Safe navigation operator

* compile.c (iseq_peephole_optimize): peephole optimization for
  branchnil jumps.
* compile.c (iseq_compile_each): generate save navigation operator
  code.
* insns.def (branchnil): new opcode to pop the tos and branch if
  it is nil.
* parse.y (NEW_QCALL, call_op, parser_yylex): parse token '.?'.
  [Feature #11537]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52214 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 17 insertions, 0 deletions

diff --git a/insns.def b/insns.def
index a923d3a4d6..9aa2dd0ef7 100644
--- a/insns.def
+++ b/insns.def
@@ -1132,6 +1132,23 @@ branchunless
     }
 }
 
+/**
+  @c jump
+  @e if val is nil, set PC to (PC + dst).
+  @j もし val が nil ならば、PC を (PC + dst) にする。
+ */
+DEFINE_INSN
+branchnil
+(OFFSET dst)
+(VALUE val)
+()
+{
+    if (NIL_P(val)) {
+	RUBY_VM_CHECK_INTS(th);
+	JUMP(dst);
+    }
+}
+
 
 /**********************************************************/
 /* for optimize                                           */