Remove duplicated code; NFC

ICmpInst::makeConstantRange does exactly the same thing as
ConstantRange::makeExactICmpRegion.

llvm-svn: 283059
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 08e82cb..8d6c83b 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2157,7 +2157,7 @@
     return nullptr;
 
   // Rule out tautological comparisons (eg., ult 0 or uge 0).
-  ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, *C);
+  ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C);
   if (RHS_CR.isEmptySet())
     return ConstantInt::getFalse(GetCompareTy(RHS));
   if (RHS_CR.isFullSet())