2018-04-24 07:13:08 -06:00
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// asmcheck
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// Copyright 2018 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 codegen
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// This file contains code generation tests related to the handling of
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// string types.
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func CountRunes(s string) int { // Issue #24923
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// amd64:`.*countrunes`
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return len([]rune(s))
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}
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cmd/compile: make []byte("...") more efficient
Do []byte(string) conversions more efficiently when the string
is a constant. Instead of calling stringtobyteslice, allocate
just the space we need and encode the initialization directly.
[]byte("foo") rewrites to the following pseudocode:
var s [3]byte // on heap or stack, depending on whether b escapes
s = *(*[3]byte)(&"foo"[0]) // initialize s from the string
b = s[:]
which generates this assembly:
0x001d 00029 (tmp1.go:9) LEAQ type.[3]uint8(SB), AX
0x0024 00036 (tmp1.go:9) MOVQ AX, (SP)
0x0028 00040 (tmp1.go:9) CALL runtime.newobject(SB)
0x002d 00045 (tmp1.go:9) MOVQ 8(SP), AX
0x0032 00050 (tmp1.go:9) MOVBLZX go.string."foo"+2(SB), CX
0x0039 00057 (tmp1.go:9) MOVWLZX go.string."foo"(SB), DX
0x0040 00064 (tmp1.go:9) MOVW DX, (AX)
0x0043 00067 (tmp1.go:9) MOVB CL, 2(AX)
// Then the slice is b = {AX, 3, 3}
The generated code is still not optimal, as it still does load/store
from read-only memory instead of constant stores. Next CL...
Update #26498
Fixes #10170
Change-Id: I4b990b19f9a308f60c8f4f148934acffefe0a5bd
Reviewed-on: https://go-review.googlesource.com/c/140698
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-10-08 18:46:45 -06:00
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func ToByteSlice() []byte { // Issue #24698
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// amd64:`LEAQ\ttype\.\[3\]uint8`
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// amd64:`CALL\truntime\.newobject`
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// amd64:-`.*runtime.stringtoslicebyte`
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return []byte("foo")
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}
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2018-10-09 23:55:36 -06:00
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// Loading from read-only symbols should get transformed into constants.
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func ConstantLoad() {
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// 12592 = 0x3130
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// 50 = 0x32
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// amd64:`MOVW\t\$12592, \(`,`MOVB\t\$50, 2\(`
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// 386:`MOVW\t\$12592, \(`,`MOVB\t\$50, 2\(`
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// arm:`MOVW\t\$48`,`MOVW\t\$49`,`MOVW\t\$50`
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// arm64:`MOVD\t\$12592`,`MOVD\t\$50`
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bsink = []byte("012")
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// 858927408 = 0x33323130
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// 13620 = 0x3534
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// amd64:`MOVL\t\$858927408`,`MOVW\t\$13620, 4\(`
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// 386:`MOVL\t\$858927408`,`MOVW\t\$13620, 4\(`
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// arm64:`MOVD\t\$858927408`,`MOVD\t\$13620`
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bsink = []byte("012345")
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// 3978425819141910832 = 0x3736353433323130
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// 7306073769690871863 = 0x6564636261393837
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// amd64:`MOVQ\t\$3978425819141910832`,`MOVQ\t\$7306073769690871863`
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// 386:`MOVL\t\$858927408, \(`,`DUFFCOPY`
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// arm64:`MOVD\t\$3978425819141910832`,`MOVD\t\$1650538808`,`MOVD\t\$25699`,`MOVD\t\$101`
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bsink = []byte("0123456789abcde")
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}
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var bsink []byte
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