Port to gcc -fcheck-pointer-bounds

This is a minimal port, just to get Emacs running;
it does not attempt to make the pointer bounds at all tight.
* src/ptr-bounds.h: New file.
* src/alloc.c, src/gmalloc.c: Include it.
* src/alloc.c (live_string_holding, live_cons_holding)
(live_symbol_holding, live_misc_holding, garbage_collect_1)
(sweep_conses, sweep_floats):
* src/gmalloc.c (malloc_initialize_1, _free_internal_nolock)
(_realloc_internal_nolock):
Widen pointer bounds as necessary.
We're in a memory allocator so this is OK.
* src/lisp.h (lisp_h_XSYMBOL, make_lisp_symbol) [__CHKP__]:
Do not convert from pointer to integer and back again, so
that GCC does not lose track of pointer bounds.
(XSYMBOL) [__CHKP__ && !USE_LSB_TAG]: Now a compile-time error.
Although it's possible to support both -fcheck-pointer-bounds and
--with-wide-int, it's more work; keep things simple for now.
(DEFINE_LISP_SYMBOL) [__CHKP__]: Now a no-op, to avoid
trouble with unbounded pointers.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/gmalloc.c b/src/gmalloc.c
index a17d39c1eeb..97ab76561f9 100644
--- a/src/gmalloc.c
+++ b/src/gmalloc.c
@@ -40,6 +40,8 @@ License along with this library.  If not, see <https://www.gnu.org/licenses/>.
 # include "lisp.h"
 #endif
 
+#include "ptr-bounds.h"
+
 #ifdef HAVE_MALLOC_H
 # if GNUC_PREREQ (4, 2, 0)
 #  pragma GCC diagnostic ignored "-Wdeprecated-declarations"
@@ -558,7 +560,7 @@ malloc_initialize_1 (void)
   _heapinfo[0].free.size = 0;
   _heapinfo[0].free.next = _heapinfo[0].free.prev = 0;
   _heapindex = 0;
-  _heapbase = (char *) _heapinfo;
+  _heapbase = (char *) ptr_bounds_init (_heapinfo);
   _heaplimit = BLOCK (_heapbase + heapsize * sizeof (malloc_info));
 
   register_heapinfo ();
@@ -997,6 +999,7 @@ _free_internal_nolock (void *ptr)
 
   if (ptr == NULL)
     return;
+  ptr = ptr_bounds_init (ptr);
 
   PROTECT_MALLOC_STATE (0);
 
@@ -1308,6 +1311,7 @@ _realloc_internal_nolock (void *ptr, size_t size)
   else if (ptr == NULL)
     return _malloc_internal_nolock (size);
 
+  ptr = ptr_bounds_init (ptr);
   block = BLOCK (ptr);
 
   PROTECT_MALLOC_STATE (0);