[mips] Add macros _MIPS_ISA and __mips_isa_rev (same expansion as defined by GCC).

Summary: The Linux Kernel is one example of a piece of software that relies on them.

Reviewers: atanasyan

Reviewed By: atanasyan

Differential Revision: http://reviews.llvm.org/D3756

llvm-svn: 210270
diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index 3a4f3e6..33b4916 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -5228,6 +5228,7 @@
     CPU = Name;
     return true;
   }
+  const std::string& getCPU() const { return CPU; }
   void getDefaultFeatures(llvm::StringMap<bool> &Features) const override {
     // The backend enables certain ABI's by default according to the
     // architecture.
@@ -5452,6 +5453,13 @@
     MipsTargetInfoBase::getTargetDefines(Opts, Builder);
 
     Builder.defineMacro("__mips", "32");
+    Builder.defineMacro("_MIPS_ISA", "_MIPS_ISA_MIPS32");
+
+    const std::string& CPUStr = getCPU();
+    if (CPUStr == "mips32")
+      Builder.defineMacro("__mips_isa_rev", "1");
+    else if (CPUStr == "mips32r2")
+      Builder.defineMacro("__mips_isa_rev", "2");
 
     if (ABI == "o32") {
       Builder.defineMacro("__mips_o32");
@@ -5587,6 +5595,13 @@
     Builder.defineMacro("__mips", "64");
     Builder.defineMacro("__mips64");
     Builder.defineMacro("__mips64__");
+    Builder.defineMacro("_MIPS_ISA", "_MIPS_ISA_MIPS64");
+
+    const std::string& CPUStr = getCPU();
+    if (CPUStr == "mips64")
+      Builder.defineMacro("__mips_isa_rev", "1");
+    else if (CPUStr == "mips64r2")
+      Builder.defineMacro("__mips_isa_rev", "2");
 
     if (ABI == "n32") {
       Builder.defineMacro("__mips_n32");