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Text file src/internal/bytealg/indexbyte_amd64.s

Documentation: internal/bytealg

     1// Copyright 2018 The Go Authors. All rights reserved.
     2// Use of this source code is governed by a BSD-style
     3// license that can be found in the LICENSE file.
     4
     5#include "go_asm.h"
     6#include "textflag.h"
     7
     8TEXT	·IndexByte(SB), NOSPLIT, $0-40
     9	MOVQ b_base+0(FP), SI
    10	MOVQ b_len+8(FP), BX
    11	MOVB c+24(FP), AL
    12	LEAQ ret+32(FP), R8
    13	JMP  indexbytebody<>(SB)
    14
    15TEXT	·IndexByteString(SB), NOSPLIT, $0-32
    16	MOVQ s_base+0(FP), SI
    17	MOVQ s_len+8(FP), BX
    18	MOVB c+16(FP), AL
    19	LEAQ ret+24(FP), R8
    20	JMP  indexbytebody<>(SB)
    21
    22// input:
    23//   SI: data
    24//   BX: data len
    25//   AL: byte sought
    26//   R8: address to put result
    27TEXT	indexbytebody<>(SB), NOSPLIT, $0
    28	// Shuffle X0 around so that each byte contains
    29	// the character we're looking for.
    30	MOVD AX, X0
    31	PUNPCKLBW X0, X0
    32	PUNPCKLBW X0, X0
    33	PSHUFL $0, X0, X0
    34
    35	CMPQ BX, $16
    36	JLT small
    37
    38	MOVQ SI, DI
    39
    40	CMPQ BX, $32
    41	JA avx2
    42sse:
    43	LEAQ	-16(SI)(BX*1), AX	// AX = address of last 16 bytes
    44	JMP	sseloopentry
    45
    46sseloop:
    47	// Move the next 16-byte chunk of the data into X1.
    48	MOVOU	(DI), X1
    49	// Compare bytes in X0 to X1.
    50	PCMPEQB	X0, X1
    51	// Take the top bit of each byte in X1 and put the result in DX.
    52	PMOVMSKB X1, DX
    53	// Find first set bit, if any.
    54	BSFL	DX, DX
    55	JNZ	ssesuccess
    56	// Advance to next block.
    57	ADDQ	$16, DI
    58sseloopentry:
    59	CMPQ	DI, AX
    60	JB	sseloop
    61
    62	// Search the last 16-byte chunk. This chunk may overlap with the
    63	// chunks we've already searched, but that's ok.
    64	MOVQ	AX, DI
    65	MOVOU	(AX), X1
    66	PCMPEQB	X0, X1
    67	PMOVMSKB X1, DX
    68	BSFL	DX, DX
    69	JNZ	ssesuccess
    70
    71failure:
    72	MOVQ $-1, (R8)
    73	RET
    74
    75// We've found a chunk containing the byte.
    76// The chunk was loaded from DI.
    77// The index of the matching byte in the chunk is DX.
    78// The start of the data is SI.
    79ssesuccess:
    80	SUBQ SI, DI	// Compute offset of chunk within data.
    81	ADDQ DX, DI	// Add offset of byte within chunk.
    82	MOVQ DI, (R8)
    83	RET
    84
    85// handle for lengths < 16
    86small:
    87	TESTQ	BX, BX
    88	JEQ	failure
    89
    90	// Check if we'll load across a page boundary.
    91	LEAQ	16(SI), AX
    92	TESTW	$0xff0, AX
    93	JEQ	endofpage
    94
    95	MOVOU	(SI), X1 // Load data
    96	PCMPEQB	X0, X1	// Compare target byte with each byte in data.
    97	PMOVMSKB X1, DX	// Move result bits to integer register.
    98	BSFL	DX, DX	// Find first set bit.
    99	JZ	failure	// No set bit, failure.
   100	CMPL	DX, BX
   101	JAE	failure	// Match is past end of data.
   102	MOVQ	DX, (R8)
   103	RET
   104
   105endofpage:
   106	MOVOU	-16(SI)(BX*1), X1	// Load data into the high end of X1.
   107	PCMPEQB	X0, X1	// Compare target byte with each byte in data.
   108	PMOVMSKB X1, DX	// Move result bits to integer register.
   109	MOVL	BX, CX
   110	SHLL	CX, DX
   111	SHRL	$16, DX	// Shift desired bits down to bottom of register.
   112	BSFL	DX, DX	// Find first set bit.
   113	JZ	failure	// No set bit, failure.
   114	MOVQ	DX, (R8)
   115	RET
   116
   117avx2:
   118	CMPB   internal∕cpu·X86+const_offsetX86HasAVX2(SB), $1
   119	JNE sse
   120	MOVD AX, X0
   121	LEAQ -32(SI)(BX*1), R11
   122	VPBROADCASTB  X0, Y1
   123avx2_loop:
   124	VMOVDQU (DI), Y2
   125	VPCMPEQB Y1, Y2, Y3
   126	VPTEST Y3, Y3
   127	JNZ avx2success
   128	ADDQ $32, DI
   129	CMPQ DI, R11
   130	JLT avx2_loop
   131	MOVQ R11, DI
   132	VMOVDQU (DI), Y2
   133	VPCMPEQB Y1, Y2, Y3
   134	VPTEST Y3, Y3
   135	JNZ avx2success
   136	VZEROUPPER
   137	MOVQ $-1, (R8)
   138	RET
   139
   140avx2success:
   141	VPMOVMSKB Y3, DX
   142	BSFL DX, DX
   143	SUBQ SI, DI
   144	ADDQ DI, DX
   145	MOVQ DX, (R8)
   146	VZEROUPPER
   147	RET

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