github.com/ice-blockchain/go/src@v0.0.0-20240403114104-1564d284e521/runtime/memmove_386.s (about)

     1  // Inferno's libkern/memmove-386.s
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/memmove-386.s
     3  //
     4  //         Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
     5  //         Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
     6  //         Portions Copyright 2009 The Go Authors. All rights reserved.
     7  //
     8  // Permission is hereby granted, free of charge, to any person obtaining a copy
     9  // of this software and associated documentation files (the "Software"), to deal
    10  // in the Software without restriction, including without limitation the rights
    11  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    12  // copies of the Software, and to permit persons to whom the Software is
    13  // furnished to do so, subject to the following conditions:
    14  //
    15  // The above copyright notice and this permission notice shall be included in
    16  // all copies or substantial portions of the Software.
    17  //
    18  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    19  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    20  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    21  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    22  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    23  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    24  // THE SOFTWARE.
    25  
    26  //go:build !plan9
    27  
    28  #include "go_asm.h"
    29  #include "textflag.h"
    30  
    31  // See memmove Go doc for important implementation constraints.
    32  
    33  // func memmove(to, from unsafe.Pointer, n uintptr)
    34  TEXT runtime·memmove(SB), NOSPLIT, $0-12
    35  	MOVL	to+0(FP), DI
    36  	MOVL	from+4(FP), SI
    37  	MOVL	n+8(FP), BX
    38  
    39  	// REP instructions have a high startup cost, so we handle small sizes
    40  	// with some straightline code. The REP MOVSL instruction is really fast
    41  	// for large sizes. The cutover is approximately 1K.  We implement up to
    42  	// 128 because that is the maximum SSE register load (loading all data
    43  	// into registers lets us ignore copy direction).
    44  tail:
    45  	// BSR+branch table make almost all memmove/memclr benchmarks worse. Not worth doing.
    46  	TESTL	BX, BX
    47  	JEQ	move_0
    48  	CMPL	BX, $2
    49  	JBE	move_1or2
    50  	CMPL	BX, $4
    51  	JB	move_3
    52  	JE	move_4
    53  	CMPL	BX, $8
    54  	JBE	move_5through8
    55  	CMPL	BX, $16
    56  	JBE	move_9through16
    57  #ifdef GO386_softfloat
    58  	JMP	nosse2
    59  #endif
    60  	CMPL	BX, $32
    61  	JBE	move_17through32
    62  	CMPL	BX, $64
    63  	JBE	move_33through64
    64  	CMPL	BX, $128
    65  	JBE	move_65through128
    66  
    67  nosse2:
    68  /*
    69   * check and set for backwards
    70   */
    71  	CMPL	SI, DI
    72  	JLS	back
    73  
    74  /*
    75   * forward copy loop
    76   */
    77  forward:
    78  	// If REP MOVSB isn't fast, don't use it
    79  	CMPB	internal∕cpu·X86+const_offsetX86HasERMS(SB), $1 // enhanced REP MOVSB/STOSB
    80  	JNE	fwdBy4
    81  
    82  	// Check alignment
    83  	MOVL	SI, AX
    84  	ORL	DI, AX
    85  	TESTL	$3, AX
    86  	JEQ	fwdBy4
    87  
    88  	// Do 1 byte at a time
    89  	MOVL	BX, CX
    90  	REP;	MOVSB
    91  	RET
    92  
    93  fwdBy4:
    94  	// Do 4 bytes at a time
    95  	MOVL	BX, CX
    96  	SHRL	$2, CX
    97  	ANDL	$3, BX
    98  	REP;	MOVSL
    99  	JMP	tail
   100  
   101  /*
   102   * check overlap
   103   */
   104  back:
   105  	MOVL	SI, CX
   106  	ADDL	BX, CX
   107  	CMPL	CX, DI
   108  	JLS	forward
   109  /*
   110   * whole thing backwards has
   111   * adjusted addresses
   112   */
   113  
   114  	ADDL	BX, DI
   115  	ADDL	BX, SI
   116  	STD
   117  
   118  /*
   119   * copy
   120   */
   121  	MOVL	BX, CX
   122  	SHRL	$2, CX
   123  	ANDL	$3, BX
   124  
   125  	SUBL	$4, DI
   126  	SUBL	$4, SI
   127  	REP;	MOVSL
   128  
   129  	CLD
   130  	ADDL	$4, DI
   131  	ADDL	$4, SI
   132  	SUBL	BX, DI
   133  	SUBL	BX, SI
   134  	JMP	tail
   135  
   136  move_1or2:
   137  	MOVB	(SI), AX
   138  	MOVB	-1(SI)(BX*1), CX
   139  	MOVB	AX, (DI)
   140  	MOVB	CX, -1(DI)(BX*1)
   141  	RET
   142  move_0:
   143  	RET
   144  move_3:
   145  	MOVW	(SI), AX
   146  	MOVB	2(SI), CX
   147  	MOVW	AX, (DI)
   148  	MOVB	CX, 2(DI)
   149  	RET
   150  move_4:
   151  	// We need a separate case for 4 to make sure we write pointers atomically.
   152  	MOVL	(SI), AX
   153  	MOVL	AX, (DI)
   154  	RET
   155  move_5through8:
   156  	MOVL	(SI), AX
   157  	MOVL	-4(SI)(BX*1), CX
   158  	MOVL	AX, (DI)
   159  	MOVL	CX, -4(DI)(BX*1)
   160  	RET
   161  move_9through16:
   162  	MOVL	(SI), AX
   163  	MOVL	4(SI), CX
   164  	MOVL	-8(SI)(BX*1), DX
   165  	MOVL	-4(SI)(BX*1), BP
   166  	MOVL	AX, (DI)
   167  	MOVL	CX, 4(DI)
   168  	MOVL	DX, -8(DI)(BX*1)
   169  	MOVL	BP, -4(DI)(BX*1)
   170  	RET
   171  move_17through32:
   172  	MOVOU	(SI), X0
   173  	MOVOU	-16(SI)(BX*1), X1
   174  	MOVOU	X0, (DI)
   175  	MOVOU	X1, -16(DI)(BX*1)
   176  	RET
   177  move_33through64:
   178  	MOVOU	(SI), X0
   179  	MOVOU	16(SI), X1
   180  	MOVOU	-32(SI)(BX*1), X2
   181  	MOVOU	-16(SI)(BX*1), X3
   182  	MOVOU	X0, (DI)
   183  	MOVOU	X1, 16(DI)
   184  	MOVOU	X2, -32(DI)(BX*1)
   185  	MOVOU	X3, -16(DI)(BX*1)
   186  	RET
   187  move_65through128:
   188  	MOVOU	(SI), X0
   189  	MOVOU	16(SI), X1
   190  	MOVOU	32(SI), X2
   191  	MOVOU	48(SI), X3
   192  	MOVOU	-64(SI)(BX*1), X4
   193  	MOVOU	-48(SI)(BX*1), X5
   194  	MOVOU	-32(SI)(BX*1), X6
   195  	MOVOU	-16(SI)(BX*1), X7
   196  	MOVOU	X0, (DI)
   197  	MOVOU	X1, 16(DI)
   198  	MOVOU	X2, 32(DI)
   199  	MOVOU	X3, 48(DI)
   200  	MOVOU	X4, -64(DI)(BX*1)
   201  	MOVOU	X5, -48(DI)(BX*1)
   202  	MOVOU	X6, -32(DI)(BX*1)
   203  	MOVOU	X7, -16(DI)(BX*1)
   204  	RET