On Tue, 25 Jul 2017, Alexander Monakov wrote:
> --- a/gcc/domwalk.c
> +++ b/gcc/domwalk.c
> @@ -128,19 +128,46 @@ along with GCC; see the file COPYING3. If not see
> which is currently an abstraction over walking tree statements. Thus
> the dominator walker is currently only useful for trees. */
>
> +/* Reverse postorder index of each basic block. */
> static int *bb_postorder;
>
> static int
> cmp_bb_postorder (const void *a, const void *b)
> {
> - basic_block bb1 = *(basic_block *)const_cast<void *>(a);
> - basic_block bb2 = *(basic_block *)const_cast<void *>(b);
> - if (bb1->index == bb2->index)
> - return 0;
> + basic_block bb1 = *(const basic_block *)(a);
> + basic_block bb2 = *(const basic_block *)(b);
> + int n1 = bb_postorder[bb1->index], n2 = bb_postorder[bb2->index];
> /* Place higher completion number first (pop off lower number first). */
> - if (bb_postorder[bb1->index] > bb_postorder[bb2->index])
> - return -1;
> - return 1;
> + return (n1 < n2) - (n1 > n2);
Actually since the 'int *bb_postorder' array is not going to hold negative
entries, this can be simply
return n2 - n1;
(the (A > B) - (A < B) formulation is useful in case signed A - B may overflow)
Alexander
