1 files changed, 30 insertions, 6 deletions
diff --git a/clang/lib/Driver/ToolChains/InterfaceStubs.cpp b/clang/lib/Driver/ToolChains/InterfaceStubs.cpp
index 6677843b2c5..b57602cd362 100644
--- a/clang/lib/Driver/ToolChains/InterfaceStubs.cpp
+++ b/clang/lib/Driver/ToolChains/InterfaceStubs.cpp
@@ -9,6 +9,7 @@
 #include "InterfaceStubs.h"
 #include "CommonArgs.h"
 #include "clang/Driver/Compilation.h"
+#include "llvm/Support/Path.h"
 
 namespace clang {
 namespace driver {
@@ -21,13 +22,36 @@ void Merger::ConstructJob(Compilation &C, const JobAction &JA,
   std::string Merger = getToolChain().GetProgramPath(getShortName());
   llvm::opt::ArgStringList CmdArgs;
   CmdArgs.push_back("-action");
-  CmdArgs.push_back(Args.getLastArg(options::OPT_emit_merged_ifs)
-                        ? "write-ifs"
-                        : "write-bin");
+  const bool WriteBin = !Args.getLastArg(options::OPT_emit_merged_ifs);
+  CmdArgs.push_back(WriteBin ? "write-bin" : "write-ifs");
   CmdArgs.push_back("-o");
-  CmdArgs.push_back(Output.getFilename());
-  for (const auto &Input : Inputs)
-    CmdArgs.push_back(Input.getFilename());
+
+  // Normally we want to write to a side-car file ending in ".ifso" so for
+  // example if `clang -emit-interface-stubs -shared -o libhello.so` were
+  // invoked then we would like to get libhello.so and libhello.ifso. If the
+  // stdout stream is given as the output file (ie `-o -`), that is the one
+  // exception where we will just append to the same filestream as the normal
+  // output.
+  SmallString<128> OutputFilename(Output.getFilename());
+  if (OutputFilename != "-") {
+    if (Args.hasArg(options::OPT_shared))
+      llvm::sys::path::replace_extension(OutputFilename,
+                                         (WriteBin ? "ifso" : "ifs"));
+    else
+      OutputFilename += ".ifso";
+  }
+
+  CmdArgs.push_back(Args.MakeArgString(OutputFilename.c_str()));
+
+  // Here we append the input files. If the input files are object files, then
+  // we look for .ifs files present in the same location as the object files.
+  for (const auto &Input : Inputs) {
+    SmallString<128> InputFilename(Input.getFilename());
+    if (Input.getType() == types::TY_Object)
+      llvm::sys::path::replace_extension(InputFilename, ".ifs");
+    CmdArgs.push_back(Args.MakeArgString(InputFilename.c_str()));
+  }
+
   C.addCommand(std::make_unique<Command>(JA, *this, Args.MakeArgString(Merger),
                                          CmdArgs, Inputs));
 }