[InstCombine] add helper function for foldICmpUsingKnownBits; NFCI

llvm-svn: 281217
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index bf0f4b2..00acab2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -556,6 +556,7 @@
                                   ICmpInst::Predicate Pred);
   Instruction *foldICmpWithCastAndCast(ICmpInst &ICI);
 
+  Instruction *foldICmpUsingKnownBits(ICmpInst &Cmp);
   Instruction *foldICmpInstWithConstant(ICmpInst &Cmp);
 
   Instruction *foldICmpTruncConstant(ICmpInst &Cmp, Instruction *Trunc,