Allow more than 256 child `irep`; fix #5310

We have introduced following new instructions.

 * `OP_LAMBDA16`
 * `OP_BLOCK16`
 * `OP_METHOD16`
 * `OP_EXEC16`

Each instruction uses 16 bits operand for `reps` index. Since new
instructions are added, `mruby/c` VM should be updated.

Due to new instructions, dump format compatibility is lost, we have
increased `RITE_BINARY_MAJOR_VER`.

In addition, we have decreased the size of `refcnt` in `mrb_irep` from
`uint32_t` to `uint16_t`, which is reasonably big enough.

2 files changed, 26 insertions, 1 deletions

diff --git a/src/codedump.c b/src/codedump.c
index 3a7b34354..f382bb7eb 100644
--- a/src/codedump.c
+++ b/src/codedump.c
@@ -371,6 +371,15 @@ codedump(mrb_state *mrb, const mrb_irep *irep)
     CASE(OP_METHOD, BB);
       printf("OP_METHOD\tR%d\tI(%d:%p)\n", a, b, (void*)irep->reps[b]);
       break;
+    CASE(OP_LAMBDA16, BS);
+      printf("OP_LAMBDA\tR%d\tI(%d:%p)\n", a, b, (void*)irep->reps[b]);
+      break;
+    CASE(OP_BLOCK16, BS);
+      printf("OP_BLOCK\tR%d\tI(%d:%p)\n", a, b, (void*)irep->reps[b]);
+      break;
+    CASE(OP_METHOD16, BS);
+      printf("OP_METHOD\tR%d\tI(%d:%p)\n", a, b, (void*)irep->reps[b]);
+      break;
     CASE(OP_RANGE_INC, B);
       printf("OP_RANGE_INC\tR%d\n", a);
       break;
diff --git a/src/vm.c b/src/vm.c
index b2fc075c8..f8b74034e 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -2644,6 +2644,18 @@ RETRY_TRY_BLOCK:
       c = OP_L_METHOD;
       goto L_MAKE_LAMBDA;
     }
+    CASE(OP_LAMBDA16, BS) {
+      c = OP_L_LAMBDA;
+      goto L_MAKE_LAMBDA;
+    }
+    CASE(OP_BLOCK16, BS) {
+      c = OP_L_BLOCK;
+      goto L_MAKE_LAMBDA;
+    }
+    CASE(OP_METHOD16, BS) {
+      c = OP_L_METHOD;
+      goto L_MAKE_LAMBDA;
+    }
 
     CASE(OP_RANGE_INC, B) {
       mrb_value val = mrb_range_new(mrb, regs[a], regs[a+1], FALSE);
@@ -2699,7 +2711,11 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_EXEC, BB) {
+    CASE(OP_EXEC16, BS)
+      goto L_EXEC;
+    CASE(OP_EXEC, BB)
+    L_EXEC:
+    {
       mrb_value recv = regs[a];
       struct RProc *p;
       const mrb_irep *nirep = irep->reps[b];