1 // Copyright 2013 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 // This could use MOVSQ, but we use MOVSL so that if an object ends in 8 // a 4 byte pointer, we copy it as a unit instead of byte by byte. 9 10 TEXT runtimememmove(SB), NOSPLIT, $0-12 11 MOVL to+0(FP), DI 12 MOVL from+4(FP), SI 13 MOVL n+8(FP), BX 14 15 CMPL SI, DI 16 JLS back 17 18 forward: 19 MOVL BX, CX 20 SHRL $2, CX 21 ANDL $3, BX 22 REP; MOVSL 23 MOVL BX, CX 24 REP; MOVSB 25 RET 26 27 back: 28 MOVL SI, CX 29 ADDL BX, CX 30 CMPL CX, DI 31 JLS forward 32 33 ADDL BX, DI 34 ADDL BX, SI 35 STD 36 37 MOVL BX, CX 38 SHRL $2, CX 39 ANDL $3, BX 40 SUBL $4, DI 41 SUBL $4, SI 42 REP; MOVSL 43 ADDL $3, DI 44 ADDL $3, SI 45 MOVL BX, CX 46 REP; MOVSB 47 CLD 48 49 // Note: we copy only 4 bytes at a time so that the tail is at most 50 // 3 bytes. That guarantees that we aren't copying pointers with MOVSB. 51 // See issue 13160. 52 RET 53
