[InstCombine] rearrange code to remove repeated constant check; NFCI

llvm-svn: 315703
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index f1404fa..88ce4de 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -663,6 +663,8 @@
   /// This is a convenience wrapper function for the above two functions.
   Instruction *foldOpWithConstantIntoOperand(BinaryOperator &I);
 
+  Instruction *foldAddWithConstant(BinaryOperator &Add);
+
   /// \brief Try to rotate an operation below a PHI node, using PHI nodes for
   /// its operands.
   Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);