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alpha: Add string-fza, string-fzb.h, string-fzi.h, and string-shift.h

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While alpha has the more important string functions in assembly,
there are still a few for find the generic routines are used.

Use the CMPBGE insn, via the builtin, for testing of zeros.  Use a
simplified expansion of __builtin_ctz when the insn isn't available.

Checked on alpha-linux-gnu.

Co-authored-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Richard Henderson 2023-01-10 18:01:03 -03:00 committed by Adhemerval Zanella
parent c62b1c29c2
commit 120ad6ed1a
4 changed files with 218 additions and 0 deletions
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60
sysdeps/alpha/string-fza.h Normal file
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/* Basic zero byte detection. Generic C version.
Copyright (C) 2023 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
<http://www.gnu.org/licenses/>. */
#ifndef _STRING_FZA_H
#define _STRING_FZA_H 1
#include <string-misc.h>
#include <string-optype.h>
/* The CMPBGE instruction creates a bit mask rather than a byte mask.
However, if we narrow find_t to either 'int' or 'uint8_t', we get
unnecessary truncation instructions from the 'unsigned long' type
returned by __builtin_alpha_cmpbge. */
typedef op_t find_t;
static __always_inline find_t
find_zero_all (op_t x)
{
return __builtin_alpha_cmpbge (0, x);
}
static __always_inline find_t
find_eq_all (op_t x1, op_t x2)
{
return find_zero_all (x1 ^ x2);
}
static __always_inline find_t
find_zero_eq_all (op_t x1, op_t x2)
{
return find_zero_all (x1) | find_zero_all (x1 ^ x2);
}
static __always_inline find_t
find_zero_ne_all (op_t x1, op_t x2)
{
return find_zero_all (x1) | (find_zero_all (x1 ^ x2) ^ 0xff);
}
/* Define the "inexact" versions in terms of the exact versions. */
#define find_zero_low find_zero_all
#define find_eq_low find_eq_all
#define find_zero_eq_low find_zero_eq_all
#endif /* _STRING_FZA_H */

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/* Zero byte detection; boolean. Alpha version.
Copyright (C) 2023 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
<http://www.gnu.org/licenses/>. */
#ifndef _STRING_FZB_H
#define _STRING_FZB_H 1
#include <sys/cdefs.h>
#include <string-optype.h>
/* Note that since CMPBGE creates a bit mask rather than a byte mask,
we cannot simply provide a target-specific string-fza.h. */
/* Determine if any byte within X is zero. This is a pure boolean test. */
static __always_inline _Bool
has_zero (op_t x)
{
return __builtin_alpha_cmpbge (0, x) != 0;
}
/* Likewise, but for byte equality between X1 and X2. */
static __always_inline _Bool
has_eq (op_t x1, op_t x2)
{
return has_zero (x1 ^ x2);
}
/* Likewise, but for zeros in X1 and equal bytes between X1 and X2. */
static __always_inline _Bool
has_zero_eq (op_t x1, op_t x2)
{
return has_zero (x1) | has_eq (x1, x2);
}
#endif /* _STRING_FZB_H */

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sysdeps/alpha/string-fzi.h Normal file
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/* string-fzi.h -- zero byte detection; indices. Alpha version.
Copyright (C) 2023 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
<http://www.gnu.org/licenses/>. */
#ifndef _STRING_FZI_H
#define _STRING_FZI_H
#include <stdint.h>
#include <string-optype.h>
#include <string-fza.h>
/* Note that since CMPBGE creates a bit mask rather than a byte mask,
we cannot simply provide a target-specific string-fza.h. */
/* A subroutine for the index_zero functions. Given a bitmask C,
return the index of the first bit set in memory order. */
static __always_inline unsigned int
index_first (find_t c)
{
#ifdef __alpha_cix__
return __builtin_ctzl (c);
#else
c = c & -c;
return (c & 0xf0 ? 4 : 0) + (c & 0xcc ? 2 : 0) + (c & 0xaa ? 1 : 0);
#endif
}
/* Similarly, but return the (memory order) index of the last bit
that is non-zero. Note that only the least 8 bits may be nonzero. */
static __always_inline unsigned int
index_last (find_t x)
{
#ifdef __alpha_cix__
return __builtin_clzl (x) ^ 63;
#else
unsigned r = 0;
if (x & 0xf0)
r += 4;
if (x & (0xc << r))
r += 2;
if (x & (0x2 << r))
r += 1;
return r;
#endif
}
#endif /* _STRING_FZI_H */

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/* Shift unaligned word read. Alpha version.
Copyright (C) 2023 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
<http://www.gnu.org/licenses/>. */
#ifndef _STRING_SHIFT_H
#define _STRING_SHIFT_H 1
#include <limits.h>
#include <stdint.h>
#include <string-fza.h>
/* Return the mask WORD shifted based on S_INT address value, to ignore
values not presented in the aligned word read. */
static __always_inline find_t
shift_find (find_t word, uintptr_t s)
{
return word >> (s % sizeof (op_t));
}
/* Mask off the bits defined the the S alignment value. */
static __always_inline find_t
shift_find_last (find_t word, uintptr_t s)
{
s = s % sizeof (op_t);
if (s == 0)
return word;
return word & ~((op_t)-1 << s);
}
#endif /* _STRING_SHIFT_H */