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bc9e160443
6a and 8a rearrange memmove such that the fallthrough from move_1or2 to move_0 ends up being a JMP to a RET. Insert an explicit RET to prevent such silliness. Do the same for memclr as prophylaxis. benchmark old ns/op new ns/op delta BenchmarkMemmove1 4.59 4.13 -10.02% BenchmarkMemmove2 4.58 4.13 -9.83% LGTM=khr R=golang-codereviews, dvyukov, minux, ruiu, bradfitz, khr CC=golang-codereviews https://golang.org/cl/120930043
52 lines
828 B
ArmAsm
52 lines
828 B
ArmAsm
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "../../cmd/ld/textflag.h"
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// void runtime·memclr(void*, uintptr)
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TEXT runtime·memclr(SB), NOSPLIT, $0-8
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MOVL ptr+0(FP), DI
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MOVL n+4(FP), BX
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XORL AX, AX
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clr_tail:
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TESTL BX, BX
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JEQ clr_0
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CMPL BX, $2
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JBE clr_1or2
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CMPL BX, $4
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JBE clr_3or4
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CMPL BX, $8
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JBE clr_5through8
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CMPL BX, $16
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JBE clr_9through16
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MOVL BX, CX
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SHRL $2, CX
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REP
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STOSL
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ANDL $3, BX
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JNE clr_tail
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RET
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clr_1or2:
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MOVB AX, (DI)
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MOVB AX, -1(DI)(BX*1)
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RET
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clr_0:
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RET
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clr_3or4:
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MOVW AX, (DI)
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MOVW AX, -2(DI)(BX*1)
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RET
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clr_5through8:
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MOVL AX, (DI)
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MOVL AX, -4(DI)(BX*1)
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RET
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clr_9through16:
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MOVL AX, (DI)
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MOVL AX, 4(DI)
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MOVL AX, -8(DI)(BX*1)
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MOVL AX, -4(DI)(BX*1)
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RET
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