Add struct new micro benchmark (#536)

Benchmark allocating, writing, and reading fields

Author: tekknolagi

benchmarks.yml

@@ -256,6 +256,10 @@ str_concat:
   category: micro
   single_file: true
   ractor: true
+struct-new-no-escape:
+  desc: instantiate new struct objects with fields in a loop to test allocation and escape analysis performance
+  category: micro
+  single_file: true
 structaref:
   desc: structaref tests the performance of getting Struct members
   category: micro

benchmarks/struct-new-no-escape.rb

@@ -0,0 +1,16 @@
+require_relative '../harness/loader'
+
+Point = Struct.new(:x, :y)
+
+def test
+  p = Point.new(1, 2)
+  p.x + p.y
+end
+
+run_benchmark(100) do
+  i = 0
+  while i < 1_000_000
+    test
+    i += 1
+  end
+end