From 35ba2783fe6b3316a6bbc6f00bf975ad7185d6e0 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <tenderlove@ruby-lang.org>
Date: Thu, 23 Jul 2020 16:00:28 -0700
Subject: Use a linked list to eliminate imemo tmp bufs for managing local
 tables

This patch changes local table memory to be managed by a linked list
rather than via the garbage collector.  It reduces allocations from the
GC and also fixes a use-after-free bug in the concurrent-with-sweep
compactor I'm working on.
---
 parse.y | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

(limited to 'parse.y')

diff --git a/parse.y b/parse.y
index ab71469a06..b29e7190eb 100644
--- a/parse.y
+++ b/parse.y
@@ -3050,11 +3050,9 @@ primary		: literal
 			ID id = internal_id(p);
 			NODE *m = NEW_ARGS_AUX(0, 0, &NULL_LOC);
 			NODE *args, *scope, *internal_var = NEW_DVAR(id, &@2);
-			VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
 			ID *tbl = ALLOC_N(ID, 3);
-			rb_imemo_tmpbuf_set_ptr(tmpbuf, tbl);
 			tbl[0] = 1 /* length of local var table */; tbl[1] = id /* internal id */;
-                        tbl[2] = tmpbuf;
+                        rb_ast_add_local_table(p->ast, tbl);
 
 			switch (nd_type($2)) {
 			  case NODE_LASGN:
@@ -3074,7 +3072,6 @@ primary		: literal
 			/* {|*internal_id| <m> = internal_id; ... } */
 			args = new_args(p, m, 0, id, 0, new_args_tail(p, 0, 0, 0, &@2), &@2);
 			scope = NEW_NODE(NODE_SCOPE, tbl, $5, args, &@$);
-                        RB_OBJ_WRITTEN(p->ast, Qnil, tmpbuf);
 			$$ = NEW_FOR($4, scope, &@$);
 			fixpos($$, $2);
 		    /*% %*/
@@ -12037,12 +12034,9 @@ local_tbl(struct parser_params *p)
     int cnt = cnt_args + cnt_vars;
     int i, j;
     ID *buf;
-    VALUE tbl = 0;
 
     if (cnt <= 0) return 0;
-    tbl = rb_imemo_tmpbuf_auto_free_pointer();
     buf = ALLOC_N(ID, cnt + 2);
-    rb_imemo_tmpbuf_set_ptr(tbl, buf);
     MEMCPY(buf+1, p->lvtbl->args->tbl, ID, cnt_args);
     /* remove IDs duplicated to warn shadowing */
     for (i = 0, j = cnt_args+1; i < cnt_vars; ++i) {
@@ -12053,11 +12047,9 @@ local_tbl(struct parser_params *p)
     }
     if (--j < cnt) {
 	REALLOC_N(buf, ID, (cnt = j) + 2);
-	rb_imemo_tmpbuf_set_ptr(tbl, buf);
     }
     buf[0] = cnt;
-    buf[cnt + 1] = (ID)tbl;
-    RB_OBJ_WRITTEN(p->ast, Qnil, tbl);
+    rb_ast_add_local_table(p->ast, buf);
 
     return buf;
 }
-- 
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