Add vm_ivar get, get_unitialized, and lazy_set benchmarks

Merged: https://github.com/ruby/ruby/pull/6376

benchmark/vm_ivar_get.yml

@@ -0,0 +1,37 @@
+prelude: |
+  class Example
+      def initialize
+          @v0 = 1
+          @v1 = 2
+          @v3 = 3
+          @levar = 1
+      end
+
+      def get_value_loop
+          sum = 0
+
+          i = 0
+          while i < 1000000
+              # 10 times to de-emphasize loop overhead
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              sum += @levar
+              i += 1
+          end
+
+          return sum
+      end
+  end
+
+  obj = Example.new
+benchmark:
+  vm_ivar_get: |
+    obj.get_value_loop
+loop_count: 100

benchmark/vm_ivar_get_unintialized.yml

@@ -0,0 +1,12 @@
+prelude: |
+  class Example 
+    def read
+      @uninitialized
+    end
+  end
+
+  obj = Example.new
+benchmark:
+  vm_ivar_get_uninitialized: |
+    obj.read
+loop_count: 30000000

benchmark/vm_ivar_lazy_set.yml

@@ -0,0 +1,12 @@
+prelude: |
+  class Example 
+    def lazy_set
+      @uninitialized ||= 123
+    end
+  end
+
+  objs = 10000000.times.map { Example.new }
+benchmark:
+  vm_ivar_lazy_set: |
+    objs.each(&:lazy_set)
+loop_count: 1