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Diffstat (limited to 'src/runtime/memmove_plan9_amd64.s')
| -rw-r--r-- | src/runtime/memmove_plan9_amd64.s | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/src/runtime/memmove_plan9_amd64.s b/src/runtime/memmove_plan9_amd64.s new file mode 100644 index 0000000..217aa60 --- /dev/null +++ b/src/runtime/memmove_plan9_amd64.s @@ -0,0 +1,135 @@ +// Derived from Inferno's libkern/memmove-386.s (adapted for amd64) +// https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/memmove-386.s +// +// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. +// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. +// Portions Copyright 2009 The Go Authors. All rights reserved. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +#include "textflag.h" + +// See memmove Go doc for important implementation constraints. + +// func memmove(to, from unsafe.Pointer, n uintptr) +TEXT runtime·memmove(SB), NOSPLIT, $0-24 + + MOVQ to+0(FP), DI + MOVQ from+8(FP), SI + MOVQ n+16(FP), BX + + // REP instructions have a high startup cost, so we handle small sizes + // with some straightline code. The REP MOVSQ instruction is really fast + // for large sizes. The cutover is approximately 1K. +tail: + TESTQ BX, BX + JEQ move_0 + CMPQ BX, $2 + JBE move_1or2 + CMPQ BX, $4 + JBE move_3or4 + CMPQ BX, $8 + JB move_5through7 + JE move_8 + CMPQ BX, $16 + JBE move_9through16 + +/* + * check and set for backwards + */ + CMPQ SI, DI + JLS back + +/* + * forward copy loop + */ +forward: + MOVQ BX, CX + SHRQ $3, CX + ANDQ $7, BX + + REP; MOVSQ + JMP tail + +back: +/* + * check overlap + */ + MOVQ SI, CX + ADDQ BX, CX + CMPQ CX, DI + JLS forward + +/* + * whole thing backwards has + * adjusted addresses + */ + ADDQ BX, DI + ADDQ BX, SI + STD + +/* + * copy + */ + MOVQ BX, CX + SHRQ $3, CX + ANDQ $7, BX + + SUBQ $8, DI + SUBQ $8, SI + REP; MOVSQ + + CLD + ADDQ $8, DI + ADDQ $8, SI + SUBQ BX, DI + SUBQ BX, SI + JMP tail + +move_1or2: + MOVB (SI), AX + MOVB -1(SI)(BX*1), CX + MOVB AX, (DI) + MOVB CX, -1(DI)(BX*1) + RET +move_0: + RET +move_3or4: + MOVW (SI), AX + MOVW -2(SI)(BX*1), CX + MOVW AX, (DI) + MOVW CX, -2(DI)(BX*1) + RET +move_5through7: + MOVL (SI), AX + MOVL -4(SI)(BX*1), CX + MOVL AX, (DI) + MOVL CX, -4(DI)(BX*1) + RET +move_8: + // We need a separate case for 8 to make sure we write pointers atomically. + MOVQ (SI), AX + MOVQ AX, (DI) + RET +move_9through16: + MOVQ (SI), AX + MOVQ -8(SI)(BX*1), CX + MOVQ AX, (DI) + MOVQ CX, -8(DI)(BX*1) + RET |