Only intern constants upon compilation entry

Before this commit the Prism compiler would try to intern constants
every time it re-entered. This pool of constants is "constant" (there is
only one pool per parser instance), so we should do it only once: upon
the top level entry to the compiler.

This change does just that: it populates the interned constants once.

Fixes: https://github.com/ruby/prism/issues/2152

1 files changed, 10 insertions, 0 deletions

diff --git a/iseq.c b/iseq.c
index f2911b43f2..3b87cdcc78 100644
--- a/iseq.c
+++ b/iseq.c
@@ -1430,10 +1430,20 @@ iseqw_s_compile_prism_compile(pm_parser_t *parser, VALUE opt, rb_iseq_t *iseq, V
 
         pm_scope_node_t scope_node;
         pm_scope_node_init(node, &scope_node, NULL, parser);
+
+        ID *constants = calloc(parser->constant_pool.size, sizeof(ID));
+        rb_encoding *encoding = rb_enc_find(parser->encoding->name);
+        for (uint32_t index = 0; index < parser->constant_pool.size; index++) {
+            pm_constant_t *constant = &parser->constant_pool.constants[index];
+            constants[index] = rb_intern3((const char *) constant->start, constant->length, encoding);
+        }
+        scope_node.constants = constants;
+
         rb_iseq_compile_prism_node(iseq, &scope_node, parser);
 
         finish_iseq_build(iseq);
         pm_node_destroy(parser, node);
+        free(constants);
     }
 }