Fix load catch table write barrier

I tried fixing this in 521b2fc, but
re-running wbcheck with the stricter WBCHECK_VERIFY_AFTER_WB, revealed
that this write barrier was fired too early, before the object was
actually written to the parent.

This solves the issue by writing the table to the parent immediately
(and using calloc so that we don't mark random garbage).

Author: jhawthorn

compile.c

@@ -13296,12 +13296,13 @@ ibf_dump_catch_table(struct ibf_dump *dump, const rb_iseq_t *iseq)
     }
 }
 
-static struct iseq_catch_table *
+static void
 ibf_load_catch_table(const struct ibf_load *load, ibf_offset_t catch_table_offset, unsigned int size, const rb_iseq_t *parent_iseq)
 {
     if (size) {
-        struct iseq_catch_table *table = ruby_xmalloc(iseq_catch_table_bytes(size));
+        struct iseq_catch_table *table = ruby_xcalloc(1, iseq_catch_table_bytes(size));
         table->size = size;
+        ISEQ_BODY(parent_iseq)->catch_table = table;
 
         ibf_offset_t reading_pos = catch_table_offset;
 
@@ -13317,10 +13318,9 @@ ibf_load_catch_table(const struct ibf_load *load, ibf_offset_t catch_table_offse
             rb_iseq_t *catch_iseq = (rb_iseq_t *)ibf_load_iseq(load, (const rb_iseq_t *)(VALUE)iseq_index);
             RB_OBJ_WRITE(parent_iseq, UNALIGNED_MEMBER_PTR(&table->entries[i], iseq), catch_iseq);
         }
-        return table;
     }
     else {
-        return NULL;
+        ISEQ_BODY(parent_iseq)->catch_table = NULL;
     }
 }
 
@@ -13833,7 +13833,8 @@ ibf_load_iseq_each(struct ibf_load *load, rb_iseq_t *iseq, ibf_offset_t offset)
     load_body->insns_info.body      = ibf_load_insns_info_body(load, insns_info_body_offset, insns_info_size);
     load_body->insns_info.positions = ibf_load_insns_info_positions(load, insns_info_positions_offset, insns_info_size);
     load_body->local_table          = ibf_load_local_table(load, local_table_offset, local_table_size);
-    load_body->catch_table          = ibf_load_catch_table(load, catch_table_offset, catch_table_size, iseq);
+    ibf_load_catch_table(load, catch_table_offset, catch_table_size, iseq);
+
     const rb_iseq_t *parent_iseq = ibf_load_iseq(load, (const rb_iseq_t *)(VALUE)parent_iseq_index);
     const rb_iseq_t *local_iseq = ibf_load_iseq(load, (const rb_iseq_t *)(VALUE)local_iseq_index);
     const rb_iseq_t *mandatory_only_iseq = ibf_load_iseq(load, (const rb_iseq_t *)(VALUE)mandatory_only_iseq_index);