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+/* Optimized version of the standard memset() function.
+ This file is part of the GNU C Library.
+ Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
+ Contributed by Dan Pop for Itanium <Dan.Pop@cern.ch>.
+ Rewritten for McKinley by Sverre Jarp, HP Labs/CERN <Sverre.Jarp@cern.ch>
+
+ 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+/* Return: dest
+
+ Inputs:
+ in0: dest
+ in1: value
+ in2: count
+
+ The algorithm is fairly straightforward: set byte by byte until we
+ we get to a 16B-aligned address, then loop on 128 B chunks using an
+ early store as prefetching, then loop on 32B chucks, then clear remaining
+ words, finally clear remaining bytes.
+ Since a stf.spill f0 can store 16B in one go, we use this instruction
+ to get peak speed when value = 0. */
+
+#include <sysdep.h>
+#undef ret
+
+#define dest in0
+#define value in1
+#define cnt in2
+
+#define tmp r31
+#define save_lc r30
+#define ptr0 r29
+#define ptr1 r28
+#define ptr2 r27
+#define ptr3 r26
+#define ptr9 r24
+#define loopcnt r23
+#define linecnt r22
+#define bytecnt r21
+
+#define fvalue f6
+
+// This routine uses only scratch predicate registers (p6 - p15)
+#define p_scr p6 // default register for same-cycle branches
+#define p_nz p7
+#define p_zr p8
+#define p_unalgn p9
+#define p_y p11
+#define p_n p12
+#define p_yy p13
+#define p_nn p14
+
+#define movi0 mov
+
+#define MIN1 15
+#define MIN1P1HALF 8
+#define LINE_SIZE 128
+#define LSIZE_SH 7 // shift amount
+#define PREF_AHEAD 8
+
+#define USE_FLP
+#if defined(USE_INT)
+#define store st8
+#define myval value
+#elif defined(USE_FLP)
+#define store stf8
+#define myval fvalue
+#endif
+
+.align 64
+ENTRY(memset)
+{ .mmi
+ .prologue
+ alloc tmp = ar.pfs, 3, 0, 0, 0
+ lfetch.nt1 [dest]
+ .save ar.lc, save_lc
+ movi0 save_lc = ar.lc
+} { .mmi
+ .body
+ mov ret0 = dest // return value
+ cmp.ne p_nz, p_zr = value, r0 // use stf.spill if value is zero
+ cmp.eq p_scr, p0 = cnt, r0
+;; }
+{ .mmi
+ and ptr2 = -(MIN1+1), dest // aligned address
+ and tmp = MIN1, dest // prepare to check for alignment
+ tbit.nz p_y, p_n = dest, 0 // Do we have an odd address? (M_B_U)
+} { .mib
+ mov ptr1 = dest
+ mux1 value = value, @brcst // create 8 identical bytes in word
+(p_scr) br.ret.dpnt.many rp // return immediately if count = 0
+;; }
+{ .mib
+ cmp.ne p_unalgn, p0 = tmp, r0
+} { .mib // NB: # of bytes to move is 1 higher
+ sub bytecnt = (MIN1+1), tmp // than loopcnt
+ cmp.gt p_scr, p0 = 16, cnt // is it a minimalistic task?
+(p_scr) br.cond.dptk.many .move_bytes_unaligned // go move just a few (M_B_U)
+;; }
+{ .mmi
+(p_unalgn) add ptr1 = (MIN1+1), ptr2 // after alignment
+(p_unalgn) add ptr2 = MIN1P1HALF, ptr2 // after alignment
+(p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 3 // should we do a st8 ?
+;; }
+{ .mib
+(p_y) add cnt = -8, cnt
+(p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 2 // should we do a st4 ?
+} { .mib
+(p_y) st8 [ptr2] = value, -4
+(p_n) add ptr2 = 4, ptr2
+;; }
+{ .mib
+(p_yy) add cnt = -4, cnt
+(p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 1 // should we do a st2 ?
+} { .mib
+(p_yy) st4 [ptr2] = value, -2
+(p_nn) add ptr2 = 2, ptr2
+;; }
+{ .mmi
+ mov tmp = LINE_SIZE+1 // for compare
+(p_y) add cnt = -2, cnt
+(p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 0 // should we do a st1 ?
+} { .mmi
+ setf.sig fvalue=value // transfer value to FLP side
+(p_y) st2 [ptr2] = value, -1
+(p_n) add ptr2 = 1, ptr2
+;; }
+
+{ .mmi
+(p_yy) st1 [ptr2] = value
+ cmp.gt p_scr, p0 = tmp, cnt // is it a minimalistic task?
+} { .mbb
+(p_yy) add cnt = -1, cnt
+(p_scr) br.cond.dpnt.many .fraction_of_line // go move just a few
+;; }
+
+{ .mib
+ nop.m 0
+ shr.u linecnt = cnt, LSIZE_SH
+(p_zr) br.cond.dptk.many .l1b // Jump to use stf.spill
+;; }
+
+#ifndef GAS_ALIGN_BREAKS_UNWIND_INFO
+ .align 32 // -------- // L1A: store ahead into cache lines; fill later
+#endif
+{ .mmi
+ and tmp = -(LINE_SIZE), cnt // compute end of range
+ mov ptr9 = ptr1 // used for prefetching
+ and cnt = (LINE_SIZE-1), cnt // remainder
+} { .mmi
+ mov loopcnt = PREF_AHEAD-1 // default prefetch loop
+ cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value
+;; }
+{ .mmi
+(p_scr) add loopcnt = -1, linecnt // start of stores
+ add ptr2 = 8, ptr1 // (beyond prefetch stores)
+ add ptr1 = tmp, ptr1 // first address beyond total
+;; } // range
+{ .mmi
+ add tmp = -1, linecnt // next loop count
+ movi0 ar.lc = loopcnt
+;; }
+.pref_l1a:
+{ .mib
+ store [ptr9] = myval, 128 // Do stores one cache line apart
+ nop.i 0
+ br.cloop.dptk.few .pref_l1a
+;; }
+{ .mmi
+ add ptr0 = 16, ptr2 // Two stores in parallel
+ movi0 ar.lc = tmp
+;; }
+.l1ax:
+ { .mmi
+ store [ptr2] = myval, 8
+ store [ptr0] = myval, 8
+ ;; }
+ { .mmi
+ store [ptr2] = myval, 24
+ store [ptr0] = myval, 24
+ ;; }
+ { .mmi
+ store [ptr2] = myval, 8
+ store [ptr0] = myval, 8
+ ;; }
+ { .mmi
+ store [ptr2] = myval, 24
+ store [ptr0] = myval, 24
+ ;; }
+ { .mmi
+ store [ptr2] = myval, 8
+ store [ptr0] = myval, 8
+ ;; }
+ { .mmi
+ store [ptr2] = myval, 24
+ store [ptr0] = myval, 24
+ ;; }
+ { .mmi
+ store [ptr2] = myval, 8
+ store [ptr0] = myval, 32
+ cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching?
+ ;; }
+{ .mmb
+ store [ptr2] = myval, 24
+(p_scr) store [ptr9] = myval, 128
+ br.cloop.dptk.few .l1ax
+;; }
+{ .mbb
+ cmp.le p_scr, p0 = 8, cnt // just a few bytes left ?
+(p_scr) br.cond.dpnt.many .fraction_of_line // Branch no. 2
+ br.cond.dpnt.many .move_bytes_from_alignment // Branch no. 3
+;; }
+
+#ifdef GAS_ALIGN_BREAKS_UNWIND_INFO
+ { nop 0 }
+#else
+ .align 32
+#endif
+.l1b: // ------------------ // L1B: store ahead into cache lines; fill later
+{ .mmi
+ and tmp = -(LINE_SIZE), cnt // compute end of range
+ mov ptr9 = ptr1 // used for prefetching
+ and cnt = (LINE_SIZE-1), cnt // remainder
+} { .mmi
+ mov loopcnt = PREF_AHEAD-1 // default prefetch loop
+ cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value
+;; }
+{ .mmi
+(p_scr) add loopcnt = -1, linecnt
+ add ptr2 = 16, ptr1 // start of stores (beyond prefetch stores)
+ add ptr1 = tmp, ptr1 // first address beyond total range
+;; }
+{ .mmi
+ add tmp = -1, linecnt // next loop count
+ movi0 ar.lc = loopcnt
+;; }
+.pref_l1b:
+{ .mib
+ stf.spill [ptr9] = f0, 128 // Do stores one cache line apart
+ nop.i 0
+ br.cloop.dptk.few .pref_l1b
+;; }
+{ .mmi
+ add ptr0 = 16, ptr2 // Two stores in parallel
+ movi0 ar.lc = tmp
+;; }
+.l1bx:
+ { .mmi
+ stf.spill [ptr2] = f0, 32
+ stf.spill [ptr0] = f0, 32
+ ;; }
+ { .mmi
+ stf.spill [ptr2] = f0, 32
+ stf.spill [ptr0] = f0, 32
+ ;; }
+ { .mmi
+ stf.spill [ptr2] = f0, 32
+ stf.spill [ptr0] = f0, 64
+ cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching?
+ ;; }
+{ .mmb
+ stf.spill [ptr2] = f0, 32
+(p_scr) stf.spill [ptr9] = f0, 128
+ br.cloop.dptk.few .l1bx
+;; }
+{ .mib
+ cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ?
+(p_scr) br.cond.dpnt.many .move_bytes_from_alignment
+;; }
+
+.fraction_of_line:
+{ .mib
+ add ptr2 = 16, ptr1
+ shr.u loopcnt = cnt, 5 // loopcnt = cnt / 32
+;; }
+{ .mib
+ cmp.eq p_scr, p0 = loopcnt, r0
+ add loopcnt = -1, loopcnt
+(p_scr) br.cond.dpnt.many store_words
+;; }
+{ .mib
+ and cnt = 0x1f, cnt // compute the remaining cnt
+ movi0 ar.lc = loopcnt
+;; }
+#ifndef GAS_ALIGN_BREAKS_UNWIND_INFO
+ .align 32
+#endif
+.l2: // ---------------------------- // L2A: store 32B in 2 cycles
+{ .mmb
+ store [ptr1] = myval, 8
+ store [ptr2] = myval, 8
+;; } { .mmb
+ store [ptr1] = myval, 24
+ store [ptr2] = myval, 24
+ br.cloop.dptk.many .l2
+;; }
+store_words:
+{ .mib
+ cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ?
+(p_scr) br.cond.dpnt.many .move_bytes_from_alignment // Branch
+;; }
+
+{ .mmi
+ store [ptr1] = myval, 8 // store
+ cmp.le p_y, p_n = 16, cnt //
+ add cnt = -8, cnt // subtract
+;; }
+{ .mmi
+(p_y) store [ptr1] = myval, 8 // store
+(p_y) cmp.le.unc p_yy, p_nn = 16, cnt //
+(p_y) add cnt = -8, cnt // subtract
+;; }
+{ .mmi // store
+(p_yy) store [ptr1] = myval, 8 //
+(p_yy) add cnt = -8, cnt // subtract
+;; }
+
+.move_bytes_from_alignment:
+{ .mib
+ cmp.eq p_scr, p0 = cnt, r0
+ tbit.nz.unc p_y, p0 = cnt, 2 // should we terminate with a st4 ?
+(p_scr) br.cond.dpnt.few .restore_and_exit
+;; }
+{ .mib
+(p_y) st4 [ptr1] = value, 4
+ tbit.nz.unc p_yy, p0 = cnt, 1 // should we terminate with a st2 ?
+;; }
+{ .mib
+(p_yy) st2 [ptr1] = value, 2
+ tbit.nz.unc p_y, p0 = cnt, 0
+;; }
+
+{ .mib
+(p_y) st1 [ptr1] = value
+;; }
+.restore_and_exit:
+{ .mib
+ nop.m 0
+ movi0 ar.lc = save_lc
+ br.ret.sptk.many rp
+;; }
+
+.move_bytes_unaligned:
+{ .mmi
+ .pred.rel "mutex",p_y, p_n
+ .pred.rel "mutex",p_yy, p_nn
+(p_n) cmp.le p_yy, p_nn = 4, cnt
+(p_y) cmp.le p_yy, p_nn = 5, cnt
+(p_n) add ptr2 = 2, ptr1
+} { .mmi
+(p_y) add ptr2 = 3, ptr1
+(p_y) st1 [ptr1] = value, 1 // fill 1 (odd-aligned) byte
+(p_y) add cnt = -1, cnt // [15, 14 (or less) left]
+;; }
+{ .mmi
+(p_yy) cmp.le.unc p_y, p0 = 8, cnt
+ add ptr3 = ptr1, cnt // prepare last store
+ movi0 ar.lc = save_lc
+} { .mmi
+(p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes
+(p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes
+(p_yy) add cnt = -4, cnt // [11, 10 (o less) left]
+;; }
+{ .mmi
+(p_y) cmp.le.unc p_yy, p0 = 8, cnt
+ add ptr3 = -1, ptr3 // last store
+ tbit.nz p_scr, p0 = cnt, 1 // will there be a st2 at the end ?
+} { .mmi
+(p_y) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes
+(p_y) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes
+(p_y) add cnt = -4, cnt // [7, 6 (or less) left]
+;; }
+{ .mmi
+(p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes
+(p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes
+ // [3, 2 (or less) left]
+ tbit.nz p_y, p0 = cnt, 0 // will there be a st1 at the end ?
+} { .mmi
+(p_yy) add cnt = -4, cnt
+;; }
+{ .mmb
+(p_scr) st2 [ptr1] = value // fill 2 (aligned) bytes
+(p_y) st1 [ptr3] = value // fill last byte (using ptr3)
+ br.ret.sptk.many rp
+;; }
+END(memset)
+libc_hidden_def (memset)
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-10 13:22:38 +0000