mirrors/emacs
1
Fork 0
mirror of git://git.sv.gnu.org/emacs.git synced 2026-01-12 06:21:02 -08:00
Code Issues Projects Releases Wiki Activity

Avoid type punning while using dylan test utilities

Browse source
This commit is contained in:
Jonathan Holburn 2023-05-17 21:30:07 +01:00
parent 6c79248c66
commit b028ba37df
1 changed files with 17 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

18
mps/code/addrobj.c
View file

@ -66,7 +66,23 @@ static void test_main(void)
/* Make an arbitrary sized object, size = (N_SLOT_TESTOBJ+2) * sizeof(mps_word_t).
(See fmtdytst.c for size calculation) */
die(make_dylan_vector((mps_word_t *)&testobj, obj_ap, N_SLOT_TESTOBJ), "make_dylan_vector");
/* Because make_dylan_vector returns its pointer-to-object as an mps_word_t rather than an
mps_addr_t, and commits the object, we need to somehow safely allocate our object without
type punning and without risking that our object be destroyed.
Rather than redefine our reference table with type mps_word_t, which hides the intention of the table,
park the arena to disable garbage collection. Allocate our dylan object on the (unregistered) stack
storing its address in an mps_word_t. Then store this mps_word_t as an mps_addr_t in our reference
table, and release the arena since our object is now safely pinned.
*/
{
mps_word_t p_word;
mps_arena_park(arena);
die(make_dylan_vector(&p_word, obj_ap, N_SLOT_TESTOBJ), "make_dylan_vector");
/* If we hadn't parked the arena, our vector might have been GC'd here */
testobj = (mps_addr_t)p_word;
mps_arena_release(arena);
}
/* Construct a pointer to roughly halfway inside the object */
in = (mps_addr_t)((char *)testobj + (N_SLOT_TESTOBJ/2) * sizeof(mps_word_t));