115 lines
3.6 KiB
C
115 lines
3.6 KiB
C
/* Copyright (C) 2012-2022 Free Software Foundation, Inc.
|
|
Contributed by Richard Henderson <rth@redhat.com>.
|
|
|
|
This file is part of the GNU Atomic Library (libatomic).
|
|
|
|
Libatomic is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
Libatomic 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 General Public License for
|
|
more details.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <libatomic_i.h>
|
|
#include <arm-config.h>
|
|
|
|
|
|
/* When using STREX to implement sub-word exchange, we can do much better
|
|
than the compiler by using the APSR.GE and APSR.C flags. */
|
|
|
|
#if !DONE && __ARM_FEATURE_SIMD32 && HAVE_STREX && !HAVE_STREXBH && N == 2
|
|
UTYPE
|
|
SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel)
|
|
{
|
|
UWORD t1, t2;
|
|
UTYPE oldval;
|
|
|
|
__atomic_thread_fence (__ATOMIC_SEQ_CST);
|
|
|
|
/* In the N=2 case, there are only two cases for MPTR: mptr % 4 == {0,2}.
|
|
Rather than computing a variable shift for this, we can store the one
|
|
bit of misalignment in the carry flag, and use conditional constant
|
|
shifts instead. This saves a register. */
|
|
#ifdef __ARMEB__
|
|
# define HI "cc" /* iff value is in high half */
|
|
# define LO "cs" /* iff value is in low half */
|
|
#else
|
|
# define HI "cs"
|
|
# define LO "cc"
|
|
#endif
|
|
|
|
asm volatile (
|
|
"lsrs %[t2],%[ptr],#2\n" /* carry = mptr & 2 */
|
|
" bic %[ptr],%[ptr],#3\n" /* align mptr */
|
|
" itt "HI"\n"
|
|
" lsl"HI" %[t1],%[t1],#16\n" /* shift mask into place */
|
|
" lsl"HI" %[new],%[new],#16\n" /* shift newval into place */
|
|
" uadd16 %[t1],%[t1],%[t1]\n" /* copy mask into APSR.GE */
|
|
"0: ldrex %[t2],[%[ptr]]\n"
|
|
" ite "LO"\n"
|
|
" uxth"LO" %[old],%[t2]\n" /* return old value */
|
|
" uxth"HI" %[old],%[t2], ror #16\n"
|
|
" sel %[t1],%[new],%[t2]\n" /* merge newval */
|
|
" strex %[t2],%[t1],[%[ptr]]\n"
|
|
" tst %[t2],%[t2]\n" /* dont clobber carry */
|
|
" bne 0b"
|
|
: [old] "=&r"(oldval), [t1] "=&r"(t1), [t2] "=&r"(t2),
|
|
[ptr] "+r"(mptr), [new] "+r"(newval)
|
|
: "1"(0xffff)
|
|
: "memory");
|
|
|
|
__atomic_thread_fence (__ATOMIC_SEQ_CST);
|
|
|
|
return oldval;
|
|
}
|
|
|
|
#define DONE 1
|
|
#endif /* !HAVE_STREXBH && N == 2 */
|
|
|
|
|
|
#if !DONE && __ARM_FEATURE_SIMD32 && HAVE_STREX && !HAVE_STREXBH && N == 1
|
|
UTYPE
|
|
SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel)
|
|
{
|
|
UWORD *wptr, woldval, wnewval, shift, mask, t1, t2;
|
|
|
|
__atomic_thread_fence (__ATOMIC_SEQ_CST);
|
|
|
|
wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
|
|
shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ INVERT_MASK_1;
|
|
mask = MASK_1 << shift;
|
|
wnewval = newval << shift;
|
|
|
|
asm volatile (
|
|
"uadd8 %[t1],%[t1],%[t1]\n" /* move mask to APSR.GE */
|
|
"0: ldrex %[old],[%[wptr]]\n"
|
|
" sel %[t1],%[new],%[old]\n" /* merge newval */
|
|
" strex %[t2],%[t1],[%[wptr]]\n"
|
|
" cmp %[t2],#0\n"
|
|
" bne 0b"
|
|
: [old] "=&r"(woldval), [t1] "=&r"(t1), [t2] "=&r"(t2)
|
|
: [new] "r"(wnewval), [wptr] "r"(wptr), "1"(mask)
|
|
: "memory");
|
|
|
|
__atomic_thread_fence (__ATOMIC_SEQ_CST);
|
|
|
|
return woldval >> shift;
|
|
}
|
|
|
|
#define DONE 1
|
|
#endif /* !HAVE_STREXBH && N == 1 */
|
|
|
|
#include "../../exch_n.c"
|