path: root/vm_backtrace.c
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authorko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2012-06-15 10:22:34 +0000
committerko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2012-06-15 10:22:34 +0000
commit745c23b2d981e23024f044e934967bc6dae66d80 (patch)
tree9fd909ad9129bf5b11bbe1cbf77a11b6d9fc37b8 /vm_backtrace.c
parent0dc5b8ce8c11d196ed44d333c4bfae8c7f2d0bac (diff)
* 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:// b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'vm_backtrace.c')
1 files changed, 1 insertions, 2 deletions
diff --git a/vm_backtrace.c b/vm_backtrace.c
index d2e519b..47ae7f1 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -379,8 +379,7 @@ backtrace_each(rb_thread_t *th,
start_cfp =
- RUBY_VM_NEXT_CONTROL_FRAME(start_cfp))); /* skip top frames */
+ RUBY_VM_NEXT_CONTROL_FRAME(start_cfp)); /* skip top frames */
if (start_cfp < last_cfp) {
size = 0;