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strings: use runtime assembly for IndexByte

Fixes #3751

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/12483043
This commit is contained in:
Brad Fitzpatrick 2013-08-05 15:04:05 -07:00
parent 8ce8adbe7a
commit 598c78967f
6 changed files with 75 additions and 15 deletions

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@ -504,7 +504,7 @@ TEXT runtime·atomicstore(SB), 7, $0-8
// so actually
// void atomicload64(uint64 *res, uint64 volatile *addr);
TEXT runtime·atomicload64(SB), 7, $0-8
MOVL 4(SP), BX
MOVL 4(SP), BX
MOVL 8(SP), AX
// MOVQ (%EAX), %MM0
BYTE $0x0f; BYTE $0x6f; BYTE $0x00
@ -1220,6 +1220,20 @@ TEXT bytes·IndexByte(SB),7,$0
MOVL DI, ret+16(FP)
RET
TEXT strings·IndexByte(SB),7,$0
MOVL s+0(FP), SI
MOVL s_len+4(FP), CX
MOVB c+8(FP), AL
MOVL SI, DI
CLD; REPN; SCASB
JZ 3(PC)
MOVL $-1, ret+12(FP)
RET
SUBL SI, DI
SUBL $1, DI
MOVL DI, ret+12(FP)
RET
// input:
// SI = a
// DI = b

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@ -1224,6 +1224,25 @@ TEXT bytes·IndexByte(SB),7,$0
MOVQ s+0(FP), SI
MOVQ s_len+8(FP), BX
MOVB c+24(FP), AL
CALL runtime·indexbytebody(SB)
MOVQ AX, ret+32(FP)
RET
TEXT strings·IndexByte(SB),7,$0
MOVQ s+0(FP), SI
MOVQ s_len+8(FP), BX
MOVB c+16(FP), AL
CALL runtime·indexbytebody(SB)
MOVQ AX, ret+24(FP)
RET
// input:
// SI: data
// BX: data len
// AL: byte sought
// output:
// AX
TEXT runtime·indexbytebody(SB),7,$0
MOVQ SI, DI
CMPQ BX, $16
@ -1281,7 +1300,7 @@ condition:
JZ success
failure:
MOVQ $-1, ret+32(FP)
MOVQ $-1, AX
RET
// handle for lengths < 16
@ -1289,7 +1308,7 @@ indexbyte_small:
MOVQ BX, CX
REPN; SCASB
JZ success
MOVQ $-1, ret+32(FP)
MOVQ $-1, AX
RET
// we've found the chunk containing the byte
@ -1299,13 +1318,13 @@ ssesuccess:
BSFW DX, DX
SUBQ SI, DI
ADDQ DI, DX
MOVQ DX, ret+32(FP)
MOVQ DX, AX
RET
success:
SUBQ SI, DI
SUBL $1, DI
MOVQ DI, ret+32(FP)
MOVQ DI, AX
RET
TEXT bytes·Equal(SB),7,$0-49

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@ -667,3 +667,27 @@ _notfound:
MOVW $-1, R0
MOVW R0, ret+16(FP)
RET
TEXT strings·IndexByte(SB),7,$0
MOVW s+0(FP), R0
MOVW s_len+4(FP), R1
MOVBU c+8(FP), R2 // byte to find
MOVW R0, R4 // store base for later
ADD R0, R1 // end
_sib_loop:
CMP R0, R1
B.EQ _sib_notfound
MOVBU.P 1(R0), R3
CMP R2, R3
B.NE _sib_loop
SUB $1, R0 // R0 will be one beyond the position we want
SUB R4, R0 // remove base
MOVW R0, ret+12(FP)
RET
_sib_notfound:
MOVW $-1, R0
MOVW R0, ret+12(FP)
RET

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@ -160,16 +160,6 @@ func Index(s, sep string) int {
return -1
}
// IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
func IndexByte(s string, c byte) int {
for i := 0; i < len(s); i++ {
if s[i] == c {
return i
}
}
return -1
}
// LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s.
func LastIndex(s, sep string) int {
n := len(sep)

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@ -0,0 +1,5 @@
// Copyright 2013 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.
// This file is here just to make the go tool happy.

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@ -0,0 +1,8 @@
// Copyright 2013 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.
package strings
// IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
func IndexByte(s string, c byte) int // ../runtime/asm_$GOARCH.s