Extended `OP_EXCEPT` and `OP_RAISE` (`OP_RAISEIF`) instructions

- `OP_EXCEPT` checks if `mrb->exc` is `NULL`, `MRB_TT_EXCEPTION` or
  `MRB_TT_BREAK`.
  If `mrb->exc` is `NULL`, it will be replaced with `nil`.

- If `OP_RAISE` is `nil`, it does nothing and the immediately
  following instruction is executed (like `OP_NOP`).
  Also, in case of `RBreak` object, it moves to the processing for
  `break`.
  With this change, the instruction name is changed from
  `OP_RAISE` to `OP_RAISEIF`.

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/opcode.md b/doc/opcode.md
index 98d29cdc0..d7e620350 100644
--- a/doc/opcode.md
+++ b/doc/opcode.md
@@ -66,7 +66,7 @@ sign) of operands.
 | OP_EXCEPT        | B            | R(a) = exc                                             |
 | OP_RESCUE        | BB           | R(b) = R(a).isa?(R(b))                                 |
 | OP_POPERR        | B            | a.times{rescue_pop()}                                  |
-| OP_RAISE         | B            | raise(R(a))                                            |
+| OP_RAISEIF       | B            | raise(R(a)) if R(a)                                    |
 | OP_EPUSH         | B            | ensure_push(SEQ[a])                                    |
 | OP_EPOP          | B            | A.times{ensure_pop().call}                             |
 | OP_SENDV         | BB           | R(a) = call(R(a),Syms(b),*R(a+1))                      |