vm: add OP_RETTRUE and OP_RETFALSE for returning boolean literals

Add single-byte opcodes for returning true/false directly, completing
the set of literal return opcodes (RETSELF, RETNIL, RETTRUE, RETFALSE).

Codegen applies peephole optimization to fuse LOADTRUE/LOADFALSE + RETURN.

Co-authored-by: Claude <noreply@anthropic.com>

NEWS.md

@@ -86,6 +86,7 @@ New super-instructions that fuse common opcode sequences to reduce bytecode size
 - `OP_MATCHERR`: Pattern matching error with conditional execution for `in` patterns ([944168a](https://github.com/mruby/mruby/commit/944168a), [e9a9ba4](https://github.com/mruby/mruby/commit/e9a9ba4))
 - `OP_BLKCALL`: Direct block call for `yield`, bypassing method dispatch (13-17% faster) ([3aa2872](https://github.com/mruby/mruby/commit/3aa2872))
 - `OP_RETNIL`: Single-byte instruction for `return nil` pattern ([64e30bf](https://github.com/mruby/mruby/commit/64e30bf))
+- `OP_RETTRUE`/`OP_RETFALSE`: Single-byte instructions for `return true`/`return false` patterns
 
 # Fixed GitHub Issues
 

include/mruby/ops.h

@@ -75,6 +75,8 @@ OPCODE(RETURN,     B)        /* return R[a] (normal) */
 OPCODE(RETURN_BLK, B)        /* return R[a] (in-block return) */
 OPCODE(RETSELF,    Z)        /* return self */
 OPCODE(RETNIL,     Z)        /* return nil */
+OPCODE(RETTRUE,    Z)        /* return true */
+OPCODE(RETFALSE,   Z)        /* return false */
 OPCODE(BREAK,      B)        /* break R[a] */
 OPCODE(BLKPUSH,    BS)       /* R[a] = block (16=m5:r1:m5:d1:lv4) */
 OPCODE(ADD,        B)        /* R[a] = R[a]+R[a+1] */

mrbgems/mruby-compiler/core/codegen.c

@@ -1156,7 +1156,18 @@ gen_return(codegen_scope *s, uint8_t op, uint16_t src)
       rewind_pc(s);
       genop_0(s, OP_RETNIL);
     }
-    else if (data.insn != OP_RETURN && data.insn != OP_RETSELF && data.insn != OP_RETNIL) {
+    else if (data.insn == OP_LOADTRUE && src == data.a && op == OP_RETURN) {
+      /* LOADTRUE + RETURN -> RETTRUE */
+      rewind_pc(s);
+      genop_0(s, OP_RETTRUE);
+    }
+    else if (data.insn == OP_LOADFALSE && src == data.a && op == OP_RETURN) {
+      /* LOADFALSE + RETURN -> RETFALSE */
+      rewind_pc(s);
+      genop_0(s, OP_RETFALSE);
+    }
+    else if (data.insn != OP_RETURN && data.insn != OP_RETSELF && data.insn != OP_RETNIL &&
+             data.insn != OP_RETTRUE && data.insn != OP_RETFALSE) {
       genop_1(s, op, src);
     }
   }

src/codedump.c

@@ -402,6 +402,12 @@ codedump(mrb_state *mrb, const mrb_irep *irep, FILE *out)
     CASE(OP_RETNIL, Z):
       fprintf(out, "RETNIL\n");
       break;
+    CASE(OP_RETTRUE, Z):
+      fprintf(out, "RETTRUE\n");
+      break;
+    CASE(OP_RETFALSE, Z):
+      fprintf(out, "RETFALSE\n");
+      break;
     CASE(OP_BREAK, B):
       fprintf(out, "BREAK\t\tR%d\t", a);
       print_lv_a(mrb, irep, a, out);

src/vm.c

@@ -2748,6 +2748,14 @@ RETRY_TRY_BLOCK:
       a = 0;
       goto L_RETURN_NIL;
     }
+    CASE(OP_RETTRUE, Z) {
+      a = 0;
+      goto L_RETURN_TRUE;
+    }
+    CASE(OP_RETFALSE, Z) {
+      a = 0;
+      goto L_RETURN_FALSE;
+    }
     CASE(OP_RETURN, B) {
       mrb_int acc;
       mrb_value v;
@@ -2758,6 +2766,12 @@ RETRY_TRY_BLOCK:
       goto L_RETURN;
     L_RETURN_NIL:
       v = mrb_nil_value();
+      goto L_RETURN;
+    L_RETURN_TRUE:
+      v = mrb_true_value();
+      goto L_RETURN;
+    L_RETURN_FALSE:
+      v = mrb_false_value();
     L_RETURN:
       mrb_gc_protect(mrb, v);
       return_ci = ci;