rb_{ary,fnd}_pattern_info: Remove imemo member to reduce memory usage

This is a partial revert commit of 8f096226e1b76f95f4d853d3dea2bc75eeeb5244.

NODE layout:

  Before:

       | ARYPTN | FNDPTN | HSHPTN
    ---+--------+--------+-----------
    u1 | pconst | pconst | pconst
    u2 | unused | unused | pkwargs
    u3 | apinfo | fpinfo | pkwrestarg

  After:

       | ARYPTN | FNDPTN | HSHPTN
    ---+--------+--------+-----------
    u1 | imemo  | imemo  | pkwargs
    u2 | pconst | pconst | pconst
    u3 | apinfo | fpinfo | pkwrestarg

node.c

@@ -1294,18 +1294,6 @@ static void
 mark_ast_value(void *ctx, NODE * node)
 {
     switch (nd_type(node)) {
-      case NODE_ARYPTN:
-        {
-            struct rb_ary_pattern_info *apinfo = node->nd_apinfo;
-            rb_gc_mark_movable(apinfo->imemo);
-            break;
-        }
-      case NODE_FNDPTN:
-        {
-            struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
-            rb_gc_mark_movable(fpinfo->imemo);
-            break;
-        }
       case NODE_ARGS:
         {
             struct rb_args_info *args = node->nd_ainfo;
@@ -1320,6 +1308,8 @@ mark_ast_value(void *ctx, NODE * node)
       case NODE_DXSTR:
       case NODE_DREGX:
       case NODE_DSYM:
+      case NODE_ARYPTN:
+      case NODE_FNDPTN:
         rb_gc_mark_movable(node->nd_lit);
         break;
       default:
@@ -1331,18 +1321,6 @@ static void
 update_ast_value(void *ctx, NODE * node)
 {
     switch (nd_type(node)) {
-      case NODE_ARYPTN:
-        {
-            struct rb_ary_pattern_info *apinfo = node->nd_apinfo;
-            apinfo->imemo = rb_gc_location(apinfo->imemo);
-            break;
-        }
-      case NODE_FNDPTN:
-        {
-            struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
-            fpinfo->imemo = rb_gc_location(fpinfo->imemo);
-            break;
-        }
       case NODE_ARGS:
         {
             struct rb_args_info *args = node->nd_ainfo;
@@ -1357,6 +1335,8 @@ update_ast_value(void *ctx, NODE * node)
       case NODE_DXSTR:
       case NODE_DREGX:
       case NODE_DSYM:
+      case NODE_ARYPTN:
+      case NODE_FNDPTN:
         node->nd_lit = rb_gc_location(node->nd_lit);
         break;
       default:

node.h

@@ -273,8 +273,8 @@ typedef struct RNode {
 
 #define nd_brace u2.argc
 
-#define nd_pconst     u1.node
+#define nd_pkwargs    u1.node
-#define nd_pkwargs    u2.node
+#define nd_pconst     u2.node
 #define nd_pkwrestarg u3.node
 
 #define nd_apinfo u3.apinfo
@@ -458,14 +458,12 @@ struct rb_ary_pattern_info {
     NODE *pre_args;
     NODE *rest_arg;
     NODE *post_args;
-    VALUE imemo;
 };
 
 struct rb_fnd_pattern_info {
     NODE *pre_rest_arg;
     NODE *args;
     NODE *post_rest_arg;
-    VALUE imemo;
 };
 
 struct parser_params;

parse.y

@@ -829,12 +829,7 @@ static VALUE
 new_array_pattern(struct parser_params *p, VALUE constant, VALUE pre_arg, VALUE aryptn, const YYLTYPE *loc)
 {
     NODE *t = (NODE *)aryptn;
-    struct rb_ary_pattern_info *apinfo = t->nd_apinfo;
+    VALUE pre_args = t->u1.value, rest_arg = t->u2.value, post_args = t->u3.value;
-    VALUE pre_args, rest_arg, post_args;
-
-    pre_args = rb_ary_entry(apinfo->imemo, 0);
-    rest_arg = rb_ary_entry(apinfo->imemo, 1);
-    post_args = rb_ary_entry(apinfo->imemo, 2);
 
     if (!NIL_P(pre_arg)) {
 	if (!NIL_P(pre_args)) {
@@ -851,7 +846,6 @@ static VALUE
 new_array_pattern_tail(struct parser_params *p, VALUE pre_args, VALUE has_rest, VALUE rest_arg, VALUE post_args, const YYLTYPE *loc)
 {
     NODE *t;
-    struct rb_ary_pattern_info *apinfo;
 
     if (has_rest) {
 	rest_arg = dispatch1(var_field, rest_arg ? rest_arg : Qnil);
@@ -860,14 +854,10 @@ new_array_pattern_tail(struct parser_params *p, VALUE pre_args, VALUE has_rest,
 	rest_arg = Qnil;
     }
 
-    VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
+    t = rb_node_newnode(NODE_ARYPTN, pre_args, rest_arg, post_args, &NULL_LOC);
-    apinfo = ZALLOC(struct rb_ary_pattern_info);
+    add_mark_object(p, pre_args);
-    rb_imemo_tmpbuf_set_ptr(tmpbuf, apinfo);
+    add_mark_object(p, rest_arg);
-    apinfo->imemo = rb_ary_new_from_args(4, pre_args, rest_arg, post_args, tmpbuf);
+    add_mark_object(p, post_args);
-
-    t = rb_node_newnode(NODE_ARYPTN, Qnil, Qnil, (VALUE)apinfo, &NULL_LOC);
-    RB_OBJ_WRITTEN(p->ast, Qnil, apinfo->imemo);
-
     return (VALUE)t;
 }
 
@@ -875,12 +865,7 @@ static VALUE
 new_find_pattern(struct parser_params *p, VALUE constant, VALUE fndptn, const YYLTYPE *loc)
 {
     NODE *t = (NODE *)fndptn;
-    struct rb_fnd_pattern_info *fpinfo = t->nd_fpinfo;
+    VALUE pre_rest_arg = t->u1.value, args = t->u2.value, post_rest_arg = t->u3.value;
-    VALUE pre_rest_arg, args, post_rest_arg;
-
-    pre_rest_arg = rb_ary_entry(fpinfo->imemo, 0);
-    args = rb_ary_entry(fpinfo->imemo, 1);
-    post_rest_arg = rb_ary_entry(fpinfo->imemo, 2);
 
     return dispatch4(fndptn, constant, pre_rest_arg, args, post_rest_arg);
 }
@@ -889,19 +874,14 @@ static VALUE
 new_find_pattern_tail(struct parser_params *p, VALUE pre_rest_arg, VALUE args, VALUE post_rest_arg, const YYLTYPE *loc)
 {
     NODE *t;
-    struct rb_fnd_pattern_info *fpinfo;
 
     pre_rest_arg = dispatch1(var_field, pre_rest_arg ? pre_rest_arg : Qnil);
     post_rest_arg = dispatch1(var_field, post_rest_arg ? post_rest_arg : Qnil);
 
-    VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
+    t = rb_node_newnode(NODE_FNDPTN, pre_rest_arg, args, post_rest_arg, &NULL_LOC);
-    fpinfo = ZALLOC(struct rb_fnd_pattern_info);
+    add_mark_object(p, pre_rest_arg);
-    rb_imemo_tmpbuf_set_ptr(tmpbuf, fpinfo);
+    add_mark_object(p, args);
-    fpinfo->imemo = rb_ary_new_from_args(4, pre_rest_arg, args, post_rest_arg, tmpbuf);
+    add_mark_object(p, post_rest_arg);
-
-    t = rb_node_newnode(NODE_FNDPTN, Qnil, Qnil, (VALUE)fpinfo, &NULL_LOC);
-    RB_OBJ_WRITTEN(p->ast, Qnil, fpinfo->imemo);
-
     return (VALUE)t;
 }
 
@@ -11602,8 +11582,7 @@ new_array_pattern_tail(struct parser_params *p, NODE *pre_args, int has_rest, ID
     VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
     struct rb_ary_pattern_info *apinfo = ZALLOC(struct rb_ary_pattern_info);
     rb_imemo_tmpbuf_set_ptr(tmpbuf, apinfo);
-    node = NEW_NODE(NODE_ARYPTN, 0, 0, apinfo, loc);
+    node = NEW_NODE(NODE_ARYPTN, tmpbuf, 0, apinfo, loc);
-    apinfo->imemo = tmpbuf;
     RB_OBJ_WRITTEN(p->ast, Qnil, tmpbuf);
 
     apinfo->pre_args = pre_args;
@@ -11642,8 +11621,7 @@ new_find_pattern_tail(struct parser_params *p, ID pre_rest_arg, NODE *args, ID p
     VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
     struct rb_fnd_pattern_info *fpinfo = ZALLOC(struct rb_fnd_pattern_info);
     rb_imemo_tmpbuf_set_ptr(tmpbuf, fpinfo);
-    node = NEW_NODE(NODE_FNDPTN, 0, 0, fpinfo, loc);
+    node = NEW_NODE(NODE_FNDPTN, tmpbuf, 0, fpinfo, loc);
-    fpinfo->imemo = tmpbuf;
     RB_OBJ_WRITTEN(p->ast, Qnil, tmpbuf);
 
     fpinfo->pre_rest_arg = pre_rest_arg ? assignable(p, pre_rest_arg, 0, loc) : NODE_SPECIAL_NO_NAME_REST;
@@ -11677,7 +11655,7 @@ new_hash_pattern_tail(struct parser_params *p, NODE *kw_args, ID kw_rest_arg, co
 	kw_rest_arg_node = NULL;
     }
 
-    node = NEW_NODE(NODE_HSHPTN, 0, kw_args, kw_rest_arg_node, loc);
+    node = NEW_NODE(NODE_HSHPTN, kw_args, 0, kw_rest_arg_node, loc);
 
     p->ruby_sourceline = saved_line;
     return node;