Re: [PATCH] powerpc: Add optimized strlen for POWER10

[Paul E Murphy <murphyp@linux.ibm.com>]

On 4/16/21 4:24 PM, Matheus Castanho via Libc-alpha wrote:

> diff --git a/sysdeps/powerpc/powerpc64/le/power10/strlen.S b/sysdeps/powerpc/powerpc64/le/power10/strlen.S
> new file mode 100644
> index 0000000000..5218a2277c
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/le/power10/strlen.S
> @@ -0,0 +1,219 @@
> +/* Optimized strlen implementation for POWER10 LE.
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <sysdep.h>
> +
> +#ifndef STRLEN
> +# define STRLEN __strlen
> +# define DEFINE_STRLEN_HIDDEN_DEF 1
> +#endif
> +
> +#define VEXTRACTBM(rt,vrb)	 \
> +	.long(((4)<<(32-6))	 \
> +	      | ((rt)<<(32-11))	 \
> +	      | ((8)<<(32-16))	 \
> +	      | ((vrb)<<(32-21)) \
> +	      | 1602)
> +
> +#define LXVP(xtp,dq,ra)		   \
> +	.long(((6)<<(32-6))		   \
> +	      | ((((xtp)-32)>>1)<<(32-10)) \
> +	      | ((1)<<(32-11))		   \
> +	      | ((ra)<<(32-16))		   \
> +	      | dq)

Can you add a comment to these noting the minimum version of binutils
which supports these instructions?

> +
> +#define CHECK16(reg,offset,addr,label)	\
> +	lxv	  reg+32,offset(addr);	\
> +	vcmpequb. reg,reg,v18;		\
> +	bne	  cr6,L(label);

Maybe rename reg to vreg for clarity?

With the trivial comments above addressed, I think this patch is OK.