{patch tree-ssa-math-opts]: Change searching direction for bswap

Richard Guenther richard.guenther@gmail.com
Tue Jun 28 10:17:00 GMT 2011


On Tue, Jun 28, 2011 at 11:29 AM, Kai Tietz <ktietz@redhat.com> wrote:
> Oh, missed to fill comment.



> Thanks,
> Kai
>
> Index: gcc-head/gcc/tree-ssa-math-opts.c
> ===================================================================
> --- gcc-head.orig/gcc/tree-ssa-math-opts.c
> +++ gcc-head/gcc/tree-ssa-math-opts.c
> @@ -1821,7 +1821,11 @@ execute_optimize_bswap (void)
>     {
>       gimple_stmt_iterator gsi;
>
> -      for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
> +      /* We scan for bswap patterns reverse for making sure we get

We do a reverse scan for bswap patterns to make sure we get the widest match.

Ok with that change.

Richard.

> +        widest match.  As bswap pattern matching doesn't handle
> +        previously inserted smaller bswap replacements as sub-
> +        patterns, the wider variant wouldn't be detected.  */
> +      for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
>         {
>          gimple stmt = gsi_stmt (gsi);
>          tree bswap_src, bswap_type;
>



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