Improve fix for Bug#33014

Although the previously-applied fix worked for its platform,
it doesn’t suffice in general.
* src/bytecode.c (exec_byte_code): Save VECTOR into stack slot
so that it survives GC.  The stack slot was otherwise unused,
so this doesn’t cost us memory, only a store insn.
* src/eval.c (Ffuncall): Do not make FUN volatile, reverting
2018-10-14T19:12:04Z!gazally@runbox.com.  Adding ‘volatile’
does not suffice, since storage for a volatile local can be
reclaimed after its last access (e.g., by tail recursion
elimination), which would make VECTOR invisible to GC.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/bytecode.c b/src/bytecode.c
index 17457fc5742..40389e08f0e 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -369,6 +369,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
   ptrdiff_t item_bytes = stack_items * word_size;
   Lisp_Object *stack_base = ptr_bounds_clip (alloc, item_bytes);
   Lisp_Object *top = stack_base;
+  *top = vector; /* Ensure VECTOR survives GC (Bug#33014).  */
   Lisp_Object *stack_lim = stack_base + stack_items;
   unsigned char *bytestr_data = alloc;
   bytestr_data = ptr_bounds_clip (bytestr_data + item_bytes, bytestr_length);