On Mon, Oct 23, 2017 at 1:30 PM, Richard Sandiford
<richard.sandif...@linaro.org> wrote:
> The repeated checks for MEM_REF made this code hard to convert to
> poly_ints as-is. Hopefully the new structure also makes it clearer
> at a glance what the two cases are.
>
>
> 2017-10-23 Richard Sandiford <richard.sandif...@linaro.org>
> Alan Hayward <alan.hayw...@arm.com>
> David Sherwood <david.sherw...@arm.com>
>
> gcc/
> * tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid repeated
> checks for MEM_REF.
>
> Index: gcc/tree-ssa-sccvn.c
> ===================================================================
> --- gcc/tree-ssa-sccvn.c 2017-10-23 11:47:03.852769480 +0100
> +++ gcc/tree-ssa-sccvn.c 2017-10-23 11:47:44.596155858 +0100
> @@ -2234,6 +2234,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> || offset % BITS_PER_UNIT != 0
> || ref->size % BITS_PER_UNIT != 0)
> return (void *)-1;
> + at = offset / BITS_PER_UNIT;
can you move this just
> /* Extract a pointer base and an offset for the destination. */
> lhs = gimple_call_arg (def_stmt, 0);
> @@ -2301,19 +2302,18 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> copy_size = tree_to_uhwi (gimple_call_arg (def_stmt, 2));
>
> /* The bases of the destination and the references have to agree. */
here? Ok with that change.
Richard.
> - if ((TREE_CODE (base) != MEM_REF
> - && !DECL_P (base))
> - || (TREE_CODE (base) == MEM_REF
> - && (TREE_OPERAND (base, 0) != lhs
> - || !tree_fits_uhwi_p (TREE_OPERAND (base, 1))))
> - || (DECL_P (base)
> - && (TREE_CODE (lhs) != ADDR_EXPR
> - || TREE_OPERAND (lhs, 0) != base)))
> + if (TREE_CODE (base) == MEM_REF)
> + {
> + if (TREE_OPERAND (base, 0) != lhs
> + || !tree_fits_uhwi_p (TREE_OPERAND (base, 1)))
> + return (void *) -1;
> + at += tree_to_uhwi (TREE_OPERAND (base, 1));
> + }
> + else if (!DECL_P (base)
> + || TREE_CODE (lhs) != ADDR_EXPR
> + || TREE_OPERAND (lhs, 0) != base)
> return (void *)-1;
>
> - at = offset / BITS_PER_UNIT;
> - if (TREE_CODE (base) == MEM_REF)
> - at += tree_to_uhwi (TREE_OPERAND (base, 1));
> /* If the access is completely outside of the memcpy destination
> area there is no aliasing. */
> if (lhs_offset >= at + maxsize / BITS_PER_UNIT
