On Thu, Feb 25, 2016 at 09:08:32PM -0800, Richard Henderson wrote:
> diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
> index 450fa8b..9d55e7b 100644
> --- a/gcc/simplify-rtx.c
> +++ b/gcc/simplify-rtx.c
> @@ -4421,9 +4421,17 @@ simplify_plus_minus (enum rtx_code code, machine_mode
> mode, rtx op0,
> n_ops = i;
> }
>
> - /* If nothing changed, fail. */
> + /* If nothing changed, check that rematerialization of rtl instructions
> + is still required. */
> if (!canonicalized)
> - return NULL_RTX;
> + {
> + /* Perform rematerialization if only all operands are registers and
> + all operations are PLUS. */
> + for (i = 0; i < n_ops; i++)
> + if (ops[i].neg || !REG_P (ops[i].op))
> + return NULL_RTX;
> + goto gen_result;
> + }
If you check for fixed registers as well here, does that work for you?
Segher
