https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124347
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |siddhesh at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I've tried
--- builtins.cc.jj3 2026-02-06 11:18:47.051640642 +0100
+++ builtins.cc 2026-03-03 14:46:28.810230892 +0100
@@ -11834,21 +11834,29 @@ fold_builtin_object_size (tree ptr, tree
if (TREE_SIDE_EFFECTS (ptr))
return build_int_cst_type (size_type_node, object_size_type < 2 ? -1 : 0);
+ tree orig_ptr = ptr;
+ STRIP_NOPS (ptr);
+ if (!POINTER_TYPE_P (TREE_TYPE (ptr)))
+ return NULL_TREE;
+
if (fcode == BUILT_IN_DYNAMIC_OBJECT_SIZE)
object_size_type |= OST_DYNAMIC;
if (TREE_CODE (ptr) == ADDR_EXPR)
{
- compute_builtin_object_size (ptr, object_size_type, &bytes);
- if ((object_size_type & OST_DYNAMIC)
- || int_fits_type_p (bytes, size_type_node))
+ /* If STRIP_NOPS stripped some casts and object size is not
+ know yet, delay folding until later. Maybe subsequent passes
+ will help determining it. */
+ if ((compute_builtin_object_size (ptr, object_size_type, &bytes)
+ || ptr == orig_ptr)
+ && ((object_size_type & OST_DYNAMIC)
+ || int_fits_type_p (bytes, size_type_node)))
return fold_convert (size_type_node, bytes);
}
else if (TREE_CODE (ptr) == SSA_NAME)
{
/* If object size is not known yet, delay folding until
- later. Maybe subsequent passes will help determining
- it. */
+ later. Maybe subsequent passes will help determining it. */
if (compute_builtin_object_size (ptr, object_size_type, &bytes)
&& ((object_size_type & OST_DYNAMIC)
|| int_fits_type_p (bytes, size_type_node)))
but that regresses builtin-dynamic-object-size-0.c
if (test_dynarray_struct_subobj (42, 48) != 0)
FAIL ();
case where it changes (among other things, but this one is what breaks)
@@ -663,8 +668,7 @@ size_t test_dynarray_struct_subobj (size
_9 = sz.30 * 32;
D.3649 = _9;
bin.32 = __builtin_alloca_with_align (D.3649, 64);
- _10 = &(*bin.32)[off].c[4];
- D.3651 = __builtin_dynamic_object_size (_10, 1);
+ D.3651 = 12;
return D.3651;
}
finally
So, I think it would be safer to do it in the C++ FE only and limit to
manifestly-constant evaluation.
