Update to use ConstantInt::isNegative()

Author: haopliu

llvm/lib/Transforms/IPO/FunctionAttrs.cpp

@@ -633,13 +633,10 @@ ArgumentAccessInfo getArgmentAccessInfo(const Instruction *I,
       [](Value *Length,
          std::optional<int64_t> Offset) -> std::optional<ConstantRange> {
     auto *ConstantLength = dyn_cast<ConstantInt>(Length);
-    if (ConstantLength && Offset) {
-      if (ConstantLength->getSExtValue() < 0)
-        return std::nullopt;
+    if (ConstantLength && Offset && !ConstantLength->isNegative())
       return ConstantRange(
           APInt(64, *Offset, true),
           APInt(64, *Offset + ConstantLength->getSExtValue(), true));
-    }
     return std::nullopt;
   };
   if (auto *SI = dyn_cast<StoreInst>(I)) {