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author | Richard Henderson <rth@twiddle.net> | 2014-02-12 06:54:57 -0800 |
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committer | Richard Henderson <rth@twiddle.net> | 2014-02-12 07:00:06 -0800 |
commit | 68b7efaadb1b6045a56277ea62d324c20ac0b633 (patch) | |
tree | 07b51c9866373430373fb90b252d46c23cc1707e /sysdeps/alpha/bzero.S | |
parent | 8fd7b0d5591e59ed5cb3078b351bd49314a66cef (diff) | |
download | glibc-68b7efaadb1b6045a56277ea62d324c20ac0b633.tar.gz glibc-68b7efaadb1b6045a56277ea62d324c20ac0b633.tar.xz glibc-68b7efaadb1b6045a56277ea62d324c20ac0b633.zip |
Relocate alpha from ports to libc
Also fixed the following whitespace nits to satisfy the push: sysdeps/alpha/alphaev6/memset.S:142: space before tab in indent. sysdeps/alpha/configure:1: new blank line at EOF. sysdeps/alpha/fpu/e_sqrt.c:126: space before tab in indent. sysdeps/alpha/preconfigure:1: new blank line at EOF. sysdeps/unix/sysv/linux/alpha/syscalls.list:1: new blank line at EOF.
Diffstat (limited to 'sysdeps/alpha/bzero.S')
-rw-r--r-- | sysdeps/alpha/bzero.S | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/sysdeps/alpha/bzero.S b/sysdeps/alpha/bzero.S new file mode 100644 index 0000000000..36e891ca85 --- /dev/null +++ b/sysdeps/alpha/bzero.S @@ -0,0 +1,110 @@ +/* Copyright (C) 1996-2014 Free Software Foundation, Inc. + Contributed by Richard Henderson (rth@tamu.edu) + 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/>. */ + +/* Fill a block of memory with zeros. Optimized for the Alpha architecture: + + - memory accessed as aligned quadwords only + - destination memory not read unless needed for good cache behaviour + - basic blocks arranged to optimize branch prediction for full-quadword + aligned memory blocks. + - partial head and tail quadwords constructed with byte-mask instructions + + This is generally scheduled for the EV5 (got to look out for my own + interests :-), but with EV4 needs in mind. There *should* be no more + stalls for the EV4 than there are for the EV5. +*/ + + +#include <sysdep.h> + + .set noat + .set noreorder + + .text + .type __bzero, @function + .globl __bzero + .usepv __bzero, USEPV_PROF + + cfi_startproc + + /* On entry to this basic block: + t3 == loop counter + t4 == bytes in partial final word + a0 == possibly misaligned destination pointer */ + + .align 3 +bzero_loop: + beq t3, $tail # + blbc t3, 0f # skip single store if count even + + stq_u zero, 0(a0) # e0 : store one word + subq t3, 1, t3 # .. e1 : + addq a0, 8, a0 # e0 : + beq t3, $tail # .. e1 : + +0: stq_u zero, 0(a0) # e0 : store two words + subq t3, 2, t3 # .. e1 : + stq_u zero, 8(a0) # e0 : + addq a0, 16, a0 # .. e1 : + bne t3, 0b # e1 : + +$tail: bne t4, 1f # is there a tail to do? + ret # no + +1: ldq_u t0, 0(a0) # yes, load original data + mskqh t0, t4, t0 # + stq_u t0, 0(a0) # + ret # + +__bzero: +#ifdef PROF + ldgp gp, 0(pv) + lda AT, _mcount + jsr AT, (AT), _mcount +#endif + + mov a0, v0 # e0 : move return value in place + beq a1, $done # .. e1 : early exit for zero-length store + and a0, 7, t1 # e0 : + addq a1, t1, a1 # e1 : add dest misalignment to count + srl a1, 3, t3 # e0 : loop = count >> 3 + and a1, 7, t4 # .. e1 : find number of bytes in tail + unop # : + beq t1, bzero_loop # e1 : aligned head, jump right in + + ldq_u t0, 0(a0) # e0 : load original data to mask into + cmpult a1, 8, t2 # .. e1 : is this a sub-word set? + bne t2, $oneq # e1 : + + mskql t0, a0, t0 # e0 : we span words. finish this partial + subq t3, 1, t3 # e0 : + addq a0, 8, a0 # .. e1 : + stq_u t0, -8(a0) # e0 : + br bzero_loop # .. e1 : + + .align 3 +$oneq: + mskql t0, a0, t2 # e0 : + mskqh t0, a1, t3 # e0 : + or t2, t3, t0 # e1 : + stq_u t0, 0(a0) # e0 : + +$done: ret + + cfi_endproc +weak_alias (__bzero, bzero) |