Re: [PATCH][AArch64] Properly handle mvn-register and add EON+shift pattern and cost appropriately

[Kyrill Tkachov <kyrylo dot tkachov at arm dot com>]

Ping.
https://gcc.gnu.org/ml/gcc-patches/2015-04/msg01434.html

Thanks,
Kyrill

On 23/04/15 17:57, Kyrill Tkachov wrote:
> [resending due to mail client messing up.]
>
> Hi all,
>
> The EON instruction can be expressed either by (xor (not a) b) or (not (xor
> a b)),
> simplify-rtx canonicalizes to the second form and we have a pattern for it
> (*xor_one_cmpl<mode>3) but we don't have a pattern for the shifted operand
> version. This patch adds that pattern as well as the proper handling of it
> in
> aarch64_rtx_costs. The zero-extend version of it is also added.
>
> While we're in the NOT case of rtx costs this patch also
> corrects the costing of MVN+shift operations.
>
> With this patch, for C code:
> unsigned long
> baz (unsigned int a, unsigned int b)
> {
>    return ~(a ^ (b << 6));
> }
>
> unsigned long
> foo (unsigned long a, unsigned long b)
> {
>    return ~(a ^ (b >> 24));
> }
>
>
> we now generate:
> baz:
> 	eon	w0, w0, w1, lsl 6
> 	ret
>
> foo:
> 	eon	x0, x0, x1, lsr 24
> 	ret
>
> instead of the previous:
> baz:
> 	eor	w0, w0, w1, lsl 6
> 	mvn	w0, w0
> 	uxtw	x0, w0
> 	ret
>
> foo:
> 	eor	x0, x0, x1, lsr 24
> 	mvn	x0, x0
> 	ret
>
>
> Bootstrapped and tested on aarch64-linux.
> Ok for trunk?
> Thanks,
> Kyrill
>
> 2015-04-23  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
>
> 	* config/aarch64/aarch64.md
> (*eor_one_cmpl_<SHIFT:optab><mode>3_alt):
> 	New pattern.
> 	(*eor_one_cmpl_<SHIFT:optab>sidi3_alt_ze): Likewise.
> 	* config/aarch64/aarch64.c (aarch64_rtx_costs): Handle MVN-shift
> 	appropriately.  Handle alternative EON form.