Avoid creating unnecessary empty arrays on splat.
But this changes requires `OP_ARYCAT` and `OP_ARYPUSH` to accept `nil`
as their first operand. Alternative VMs (e.g. `mruby/c`) that understand
mruby bytecode need to be updated.
MODIFY
mrbgems/mruby-compiler/core/codegen.c
mrbgems/mruby-compiler/core/codegen.c
@@ -956,7 +956,12 @@ gen_values(codegen_scope *s, node *t, int val, int extra)
}
else {
pop_n(n);
+ if (n == 0 && is_splat) {
+ genop_1(s, OP_LOADNIL, cursp());
+ }
+ else {
genop_2(s, OP_ARRAY, cursp(), n);
+ }
push();
codegen(s, t->car, VAL);
pop(); pop();

MODIFY
src/vm.c
src/vm.c
@@ -2441,7 +2441,12 @@ RETRY_TRY_BLOCK:
CASE(OP_ARYCAT, B) {
mrb_value splat = mrb_ary_splat(mrb, regs[a+1]);
+ if (mrb_nil_p(regs[a])) {
+ regs[a] = splat;
+ }
+ else {
mrb_ary_concat(mrb, regs[a], splat);
+ }
mrb_gc_arena_restore(mrb, ai);
NEXT;
}

Avoid creating unnecessary empty arrays on splat.

But this changes requires `OP_ARYCAT` and `OP_ARYPUSH` to accept `nil`
as their first operand. Alternative VMs (e.g. `mruby/c`) that understand
mruby bytecode need to be updated.