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7395083136
Currently, order desugars map assignment operations like
m[k] op= r
into
m[k] = m[k] op r
which in turn is transformed during walk into:
tmp := *mapaccess(m, k)
tmp = tmp op r
*mapassign(m, k) = tmp
However, this is suboptimal, as we could instead produce just:
*mapassign(m, k) op= r
One complication though is if "r == 0", then "m[k] /= r" and "m[k] %=
r" will panic, and they need to do so *before* calling mapassign,
otherwise we may insert a new zero-value element into the map.
It would be spec compliant to just emit the "r != 0" check before
calling mapassign (see #23735), but currently these checks aren't
generated until SSA construction. For now, it's simpler to continue
desugaring /= and %= into two map indexing operations.
Fixes #23661.
Change-Id: I46e3739d9adef10e92b46fdd78b88d5aabe68952
Reviewed-on: https://go-review.googlesource.com/91557
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
66 lines
1.3 KiB
Go
66 lines
1.3 KiB
Go
// run
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// Copyright 2017 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 "fmt"
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func set(m map[interface{}]interface{}, key interface{}) (err error) {
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defer func() {
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if r := recover(); r != nil {
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err = fmt.Errorf("set failed: %v", r)
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}
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}()
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m[key] = nil
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return nil
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}
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func del(m map[interface{}]interface{}, key interface{}) (err error) {
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defer func() {
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if r := recover(); r != nil {
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err = fmt.Errorf("del failed: %v", r)
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}
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}()
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delete(m, key)
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return nil
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}
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func addInt(m map[interface{}]int, key interface{}) (err error) {
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defer func() {
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if r := recover(); r != nil {
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err = fmt.Errorf("addInt failed: %v", r)
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}
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}()
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m[key] += 2018
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return nil
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}
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func addStr(m map[interface{}]string, key interface{}) (err error) {
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defer func() {
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if r := recover(); r != nil {
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err = fmt.Errorf("addStr failed: %v", r)
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}
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}()
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m[key] += "hello, go"
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return nil
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}
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func main() {
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m := make(map[interface{}]interface{})
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set(m, []int{1, 2, 3})
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set(m, "abc") // used to throw
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del(m, []int{1, 2, 3})
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del(m, "abc") // used to throw
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mi := make(map[interface{}]int)
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addInt(mi, []int{1, 2, 3})
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addInt(mi, "abc") // used to throw
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ms := make(map[interface{}]string)
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addStr(ms, []int{1, 2, 3})
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addStr(ms, "abc") // used to throw
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}
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