On Thu, May 28, 2026 at 3:05 PM Iain Sandoe <[email protected]> wrote:
>
>
>
> > On 28 May 2026, at 07:54, H.J. Lu <[email protected]> wrote:
> >
> > On Thu, May 28, 2026 at 2:45 PM Iain Sandoe <[email protected]> wrote:
> >>
> >>
> >>
> >>> On 28 May 2026, at 00:15, H.J. Lu <[email protected]> wrote:
> >>>
> >>> On Thu, May 28, 2026 at 7:11 AM Iain Sandoe <[email protected]>
> >>> wrote:
> >>>>
> >>>>
> >>>>
> >>>>> On 27 May 2026, at 23:41, H.J. Lu <[email protected]> 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. Update default_stack_protect_guard to
> >>>>> check UINTPTR_TYPE to get unsigned integer type for uintptr_t instead.
> >>>>>
> >>>>> gcc/c-family/
> >>>>>
> >>>>> PR c/125226
> >>>>> * targhooks.cc (default_stack_protect_guard): Check UINTPTR_TYPE
> >>>>> to get unsigned integer type for uintptr_t.
> >>>>
> >>>> maybe making uintptr_type_node available would make the code smaller
> >>>> overall?
> >>>
> >>> That will be a much bigger change.
> >>
> >> It’s already computed for c-family (in c_common_nodes_and_builtins and
> >> saved in c_global_trees) - so it’s already available to c-family.
> >>
> >> Assuming that the stack protector could be used by non-c-family languages
> >> then moving the computation to tree.cc/build_common_tree_nodes
> >> <http://tree.cc/build_common_tree_nodes>
> >> and the node to global_trees (c.f. size_type_node, ptr_type_node et . al)
> >> seems plausible - maybe I miss something, Jason?
> >>
> >
> > rust also defines intptr_type_node and uintptr_type_node:
> >
> > c-family/c-common.h: CTI_INTPTR_TYPE,
> > c-family/c-common.h: CTI_UINTPTR_TYPE,
> > c-family/c-common.h:#define intptr_type_node
> > c_global_trees[CTI_INTPTR_TYPE]
> > c-family/c-common.h:#define uintptr_type_node
> > c_global_trees[CTI_UINTPTR_TYPE]
> > rust/backend/rust-tree.h: CTI_INTPTR_TYPE,
> > rust/backend/rust-tree.h: CTI_UINTPTR_TYPE,
> > rust/backend/rust-tree.h:#define intptr_type_node
> > c_global_trees[CTI_INTPTR_TYPE]
> > rust/backend/rust-tree.h:#define uintptr_type_node
> > c_global_trees[CTI_UINTPTR_TYPE]
> >
> > I guess they can be moved to tree-core.h as TI_INTPTR_TYPE/TI_UINTPTR_TYPE.
> > This will be a much bigger change with rust testing.
>
> well, not my call, on that (just a suggestion)…
>
> … but if you leave it as computed locally, maybe do it once lazily and save
> the result - to avoid all those string comparisons being repeated for every
> check.
>
It is only done once:
static GTY(()) tree stack_chk_guard_decl;
tree
default_stack_protect_guard (void)
{
tree t = stack_chk_guard_decl;
if (t == NULL)
{
Check UINTPTR_TYPE ...
}
--
H.J.
