[Mips] Support -mnan=2008 option. Define "__mips_nan2008" macros and pass
this option to the assembler.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191282 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 76d0f20..23f3648 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -948,6 +948,11 @@
     Features.push_back("+soft-float");
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_mnan_EQ)) {
+    if (StringRef(A->getValue()) == "2008")
+      Features.push_back("+nan2008");
+  }
+
   AddTargetFeature(Args, Features, options::OPT_msingle_float,
                    options::OPT_mdouble_float, "single-float");
   AddTargetFeature(Args, Features, options::OPT_mips16, options::OPT_mno_mips16,
@@ -5942,6 +5947,11 @@
     else
       CmdArgs.push_back("-EL");
 
+    if (Arg *A = Args.getLastArg(options::OPT_mnan_EQ)) {
+      if (StringRef(A->getValue()) == "2008")
+        CmdArgs.push_back(Args.MakeArgString("-mnan=2008"));
+    }
+
     Args.AddLastArg(CmdArgs, options::OPT_mips16, options::OPT_mno_mips16);
     Args.AddLastArg(CmdArgs, options::OPT_mmicromips,
                     options::OPT_mno_micromips);