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mruby-compiler: optimize array literal pattern matching

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When pattern matching an array literal against an array pattern with
matching sizes (e.g., `[1,2] => a,b`), skip the runtime calls to
#deconstruct and #size. Instead, directly extract elements using the
VM's GETIDX opcode.

This reduces bytecode from 72 to 28 bytes (61% reduction) and
eliminates 4 method calls per pattern match.

Co-authored-by: Claude <noreply@anthropic.com>
This commit is contained in:
Yukihiro "Matz" Matsumoto
2025-12-24 07:35:55 +09:00
parent 2b72d8a7c1
commit fd01a0af73
1 changed files with 44 additions and 0 deletions
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mrbgems/mruby-compiler/core/codegen.c
+44
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@@ -6384,6 +6384,49 @@ codegen(codegen_scope *s, node *tree, int val)
break;
}
/* Optimize: array literal => array pattern with matching sizes */
if (node_type(mp->value) == NODE_ARRAY &&
node_type(mp->pattern) == NODE_PAT_ARRAY) {
struct mrb_ast_array_node *arr = array_node(mp->value);
struct mrb_ast_pat_array_node *pat = pat_array_node(mp->pattern);
/* Only optimize for exact match (no rest, no post) */
if (pat->rest == 0 && pat->post == NULL) {
/* Count array elements and pattern pre elements */
int arr_len = 0, pat_len = 0;
node *e;
for (e = arr->elements; e; e = e->cdr) arr_len++;
for (e = pat->pre; e; e = e->cdr) pat_len++;
if (arr_len == pat_len) {
/* Sizes match - skip deconstruct and size check */
int arr_reg = cursp();
int i = 0;
codegen(s, mp->value, VAL); /* Generate array */
/* Extract elements directly with GETIDX */
for (e = pat->pre; e; e = e->cdr, i++) {
gen_move(s, cursp(), arr_reg, 0);
push();
gen_int(s, cursp(), i);
push();
genop_1(s, OP_GETIDX, cursp() - 2); /* R[a] = R[a][R[a+1]] */
pop();
/* Match element pattern (element is now at cursp()-1) */
codegen_pattern(s, e->car, cursp() - 1, &fail_pos);
pop(); /* clean up array copy slot */
}
pop(); /* pop array */
if (fail_pos != JMPLINK_START) {
goto pattern_fail_handling;
}
/* Pattern always matches - for 'in' pattern, return true */
if (!mp->raise_on_fail && val) {
genop_1(s, OP_LOADT, cursp());
push();
}
break;
}
}
}
head = cursp();
/* Evaluate the value */
@@ -6394,6 +6437,7 @@ codegen(codegen_scope *s, node *tree, int val)
/* Pattern matched */
pop(); /* pop the value */
pattern_fail_handling:
if (fail_pos != JMPLINK_START) {
/* Pattern can fail - generate failure handling code */
uint32_t match_pos;