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internal/lz4block: Copy literals of <=48 bytes through XMM registers in amd64 decoder #161

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merged 1 commit into from Jan 31, 2022
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internal/lz4block: Copy literals of <=48 bytes through XMM registers in amd64 decoder #161

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20 changes: 12 additions & 8 deletions internal/lz4block/decode_amd64.s
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Expand Up @@ -157,24 +157,28 @@ copy_literal:
CMPQ BX, R8
JA err_short_buf

// whats a good cut off to call memmove?
CMPQ CX, $16
// Copy matches of <=48 bytes through the XMM registers.
CMPQ CX, $48
JGT memmove_lit

// if len(dst[di:]) < 16
// if len(dst[di:]) < 48
MOVQ R8, AX
SUBQ DI, AX
CMPQ AX, $16
CMPQ AX, $48
JLT memmove_lit

// if len(src[si:]) < 16
MOVQ R9, AX
SUBQ SI, AX
CMPQ AX, $16
// if len(src[si:]) < 48
MOVQ R9, BX
SUBQ SI, BX
CMPQ BX, $48
JLT memmove_lit

MOVOU (SI), X0
MOVOU 16(SI), X1
MOVOU 32(SI), X2
MOVOU X0, (DI)
MOVOU X1, 16(DI)
MOVOU X2, 32(DI)

ADDQ CX, SI
ADDQ CX, DI
Expand Down