On Mon, Oct 23, 2017 at 1:25 PM, Richard Sandiford
<richard.sandif...@linaro.org> wrote:
> alias.c:find_base_term and find_base_value checked:
>
> if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
>
> but (a) comparing the precision seems more correct, since it's possible
> for modes to have the same memory size as Pmode but fewer bits and
> (b) the functions are called on arbitrary rtl, so there's no guarantee
> that we're handling an integer truncation.
>
> Since there's no point processing truncations of anything other than an
> integer, this patch checks that first.
Ok.
Richard.
>
> 2017-10-23 Richard Sandiford <richard.sandif...@linaro.org>
> Alan Hayward <alan.hayw...@arm.com>
> David Sherwood <david.sherw...@arm.com>
>
> gcc/
> * alias.c (find_base_value, find_base_term): Only process integer
> truncations. Check the precision rather than the size.
>
> Index: gcc/alias.c
> ===================================================================
> --- gcc/alias.c 2017-10-23 11:41:25.511925516 +0100
> +++ gcc/alias.c 2017-10-23 11:44:27.544693078 +0100
> @@ -1349,6 +1349,7 @@ known_base_value_p (rtx x)
> find_base_value (rtx src)
> {
> unsigned int regno;
> + scalar_int_mode int_mode;
>
> #if defined (FIND_BASE_TERM)
> /* Try machine-dependent ways to find the base term. */
> @@ -1475,7 +1476,8 @@ find_base_value (rtx src)
> address modes depending on the address space. */
> if (!target_default_pointer_address_modes_p ())
> break;
> - if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
> + if (!is_a <scalar_int_mode> (GET_MODE (src), &int_mode)
> + || GET_MODE_PRECISION (int_mode) < GET_MODE_PRECISION (Pmode))
> break;
> /* Fall through. */
> case HIGH:
> @@ -1876,6 +1878,7 @@ find_base_term (rtx x)
> cselib_val *val;
> struct elt_loc_list *l, *f;
> rtx ret;
> + scalar_int_mode int_mode;
>
> #if defined (FIND_BASE_TERM)
> /* Try machine-dependent ways to find the base term. */
> @@ -1893,7 +1896,8 @@ find_base_term (rtx x)
> address modes depending on the address space. */
> if (!target_default_pointer_address_modes_p ())
> return 0;
> - if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode))
> + if (!is_a <scalar_int_mode> (GET_MODE (x), &int_mode)
> + || GET_MODE_PRECISION (int_mode) < GET_MODE_PRECISION (Pmode))
> return 0;
> /* Fall through. */
> case HIGH:
