enabled we want to be able to generate the stub file at the same time that
+  // we generate the real library/a.out. So when a .o, .so, etc are the output,
+  // with clang interface stubs there will also be a .ifs and .ifso at the same
+  // location.
   if (FinalOutput) {
     unsigned NumOutputs = 0;
     for (const Action *A : C.getActions())
-      if (A->getType() != types::TY_Nothing)
+      if (A->getType() != types::TY_Nothing &&
+          A->getKind() != Action::IfsMergeJobClass)
         ++NumOutputs;
 
     if (NumOutputs > 1) {