memclr_riscv64.s

Documentation: runtime

     1// Copyright 2016 The Go Authors. All rights reserved.
     2// Use of this source code is governed by a BSD-style
     3// license that can be found in the LICENSE file.
     4
     5#include "textflag.h"
     6
     7// See memclrNoHeapPointers Go doc for important implementation constraints.
     8
     9// void runtime·memclrNoHeapPointers(void*, uintptr)
    10TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
    11	// X10 = ptr
    12	// X11 = n
    13
    14	// If less than 8 bytes, do single byte zeroing.
    15	MOV	$8, X9
    16	BLT	X11, X9, check4
    17
    18	// Check alignment
    19	AND	$7, X10, X5
    20	BEQZ	X5, aligned
    21
    22	// Zero one byte at a time until we reach 8 byte alignment.
    23	SUB	X5, X9, X5
    24	SUB	X5, X11, X11
    25align:
    26	SUB	$1, X5
    27	MOVB	ZERO, 0(X10)
    28	ADD	$1, X10
    29	BNEZ	X5, align
    30
    31aligned:
    32	// X9 already contains $8
    33	BLT	X11, X9, check4
    34	MOV	$16, X9
    35	BLT	X11, X9, zero8
    36	MOV	$32, X9
    37	BLT	X11, X9, zero16
    38	MOV	$64, X9
    39	BLT	X11, X9, zero32
    40loop64:
    41	MOV	ZERO, 0(X10)
    42	MOV	ZERO, 8(X10)
    43	MOV	ZERO, 16(X10)
    44	MOV	ZERO, 24(X10)
    45	MOV	ZERO, 32(X10)
    46	MOV	ZERO, 40(X10)
    47	MOV	ZERO, 48(X10)
    48	MOV	ZERO, 56(X10)
    49	ADD	$64, X10
    50	SUB	$64, X11
    51	BGE	X11, X9, loop64
    52	BEQZ	X11, done
    53
    54check32:
    55	MOV	$32, X9
    56	BLT	X11, X9, check16
    57zero32:
    58	MOV	ZERO, 0(X10)
    59	MOV	ZERO, 8(X10)
    60	MOV	ZERO, 16(X10)
    61	MOV	ZERO, 24(X10)
    62	ADD	$32, X10
    63	SUB	$32, X11
    64	BEQZ	X11, done
    65
    66check16:
    67	MOV	$16, X9
    68	BLT	X11, X9, check8
    69zero16:
    70	MOV	ZERO, 0(X10)
    71	MOV	ZERO, 8(X10)
    72	ADD	$16, X10
    73	SUB	$16, X11
    74	BEQZ	X11, done
    75
    76check8:
    77	MOV	$8, X9
    78	BLT	X11, X9, check4
    79zero8:
    80	MOV	ZERO, 0(X10)
    81	ADD	$8, X10
    82	SUB	$8, X11
    83	BEQZ	X11, done
    84
    85check4:
    86	MOV	$4, X9
    87	BLT	X11, X9, loop1
    88zero4:
    89	MOVB	ZERO, 0(X10)
    90	MOVB	ZERO, 1(X10)
    91	MOVB	ZERO, 2(X10)
    92	MOVB	ZERO, 3(X10)
    93	ADD	$4, X10
    94	SUB	$4, X11
    95
    96loop1:
    97	BEQZ	X11, done
    98	MOVB	ZERO, 0(X10)
    99	ADD	$1, X10
   100	SUB	$1, X11
   101	JMP	loop1
   102
   103done:
   104	RET
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