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`.

5 files changed, 34 insertions, 10 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))                      |
diff --git a/include/mruby/ops.h b/include/mruby/ops.h
index 7d20ac0ad..45397e2ed 100644
--- a/include/mruby/ops.h
+++ b/include/mruby/ops.h
@@ -53,7 +53,7 @@ OPCODE(ONERR,      S)        /* rescue_push(a) */
 OPCODE(EXCEPT,     B)        /* R(a) = exc */
 OPCODE(RESCUE,     BB)       /* R(b) = R(a).isa?(R(b)) */
 OPCODE(POPERR,     B)        /* a.times{rescue_pop()} */
-OPCODE(RAISE,      B)        /* raise(R(a)) */
+OPCODE(RAISEIF,    B)        /* raise(R(a)) if R(a) */
 OPCODE(EPUSH,      B)        /* ensure_push(SEQ[a]) */
 OPCODE(EPOP,       B)        /* A.times{ensure_pop().call} */
 OPCODE(SENDV,      BB)       /* R(a) = call(R(a),Syms(b),*R(a+1)) */
diff --git a/mrbgems/mruby-compiler/core/codegen.c b/mrbgems/mruby-compiler/core/codegen.c
index e55b6791d..7911ecb36 100644
--- a/mrbgems/mruby-compiler/core/codegen.c
+++ b/mrbgems/mruby-compiler/core/codegen.c
@@ -1533,7 +1533,7 @@ codegen(codegen_scope *s, node *tree, int val)
         }
         if (pos1) {
           dispatch(s, pos1);
-          genop_1(s, OP_RAISE, exc);
+          genop_1(s, OP_RAISEIF, exc);
         }
       }
       pop();
diff --git a/src/codedump.c b/src/codedump.c
index a19d60708..2225da4ce 100644
--- a/src/codedump.c
+++ b/src/codedump.c
@@ -507,8 +507,8 @@ codedump(mrb_state *mrb, const mrb_irep *irep)
       printf("OP_RESCUE\tR%d\tR%d", a, b);
       print_lv_ab(mrb, irep, a, b);
       break;
-    CASE(OP_RAISE, B);
-      printf("OP_RAISE\tR%d\t\t", a);
+    CASE(OP_RAISEIF, B);
+      printf("OP_RAISEIF\tR%d\t\t", a);
       print_lv_a(mrb, irep, a);
       break;
     CASE(OP_POPERR, B);
diff --git a/src/vm.c b/src/vm.c
index 3faecfaf2..2dbbe85f8 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -1255,8 +1255,24 @@ RETRY_TRY_BLOCK:
     }
 
     CASE(OP_EXCEPT, B) {
-      mrb_value exc = mrb_obj_value(mrb->exc);
-      mrb->exc = 0;
+      mrb_value exc;
+
+      if (mrb->exc == NULL) {
+        exc = mrb_nil_value();
+      }
+      else {
+        switch (mrb->exc->tt) {
+        case MRB_TT_BREAK:
+        case MRB_TT_EXCEPTION:
+          exc = mrb_obj_value(mrb->exc);
+          break;
+        default:
+          mrb_assert(!"bad mrb_type");
+          exc = mrb_nil_value();
+          break;
+        }
+        mrb->exc = NULL;
+      }
       regs[a] = exc;
       NEXT;
     }
@@ -1289,9 +1305,17 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_RAISE, B) {
-      mrb_exc_set(mrb, regs[a]);
-      goto L_RAISE;
+    CASE(OP_RAISEIF, B) {
+      mrb_value exc = regs[a];
+      if (mrb_break_p(exc)) {
+        mrb->exc = mrb_obj_ptr(exc);
+        goto L_BREAK;
+      }
+      mrb_exc_set(mrb, exc);
+      if (mrb->exc) {
+        goto L_RAISE;
+      }
+      NEXT;
     }
 
     CASE(OP_EPUSH, B) {