2014-03-12 19:12:25 -06:00
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// Derived from Inferno's libkern/memmove-386.s (adapted for amd64)
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// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
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//
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// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
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// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
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// Portions Copyright 2009 The Go Authors. All rights reserved.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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2014-09-04 21:05:18 -06:00
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#include "textflag.h"
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2014-03-12 19:12:25 -06:00
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// void runtime·memmove(void*, void*, uintptr)
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TEXT runtime·memmove(SB), NOSPLIT, $0-24
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MOVQ to+0(FP), DI
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cmd/cc, runtime: convert C compilers to use Go calling convention
To date, the C compilers and Go compilers differed only in how
values were returned from functions. This made it difficult to call
Go from C or C from Go if return values were involved. It also made
assembly called from Go and assembly called from C different.
This CL changes the C compiler to use the Go conventions, passing
results on the stack, after the arguments.
[Exception: this does not apply to C ... functions, because you can't
know where on the stack the arguments end.]
By doing this, the CL makes it possible to rewrite C functions into Go
one at a time, without worrying about which languages call that
function or which languages it calls.
This CL also updates all the assembly files in package runtime to use
the new conventions. Argument references of the form 40(SP) have
been rewritten to the form name+10(FP) instead, and there are now
Go func prototypes for every assembly function called from C or Go.
This means that 'go vet runtime' checks effectively every assembly
function, and go vet's output was used to automate the bulk of the
conversion.
Some functions, like seek and nsec on Plan 9, needed to be rewritten.
Many assembly routines called from C were reading arguments
incorrectly, using MOVL instead of MOVQ or vice versa, especially on
the less used systems like openbsd.
These were found by go vet and have been corrected too.
If we're lucky, this may reduce flakiness on those systems.
Tested on:
darwin/386
darwin/amd64
linux/arm
linux/386
linux/amd64
If this breaks another system, the bug is almost certainly in the
sys_$GOOS_$GOARCH.s file, since the rest of the CL is tested
by the combination of the above systems.
LGTM=dvyukov, iant
R=golang-codereviews, 0intro, dave, alex.brainman, dvyukov, iant
CC=golang-codereviews, josharian, r
https://golang.org/cl/135830043
2014-08-27 09:32:17 -06:00
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MOVQ from+8(FP), SI
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2014-03-12 19:12:25 -06:00
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MOVQ n+16(FP), BX
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// REP instructions have a high startup cost, so we handle small sizes
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// with some straightline code. The REP MOVSQ instruction is really fast
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// for large sizes. The cutover is approximately 1K.
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tail:
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TESTQ BX, BX
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JEQ move_0
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CMPQ BX, $2
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JBE move_1or2
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CMPQ BX, $4
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JBE move_3or4
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CMPQ BX, $8
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JBE move_5through8
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CMPQ BX, $16
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JBE move_9through16
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/*
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* check and set for backwards
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*/
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CMPQ SI, DI
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JLS back
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/*
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* forward copy loop
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*/
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forward:
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MOVQ BX, CX
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SHRQ $3, CX
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ANDQ $7, BX
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REP; MOVSQ
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JMP tail
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back:
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/*
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* check overlap
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*/
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MOVQ SI, CX
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ADDQ BX, CX
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CMPQ CX, DI
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JLS forward
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/*
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* whole thing backwards has
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* adjusted addresses
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*/
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ADDQ BX, DI
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ADDQ BX, SI
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STD
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/*
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* copy
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*/
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MOVQ BX, CX
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SHRQ $3, CX
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ANDQ $7, BX
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SUBQ $8, DI
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SUBQ $8, SI
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REP; MOVSQ
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CLD
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ADDQ $8, DI
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ADDQ $8, SI
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SUBQ BX, DI
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SUBQ BX, SI
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JMP tail
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move_1or2:
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MOVB (SI), AX
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MOVB -1(SI)(BX*1), CX
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MOVB AX, (DI)
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MOVB CX, -1(DI)(BX*1)
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2014-08-01 07:21:08 -06:00
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RET
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2014-03-12 19:12:25 -06:00
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move_0:
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RET
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move_3or4:
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MOVW (SI), AX
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MOVW -2(SI)(BX*1), CX
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MOVW AX, (DI)
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MOVW CX, -2(DI)(BX*1)
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RET
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move_5through8:
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MOVL (SI), AX
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MOVL -4(SI)(BX*1), CX
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MOVL AX, (DI)
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MOVL CX, -4(DI)(BX*1)
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RET
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move_9through16:
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MOVQ (SI), AX
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MOVQ -8(SI)(BX*1), CX
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MOVQ AX, (DI)
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MOVQ CX, -8(DI)(BX*1)
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RET
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