mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-29 08:11:08 +00:00
c62b1c29c2
Use UXOR,SBZ to test for a zero byte within a word. While we can get semi-decent code out of asm-goto, we would do slightly better with a compiler builtin. For index_zero et al, sequential testing of bytes is less expensive than any tricks that involve a count-leading-zeros insn that we don't have. Checked on hppa-linux-gnu. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
64 lines
1.8 KiB
C
64 lines
1.8 KiB
C
/* Zero byte detection, boolean. HPPA 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>
|
|
|
|
_Static_assert (sizeof (op_t) == 4, "64-bit not supported");
|
|
|
|
/* Determine if any byte within X is zero. This is a pure boolean test. */
|
|
static __always_inline _Bool
|
|
has_zero (op_t x)
|
|
{
|
|
/* It's more useful to expose a control transfer to the compiler
|
|
than to expose a proper boolean result. */
|
|
asm goto ("uxor,sbz %%r0,%0,%%r0\n\t"
|
|
"b,n %l1" : : "r"(x) : : nbz);
|
|
return 1;
|
|
nbz:
|
|
return 0;
|
|
}
|
|
|
|
/* Likewise, but for byte equality between X1 and X2. */
|
|
static __always_inline _Bool
|
|
has_eq (op_t x1, op_t x2)
|
|
{
|
|
asm goto ("uxor,sbz %0,%1,%%r0\n\t"
|
|
"b,n %l2" : : "r"(x1), "r"(x2) : : nbz);
|
|
return 1;
|
|
nbz:
|
|
return 0;
|
|
}
|
|
|
|
/* 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)
|
|
{
|
|
asm goto ("uxor,sbz %%r0,%0,%%r0\n\t"
|
|
"uxor,nbz %0,%1,%%r0\n\t"
|
|
"b,n %l2" : : "r"(x1), "r"(x2) : : sbz);
|
|
return 0;
|
|
sbz:
|
|
return 1;
|
|
}
|
|
|
|
#endif /* _STRING_FZB_H */
|