compile optimized case dispatch for nil/true/false

nil/true/false are special literals just like floats, integers,
literal strings, and symbols.  Optimize when statements with
them by using a jump table, too.

target 0: a (ruby 2.3.0dev (2015-12-08 trunk 52928) [x86_64-linux]) at "/home/ew/rrrr/b/ruby"
target 1: b (ruby 2.3.0dev (2015-12-08 master 52928) [x86_64-linux]) at "/home/ew/ruby/b/ruby"

benchmark results:
minimum results in each 5 measurements.
Execution time (sec)
name	a	b
loop_whileloop2	0.102	0.103
vm2_case_lit*	1.657	0.549

Speedup ratio: compare with the result of `a' (greater is better)
name	b
loop_whileloop2	0.988
vm2_case_lit*	3.017

* benchmark/bm_vm2_case_lit.rb: new benchmark
* compile.c (case_when_optimizable_literal): add nil/true/false
* insns.def (opt_case_dispatch): ditto
* vm.c (vm_redefinition_check_flag): ditto
* vm.c (vm_init_redefined_flag): ditto
* vm_core.h: ditto
* object.c (InitVM_Object): define === explicitly for nil/true/false
* test/ruby/test_case.rb (test_deoptimize_nil): new test
* test/ruby/test_optimization.rb (test_opt_case_dispatch): update
  (test_eqq): new test
  [ruby-core:71923] [Feature #11769]
  Original patch by Aaron Patterson <[email protected]>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52931 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 0 deletions

diff --git a/compile.c b/compile.c
index 9be8fd57c8..abb5306759 100644
--- a/compile.c
+++ b/compile.c
@@ -2919,6 +2919,12 @@ case_when_optimizable_literal(NODE * node)
 	}
 	break;
       }
+      case NODE_NIL:
+	return Qnil;
+      case NODE_TRUE:
+	return Qtrue;
+      case NODE_FALSE:
+	return Qfalse;
       case NODE_STR:
 	return node->nd_lit = rb_fstring(node->nd_lit);
     }