58 lines
1.4 KiB
ArmAsm
58 lines
1.4 KiB
ArmAsm
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: BSD-3-Clause
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#include "textflag.h"
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// The link-regression kernel for the amd64 SSE families: fold XOR-folds
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// every 16-byte block of a buffer into one octa with MOVOU and PXOR,
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// folds any remaining bytes with a scalar loop, combines the two octa
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// lanes with PEXTRQ, passes the total to mixq through the ABI0 stack slot
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// and XORs the seed into the returned mix. mixq multiplies by the odd
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// golden-ratio constant, the same arithmetic the Go side of the regression
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// mirrors bit for bit. The run claim is native: the host is amd64.
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// func mixq(x uint64) uint64
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TEXT ·mixq(SB), NOSPLIT, $0-16
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MOVQ x+0(FP), AX
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MOVQ $0x9e3779b97f4a7c15, CX
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IMULQ CX, AX
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MOVQ AX, ret+8(FP)
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RET
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// func fold(buf []byte, seed uint64) uint64
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TEXT ·fold(SB), NOSPLIT, $16-40
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MOVQ buf+0(FP), SI
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MOVQ buf_len+8(FP), CX
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MOVQ seed+24(FP), BX
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PXOR X1, X1
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XORQ AX, AX
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blocks:
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CMPQ CX, $16
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JB tail
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MOVOU (SI), X2
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PXOR X2, X1
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ADDQ $16, SI
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SUBQ $16, CX
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JMP blocks
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tail:
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TESTQ CX, CX
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JE gathered
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MOVBQZX (SI), DX
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ADDQ DX, AX
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ADDQ $1, SI
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SUBQ $1, CX
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JMP tail
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gathered:
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MOVQ X1, DX
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PEXTRQ $1, X1, CX
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ADDQ CX, DX
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ADDQ AX, DX
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MOVQ DX, 0(SP)
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CALL ·mixq(SB)
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MOVQ 8(SP), DX
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XORQ BX, DX
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MOVQ DX, ret+32(FP)
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RET
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