Text file src/pkg/internal/bytealg/indexbyte_s390x.s

     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	
     8	TEXT ·IndexByte(SB),NOSPLIT|NOFRAME,$0-40
     9		MOVD	b_base+0(FP), R3// b_base => R3
    10		MOVD	b_len+8(FP), R4 // b_len => R4
    11		MOVBZ	c+24(FP), R5    // c => R5
    12		MOVD	$ret+32(FP), R2 // &ret => R9
    13		BR	indexbytebody<>(SB)
    14	
    15	TEXT ·IndexByteString(SB),NOSPLIT|NOFRAME,$0-32
    16		MOVD	s_base+0(FP), R3// s_base => R3
    17		MOVD	s_len+8(FP), R4 // s_len => R4
    18		MOVBZ	c+16(FP), R5    // c => R5
    19		MOVD	$ret+24(FP), R2 // &ret => R9
    20		BR	indexbytebody<>(SB)
    21	
    22	// input:
    23	// R3: s
    24	// R4: s_len
    25	// R5: c -- byte sought
    26	// R2: &ret -- address to put index into
    27	TEXT indexbytebody<>(SB),NOSPLIT|NOFRAME,$0
    28		CMPBEQ	R4, $0, notfound
    29		MOVD	R3, R6          // store base for later
    30		ADD	R3, R4, R8      // the address after the end of the string
    31		//if the length is small, use loop; otherwise, use vector or srst search
    32		CMPBGE	R4, $16, large
    33	
    34	residual:
    35		CMPBEQ	R3, R8, notfound
    36		MOVBZ	0(R3), R7
    37		LA	1(R3), R3
    38		CMPBNE	R7, R5, residual
    39	
    40	found:
    41		SUB	R6, R3
    42		SUB	$1, R3
    43		MOVD	R3, 0(R2)
    44		RET
    45	
    46	notfound:
    47		MOVD	$-1, 0(R2)
    48		RET
    49	
    50	large:
    51		MOVBZ	internal∕cpu·S390X+const_offsetS390xHasVX(SB), R1
    52		CMPBNE	R1, $0, vectorimpl
    53	
    54	srstimpl:                       // no vector facility
    55		MOVBZ	R5, R0          // c needs to be in R0, leave until last minute as currently R0 is expected to be 0
    56	srstloop:
    57		WORD	$0xB25E0083     // srst %r8, %r3 (search the range [R3, R8))
    58		BVS	srstloop        // interrupted - continue
    59		BGT	notfoundr0
    60	foundr0:
    61		XOR	R0, R0          // reset R0
    62		SUB	R6, R8          // remove base
    63		MOVD	R8, 0(R2)
    64		RET
    65	notfoundr0:
    66		XOR	R0, R0          // reset R0
    67		MOVD	$-1, 0(R2)
    68		RET
    69	
    70	vectorimpl:
    71		//if the address is not 16byte aligned, use loop for the header
    72		MOVD	R3, R8
    73		AND	$15, R8
    74		CMPBGT	R8, $0, notaligned
    75	
    76	aligned:
    77		ADD	R6, R4, R8
    78		MOVD	R8, R7
    79		AND	$-16, R7
    80		// replicate c across V17
    81		VLVGB	$0, R5, V19
    82		VREPB	$0, V19, V17
    83	
    84	vectorloop:
    85		CMPBGE	R3, R7, residual
    86		VL	0(R3), V16    // load string to be searched into V16
    87		ADD	$16, R3
    88		VFEEBS	V16, V17, V18 // search V17 in V16 and set conditional code accordingly
    89		BVS	vectorloop
    90	
    91		// when vector search found c in the string
    92		VLGVB	$7, V18, R7   // load 7th element of V18 containing index into R7
    93		SUB	$16, R3
    94		SUB	R6, R3
    95		ADD	R3, R7
    96		MOVD	R7, 0(R2)
    97		RET
    98	
    99	notaligned:
   100		MOVD	R3, R8
   101		AND	$-16, R8
   102		ADD     $16, R8
   103	notalignedloop:
   104		CMPBEQ	R3, R8, aligned
   105		MOVBZ	0(R3), R7
   106		LA	1(R3), R3
   107		CMPBNE	R7, R5, notalignedloop
   108		BR	found

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