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strings: use runtime assembly for IndexByte
Fixes #3751 R=golang-dev, khr CC=golang-dev https://golang.org/cl/12483043
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@ -504,7 +504,7 @@ TEXT runtime·atomicstore(SB), 7, $0-8
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// so actually
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// void atomicload64(uint64 *res, uint64 volatile *addr);
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TEXT runtime·atomicload64(SB), 7, $0-8
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MOVL 4(SP), BX
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MOVL 4(SP), BX
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MOVL 8(SP), AX
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// MOVQ (%EAX), %MM0
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BYTE $0x0f; BYTE $0x6f; BYTE $0x00
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@ -1220,6 +1220,20 @@ TEXT bytes·IndexByte(SB),7,$0
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MOVL DI, ret+16(FP)
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RET
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TEXT strings·IndexByte(SB),7,$0
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MOVL s+0(FP), SI
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MOVL s_len+4(FP), CX
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MOVB c+8(FP), AL
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MOVL SI, DI
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CLD; REPN; SCASB
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JZ 3(PC)
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MOVL $-1, ret+12(FP)
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RET
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SUBL SI, DI
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SUBL $1, DI
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MOVL DI, ret+12(FP)
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RET
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// input:
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// SI = a
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// DI = b
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@ -1224,6 +1224,25 @@ TEXT bytes·IndexByte(SB),7,$0
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MOVQ s+0(FP), SI
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MOVQ s_len+8(FP), BX
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MOVB c+24(FP), AL
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CALL runtime·indexbytebody(SB)
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MOVQ AX, ret+32(FP)
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RET
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TEXT strings·IndexByte(SB),7,$0
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MOVQ s+0(FP), SI
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MOVQ s_len+8(FP), BX
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MOVB c+16(FP), AL
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CALL runtime·indexbytebody(SB)
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MOVQ AX, ret+24(FP)
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RET
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// input:
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// SI: data
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// BX: data len
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// AL: byte sought
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// output:
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// AX
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TEXT runtime·indexbytebody(SB),7,$0
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MOVQ SI, DI
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CMPQ BX, $16
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@ -1281,7 +1300,7 @@ condition:
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JZ success
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failure:
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MOVQ $-1, ret+32(FP)
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MOVQ $-1, AX
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RET
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// handle for lengths < 16
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@ -1289,7 +1308,7 @@ indexbyte_small:
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MOVQ BX, CX
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REPN; SCASB
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JZ success
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MOVQ $-1, ret+32(FP)
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MOVQ $-1, AX
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RET
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// we've found the chunk containing the byte
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@ -1299,13 +1318,13 @@ ssesuccess:
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BSFW DX, DX
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SUBQ SI, DI
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ADDQ DI, DX
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MOVQ DX, ret+32(FP)
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MOVQ DX, AX
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RET
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success:
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SUBQ SI, DI
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SUBL $1, DI
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MOVQ DI, ret+32(FP)
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MOVQ DI, AX
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RET
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TEXT bytes·Equal(SB),7,$0-49
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@ -667,3 +667,27 @@ _notfound:
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MOVW $-1, R0
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MOVW R0, ret+16(FP)
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RET
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TEXT strings·IndexByte(SB),7,$0
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MOVW s+0(FP), R0
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MOVW s_len+4(FP), R1
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MOVBU c+8(FP), R2 // byte to find
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MOVW R0, R4 // store base for later
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ADD R0, R1 // end
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_sib_loop:
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CMP R0, R1
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B.EQ _sib_notfound
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MOVBU.P 1(R0), R3
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CMP R2, R3
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B.NE _sib_loop
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SUB $1, R0 // R0 will be one beyond the position we want
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SUB R4, R0 // remove base
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MOVW R0, ret+12(FP)
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RET
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_sib_notfound:
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MOVW $-1, R0
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MOVW R0, ret+12(FP)
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RET
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@ -160,16 +160,6 @@ func Index(s, sep string) int {
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return -1
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}
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// IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
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func IndexByte(s string, c byte) int {
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for i := 0; i < len(s); i++ {
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if s[i] == c {
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return i
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}
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}
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return -1
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}
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// LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s.
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func LastIndex(s, sep string) int {
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n := len(sep)
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5
src/pkg/strings/strings.s
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5
src/pkg/strings/strings.s
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@ -0,0 +1,5 @@
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file is here just to make the go tool happy.
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8
src/pkg/strings/strings_decl.go
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8
src/pkg/strings/strings_decl.go
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@ -0,0 +1,8 @@
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package strings
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// IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
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func IndexByte(s string, c byte) int // ../runtime/asm_$GOARCH.s
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