[Universal parser] DeVALUE of p->debug_lines and ast->body.script_lines

This patch is part of universal parser work.

## Summary
- Decouple VALUE from members below:
  - `(struct parser_params *)->debug_lines`
  - `(rb_ast_t *)->body.script_lines`
- Instead, they are now `rb_parser_ary_t *`
  - They can also be a `(VALUE)FIXNUM` as before to hold line count
- `ISEQ_BODY(iseq)->variable.script_lines` remains VALUE
  - In order to do this,
  - Add `VALUE script_lines` param to `rb_iseq_new_with_opt()`
  - Introduce `rb_parser_build_script_lines_from()` to convert `rb_parser_ary_t *` into `VALUE`

## Other details
- Extend `rb_parser_ary_t *`. It previously could only store `rb_parser_ast_token *`, now can store script_lines, too
- Change tactics of building the top-level `SCRIPT_LINES__` in `yycompile0()`
  - Before: While parsing, each line of the script is added to `SCRIPT_LINES__[path]`
  - After: After `yyparse(p)`, `SCRIPT_LINES__[path]` will be built from `p->debug_lines`
- Remove the second parameter of `rb_parser_set_script_lines()` to make it simple
- Introduce `script_lines_free()` to be called from `rb_ast_free()` because the GC no longer takes care of the script_lines
- Introduce `rb_parser_string_deep_copy()` in parse.y to maintain script_lines when `rb_ruby_parser_free()` called
  - With regard to this, please see *Future tasks* below

## Future tasks
- Decouple IMEMO from `rb_ast_t *`
  - This lifts the five-members-restriction of Ruby object,
  - So we will be able to move the ownership of the `lex.string_buffer` from parser to AST
  - Then we remove `rb_parser_string_deep_copy()` to make the whole thing simple

17 files changed, 234 insertions, 110 deletions

diff --git a/ast.c b/ast.c
index 70f298c7f8..a4c57b898b 100644
--- a/ast.c
+++ b/ast.c
@@ -97,7 +97,7 @@ rb_ast_parse_str(VALUE str, VALUE keep_script_lines, VALUE error_tolerant, VALUE
 
     StringValue(str);
     VALUE vparser = ast_parse_new();
-    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser, Qtrue);
+    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser);
     if (RTEST(error_tolerant)) rb_parser_error_tolerant(vparser);
     if (RTEST(keep_tokens)) rb_parser_keep_tokens(vparser);
     ast = rb_parser_compile_string_path(vparser, Qnil, str, 1);
@@ -120,7 +120,7 @@ rb_ast_parse_file(VALUE path, VALUE keep_script_lines, VALUE error_tolerant, VAL
     f = rb_file_open_str(path, "r");
     rb_funcall(f, rb_intern("set_encoding"), 2, rb_enc_from_encoding(enc), rb_str_new_cstr("-"));
     VALUE vparser = ast_parse_new();
-    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser, Qtrue);
+    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser);
     if (RTEST(error_tolerant))  rb_parser_error_tolerant(vparser);
     if (RTEST(keep_tokens))  rb_parser_keep_tokens(vparser);
     ast = rb_parser_compile_file_path(vparser, Qnil, f, 1);
@@ -148,7 +148,7 @@ rb_ast_parse_array(VALUE array, VALUE keep_script_lines, VALUE error_tolerant, V
 
     array = rb_check_array_type(array);
     VALUE vparser = ast_parse_new();
-    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser, Qtrue);
+    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser);
     if (RTEST(error_tolerant)) rb_parser_error_tolerant(vparser);
     if (RTEST(keep_tokens)) rb_parser_keep_tokens(vparser);
     ast = rb_parser_compile_generic(vparser, lex_array, Qnil, array, 1);
@@ -806,9 +806,9 @@ ast_node_script_lines(rb_execution_context_t *ec, VALUE self)
 {
     struct ASTNodeData *data;
     TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
-    VALUE ret = data->ast->body.script_lines;
-    if (!RB_TYPE_P(ret, T_ARRAY)) return Qnil;
-    return ret;
+    rb_parser_ary_t *ret = data->ast->body.script_lines;
+    if (!ret || FIXNUM_P((VALUE)ret)) return Qnil;
+    return rb_parser_build_script_lines_from(ret);
 }
 
 #include "ast.rbinc"
diff --git a/compile.c b/compile.c
index 0fb3b85583..d5fa6a5c74 100644
--- a/compile.c
+++ b/compile.c
@@ -1483,7 +1483,7 @@ new_child_iseq(rb_iseq_t *iseq, const NODE *const node,
     ast.root = node;
     ast.frozen_string_literal = -1;
     ast.coverage_enabled = -1;
-    ast.script_lines = ISEQ_BODY(iseq)->variable.script_lines;
+    ast.script_lines = NULL;
 
     debugs("[new_child_iseq]> ---------------------------------------\n");
     int isolated_depth = ISEQ_COMPILE_DATA(iseq)->isolated_depth;
@@ -1491,7 +1491,8 @@ new_child_iseq(rb_iseq_t *iseq, const NODE *const node,
                                     rb_iseq_path(iseq), rb_iseq_realpath(iseq),
                                     line_no, parent,
                                     isolated_depth ? isolated_depth + 1 : 0,
-                                    type, ISEQ_COMPILE_DATA(iseq)->option);
+                                    type, ISEQ_COMPILE_DATA(iseq)->option,
+                                    ISEQ_BODY(iseq)->variable.script_lines);
     debugs("[new_child_iseq]< ---------------------------------------\n");
     return ret_iseq;
 }
@@ -8740,14 +8741,15 @@ compile_builtin_mandatory_only_method(rb_iseq_t *iseq, const NODE *node, const N
         .root = RNODE(&scope_node),
         .frozen_string_literal = -1,
         .coverage_enabled = -1,
-        .script_lines = ISEQ_BODY(iseq)->variable.script_lines,
+        .script_lines = NULL
     };
 
     ISEQ_BODY(iseq)->mandatory_only_iseq =
       rb_iseq_new_with_opt(&ast, rb_iseq_base_label(iseq),
                            rb_iseq_path(iseq), rb_iseq_realpath(iseq),
                            nd_line(line_node), NULL, 0,
-                           ISEQ_TYPE_METHOD, ISEQ_COMPILE_DATA(iseq)->option);
+                           ISEQ_TYPE_METHOD, ISEQ_COMPILE_DATA(iseq)->option,
+                           ISEQ_BODY(iseq)->variable.script_lines);
 
     ALLOCV_END(idtmp);
     return COMPILE_OK;
diff --git a/imemo.c b/imemo.c
index 0031b3322c..8403859146 100644
--- a/imemo.c
+++ b/imemo.c
@@ -274,7 +274,7 @@ rb_imemo_mark_and_move(VALUE obj, bool reference_updating)
 {
     switch (imemo_type(obj)) {
       case imemo_ast:
-        rb_ast_mark_and_move((rb_ast_t *)obj, reference_updating);
+        // TODO: Make AST decoupled from IMEMO
 
         break;
       case imemo_callcache: {
diff --git a/internal/parse.h b/internal/parse.h
index 20367730d1..80328686c1 100644
--- a/internal/parse.h
+++ b/internal/parse.h
@@ -51,7 +51,7 @@ size_t rb_ruby_parser_memsize(const void *ptr);
 
 void rb_ruby_parser_set_options(rb_parser_t *p, int print, int loop, int chomp, int split);
 rb_parser_t *rb_ruby_parser_set_context(rb_parser_t *p, const struct rb_iseq_struct *base, int main);
-void rb_ruby_parser_set_script_lines(rb_parser_t *p, VALUE lines_array);
+void rb_ruby_parser_set_script_lines(rb_parser_t *p);
 void rb_ruby_parser_error_tolerant(rb_parser_t *p);
 rb_ast_t* rb_ruby_parser_compile_file_path(rb_parser_t *p, VALUE fname, VALUE file, int start);
 void rb_ruby_parser_keep_tokens(rb_parser_t *p);
diff --git a/internal/ruby_parser.h b/internal/ruby_parser.h
index 0a00075211..f0cec86668 100644
--- a/internal/ruby_parser.h
+++ b/internal/ruby_parser.h
@@ -39,9 +39,11 @@ RUBY_SYMBOL_EXPORT_END
 VALUE rb_parser_end_seen_p(VALUE);
 VALUE rb_parser_encoding(VALUE);
 VALUE rb_parser_set_yydebug(VALUE, VALUE);
+VALUE rb_parser_build_script_lines_from(rb_parser_ary_t *script_lines);
+void rb_parser_aset_script_lines_for(VALUE path, rb_parser_ary_t *script_lines);
 void rb_parser_set_options(VALUE, int, int, int, int);
 void *rb_parser_load_file(VALUE parser, VALUE name);
-void rb_parser_set_script_lines(VALUE vparser, VALUE lines_array);
+void rb_parser_set_script_lines(VALUE vparser);
 void rb_parser_error_tolerant(VALUE vparser);
 void rb_parser_keep_tokens(VALUE vparser);
 
diff --git a/iseq.c b/iseq.c
index 4d4006777e..6d4fa5bd33 100644
--- a/iseq.c
+++ b/iseq.c
@@ -839,20 +839,21 @@ rb_iseq_new(const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE realpath,
             const rb_iseq_t *parent, enum rb_iseq_type type)
 {
     return rb_iseq_new_with_opt(ast, name, path, realpath, 0, parent,
-                                0, type, &COMPILE_OPTION_DEFAULT);
+                                0, type, &COMPILE_OPTION_DEFAULT,
+                                Qnil);
 }
 
 static int
 ast_line_count(const rb_ast_body_t *ast)
 {
-    if (ast->script_lines == Qfalse) {
+    if (ast->script_lines == NULL) {
         // this occurs when failed to parse the source code with a syntax error
         return 0;
     }
-    if (RB_TYPE_P(ast->script_lines, T_ARRAY)){
-        return (int)RARRAY_LEN(ast->script_lines);
+    if (!FIXNUM_P((VALUE)ast->script_lines)) {
+        return (int)ast->script_lines->len;
     }
-    return FIX2INT(ast->script_lines);
+    return FIX2INT((VALUE)ast->script_lines);
 }
 
 static VALUE
@@ -888,7 +889,8 @@ rb_iseq_new_top(const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE realpath
     iseq_new_setup_coverage(path, ast, 0);
 
     return rb_iseq_new_with_opt(ast, name, path, realpath, 0, parent, 0,
-                                ISEQ_TYPE_TOP, &COMPILE_OPTION_DEFAULT);
+                                ISEQ_TYPE_TOP, &COMPILE_OPTION_DEFAULT,
+                                Qnil);
 }
 
 /**
@@ -910,7 +912,8 @@ rb_iseq_new_main(const rb_ast_body_t *ast, VALUE path, VALUE realpath, const rb_
 
     return rb_iseq_new_with_opt(ast, rb_fstring_lit("<main>"),
                                 path, realpath, 0,
-                                parent, 0, ISEQ_TYPE_MAIN, opt ? &COMPILE_OPTION_DEFAULT : &COMPILE_OPTION_FALSE);
+                                parent, 0, ISEQ_TYPE_MAIN, opt ? &COMPILE_OPTION_DEFAULT : &COMPILE_OPTION_FALSE,
+                                Qnil);
 }
 
 /**
@@ -938,7 +941,8 @@ rb_iseq_new_eval(const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE realpat
     }
 
     return rb_iseq_new_with_opt(ast, name, path, realpath, first_lineno,
-                                parent, isolated_depth, ISEQ_TYPE_EVAL, &COMPILE_OPTION_DEFAULT);
+                                parent, isolated_depth, ISEQ_TYPE_EVAL, &COMPILE_OPTION_DEFAULT,
+                                Qnil);
 }
 
 rb_iseq_t *
@@ -966,7 +970,8 @@ iseq_translate(rb_iseq_t *iseq)
 rb_iseq_t *
 rb_iseq_new_with_opt(const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE realpath,
                      int first_lineno, const rb_iseq_t *parent, int isolated_depth,
-                     enum rb_iseq_type type, const rb_compile_option_t *option)
+                     enum rb_iseq_type type, const rb_compile_option_t *option,
+                     VALUE script_lines)
 {
     const NODE *node = ast ? ast->root : 0;
     /* TODO: argument check */
@@ -979,10 +984,11 @@ rb_iseq_new_with_opt(const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE rea
         option = set_compile_option_from_ast(&new_opt, ast);
     }
 
-    VALUE script_lines = Qnil;
-
-    if (ast && !FIXNUM_P(ast->script_lines) && ast->script_lines) {
-        script_lines = ast->script_lines;
+    if (!NIL_P(script_lines)) {
+        // noop
+    }
+    else if (ast && !FIXNUM_P((VALUE)ast->script_lines) && ast->script_lines) {
+        script_lines = rb_parser_build_script_lines_from(ast->script_lines);
     }
     else if (parent) {
         script_lines = ISEQ_BODY(parent)->variable.script_lines;
@@ -1225,7 +1231,7 @@ rb_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
         const rb_iseq_t *outer_scope = rb_iseq_new(NULL, name, name, Qnil, 0, ISEQ_TYPE_TOP);
         VALUE outer_scope_v = (VALUE)outer_scope;
         rb_parser_set_context(parser, outer_scope, FALSE);
-        rb_parser_set_script_lines(parser, RBOOL(ruby_vm_keep_script_lines));
+        if (ruby_vm_keep_script_lines) rb_parser_set_script_lines(parser);
         RB_GC_GUARD(outer_scope_v);
         ast = (*parse)(parser, file, src, ln);
     }
@@ -1236,7 +1242,8 @@ rb_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
     }
     else {
         iseq = rb_iseq_new_with_opt(&ast->body, name, file, realpath, ln,
-                                    NULL, 0, ISEQ_TYPE_TOP, &option);
+                                    NULL, 0, ISEQ_TYPE_TOP, &option,
+                                    Qnil);
         rb_ast_dispose(ast);
     }
 
@@ -1627,7 +1634,8 @@ iseqw_s_compile_file(int argc, VALUE *argv, VALUE self)
     ret = iseqw_new(rb_iseq_new_with_opt(&ast->body, rb_fstring_lit("<main>"),
                                          file,
                                          rb_realpath_internal(Qnil, file, 1),
-                                         1, NULL, 0, ISEQ_TYPE_TOP, &option));
+                                         1, NULL, 0, ISEQ_TYPE_TOP, &option,
+                                         Qnil));
     rb_ast_dispose(ast);
 
     rb_vm_pop_frame(ec);
diff --git a/mini_builtin.c b/mini_builtin.c
index dce822a86c..38b0ca8d81 100644
--- a/mini_builtin.c
+++ b/mini_builtin.c
@@ -39,7 +39,7 @@ builtin_iseq_load(const char *feature_name, const struct rb_builtin_function *ta
         .coverage_enabled = FALSE,
         .debug_level = 0,
     };
-    const rb_iseq_t *iseq = rb_iseq_new_with_opt(&ast->body, name_str, name_str, Qnil, 0, NULL, 0, ISEQ_TYPE_TOP, &optimization);
+    const rb_iseq_t *iseq = rb_iseq_new_with_opt(&ast->body, name_str, name_str, Qnil, 0, NULL, 0, ISEQ_TYPE_TOP, &optimization, Qnil);
     GET_VM()->builtin_function_table = NULL;
 
     rb_ast_dispose(ast);
diff --git a/node.c b/node.c
index 79520f0a1e..8a6b55b0b5 100644
--- a/node.c
+++ b/node.c
@@ -20,12 +20,13 @@
 
 #include "internal.h"
 #include "internal/hash.h"
-#include "internal/variable.h"
 #include "ruby/ruby.h"
 #include "vm_core.h"
 
 #endif
 
+#include "internal/variable.h"
+
 #define NODE_BUF_DEFAULT_SIZE (sizeof(struct RNode) * 16)
 
 static void
@@ -344,18 +345,24 @@ iterate_node_values(rb_ast_t *ast, node_buffer_list_t *nb, node_itr_t * func, vo
     }
 }
 
-void
-rb_ast_mark_and_move(rb_ast_t *ast, bool reference_updating)
+static void
+script_lines_free(rb_ast_t *ast, rb_parser_ary_t *script_lines)
 {
-    if (ast->node_buffer) {
-        if (ast->body.script_lines) rb_gc_mark_and_move(&ast->body.script_lines);
+    for (long i = 0; i < script_lines->len; i++) {
+        parser_string_free(ast, (rb_parser_string_t *)script_lines->data[i]);
     }
+    xfree(script_lines->data);
+    xfree(script_lines);
 }
 
 void
 rb_ast_free(rb_ast_t *ast)
 {
     if (ast->node_buffer) {
+        if (ast->body.script_lines && !FIXNUM_P((VALUE)ast->body.script_lines)) {
+            script_lines_free(ast, ast->body.script_lines);
+            ast->body.script_lines = NULL;
+        }
         rb_node_buffer_free(ast, ast->node_buffer);
         ast->node_buffer = 0;
     }
diff --git a/node.h b/node.h
index d5522c82ec..bcc7e451d2 100644
--- a/node.h
+++ b/node.h
@@ -56,7 +56,6 @@ void rb_ast_dispose(rb_ast_t*);
 const char *ruby_node_name(int node);
 void rb_node_init(NODE *n, enum node_type type);
 
-void rb_ast_mark_and_move(rb_ast_t *ast, bool reference_updating);
 void rb_ast_update_references(rb_ast_t*);
 void rb_ast_free(rb_ast_t*);
 NODE *rb_ast_newnode(rb_ast_t*, enum node_type type, size_t size, size_t alignment);
diff --git a/parse.y b/parse.y
index 1a052d4757..a87be73e3c 100644
--- a/parse.y
+++ b/parse.y
@@ -86,6 +86,10 @@ VALUE rb_io_gets_internal(VALUE io);
 
 static int rb_parser_string_hash_cmp(rb_parser_string_t *str1, rb_parser_string_t *str2);
 
+#ifndef RIPPER
+static rb_parser_string_t *rb_parser_string_deep_copy(struct parser_params *p, const rb_parser_string_t *original);
+#endif
+
 static int
 node_integer_cmp(rb_node_integer_t *n1, rb_node_integer_t *n2)
 {
@@ -582,7 +586,7 @@ struct parser_params {
     unsigned int keep_tokens: 1;
 
     VALUE error_buffer;
-    VALUE debug_lines;
+    rb_parser_ary_t *debug_lines;
     /*
      * Store specific keyword locations to generate dummy end token.
      * Refer to the tail of list element.
@@ -2559,15 +2563,19 @@ rb_parser_ary_extend(rb_parser_t *p, rb_parser_ary_t *ary, long len)
     long i;
     if (ary->capa < len) {
         ary->capa = len;
-        ary->data = xrealloc(ary->data, sizeof(void *) * len);
+        ary->data = (rb_parser_ary_data *)xrealloc(ary->data, sizeof(rb_parser_ary_data) * len);
         for (i = ary->len; i < len; i++) {
             ary->data[i] = 0;
         }
     }
 }
 
+/*
+ * Do not call this directly.
+ * Use rb_parser_ary_new_capa_for_script_line() or rb_parser_ary_new_capa_for_ast_token() instead.
+ */
 static rb_parser_ary_t *
-rb_parser_ary_new_capa(rb_parser_t *p, long len)
+parser_ary_new_capa(rb_parser_t *p, long len)
 {
     if (len < 0) {
         rb_bug("negative array size (or size too big): %ld", len);
@@ -2576,17 +2584,36 @@ rb_parser_ary_new_capa(rb_parser_t *p, long len)
     ary->len = 0;
     ary->capa = len;
     if (0 < len) {
-        ary->data = (rb_parser_ast_token_t **)xcalloc(len, sizeof(rb_parser_ast_token_t *));
+        ary->data = (rb_parser_ary_data *)xcalloc(len, sizeof(rb_parser_ary_data));
     }
     else {
         ary->data = NULL;
     }
     return ary;
 }
-#define rb_parser_ary_new2 rb_parser_ary_new_capa
 
 static rb_parser_ary_t *
-rb_parser_ary_push(rb_parser_t *p, rb_parser_ary_t *ary, rb_parser_ast_token_t *val)
+rb_parser_ary_new_capa_for_script_line(rb_parser_t *p, long len)
+{
+    rb_parser_ary_t *ary = parser_ary_new_capa(p, len);
+    ary->data_type = PARSER_ARY_DATA_SCRIPT_LINE;
+    return ary;
+}
+
+static rb_parser_ary_t *
+rb_parser_ary_new_capa_for_ast_token(rb_parser_t *p, long len)
+{
+    rb_parser_ary_t *ary = parser_ary_new_capa(p, len);
+    ary->data_type = PARSER_ARY_DATA_AST_TOKEN;
+    return ary;
+}
+
+/*
+ * Do not call this directly.
+ * Use rb_parser_ary_push_script_line() or rb_parser_ary_push_ast_token() instead.
+ */
+static rb_parser_ary_t *
+parser_ary_push(rb_parser_t *p, rb_parser_ary_t *ary, rb_parser_ary_data val)
 {
     if (ary->len == ary->capa) {
         rb_parser_ary_extend(p, ary, ary->len == 0 ? 1 : ary->len * 2);
@@ -2595,6 +2622,24 @@ rb_parser_ary_push(rb_parser_t *p, rb_parser_ary_t *ary, rb_parser_ast_token_t *
     return ary;
 }
 
+static rb_parser_ary_t *
+rb_parser_ary_push_ast_token(rb_parser_t *p, rb_parser_ary_t *ary, rb_parser_ast_token_t *val)
+{
+    if (ary->data_type != PARSER_ARY_DATA_AST_TOKEN) {
+        rb_bug("unexpected rb_parser_ary_data_type: %d", ary->data_type);
+    }
+    return parser_ary_push(p, ary, val);
+}
+
+static rb_parser_ary_t *
+rb_parser_ary_push_script_line(rb_parser_t *p, rb_parser_ary_t *ary, rb_parser_string_t *val)
+{
+    if (ary->data_type != PARSER_ARY_DATA_SCRIPT_LINE) {
+        rb_bug("unexpected rb_parser_ary_data_type: %d", ary->data_type);
+    }
+    return parser_ary_push(p, ary, val);
+}
+
 static void
 rb_parser_ast_token_free(rb_parser_t *p, rb_parser_ast_token_t *token)
 {
@@ -2604,12 +2649,24 @@ rb_parser_ast_token_free(rb_parser_t *p, rb_parser_ast_token_t *token)
 }
 
 static void
-rb_parser_tokens_free(rb_parser_t *p, rb_parser_ary_t *tokens)
+rb_parser_ary_free(rb_parser_t *p, rb_parser_ary_t *ary)
 {
-    for (long i = 0; i < tokens->len; i++) {
-        rb_parser_ast_token_free(p, tokens->data[i]);
+    void (*free_func)(rb_parser_t *, rb_parser_ary_data) = NULL;
+    switch (ary->data_type) {
+      case PARSER_ARY_DATA_AST_TOKEN:
+        free_func = (void (*)(rb_parser_t *, rb_parser_ary_data))rb_parser_ast_token_free;
+        break;
+      case PARSER_ARY_DATA_SCRIPT_LINE:
+        free_func = (void (*)(rb_parser_t *, rb_parser_ary_data))rb_parser_string_free;
+        break;
+      default:
+        rb_bug("unexpected rb_parser_ary_data_type: %d", ary->data_type);
+        break;
     }
-    xfree(tokens);
+    for (long i = 0; i < ary->len; i++) {
+        free_func(p, ary->data[i]);
+    }
+    xfree(ary);
 }
 
 #endif /* !RIPPER */
@@ -7144,7 +7201,7 @@ parser_append_tokens(struct parser_params *p, rb_parser_string_t *str, enum yyto
     token->str = str;
     token->loc.beg_pos = p->yylloc->beg_pos;
     token->loc.end_pos = p->yylloc->end_pos;
-    rb_parser_ary_push(p, p->tokens, token);
+    rb_parser_ary_push_ast_token(p, p->tokens, token);
     p->token_id++;
 
     if (p->debug) {
@@ -7656,22 +7713,12 @@ yycompile0(VALUE arg)
     struct parser_params *p = (struct parser_params *)arg;
     int cov = FALSE;
 
-    if (!compile_for_eval && !NIL_P(p->ruby_sourcefile_string)) {
-        if (p->debug_lines && p->ruby_sourceline > 0) {
-            VALUE str = rb_default_rs;
-            n = p->ruby_sourceline;
-            do {
-                rb_ary_push(p->debug_lines, str);
-            } while (--n);
-        }
-
-        if (!e_option_supplied(p)) {
-            cov = TRUE;
-        }
+    if (!compile_for_eval && !NIL_P(p->ruby_sourcefile_string) && !e_option_supplied(p)) {
+        cov = TRUE;
     }
 
     if (p->debug_lines) {
-        RB_OBJ_WRITE(p->ast, &p->ast->body.script_lines, p->debug_lines);
+        p->ast->body.script_lines = p->debug_lines;
     }
 
     parser_prepare(p);
@@ -7682,6 +7729,8 @@ yycompile0(VALUE arg)
     RUBY_DTRACE_PARSE_HOOK(BEGIN);
     n = yyparse(p);
     RUBY_DTRACE_PARSE_HOOK(END);
+
+    rb_parser_aset_script_lines_for(p->ruby_sourcefile_string, p->debug_lines);
     p->debug_lines = 0;
 
     xfree(p->lex.strterm);
@@ -7715,7 +7764,7 @@ yycompile0(VALUE arg)
         }
     }
     p->ast->body.root = tree;
-    if (!p->ast->body.script_lines) p->ast->body.script_lines = INT2FIX(p->line_count);
+    if (!p->ast->body.script_lines) p->ast->body.script_lines = (rb_parser_ary_t *)INT2FIX(p->line_count);
     return TRUE;
 }
 
@@ -7975,9 +8024,9 @@ nextline(struct parser_params *p, int set_encoding)
         }
 #ifndef RIPPER
         if (p->debug_lines) {
-            VALUE v = rb_str_new_mutable_parser_string(str);
-            if (set_encoding) rb_enc_associate(v, p->enc);
-            rb_ary_push(p->debug_lines, v);
+            if (set_encoding) rb_parser_enc_associate(p, str, p->enc);
+            rb_parser_string_t *copy = rb_parser_string_deep_copy(p, str);
+            rb_parser_ary_push_script_line(p, p->debug_lines, copy);
         }
 #endif
         p->cr_seen = FALSE;
@@ -9653,10 +9702,9 @@ parser_set_encode(struct parser_params *p, const char *name)
     p->enc = enc;
 #ifndef RIPPER
     if (p->debug_lines) {
-        VALUE lines = p->debug_lines;
-        long i, n = RARRAY_LEN(lines);
-        for (i = 0; i < n; ++i) {
-            rb_enc_associate_index(RARRAY_AREF(lines, i), idx);
+        long i;
+        for (i = 0; i < p->debug_lines->len; i++) {
+            rb_parser_enc_associate(p, p->debug_lines->data[i], enc);
         }
     }
 #endif
@@ -12870,6 +12918,19 @@ string_literal_head(struct parser_params *p, enum node_type htype, NODE *head)
     return lit;
 }
 
+#ifndef RIPPER
+static rb_parser_string_t *
+rb_parser_string_deep_copy(struct parser_params *p, const rb_parser_string_t *orig)
+{
+    rb_parser_string_t *copy;
+    if (!orig) return NULL;
+    copy = rb_parser_string_new(p, PARSER_STRING_PTR(orig), PARSER_STRING_LEN(orig));
+    copy->coderange = orig->coderange;
+    copy->enc = orig->enc;
+    return copy;
+}
+#endif
+
 /* concat two string literals */
 static NODE *
 literal_concat(struct parser_params *p, NODE *head, NODE *tail, const YYLTYPE *loc)
@@ -15826,7 +15887,6 @@ rb_ruby_parser_mark(void *ptr)
     rb_gc_mark(p->ruby_sourcefile_string);
     rb_gc_mark((VALUE)p->ast);
 #ifndef RIPPER
-    rb_gc_mark(p->debug_lines);
     rb_gc_mark(p->error_buffer);
 #else
     rb_gc_mark(p->value);
@@ -15848,7 +15908,7 @@ rb_ruby_parser_free(void *ptr)
 
 #ifndef RIPPER
     if (p->tokens) {
-        rb_parser_tokens_free(p, p->tokens);
+        rb_parser_ary_free(p, p->tokens);
     }
 #endif
 
@@ -15948,19 +16008,9 @@ rb_ruby_parser_set_context(rb_parser_t *p, const struct rb_iseq_struct *base, in
 }
 
 void
-rb_ruby_parser_set_script_lines(rb_parser_t *p, VALUE lines)
+rb_ruby_parser_set_script_lines(rb_parser_t *p)
 {
-    if (!RTEST(lines)) {
-        lines = Qfalse;
-    }
-    else if (lines == Qtrue) {
-        lines = rb_ary_new();
-    }
-    else {
-        Check_Type(lines, T_ARRAY);
-        rb_ary_modify(lines);
-    }
-    p->debug_lines = lines;
+    p->debug_lines = rb_parser_ary_new_capa_for_script_line(p, 10);
 }
 
 void
@@ -15973,7 +16023,7 @@ void
 rb_ruby_parser_keep_tokens(rb_parser_t *p)
 {
     p->keep_tokens = 1;
-    p->tokens = rb_parser_ary_new_capa(p, 10);
+    p->tokens = rb_parser_ary_new_capa_for_ast_token(p, 10);
 }
 
 #ifndef UNIVERSAL_PARSER
@@ -16045,12 +16095,12 @@ rb_parser_error_tolerant(VALUE vparser)
 }
 
 void
-rb_parser_set_script_lines(VALUE vparser, VALUE lines)
+rb_parser_set_script_lines(VALUE vparser)
 {
     struct parser_params *p;
 
     TypedData_Get_Struct(vparser, struct parser_params, &parser_data_type, p);
-    rb_ruby_parser_set_script_lines(p, lines);
+    rb_ruby_parser_set_script_lines(p);
 }
 
 void
@@ -16100,6 +16150,22 @@ rb_parser_set_yydebug(VALUE self, VALUE flag)
     rb_ruby_parser_set_yydebug(p, RTEST(flag));
     return flag;
 }
+
+void
+rb_set_script_lines_for(VALUE self, VALUE path)
+{
+    struct parser_params *p;
+    VALUE hash;
+    ID script_lines;
+    CONST_ID(script_lines, "SCRIPT_LINES__");
+    if (!rb_const_defined_at(rb_cObject, script_lines)) return;
+    hash = rb_const_get_at(rb_cObject, script_lines);
+    if (RB_TYPE_P(hash, T_HASH)) {
+        rb_hash_aset(hash, path, Qtrue);
+        TypedData_Get_Struct(self, struct parser_params, &parser_data_type, p);
+        rb_ruby_parser_set_script_lines(p);
+    }
+}
 #endif /* !UNIVERSAL_PARSER */
 
 VALUE
diff --git a/ruby.c b/ruby.c
index 3234460894..fb60551c3f 100644
--- a/ruby.c
+++ b/ruby.c
@@ -2592,7 +2592,7 @@ struct load_file_arg {
     VALUE f;
 };
 
-VALUE rb_script_lines_for(VALUE path);
+void rb_set_script_lines_for(VALUE vparser, VALUE path);
 
 static VALUE
 load_file_internal(VALUE argp_v)
@@ -2697,10 +2697,7 @@ load_file_internal(VALUE argp_v)
     rb_parser_set_options(parser, opt->do_print, opt->do_loop,
                           opt->do_line, opt->do_split);
 
-    VALUE lines = rb_script_lines_for(orig_fname);
-    if (!NIL_P(lines)) {
-        rb_parser_set_script_lines(parser, lines);
-    }
+    rb_set_script_lines_for(parser, orig_fname);
 
     if (NIL_P(f)) {
         f = rb_str_new(0, 0);
diff --git a/ruby_parser.c b/ruby_parser.c
index 1991735af4..5d9c6c938f 100644
--- a/ruby_parser.c
+++ b/ruby_parser.c
@@ -622,12 +622,12 @@ rb_parser_set_context(VALUE vparser, const struct rb_iseq_struct *base, int main
 }
 
 void
-rb_parser_set_script_lines(VALUE vparser, VALUE lines)
+rb_parser_set_script_lines(VALUE vparser)
 {
     struct ruby_parser *parser;
 
     TypedData_Get_Struct(vparser, struct ruby_parser, &ruby_parser_data_type, parser);
-    rb_ruby_parser_set_script_lines(parser->parser_params, lines);
+    rb_ruby_parser_set_script_lines(parser->parser_params);
 }
 
 void
@@ -727,9 +727,40 @@ rb_parser_set_yydebug(VALUE vparser, VALUE flag)
     rb_ruby_parser_set_yydebug(parser->parser_params, RTEST(flag));
     return flag;
 }
+
+void
+rb_set_script_lines_for(VALUE vparser, VALUE path)
+{
+    struct ruby_parser *parser;
+    VALUE hash;
+    ID script_lines;
+    CONST_ID(script_lines, "SCRIPT_LINES__");
+    if (!rb_const_defined_at(rb_cObject, script_lines)) return;
+    hash = rb_const_get_at(rb_cObject, script_lines);
+    if (RB_TYPE_P(hash, T_HASH)) {
+        rb_hash_aset(hash, path, Qtrue);
+        TypedData_Get_Struct(vparser, struct ruby_parser, &ruby_parser_data_type, parser);
+        rb_ruby_parser_set_script_lines(parser->parser_params);
+    }
+}
 #endif
 
 VALUE
+rb_parser_build_script_lines_from(rb_parser_ary_t *lines)
+{
+    int i;
+    if (lines->data_type != PARSER_ARY_DATA_SCRIPT_LINE) {
+        rb_bug("unexpected rb_parser_ary_data_type (%d) for script lines", lines->data_type);
+    }
+    VALUE script_lines = rb_ary_new_capa(lines->len);
+    for (i = 0; i < lines->len; i++) {
+        rb_parser_string_t *str = (rb_parser_string_t *)lines->data[i];
+        rb_ary_push(script_lines, rb_enc_str_new(str->ptr, str->len, str->enc));
+    }
+    return script_lines;
+}
+
+VALUE
 rb_str_new_parser_string(rb_parser_string_t *str)
 {
     VALUE string = rb_enc_interned_str(str->ptr, str->len, str->enc);
@@ -935,15 +966,17 @@ rb_node_encoding_val(const NODE *node)
     return rb_enc_from_encoding(RNODE_ENCODING(node)->enc);
 }
 
-VALUE
-rb_script_lines_for(VALUE path)
-{
-    VALUE hash, lines;
-    ID script_lines;
-    CONST_ID(script_lines, "SCRIPT_LINES__");
-    if (!rb_const_defined_at(rb_cObject, script_lines)) return Qnil;
-    hash = rb_const_get_at(rb_cObject, script_lines);
-    if (!RB_TYPE_P(hash, T_HASH)) return Qnil;
-    rb_hash_aset(hash, path, lines = rb_ary_new());
-    return lines;
+void
+rb_parser_aset_script_lines_for(VALUE path, rb_parser_ary_t *lines)
+{
+    VALUE hash, script_lines;
+    ID script_lines_id;
+    if (NIL_P(path) || !lines || FIXNUM_P((VALUE)lines)) return;
+    CONST_ID(script_lines_id, "SCRIPT_LINES__");
+    if (!rb_const_defined_at(rb_cObject, script_lines_id)) return;
+    hash = rb_const_get_at(rb_cObject, script_lines_id);
+    if (!RB_TYPE_P(hash, T_HASH)) return;
+    if (rb_hash_lookup(hash, path) == Qnil) return;
+    script_lines = rb_parser_build_script_lines_from(lines);
+    rb_hash_aset(hash, path, script_lines);
 }
diff --git a/rubyparser.h b/rubyparser.h
index c51b9ee44a..d36e8dcede 100644
--- a/rubyparser.h
+++ b/rubyparser.h
@@ -219,8 +219,16 @@ typedef struct rb_parser_ast_token {
 /*
  * Array-like object for parser
  */
+typedef void* rb_parser_ary_data;
+
+enum rb_parser_ary_data_type {
+    PARSER_ARY_DATA_AST_TOKEN,
+    PARSER_ARY_DATA_SCRIPT_LINE
+};
+
 typedef struct rb_parser_ary {
-    rb_parser_ast_token_t **data;
+    enum rb_parser_ary_data_type data_type;
+    rb_parser_ary_data *data;
     long len;  // current size
     long capa; // capacity
 } rb_parser_ary_t;
@@ -1201,10 +1209,10 @@ typedef struct node_buffer_struct node_buffer_t;
 /* T_IMEMO/ast */
 typedef struct rb_ast_body_struct {
     const NODE *root;
-    VALUE script_lines;
+    rb_parser_ary_t *script_lines;
     // script_lines is either:
     // - a Fixnum that represents the line count of the original source, or
-    // - an Array that contains the lines of the original source
+    // - an rb_parser_ary_t* that contains the lines of the original source
     signed int frozen_string_literal:2; /* -1: not specified, 0: false, 1: true */
     signed int coverage_enabled:2; /* -1: not specified, 0: false, 1: true */
 } rb_ast_body_t;
diff --git a/template/prelude.c.tmpl b/template/prelude.c.tmpl
index 74f6c08da7..dc0a143004 100644
--- a/template/prelude.c.tmpl
+++ b/template/prelude.c.tmpl
@@ -198,7 +198,8 @@ prelude_eval(VALUE code, VALUE name, int line)
 
     rb_ast_t *ast = prelude_ast(name, code, line);
     rb_iseq_eval(rb_iseq_new_with_opt(&ast->body, name, name, Qnil, line,
-                                      NULL, 0, ISEQ_TYPE_TOP, &optimization));
+                                      NULL, 0, ISEQ_TYPE_TOP, &optimization,
+                                      Qnil));
     rb_ast_dispose(ast);
 }
 COMPILER_WARNING_POP
diff --git a/vm.c b/vm.c
index 328187c790..e7335aa1bd 100644
--- a/vm.c
+++ b/vm.c
@@ -1479,7 +1479,7 @@ rb_binding_add_dynavars(VALUE bindval, rb_binding_t *bind, int dyncount, const I
     ast.root = RNODE(&tmp_node);
     ast.frozen_string_literal = -1;
     ast.coverage_enabled = -1;
-    ast.script_lines = INT2FIX(-1);
+    ast.script_lines = (rb_parser_ary_t *)INT2FIX(-1);
 
     if (base_iseq) {
         iseq = rb_iseq_new(&ast, ISEQ_BODY(base_iseq)->location.label, path, realpath, base_iseq, ISEQ_TYPE_EVAL);
diff --git a/vm_core.h b/vm_core.h
index 57d90b343f..9873ada2d5 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -1201,7 +1201,8 @@ rb_iseq_t *rb_iseq_new_top     (const rb_ast_body_t *ast, VALUE name, VALUE path
 rb_iseq_t *rb_iseq_new_main    (const rb_ast_body_t *ast,             VALUE path, VALUE realpath,                     const rb_iseq_t *parent, int opt);
 rb_iseq_t *rb_iseq_new_eval    (const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE realpath, int first_lineno, const rb_iseq_t *parent, int isolated_depth);
 rb_iseq_t *rb_iseq_new_with_opt(const rb_ast_body_t *ast, VALUE name, VALUE path, VALUE realpath, int first_lineno, const rb_iseq_t *parent, int isolated_depth,
-                                enum rb_iseq_type, const rb_compile_option_t*);
+                                enum rb_iseq_type, const rb_compile_option_t*,
+                                VALUE script_lines);
 
 struct iseq_link_anchor;
 struct rb_iseq_new_with_callback_callback_func {
diff --git a/vm_eval.c b/vm_eval.c
index d7447bd060..25fa28d828 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1809,7 +1809,7 @@ eval_make_iseq(VALUE src, VALUE fname, int line,
     }
 
     rb_parser_set_context(parser, parent, FALSE);
-    rb_parser_set_script_lines(parser, RBOOL(ruby_vm_keep_script_lines));
+    if (ruby_vm_keep_script_lines) rb_parser_set_script_lines(parser);
     ast = rb_parser_compile_string_path(parser, fname, src, line);
     if (ast->body.root) {
         ast->body.coverage_enabled = coverage_enabled;