398 lines
9.9 KiB
ArmAsm
398 lines
9.9 KiB
ArmAsm
/* Optimized version of the standard memset() function.
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This file is part of the GNU C Library.
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Copyright (C) 2000-2022 Free Software Foundation, Inc.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Return: dest
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Inputs:
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in0: dest
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in1: value
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in2: count
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The algorithm is fairly straightforward: set byte by byte until we
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we get to a 16B-aligned address, then loop on 128 B chunks using an
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early store as prefetching, then loop on 32B chucks, then clear remaining
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words, finally clear remaining bytes.
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Since a stf.spill f0 can store 16B in one go, we use this instruction
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to get peak speed when value = 0. */
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#include <sysdep.h>
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#undef ret
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#define dest in0
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#define value in1
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#define cnt in2
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#define tmp r31
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#define save_lc r30
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#define ptr0 r29
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#define ptr1 r28
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#define ptr2 r27
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#define ptr3 r26
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#define ptr9 r24
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#define loopcnt r23
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#define linecnt r22
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#define bytecnt r21
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#define fvalue f6
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// This routine uses only scratch predicate registers (p6 - p15)
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#define p_scr p6 // default register for same-cycle branches
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#define p_nz p7
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#define p_zr p8
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#define p_unalgn p9
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#define p_y p11
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#define p_n p12
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#define p_yy p13
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#define p_nn p14
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#define movi0 mov
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#define MIN1 15
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#define MIN1P1HALF 8
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#define LINE_SIZE 128
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#define LSIZE_SH 7 // shift amount
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#define PREF_AHEAD 8
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#define USE_FLP
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#if defined(USE_INT)
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#define store st8
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#define myval value
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#elif defined(USE_FLP)
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#define store stf8
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#define myval fvalue
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#endif
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.align 64
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ENTRY(memset)
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{ .mmi
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.prologue
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alloc tmp = ar.pfs, 3, 0, 0, 0
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lfetch.nt1 [dest]
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.save ar.lc, save_lc
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movi0 save_lc = ar.lc
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} { .mmi
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.body
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mov ret0 = dest // return value
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cmp.ne p_nz, p_zr = value, r0 // use stf.spill if value is zero
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cmp.eq p_scr, p0 = cnt, r0
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;; }
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{ .mmi
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and ptr2 = -(MIN1+1), dest // aligned address
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and tmp = MIN1, dest // prepare to check for alignment
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tbit.nz p_y, p_n = dest, 0 // Do we have an odd address? (M_B_U)
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} { .mib
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mov ptr1 = dest
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mux1 value = value, @brcst // create 8 identical bytes in word
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(p_scr) br.ret.dpnt.many rp // return immediately if count = 0
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;; }
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{ .mib
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cmp.ne p_unalgn, p0 = tmp, r0
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} { .mib // NB: # of bytes to move is 1 higher
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sub bytecnt = (MIN1+1), tmp // than loopcnt
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cmp.gt p_scr, p0 = 16, cnt // is it a minimalistic task?
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(p_scr) br.cond.dptk.many .move_bytes_unaligned // go move just a few (M_B_U)
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;; }
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{ .mmi
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(p_unalgn) add ptr1 = (MIN1+1), ptr2 // after alignment
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(p_unalgn) add ptr2 = MIN1P1HALF, ptr2 // after alignment
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(p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 3 // should we do a st8 ?
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;; }
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{ .mib
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(p_y) add cnt = -8, cnt
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(p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 2 // should we do a st4 ?
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} { .mib
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(p_y) st8 [ptr2] = value, -4
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(p_n) add ptr2 = 4, ptr2
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;; }
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{ .mib
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(p_yy) add cnt = -4, cnt
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(p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 1 // should we do a st2 ?
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} { .mib
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(p_yy) st4 [ptr2] = value, -2
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(p_nn) add ptr2 = 2, ptr2
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;; }
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{ .mmi
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mov tmp = LINE_SIZE+1 // for compare
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(p_y) add cnt = -2, cnt
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(p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 0 // should we do a st1 ?
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} { .mmi
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setf.sig fvalue=value // transfer value to FLP side
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(p_y) st2 [ptr2] = value, -1
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(p_n) add ptr2 = 1, ptr2
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;; }
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{ .mmi
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(p_yy) st1 [ptr2] = value
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cmp.gt p_scr, p0 = tmp, cnt // is it a minimalistic task?
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} { .mbb
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(p_yy) add cnt = -1, cnt
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(p_scr) br.cond.dpnt.many .fraction_of_line // go move just a few
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;; }
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{ .mib
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nop.m 0
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shr.u linecnt = cnt, LSIZE_SH
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(p_zr) br.cond.dptk.many .l1b // Jump to use stf.spill
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;; }
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#ifndef GAS_ALIGN_BREAKS_UNWIND_INFO
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.align 32 // -------- // L1A: store ahead into cache lines; fill later
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#endif
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{ .mmi
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and tmp = -(LINE_SIZE), cnt // compute end of range
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mov ptr9 = ptr1 // used for prefetching
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and cnt = (LINE_SIZE-1), cnt // remainder
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} { .mmi
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mov loopcnt = PREF_AHEAD-1 // default prefetch loop
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cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value
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;; }
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{ .mmi
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(p_scr) add loopcnt = -1, linecnt // start of stores
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add ptr2 = 8, ptr1 // (beyond prefetch stores)
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add ptr1 = tmp, ptr1 // first address beyond total
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;; } // range
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{ .mmi
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add tmp = -1, linecnt // next loop count
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movi0 ar.lc = loopcnt
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;; }
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.pref_l1a:
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{ .mib
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store [ptr9] = myval, 128 // Do stores one cache line apart
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nop.i 0
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br.cloop.dptk.few .pref_l1a
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;; }
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{ .mmi
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add ptr0 = 16, ptr2 // Two stores in parallel
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movi0 ar.lc = tmp
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;; }
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.l1ax:
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{ .mmi
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store [ptr2] = myval, 8
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store [ptr0] = myval, 8
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;; }
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{ .mmi
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store [ptr2] = myval, 24
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store [ptr0] = myval, 24
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;; }
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{ .mmi
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store [ptr2] = myval, 8
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store [ptr0] = myval, 8
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;; }
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{ .mmi
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store [ptr2] = myval, 24
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store [ptr0] = myval, 24
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;; }
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{ .mmi
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store [ptr2] = myval, 8
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store [ptr0] = myval, 8
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;; }
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{ .mmi
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store [ptr2] = myval, 24
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store [ptr0] = myval, 24
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;; }
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{ .mmi
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store [ptr2] = myval, 8
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store [ptr0] = myval, 32
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cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching?
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;; }
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{ .mmb
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store [ptr2] = myval, 24
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(p_scr) store [ptr9] = myval, 128
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br.cloop.dptk.few .l1ax
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;; }
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{ .mbb
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cmp.le p_scr, p0 = 8, cnt // just a few bytes left ?
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(p_scr) br.cond.dpnt.many .fraction_of_line // Branch no. 2
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br.cond.dpnt.many .move_bytes_from_alignment // Branch no. 3
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;; }
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#ifdef GAS_ALIGN_BREAKS_UNWIND_INFO
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{ nop 0 }
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#else
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.align 32
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#endif
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.l1b: // ------------------ // L1B: store ahead into cache lines; fill later
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{ .mmi
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and tmp = -(LINE_SIZE), cnt // compute end of range
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mov ptr9 = ptr1 // used for prefetching
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and cnt = (LINE_SIZE-1), cnt // remainder
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} { .mmi
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mov loopcnt = PREF_AHEAD-1 // default prefetch loop
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cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value
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;; }
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{ .mmi
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(p_scr) add loopcnt = -1, linecnt
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add ptr2 = 16, ptr1 // start of stores (beyond prefetch stores)
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add ptr1 = tmp, ptr1 // first address beyond total range
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;; }
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{ .mmi
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add tmp = -1, linecnt // next loop count
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movi0 ar.lc = loopcnt
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;; }
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.pref_l1b:
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{ .mib
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stf.spill [ptr9] = f0, 128 // Do stores one cache line apart
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nop.i 0
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br.cloop.dptk.few .pref_l1b
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;; }
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{ .mmi
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add ptr0 = 16, ptr2 // Two stores in parallel
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movi0 ar.lc = tmp
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;; }
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.l1bx:
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{ .mmi
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stf.spill [ptr2] = f0, 32
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stf.spill [ptr0] = f0, 32
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;; }
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{ .mmi
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stf.spill [ptr2] = f0, 32
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stf.spill [ptr0] = f0, 32
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;; }
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{ .mmi
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stf.spill [ptr2] = f0, 32
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stf.spill [ptr0] = f0, 64
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cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching?
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;; }
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{ .mmb
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stf.spill [ptr2] = f0, 32
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(p_scr) stf.spill [ptr9] = f0, 128
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br.cloop.dptk.few .l1bx
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;; }
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{ .mib
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cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ?
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(p_scr) br.cond.dpnt.many .move_bytes_from_alignment
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;; }
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.fraction_of_line:
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{ .mib
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add ptr2 = 16, ptr1
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shr.u loopcnt = cnt, 5 // loopcnt = cnt / 32
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;; }
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{ .mib
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cmp.eq p_scr, p0 = loopcnt, r0
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add loopcnt = -1, loopcnt
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(p_scr) br.cond.dpnt.many store_words
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;; }
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{ .mib
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and cnt = 0x1f, cnt // compute the remaining cnt
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movi0 ar.lc = loopcnt
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;; }
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#ifndef GAS_ALIGN_BREAKS_UNWIND_INFO
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.align 32
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#endif
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.l2: // ---------------------------- // L2A: store 32B in 2 cycles
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{ .mmb
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store [ptr1] = myval, 8
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store [ptr2] = myval, 8
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;; } { .mmb
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store [ptr1] = myval, 24
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store [ptr2] = myval, 24
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br.cloop.dptk.many .l2
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;; }
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store_words:
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{ .mib
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cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ?
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(p_scr) br.cond.dpnt.many .move_bytes_from_alignment // Branch
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;; }
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{ .mmi
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store [ptr1] = myval, 8 // store
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cmp.le p_y, p_n = 16, cnt //
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add cnt = -8, cnt // subtract
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;; }
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{ .mmi
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(p_y) store [ptr1] = myval, 8 // store
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(p_y) cmp.le.unc p_yy, p_nn = 16, cnt //
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(p_y) add cnt = -8, cnt // subtract
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;; }
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{ .mmi // store
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(p_yy) store [ptr1] = myval, 8 //
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(p_yy) add cnt = -8, cnt // subtract
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;; }
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.move_bytes_from_alignment:
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{ .mib
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cmp.eq p_scr, p0 = cnt, r0
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tbit.nz.unc p_y, p0 = cnt, 2 // should we terminate with a st4 ?
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(p_scr) br.cond.dpnt.few .restore_and_exit
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;; }
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{ .mib
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(p_y) st4 [ptr1] = value, 4
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tbit.nz.unc p_yy, p0 = cnt, 1 // should we terminate with a st2 ?
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;; }
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{ .mib
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(p_yy) st2 [ptr1] = value, 2
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tbit.nz.unc p_y, p0 = cnt, 0
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;; }
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{ .mib
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(p_y) st1 [ptr1] = value
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;; }
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.restore_and_exit:
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{ .mib
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nop.m 0
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movi0 ar.lc = save_lc
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br.ret.sptk.many rp
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;; }
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.move_bytes_unaligned:
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{ .mmi
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.pred.rel "mutex",p_y, p_n
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.pred.rel "mutex",p_yy, p_nn
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(p_n) cmp.le p_yy, p_nn = 4, cnt
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(p_y) cmp.le p_yy, p_nn = 5, cnt
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(p_n) add ptr2 = 2, ptr1
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} { .mmi
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(p_y) add ptr2 = 3, ptr1
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(p_y) st1 [ptr1] = value, 1 // fill 1 (odd-aligned) byte
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(p_y) add cnt = -1, cnt // [15, 14 (or less) left]
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;; }
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{ .mmi
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(p_yy) cmp.le.unc p_y, p0 = 8, cnt
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add ptr3 = ptr1, cnt // prepare last store
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movi0 ar.lc = save_lc
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} { .mmi
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(p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes
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(p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes
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(p_yy) add cnt = -4, cnt // [11, 10 (o less) left]
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;; }
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{ .mmi
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(p_y) cmp.le.unc p_yy, p0 = 8, cnt
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add ptr3 = -1, ptr3 // last store
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tbit.nz p_scr, p0 = cnt, 1 // will there be a st2 at the end ?
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} { .mmi
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(p_y) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes
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(p_y) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes
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(p_y) add cnt = -4, cnt // [7, 6 (or less) left]
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;; }
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{ .mmi
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(p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes
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(p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes
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// [3, 2 (or less) left]
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tbit.nz p_y, p0 = cnt, 0 // will there be a st1 at the end ?
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} { .mmi
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(p_yy) add cnt = -4, cnt
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;; }
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{ .mmb
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(p_scr) st2 [ptr1] = value // fill 2 (aligned) bytes
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(p_y) st1 [ptr3] = value // fill last byte (using ptr3)
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br.ret.sptk.many rp
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;; }
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END(memset)
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libc_hidden_builtin_def (memset)
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