_mjit_compile_pc_and_sp.erb: skip moving pc

when catch_except_p is false and insn.always_leaf? is true (never makes
arbitrary method call in the insn).

On Optcarrot, unfortunately this didn't have measureable performance impact.
But still this is a good direction since it becomes much faster when
marking all insns as always leaf.

bare_instructions.rb: add `#always_leaf?` that indicates the insn can
always be considered as leaf. Using dynamic leaf for JIT would be hard
since it requires to discard outdated code somehow.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64683 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/ruby_vm/models/bare_instructions.rb

@@ -105,6 +105,10 @@ class RubyVM::BareInstructions
     /\b(false|0)\b/ !~ @attrs['handles_sp'].expr.expr
   end
 
+  def always_leaf?
+    @attrs['leaf'].expr.expr == 'true;'
+  end
+
   def complicated_return_values?
     @sig[:ret].any? {|i| i == '...' }
   end

tool/ruby_vm/views/_mjit_compile_pc_and_sp.erb

@@ -5,8 +5,10 @@
 % # conditions mentioned  in the  file COPYING  are met.   Consult the  file for
 % # details.
 %
-% # JIT: Move pc so that catch table lookup condition is met, and for #caller_locations and rb_profile_frames.
-        fprintf(f, "    reg_cfp->pc = original_body_iseq + %d;\n", next_pos); /* ADD_PC(INSN_ATTR(width)); */
+% # JIT: Move pc for catch table on catch_except_p, and for #caller_locations and rb_profile_frames on !insn.always_leaf?
+        if (body->catch_except_p || <%= insn.always_leaf? ? 'FALSE' : 'TRUE' %>) {
+            fprintf(f, "    reg_cfp->pc = original_body_iseq + %d;\n", next_pos); /* ADD_PC(INSN_ATTR(width)); */
+        }
 %
 % # JIT: move sp to use or preserve stack variables
         if (status->local_stack_p) {