Driver: Pass down the -march setting down to -cc1as on x86 too.

The assembler historically didn't make use of any target features, but this has
changed when support for old CPUs that don't support long nops was added.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175919 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 445ae53..12833a8 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -3325,6 +3325,15 @@
     addFPMathArgs(D, A, Args, CmdArgs, getARMTargetCPU(Args, Triple));
 }
 
+void ClangAs::AddX86TargetArgs(const ArgList &Args,
+                               ArgStringList &CmdArgs) const {
+  // Set the CPU based on -march=.
+  if (const char *CPUName = getX86TargetCPU(Args, getToolChain().getTriple())) {
+    CmdArgs.push_back("-target-cpu");
+    CmdArgs.push_back(CPUName);
+  }
+}
+
 /// Add options related to the Objective-C runtime/ABI.
 ///
 /// Returns true if the runtime is non-fragile.
@@ -3500,6 +3509,11 @@
   case llvm::Triple::thumb:
     AddARMTargetArgs(Args, CmdArgs);
     break;
+
+  case llvm::Triple::x86:
+  case llvm::Triple::x86_64:
+    AddX86TargetArgs(Args, CmdArgs);
+    break;
   }
 
   // Ignore explicit -force_cpusubtype_ALL option.
diff --git a/lib/Driver/Tools.h b/lib/Driver/Tools.h
index f4aebd8..846c834 100644
--- a/lib/Driver/Tools.h
+++ b/lib/Driver/Tools.h
@@ -77,6 +77,7 @@
   /// \brief Clang integrated assembler tool.
   class LLVM_LIBRARY_VISIBILITY ClangAs : public Tool {
     void AddARMTargetArgs(const ArgList &Args, ArgStringList &CmdArgs) const;
+    void AddX86TargetArgs(const ArgList &Args, ArgStringList &CmdArgs) const;
   public:
     ClangAs(const ToolChain &TC) : Tool("clang::as",
                                         "clang integrated assembler", TC) {}