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https://github.com/golang/go
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36f30ba289
Right now we generate hash functions for all types, just in case they are used as map keys. That's a lot of wasted effort and binary size for types which will never be used as a map key. Instead, generate hash functions only for types that we know are map keys. Just doing that is a bit too simple, since maps with an interface type as a key might have to hash any concrete key type that implements that interface. So for that case, implement hashing of such types at runtime (instead of with generated code). It will be slower, but only for maps with interface types as keys, and maybe only a bit slower as the aeshash time probably dominates the dispatch time. Reorg where we keep the equals and hash functions. Move the hash function from the key type to the map type, saving a field in every non-map type. That leaves only one function in the alg structure, so get rid of that and just keep the equal function in the type descriptor itself. cmd/go now has 10 generated hash functions, instead of 504. Makes cmd/go 1.0% smaller. Update #6853. Speed on non-interface keys is unchanged. Speed on interface keys is ~20% slower: name old time/op new time/op delta MapInterfaceString-8 23.0ns ±21% 27.6ns ±14% +20.01% (p=0.002 n=10+10) MapInterfacePtr-8 19.4ns ±16% 23.7ns ± 7% +22.48% (p=0.000 n=10+8) Change-Id: I7c2e42292a46b5d4e288aaec4029bdbb01089263 Reviewed-on: https://go-review.googlesource.com/c/go/+/191198 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Martin Möhrmann <moehrmann@google.com>
86 lines
1.2 KiB
Go
86 lines
1.2 KiB
Go
// run
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// Copyright 2010 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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// Test of recover for run-time errors.
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// TODO(rsc):
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// null pointer accesses
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package main
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import "strings"
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var x = make([]byte, 10)
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func main() {
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test1()
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test2()
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test3()
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test4()
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test5()
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test6()
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test7()
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}
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func mustRecover(s string) {
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v := recover()
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if v == nil {
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panic("expected panic")
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}
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if e := v.(error).Error(); strings.Index(e, s) < 0 {
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panic("want: " + s + "; have: " + e)
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}
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}
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func test1() {
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defer mustRecover("index")
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println(x[123])
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}
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func test2() {
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defer mustRecover("slice")
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println(x[5:15])
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}
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func test3() {
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defer mustRecover("slice")
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var lo = 11
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var hi = 9
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println(x[lo:hi])
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}
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func test4() {
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defer mustRecover("interface")
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var x interface{} = 1
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println(x.(float32))
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}
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type T struct {
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a, b int
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c []int
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}
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func test5() {
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defer mustRecover("uncomparable")
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var x T
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var z interface{} = x
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println(z != z)
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}
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func test6() {
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defer mustRecover("unhashable type main.T")
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var x T
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var z interface{} = x
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m := make(map[interface{}]int)
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m[z] = 1
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}
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func test7() {
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defer mustRecover("divide by zero")
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var x, y int
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println(x / y)
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}
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