* vm_core.h: remove VM_FRAME_MAGIC_FINISH (finish frame type).

  Before this commit:
  `finish frame' was place holder which indicates that VM loop
  needs to return function.
  If a C method calls a Ruby methods (a method written by Ruby),
  then VM loop will be (re-)invoked.  When the Ruby method returns,
  then also VM loop should be escaped.  `finish frame' has only
  one instruction `finish', which returns VM loop function.
  VM loop function executes `finish' instruction, then VM loop
  function returns itself.
  With such mechanism, `leave' instruction (which returns one
  frame from current scope) doesn't need to check that this `leave'
  should also return from VM loop function.
  Strictly, one branch can be removed from `leave' instructon.
  Consideration:
  However, pushing the `finish frame' needs costs because
  it needs several memory accesses.  The number of pushing
  `finish frame' is greater than I had assumed.  Of course,
  pushing `finish frame' consumes additional control frame.
  Moreover, recent processors has good branch prediction,
  with which we can ignore such trivial checking.
  After this commit:
  Finally, I decide to remove `finish frame' and `finish'
  instruction.  Some parts of VM depend on `finish frame',
  so the new frame flag VM_FRAME_FLAG_FINISH is introduced.
  If this frame should escape from VM function loop, then
  the result of VM_FRAME_TYPE_FINISH_P(cfp) is true.
  `leave' instruction checks this flag every time.
  I measured performance on it.  However on my environments,
  it improves some benchmarks and slows some benchmarks down.
  Maybe it is because of C compiler optimization parameters.
  I'll re-visit here if this cause problems.
* insns.def (leave, finish): remove finish instruction.
* vm.c, vm_eval.c, vm_exec.c, vm_backtrace.c, vm_dump.c:
  apply above changes.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36099 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 14 deletions

diff --git a/vm_exec.c b/vm_exec.c
index fdfaa29823..e72bc487df 100644
--- a/vm_exec.c
+++ b/vm_exec.c
@@ -25,14 +25,6 @@
 #endif
 /* #define DECL_SC_REG(r, reg) VALUE reg_##r */
 
-#if OPT_STACK_CACHING
-static VALUE finish_insn_seq[1] = { BIN(finish_SC_ax_ax) };
-#elif OPT_CALL_THREADED_CODE
-static VALUE const finish_insn_seq[1] = { 0 };
-#else
-static VALUE finish_insn_seq[1] = { BIN(finish) };
-#endif
-
 #if !OPT_CALL_THREADED_CODE
 static VALUE
 vm_exec_core(rb_thread_t *th, VALUE initial)
@@ -84,11 +76,6 @@ vm_exec_core(rb_thread_t *th, VALUE initial)
 #if OPT_TOKEN_THREADED_CODE || OPT_DIRECT_THREADED_CODE
 #include "vmtc.inc"
     if (UNLIKELY(th == 0)) {
-#if OPT_STACK_CACHING
-	finish_insn_seq[0] = (VALUE)&&LABEL (finish_SC_ax_ax);
-#else
-	finish_insn_seq[0] = (VALUE)&&LABEL (finish);
-#endif
 	return (VALUE)insns_address_table;
     }
 #endif
@@ -145,7 +132,7 @@ vm_exec_core(rb_thread_t *th, VALUE initial)
 	}
     }
 
-    if (VM_FRAME_TYPE(th->cfp) != VM_FRAME_MAGIC_FINISH) {
+    if (VM_FRAME_TYPE_FINISH_P(th->cfp)) {
 	rb_bug("cfp consistency error");
     }