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https://github.com/golang/go
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7b30a2d268
If slice cap is not set, it will be equal to slice len. So
isSmallMakeSlice only needs to check whether slice cap is constant.
While at it, also add test to make sure panicmakeslicecap is called
when make slice contains invalid non-constant len.
For this benchmark:
func BenchmarkMakeSliceNonConstantLen(b *testing.B) {
len := 1
for i := 0; i < b.N; i++ {
s := make([]int, len, 2)
_ = s
}
}
Result compare with parent:
name old time/op new time/op delta
MakeSliceNonConstantLen-12 18.4ns ± 1% 0.2ns ± 2% -98.66% (p=0.008 n=5+5)
Fixes #37975
Change-Id: I4bc926361bc2ffeab4cfaa888ef0a30cbc3b80e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/226278
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
55 lines
979 B
Go
55 lines
979 B
Go
// run
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// Copyright 2020 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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// Make sure runtime.panicmakeslice* are called.
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package main
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import "strings"
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func main() {
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// Test typechecking passes if len is valid
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// but cap is out of range for len's type.
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var x byte
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_ = make([]int, x, 300)
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capOutOfRange := func() {
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i := 2
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s := make([]int, i, 1)
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s[0] = 1
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}
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lenOutOfRange := func() {
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i := -1
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s := make([]int, i, 3)
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s[0] = 1
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}
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tests := []struct {
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f func()
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panicStr string
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}{
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{capOutOfRange, "cap out of range"},
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{lenOutOfRange, "len out of range"},
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}
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for _, tc := range tests {
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shouldPanic(tc.panicStr, tc.f)
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}
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}
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func shouldPanic(str string, f func()) {
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defer func() {
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err := recover()
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runtimeErr := err.(error).Error()
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if !strings.Contains(runtimeErr, str) {
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panic("got panic " + runtimeErr + ", want " + str)
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}
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}()
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f()
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}
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