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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "go_asm.h"
#include "textflag.h"
// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal(SB),NOSPLIT,$0-13
MOVL a+0(FP), SI
MOVL b+4(FP), DI
CMPL SI, DI
JEQ eq
MOVL size+8(FP), BX
LEAL ret+12(FP), AX
JMP memeqbody<>(SB)
eq:
MOVB $1, ret+12(FP)
RET
// memequal_varlen(a, b unsafe.Pointer) bool
TEXT runtime·memequal_varlen(SB),NOSPLIT,$0-9
MOVL a+0(FP), SI
MOVL b+4(FP), DI
CMPL SI, DI
JEQ eq
MOVL 4(DX), BX // compiler stores size at offset 4 in the closure
LEAL ret+8(FP), AX
JMP memeqbody<>(SB)
eq:
MOVB $1, ret+8(FP)
RET
// a in SI
// b in DI
// count in BX
// address of result byte in AX
TEXT memeqbody<>(SB),NOSPLIT,$0-0
CMPL BX, $4
JB small
// 64 bytes at a time using xmm registers
hugeloop:
CMPL BX, $64
JB bigloop
CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
JNE bigloop
MOVOU (SI), X0
MOVOU (DI), X1
MOVOU 16(SI), X2
MOVOU 16(DI), X3
MOVOU 32(SI), X4
MOVOU 32(DI), X5
MOVOU 48(SI), X6
MOVOU 48(DI), X7
PCMPEQB X1, X0
PCMPEQB X3, X2
PCMPEQB X5, X4
PCMPEQB X7, X6
PAND X2, X0
PAND X6, X4
PAND X4, X0
PMOVMSKB X0, DX
ADDL $64, SI
ADDL $64, DI
SUBL $64, BX
CMPL DX, $0xffff
JEQ hugeloop
MOVB $0, (AX)
RET
// 4 bytes at a time using 32-bit register
bigloop:
CMPL BX, $4
JBE leftover
MOVL (SI), CX
MOVL (DI), DX
ADDL $4, SI
ADDL $4, DI
SUBL $4, BX
CMPL CX, DX
JEQ bigloop
MOVB $0, (AX)
RET
// remaining 0-4 bytes
leftover:
MOVL -4(SI)(BX*1), CX
MOVL -4(DI)(BX*1), DX
CMPL CX, DX
SETEQ (AX)
RET
small:
CMPL BX, $0
JEQ equal
LEAL 0(BX*8), CX
NEGL CX
MOVL SI, DX
CMPB DX, $0xfc
JA si_high
// load at SI won't cross a page boundary.
MOVL (SI), SI
JMP si_finish
si_high:
// address ends in 111111xx. Load up to bytes we want, move to correct position.
MOVL -4(SI)(BX*1), SI
SHRL CX, SI
si_finish:
// same for DI.
MOVL DI, DX
CMPB DX, $0xfc
JA di_high
MOVL (DI), DI
JMP di_finish
di_high:
MOVL -4(DI)(BX*1), DI
SHRL CX, DI
di_finish:
SUBL SI, DI
SHLL CX, DI
equal:
SETEQ (AX)
RET
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