Add the skeleton for the Mips constant island pass.
It will only be used for Mips 16 at this time.
 

llvm-svn: 176161
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.cpp b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
index 1b91e8b..fd930f0 100644
--- a/llvm/lib/Target/Mips/MipsTargetMachine.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
@@ -116,6 +116,8 @@
   // NOTE: long branch has not been implemented for mips16.
   if (TM.getSubtarget<MipsSubtarget>().hasStandardEncoding())
     addPass(createMipsLongBranchPass(TM));
+  if (TM.getSubtarget<MipsSubtarget>().inMips16Mode())
+    addPass(createMipsConstantIslandPass(TM));
 
   return true;
 }