Add struct aref benchmark

benchmarks.yml

@@ -152,6 +152,10 @@ getivar:
   category: micro
   single_file: true
   ractor: true
+structaref:
+  desc: structaref tests the performance of getting struct members
+  category: micro
+  single_file: true
 keyword_args:
   desc: keyword_args tests the performance of method calls with keyword arguments.
   category: micro

benchmarks/structaref.rb

@@ -0,0 +1,31 @@
+require_relative '../harness/loader'
+
+TheClass = Struct.new(:v0, :v1, :v2, :levar)
+
+def get_value_loop obj
+  sum = 0
+  # 1M
+  i = 0
+  while i < 1000000
+    # 10 times to de-emphasize loop overhead
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    sum += obj.levar
+    i += 1
+  end
+
+  return sum
+end
+
+obj = TheClass.new(1, 2, 3, 1)
+
+run_benchmark(850) do
+  get_value_loop obj
+end