diff options
Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 40 |
1 files changed, 40 insertions, 0 deletions
@@ -1,3 +1,43 @@ +Fri Jun 15 19:22:13 2012 Koichi Sasada <ko1@atdot.net> + + * 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. + Fri Jun 15 19:11:23 2012 Nobuyoshi Nakada <nobu@ruby-lang.org> * lib/test/unit.rb (Test::Unit::Runner#puke): always add skipped |