[SCEV] Add and use SCEVConstant::getAPInt; NFCI

llvm-svn: 255921
diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index 5fb517e..4b244ec 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -324,8 +324,7 @@
       if (M->getOperand(0)->getSCEVType() != scConstant)
         return nullptr;
 
-      const APInt &APStepVal =
-          cast<SCEVConstant>(M->getOperand(0))->getValue()->getValue();
+      const APInt &APStepVal = cast<SCEVConstant>(M->getOperand(0))->getAPInt();
 
       // Huge step value - give up.
       if (APStepVal.getBitWidth() > 64)