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diff --git a/src/runtime/memmove_mips64x.s b/src/runtime/memmove_mips64x.s
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+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips64 || mips64le
+
+#include "textflag.h"
+
+// See memmove Go doc for important implementation constraints.
+
+// func memmove(to, from unsafe.Pointer, n uintptr)
+TEXT runtime·memmove(SB), NOSPLIT|NOFRAME, $0-24
+ MOVV to+0(FP), R1
+ MOVV from+8(FP), R2
+ MOVV n+16(FP), R3
+ BNE R3, check
+ RET
+
+check:
+ SGTU R1, R2, R4
+ BNE R4, backward
+
+ ADDV R1, R3, R6 // end pointer
+
+ // if the two pointers are not of same alignments, do byte copying
+ SUBVU R2, R1, R4
+ AND $7, R4
+ BNE R4, out
+
+ // if less than 8 bytes, do byte copying
+ SGTU $8, R3, R4
+ BNE R4, out
+
+ // do one byte at a time until 8-aligned
+ AND $7, R1, R5
+ BEQ R5, words
+ MOVB (R2), R4
+ ADDV $1, R2
+ MOVB R4, (R1)
+ ADDV $1, R1
+ JMP -6(PC)
+
+words:
+ // do 8 bytes at a time if there is room
+ ADDV $-7, R6, R3 // R3 is end pointer-7
+
+ SGTU R3, R1, R5
+ BEQ R5, out
+ MOVV (R2), R4
+ ADDV $8, R2
+ MOVV R4, (R1)
+ ADDV $8, R1
+ JMP -6(PC)
+
+out:
+ BEQ R1, R6, done
+ MOVB (R2), R4
+ ADDV $1, R2
+ MOVB R4, (R1)
+ ADDV $1, R1
+ JMP -5(PC)
+done:
+ RET
+
+backward:
+ ADDV R3, R2 // from-end pointer
+ ADDV R1, R3, R6 // to-end pointer
+
+ // if the two pointers are not of same alignments, do byte copying
+ SUBVU R6, R2, R4
+ AND $7, R4
+ BNE R4, out1
+
+ // if less than 8 bytes, do byte copying
+ SGTU $8, R3, R4
+ BNE R4, out1
+
+ // do one byte at a time until 8-aligned
+ AND $7, R6, R5
+ BEQ R5, words1
+ ADDV $-1, R2
+ MOVB (R2), R4
+ ADDV $-1, R6
+ MOVB R4, (R6)
+ JMP -6(PC)
+
+words1:
+ // do 8 bytes at a time if there is room
+ ADDV $7, R1, R3 // R3 is start pointer+7
+
+ SGTU R6, R3, R5
+ BEQ R5, out1
+ ADDV $-8, R2
+ MOVV (R2), R4
+ ADDV $-8, R6
+ MOVV R4, (R6)
+ JMP -6(PC)
+
+out1:
+ BEQ R1, R6, done1
+ ADDV $-1, R2
+ MOVB (R2), R4
+ ADDV $-1, R6
+ MOVB R4, (R6)
+ JMP -5(PC)
+done1:
+ RET