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+/* SPDX-License-Identifier: GPL-2.0 */
+/* Optimized version of the standard memset() function.
+
+ Copyright (c) 2002 Hewlett-Packard Co/CERN
+ Sverre Jarp <Sverre.Jarp@cern.ch>
+
+ 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 <asm/asmmacro.h>
+#include <asm/export.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 MIN1 15
+#define MIN1P1HALF 8
+#define LINE_SIZE 128
+#define LSIZE_SH 7 // shift amount
+#define PREF_AHEAD 8
+
+GLOBAL_ENTRY(memset)
+{ .mmi
+ .prologue
+ alloc tmp = ar.pfs, 3, 0, 0, 0
+ lfetch.nt1 [dest] //
+ .save ar.lc, save_lc
+ mov.i save_lc = ar.lc
+ .body
+} { .mmi
+ 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 correct 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
+ sub bytecnt = (MIN1+1), tmp // NB: # of bytes to move is 1 higher 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
+;; }
+
+ TEXT_ALIGN(32) // --------------------- // L1A: 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 = 8, ptr1 // start of stores (beyond prefetch stores)
+ add ptr1 = tmp, ptr1 // first address beyond total range
+;; }
+{ .mmi
+ add tmp = -1, linecnt // next loop count
+ mov.i ar.lc = loopcnt //
+;; }
+.pref_l1a:
+{ .mib
+ stf8 [ptr9] = fvalue, 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
+ mov.i ar.lc = tmp //
+;; }
+.l1ax:
+ { .mmi
+ stf8 [ptr2] = fvalue, 8
+ stf8 [ptr0] = fvalue, 8
+ ;; }
+ { .mmi
+ stf8 [ptr2] = fvalue, 24
+ stf8 [ptr0] = fvalue, 24
+ ;; }
+ { .mmi
+ stf8 [ptr2] = fvalue, 8
+ stf8 [ptr0] = fvalue, 8
+ ;; }
+ { .mmi
+ stf8 [ptr2] = fvalue, 24
+ stf8 [ptr0] = fvalue, 24
+ ;; }
+ { .mmi
+ stf8 [ptr2] = fvalue, 8
+ stf8 [ptr0] = fvalue, 8
+ ;; }
+ { .mmi
+ stf8 [ptr2] = fvalue, 24
+ stf8 [ptr0] = fvalue, 24
+ ;; }
+ { .mmi
+ stf8 [ptr2] = fvalue, 8
+ stf8 [ptr0] = fvalue, 32
+ cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching?
+ ;; }
+{ .mmb
+ stf8 [ptr2] = fvalue, 24
+(p_scr) stf8 [ptr9] = fvalue, 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
+;; }
+
+ TEXT_ALIGN(32)
+.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
+ mov.i 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
+ mov.i 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
+ mov.i ar.lc = loopcnt
+;; }
+ TEXT_ALIGN(32)
+.l2: // ------------------------------------ // L2A: store 32B in 2 cycles
+{ .mmb
+ stf8 [ptr1] = fvalue, 8
+ stf8 [ptr2] = fvalue, 8
+;; } { .mmb
+ stf8 [ptr1] = fvalue, 24
+ stf8 [ptr2] = fvalue, 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
+ stf8 [ptr1] = fvalue, 8 // store
+ cmp.le p_y, p_n = 16, cnt
+ add cnt = -8, cnt // subtract
+;; }
+{ .mmi
+(p_y) stf8 [ptr1] = fvalue, 8 // store
+(p_y) cmp.le.unc p_yy, p_nn = 16, cnt
+(p_y) add cnt = -8, cnt // subtract
+;; }
+{ .mmi // store
+(p_yy) stf8 [ptr1] = fvalue, 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 // should we terminate with a st1 ?
+;; }
+
+{ .mib
+(p_y) st1 [ptr1] = value
+;; }
+.restore_and_exit:
+{ .mib
+ nop.m 0
+ mov.i 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 [15, 14 (or less) left]
+(p_y) add cnt = -1, cnt
+;; }
+{ .mmi
+(p_yy) cmp.le.unc p_y, p0 = 8, cnt
+ add ptr3 = ptr1, cnt // prepare last store
+ mov.i 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 [11, 10 (o less) left]
+(p_yy) add cnt = -4, cnt
+;; }
+{ .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 [7, 6 (or less) left]
+(p_y) add cnt = -4, cnt
+;; }
+{ .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)
+EXPORT_SYMBOL(memset)
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