Add support for the inline asm constraint 'K'.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156282 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 97332cf..d056f54 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -3041,6 +3041,7 @@
     break;
   case 'I': // signed 16 bit immediate
   case 'J': // integer zero
+  case 'K': // unsigned 16 bit immediate
     if (isa<ConstantInt>(CallOperandVal))
       weight = CW_Constant;
     break;
@@ -3113,6 +3114,16 @@
       }
     }
     return;
+  case 'K': // unsigned 16 bit immediate
+    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
+      EVT Type = Op.getValueType();
+      uint64_t Val = (uint64_t)C->getZExtValue();
+      if (isUInt<16>(Val)) {
+        Result = DAG.getTargetConstant(Val, Type);
+        break;
+      }
+    }
+    return;
   }
 
   if (Result.getNode()) {