github.com/ice-blockchain/go/src@v0.0.0-20240403114104-1564d284e521/runtime/memmove_loong64.s (about)

     1  // Copyright 2022 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 memmove Go doc for important implementation constraints.
     8  
     9  // func memmove(to, from unsafe.Pointer, n uintptr)
    10  TEXT runtime·memmove<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-24
    11  #ifndef GOEXPERIMENT_regabiargs
    12  	MOVV	to+0(FP), R4
    13  	MOVV	from+8(FP), R5
    14  	MOVV	n+16(FP), R6
    15  #endif
    16  	BNE	R6, check
    17  	RET
    18  
    19  check:
    20  	SGTU	R4, R5, R7
    21  	BNE	R7, backward
    22  
    23  	ADDV	R4, R6, R9 // end pointer
    24  
    25  	// if the two pointers are not of same alignments, do byte copying
    26  	SUBVU	R5, R4, R7
    27  	AND	$7, R7
    28  	BNE	R7, out
    29  
    30  	// if less than 8 bytes, do byte copying
    31  	SGTU	$8, R6, R7
    32  	BNE	R7, out
    33  
    34  	// do one byte at a time until 8-aligned
    35  	AND	$7, R4, R8
    36  	BEQ	R8, words
    37  	MOVB	(R5), R7
    38  	ADDV	$1, R5
    39  	MOVB	R7, (R4)
    40  	ADDV	$1, R4
    41  	JMP	-6(PC)
    42  
    43  words:
    44  	// do 8 bytes at a time if there is room
    45  	ADDV	$-7, R9, R6 // R6 is end pointer-7
    46  
    47  	PCALIGN	$16
    48  	SGTU	R6, R4, R8
    49  	BEQ	R8, out
    50  	MOVV	(R5), R7
    51  	ADDV	$8, R5
    52  	MOVV	R7, (R4)
    53  	ADDV	$8, R4
    54  	JMP	-6(PC)
    55  
    56  out:
    57  	BEQ	R4, R9, done
    58  	MOVB	(R5), R7
    59  	ADDV	$1, R5
    60  	MOVB	R7, (R4)
    61  	ADDV	$1, R4
    62  	JMP	-5(PC)
    63  done:
    64  	RET
    65  
    66  backward:
    67  	ADDV	R6, R5 // from-end pointer
    68  	ADDV	R4, R6, R9 // to-end pointer
    69  
    70  	// if the two pointers are not of same alignments, do byte copying
    71  	SUBVU	R9, R5, R7
    72  	AND	$7, R7
    73  	BNE	R7, out1
    74  
    75  	// if less than 8 bytes, do byte copying
    76  	SGTU	$8, R6, R7
    77  	BNE	R7, out1
    78  
    79  	// do one byte at a time until 8-aligned
    80  	AND	$7, R9, R8
    81  	BEQ	R8, words1
    82  	ADDV	$-1, R5
    83  	MOVB	(R5), R7
    84  	ADDV	$-1, R9
    85  	MOVB	R7, (R9)
    86  	JMP	-6(PC)
    87  
    88  words1:
    89  	// do 8 bytes at a time if there is room
    90  	ADDV	$7, R4, R6 // R6 is start pointer+7
    91  
    92  	PCALIGN	$16
    93  	SGTU	R9, R6, R8
    94  	BEQ	R8, out1
    95  	ADDV	$-8, R5
    96  	MOVV	(R5), R7
    97  	ADDV	$-8, R9
    98  	MOVV	R7, (R9)
    99  	JMP	-6(PC)
   100  
   101  out1:
   102  	BEQ	R4, R9, done1
   103  	ADDV	$-1, R5
   104  	MOVB	(R5), R7
   105  	ADDV	$-1, R9
   106  	MOVB	R7, (R9)
   107  	JMP	-5(PC)
   108  done1:
   109  	RET