On Thu, Jul 17, 2025 at 03:26:05PM +0000, Qing Zhao wrote:
> How about add a new flag to distinguish these two cases, and put it to the
> 3th argument:
>
> ACCESS_WITH_SIZE (REF_TO_OBJ, REF_TO_SIZE,
> TYPE_OF_SIZE + ACCESS_MODE + IS_POINTER, TYPE_SIZE_UNIT
> for element)
> which returns the REF_TO_OBJ same as the 1st argument;
>
> 1st argument REF_TO_OBJ: The reference to the object when IS_POINTER is
> false;
> The address of the reference
> to the object when IS_POINTER is true;
> 2nd argument REF_TO_SIZE: The reference to the size of the object,
> 3rd argument TYPE_OF_SIZE + ACCESS_MODE + IS_POINTER An integer constant
> with a pointer
> TYPE.
> The pointee TYPE of the pointer TYPE is the TYPE of the object referenced
> by REF_TO_SIZE.
> The integer constant value represents the ACCESS_MODE + IS_POINTER:
> 00: none
> 01: read_only
> 10: write_only
> 11: read_write
> 100: IS_POINTER
Sure, I was talking about it before, the value of the 3rd argument can be a
set of various bit flags.
I still don't understand what do you want to use that
read_only/write_only/read_write flags for, if you mark loads from the
pointer, those will be always reads and whether something is load, store or
load/store of data pointed by that pointer is something normally visible in
the IL (plus you probably don't know it in the FE).
So say for
struct S { int s; int *p __attribute__((counted_by (s))); };
int
foo (struct S *x, int y)
{
return x->p[y];
}
I would have expected you emit something like
_1 = x->p;
_6 = &x->s;
_5 = .ACCESS_WITH_SIZE (_1, _6, IS_POINTER, 4);
_2 = (long unsigned int) y;
_3 = _2 * 4;
_4 = _5 + _3;
D.2965 = *_4;
and for
x->p = whatever;
no .ACCESS_WITH_SIZE.
Jakub
