43 lines
1.0 KiB
ArmAsm
43 lines
1.0 KiB
ArmAsm
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// Copyright (c) 2020 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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//go:build arm64 && gc && !purego
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#include "textflag.h"
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// carryPropagate works exactly like carryPropagateGeneric and uses the
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// same AND, ADD, and LSR+MADD instructions emitted by the compiler, but
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// avoids loading R0-R4 twice and uses LDP and STP.
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//
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// See https://golang.org/issues/43145 for the main compiler issue.
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//
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// func carryPropagate(v *Element)
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TEXT ·carryPropagate(SB),NOFRAME|NOSPLIT,$0-8
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MOVD v+0(FP), R20
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LDP 0(R20), (R0, R1)
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LDP 16(R20), (R2, R3)
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MOVD 32(R20), R4
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AND $0x7ffffffffffff, R0, R10
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AND $0x7ffffffffffff, R1, R11
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AND $0x7ffffffffffff, R2, R12
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AND $0x7ffffffffffff, R3, R13
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AND $0x7ffffffffffff, R4, R14
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ADD R0>>51, R11, R11
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ADD R1>>51, R12, R12
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ADD R2>>51, R13, R13
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ADD R3>>51, R14, R14
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// R4>>51 * 19 + R10 -> R10
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LSR $51, R4, R21
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MOVD $19, R22
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MADD R22, R10, R21, R10
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STP (R10, R11), 0(R20)
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STP (R12, R13), 16(R20)
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MOVD R14, 32(R20)
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RET
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