On Thu, May 28, 2026 at 4:16 AM Jason Merrill <[email protected]> wrote:
>
> On 5/8/26 6:05 AM, H.J. Lu wrote:
> > default_stack_protect_guard calls
> >
> > lang_hooks.types.type_for_mode (ptr_mode, 1);
> >
> > to get an integer type for __stack_chk_guard which is declared as a
> > global symbol of type uintptr_t. For 32-bit systems, uintptr_t may
> > be either unsigned int or unsigned long int. On 32-bit Darwin, we get
> >
> > $ cat /tmp/x.c
> > __UINTPTR_TYPE__ __stack_chk_guard = 0x1000;
> > $ ./xgcc -B./ -S /tmp/x.c -m32
> > /tmp/x.c:1:18: error: conflicting types for ‘__stack_chk_guard’; have
> > ‘long unsigned int’
> > 1 | __UINTPTR_TYPE__ __stack_chk_guard = 0x1000;
> > | ^~~~~~~~~~~~~~~~~
> > cc1: note: previous declaration of ‘__stack_chk_guard’ with type ‘unsigned
> > int’
> > $
> >
> > since lang_hooks.types.type_for_mode returns unsigned int while Darwin's
> > uintptr_t is unsigned long int.
> >
> > Add LANG_HOOKS_TYPE_FOR_MODE_KIND to specify signed or unsigned integer
> > type for pointer and update default_stack_protect_guard to call
> >
> > lang_hooks.types.type_for_mode_kind
> > (ptr_mode, 1, KIND_IS_INTEGER_FOR_POINTER);
> >
> > to get unsigned integer type for pointer.
>
> Instead of adding this additional parameter; can we just adjust the
> existing c_common_type_for_mode handling of pointer modes, i.e.
>
> > if (mode == TYPE_MODE (build_pointer_type (char_type_node))
> > || mode == TYPE_MODE (build_pointer_type (integer_type_node)))
> > {
> > unsigned int precision
> > = GET_MODE_PRECISION (as_a <scalar_int_mode> (mode));
> > return (unsignedp
> > ? make_unsigned_type (precision)
> > : make_signed_type (precision));
> > }
>
> to return [u]intptr_type_node?
>
> Jason
>
This:
diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index ac9c681d4b8..992e279f332 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -2455,6 +2455,9 @@ c_common_type_for_mode (machine_mode mode, int unsignedp)
tree t;
int i;
+ if (mode == TYPE_MODE (intptr_type_node))
+ return unsignedp ? uintptr_type_node : intptr_type_node;
+
if (mode == TYPE_MODE (integer_type_node))
return unsignedp ? unsigned_type_node : integer_type_node;
works for
__UINTPTR_TYPE__ __stack_chk_guard = 0x1000;
on Darwin. But I don't know if it will cause other issues for Darwin.
--
H.J.
