[clang][IFS] Allow 2 output files when using -o and -c with clang IFS stubs.

[plotfi]

Summary

This patch allows for -o to be used with -c when compiling with clang interface stubs enabled. This is because the second file will be an intermediate ifs stubs file that is the text stub analog of the .o file. Both get produces in this case, so two files.

Why are we doing this? Because we want to support the case where interface stubs are used bu first invoking clang like so:

clang -c <other flags> -emit-interface-stubs foo.c -o foo.o
...
clang -emit-interface-stubs <.o files> -o libfoo.so

This should generate N .ifs files, and one .ifso file. Prior to this patch, using -o with the -c invocation was not possible. Currently the clang driver supports generating a a.out/.so file at the same time as a merged ifs file / ifso file, but this is done by checking that the final job is the IfsMerge job. When -c is used, the final job is a Compile job so what this patch does is check to figure out of the job type is TY_IFS_CPP.

[cishida]

clang/test/InterfaceStubs/driver-test3.c

7

wouldn't hurt to validate that the object file was generated

[plotfi]

Updating comments and altering test as per @cishida and @compnerd's feedback

[plotfi]

clang/test/InterfaceStubs/driver-test3.c

7

ditto.

clang/lib/Driver/Driver.cpp

 }
 
 void Driver::BuildJobs(Compilation &C) const {
   llvm::PrettyStackTraceString CrashInfo("Building compilation jobs");
 
   Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o);
 
   // It is an error to provide a -o option if we are making multiple output
-  // 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.
+  // files. There are exceptions:
+  //
+  // 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.
+  //
+  // CompileJob of type TY_IFS_CPP: when generating interface stubs is enabled
+  // and -c is passed, we still want to be able to generate a .ifs file while
+  // we are also generating .o files. So we allow more than one output file in
+  // this case as well.
+  //
   if (FinalOutput) {
     unsigned NumOutputs = 0;
+    unsigned NumIfsOutputs = 0;
     for (const Action *A : C.getActions())
       if (A->getType() != types::TY_Nothing &&
           !(A->getKind() == Action::IfsMergeJobClass ||
+            (A->getType() == clang::driver::types::TY_IFS_CPP &&
+             A->getKind() == clang::driver::Action::CompileJobClass &&
+             0 == NumIfsOutputs++) ||
             (A->getKind() == Action::BindArchClass && A->getInputs().size() &&
              A->getInputs().front()->getKind() == Action::IfsMergeJobClass)))
         ++NumOutputs;
 
     if (NumOutputs > 1) {
       Diag(clang::diag::err_drv_output_argument_with_multiple_files);
       FinalOutput = nullptr;
     }

clang/lib/Driver/ToolChains/Clang.cpp

if (Arg *A = Args.getLastArg(options::OPT_fsymbol_partition_EQ)) {
     CmdArgs.push_back(Args.MakeArgString(Str));
   }
 
   // Add the "-o out -x type src.c" flags last. This is done primarily to make
   // the -cc1 command easier to edit when reproducing compiler crashes.
   if (Output.getType() == types::TY_Dependencies) {
     // Handled with other dependency code.
   } else if (Output.isFilename()) {
+    if (Output.getType() == clang::driver::types::TY_IFS_CPP ||
+        Output.getType() == clang::driver::types::TY_IFS) {
+      SmallString<128> OutputFilename(Output.getFilename());
+      llvm::sys::path::replace_extension(OutputFilename, "ifs");
+      CmdArgs.push_back("-o");
+      CmdArgs.push_back(Args.MakeArgString(OutputFilename));
+    } else {
       CmdArgs.push_back("-o");
       CmdArgs.push_back(Output.getFilename());
+    }
   } else {
     assert(Output.isNothing() && "Invalid output.");
   }
 
   addDashXForInput(Args, Input, CmdArgs);
 
   ArrayRef<InputInfo> FrontendInputs = Input;
   if (IsHeaderModulePrecompile)

clang/test/InterfaceStubs/driver-test3.c

+// REQUIRES: x86-registered-target
+// REQUIRES: shell
+
+// RUN: mkdir -p %t; cd %t
+// RUN: %clang -target x86_64-unknown-linux-gnu -c -emit-interface-stubs %s -o %t/driver-test3.o
+// RUN: llvm-nm %t/driver-test3.o | FileCheck --check-prefix=CHECK-OBJ %s
+// RUN: cat %t/driver-test3.ifs | FileCheck --check-prefix=CHECK-IFS %s
+
+// CHECK-OBJ: bar
+
+// CHECK-IFS: --- !experimental-ifs-v1
+// CHECK-IFS-NEXT: IfsVersion:
+// CHECK-IFS-NEXT: Triple:
+// CHECK-IFS-NEXT: ObjectFileFormat:
+// CHECK-IFS-NEXT: Symbols:
+// CHECK-IFS-NEXT:   "bar" : { Type: Func }
+// CHECK-IFS-NEXT: ...
+
+int bar(int a) { return a; }