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https://github.com/golang/go
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ec4e8517cd
golang.org/cl/109517 optimized the compiler to avoid the allocation for make in append(x, make([]T, y)...). This was only implemented for the case that y has type int. This change extends the optimization to trigger for all integer types where the value is known at compile time to fit into an int. name old time/op new time/op delta ExtendInt-12 106ns ± 4% 106ns ± 0% ~ (p=0.351 n=10+6) ExtendUint64-12 1.03µs ± 5% 0.10µs ± 4% -90.01% (p=0.000 n=9+10) name old alloc/op new alloc/op delta ExtendInt-12 0.00B 0.00B ~ (all equal) ExtendUint64-12 13.6kB ± 0% 0.0kB -100.00% (p=0.000 n=10+10) name old allocs/op new allocs/op delta ExtendInt-12 0.00 0.00 ~ (all equal) ExtendUint64-12 1.00 ± 0% 0.00 -100.00% (p=0.000 n=10+10) Updates #29785 Change-Id: Ief7760097c285abd591712da98c5b02bc3961fcd Reviewed-on: https://go-review.googlesource.com/c/go/+/182559 Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
86 lines
2.9 KiB
Go
86 lines
2.9 KiB
Go
// run
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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 main
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import (
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"strings"
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"unsafe"
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)
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type T []int
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func main() {
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n := -1
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shouldPanic("len out of range", func() { _ = make(T, n) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, n) })
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shouldPanic("len out of range", func() { _ = make(T, int64(n)) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, int64(n)) })
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testMakeInAppend(n)
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var t *byte
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if unsafe.Sizeof(t) == 8 {
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// Test mem > maxAlloc
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var n2 int64 = 1 << 59
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shouldPanic("len out of range", func() { _ = make(T, int(n2)) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, int(n2)) })
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testMakeInAppend(int(n2))
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// Test elem.size*cap overflow
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n2 = 1<<63 - 1
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shouldPanic("len out of range", func() { _ = make(T, int(n2)) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, int(n2)) })
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testMakeInAppend(int(n2))
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var x uint64 = 1<<64 - 1
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shouldPanic("len out of range", func() { _ = make([]byte, x) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, x) })
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testMakeInAppend(int(x))
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} else {
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n = 1<<31 - 1
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shouldPanic("len out of range", func() { _ = make(T, n) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, n) })
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shouldPanic("len out of range", func() { _ = make(T, int64(n)) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, int64(n)) })
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testMakeInAppend(n)
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var x uint64 = 1<<32 - 1
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shouldPanic("len out of range", func() { _ = make([]byte, x) })
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shouldPanic("cap out of range", func() { _ = make(T, 0, x) })
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testMakeInAppend(int(x))
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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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if err == nil {
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panic("did not panic")
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}
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s := err.(error).Error()
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if !strings.Contains(s, str) {
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panic("got panic " + s + ", want " + str)
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}
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}()
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f()
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}
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// Test make in append panics since the gc compiler optimizes makes in appends.
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func testMakeInAppend(n int) {
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lengths := []int{0, 1}
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for _, length := range lengths {
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t := make(T, length)
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shouldPanic("len out of range", func() { _ = append(t, make(T, n)...) })
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shouldPanic("cap out of range", func() { _ = append(t, make(T, 0, n)...) })
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shouldPanic("len out of range", func() { _ = append(t, make(T, int64(n))...) })
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shouldPanic("cap out of range", func() { _ = append(t, make(T, 0, int64(n))...) })
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shouldPanic("len out of range", func() { _ = append(t, make(T, uint64(n))...) })
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shouldPanic("cap out of range", func() { _ = append(t, make(T, 0, uint64(n))...) })
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shouldPanic("len out of range", func() { _ = append(t, make(T, int(n))...) })
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shouldPanic("cap out of range", func() { _ = append(t, make(T, 0, int(n))...) })
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shouldPanic("len out of range", func() { _ = append(t, make(T, uint(n))...) })
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shouldPanic("cap out of range", func() { _ = append(t, make(T, 0, uint(n))...) })
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}
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}
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