[Driver] Fix the case when use -fembed-bitcode and -flto= together

[steven_wu]

Summary

-fembed-bitcode was only checking for old style LTO flag (-flto) but not
considering the new -flto= style option. That makes clang output bitcode
embedded in bitcode object when using -flto= and -fembed-bitcode= together.
Now clang should output normal bitcode file when using LTO and ignores
-fembed-bitcode option.

[mehdi_amini]

LGTM.

cfe/trunk/lib/Driver/Driver.cpp

Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
 
   if (const Arg *A = Args.getLastArg(options::OPT_save_temps_EQ)) {
     SaveTemps = llvm::StringSwitch<SaveTempsMode>(A->getValue())
                     .Case("cwd", SaveTempsCwd)
                     .Case("obj", SaveTempsObj)
                     .Default(SaveTempsCwd);
   }
 
+  setLTOMode(Args);
+
   // Ignore -fembed-bitcode options with LTO
   // since the output will be bitcode anyway.
-  if (!Args.hasFlag(options::OPT_flto, options::OPT_fno_lto, false)) {
+  if (getLTOMode() == LTOK_None) {
     if (Arg *A = Args.getLastArg(options::OPT_fembed_bitcode_EQ)) {
       StringRef Name = A->getValue();
       unsigned Model = llvm::StringSwitch<unsigned>(Name)
           .Case("off", EmbedNone)
           .Case("all", EmbedBitcode)
           .Case("bitcode", EmbedBitcode)
           .Case("marker", EmbedMarker)
           .Default(~0U);
       if (Model == ~0U) {
         Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args)
                                                   << Name;
       } else
         BitcodeEmbed = static_cast<BitcodeEmbedMode>(Model);
     }
   } else {
     // claim the bitcode option under LTO so no warning is issued.
     Args.ClaimAllArgs(options::OPT_fembed_bitcode_EQ);
   }
 
-  setLTOMode(Args);
-
   std::unique_ptr<llvm::opt::InputArgList> UArgs =
       llvm::make_unique<InputArgList>(std::move(Args));
 
   // Perform the default argument translations.
   DerivedArgList *TranslatedArgs = TranslateInputArgs(*UArgs);
 
   // Owned by the host.
   const ToolChain &TC = getToolChain(

cfe/trunk/test/Driver/embed-bitcode.c

 // CHECK-SAVE-TEMP: -cc1
 // CHECK-SAVE-TEMP: -emit-llvm-bc
 // CHECK-SAVE-TEMP: -cc1
 // CHECK-SAVE-TEMP: -S
 // CHECK-SAVE-TEMP: -fembed-bitcode=all
 // CHECK-SAVE-TEMP: -cc1as
 
 // RUN: %clang -c %s -flto -fembed-bitcode 2>&1 -### | FileCheck %s -check-prefix=CHECK-LTO
+// RUN: %clang -c %s -flto=full -fembed-bitcode 2>&1 -### | FileCheck %s -check-prefix=CHECK-LTO
+// RUN: %clang -c %s -flto=thin -fembed-bitcode 2>&1 -### | FileCheck %s -check-prefix=CHECK-LTO
 // CHECK-LTO: -cc1
 // CHECK-LTO: -emit-llvm-bc
 // CHECK-LTO-NOT: warning: argument unused during compilation: '-fembed-bitcode'
 // CHECK-LTO-NOT: -cc1
 // CHECK-LTO-NOT: -fembed-bitcode=all
 
 // RUN: %clang -c %s -fembed-bitcode-marker -fintegrated-as 2>&1 -### | FileCheck %s -check-prefix=CHECK-MARKER
 // CHECK-MARKER: -cc1
 // CHECK-MARKER: -emit-obj
 // CHECK-MARKER: -fembed-bitcode=marker
 // CHECK-MARKER-NOT: -cc1