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go/test/codegen/maps.go

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// asmcheck
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package codegen
// This file contains code generation tests related to the handling of
// map types.
// ------------------- //
// Access Const //
// ------------------- //
// Direct use of constants in fast map access calls (Issue #19015).
func AccessInt1(m map[int]int) int {
// amd64:"MOVQ\t[$]5"
return m[5]
}
func AccessInt2(m map[int]int) bool {
// amd64:"MOVQ\t[$]5"
_, ok := m[5]
return ok
}
func AccessString1(m map[string]int) int {
// amd64:`.*"abc"`
return m["abc"]
}
func AccessString2(m map[string]int) bool {
// amd64:`.*"abc"`
_, ok := m["abc"]
return ok
}
cmd/compile: avoid string allocations when map key is struct or array literal x = map[string(byteslice)] is already optimized by the compiler to avoid a string allocation. This CL generalizes this optimization to: x = map[T1{ ... Tn{..., string(byteslice), ...} ... }] where T1 to Tn is a nesting of struct and array literals. Found in a hot code path that used a struct of strings made from []byte slices to make a map lookup. There are no uses of the more generalized optimization in the standard library. Passes toolstash -cmp. MapStringConversion/32/simple 21.9ns ± 2% 21.9ns ± 3% ~ (p=0.995 n=17+20) MapStringConversion/32/struct 28.8ns ± 3% 22.0ns ± 2% -23.80% (p=0.000 n=20+20) MapStringConversion/32/array 28.5ns ± 2% 21.9ns ± 2% -23.14% (p=0.000 n=19+16) MapStringConversion/64/simple 21.0ns ± 2% 21.1ns ± 3% ~ (p=0.072 n=19+18) MapStringConversion/64/struct 72.4ns ± 3% 21.3ns ± 2% -70.53% (p=0.000 n=20+20) MapStringConversion/64/array 72.8ns ± 1% 21.0ns ± 2% -71.13% (p=0.000 n=17+19) name old allocs/op new allocs/op delta MapStringConversion/32/simple 0.00 0.00 ~ (all equal) MapStringConversion/32/struct 0.00 0.00 ~ (all equal) MapStringConversion/32/array 0.00 0.00 ~ (all equal) MapStringConversion/64/simple 0.00 0.00 ~ (all equal) MapStringConversion/64/struct 1.00 ± 0% 0.00 -100.00% (p=0.000 n=20+20) MapStringConversion/64/array 1.00 ± 0% 0.00 -100.00% (p=0.000 n=20+20) Change-Id: I483b4d84d8d74b1025b62c954da9a365e79b7a3a Reviewed-on: https://go-review.googlesource.com/c/116275 Reviewed-by: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2018-06-04 00:24:11 -06:00
// ------------------- //
// String Conversion //
// ------------------- //
func LookupStringConversionSimple(m map[string]int, bytes []byte) int {
// amd64:-`.*runtime\.slicebytetostring\(`
return m[string(bytes)]
}
func LookupStringConversionStructLit(m map[struct{ string }]int, bytes []byte) int {
// amd64:-`.*runtime\.slicebytetostring\(`
return m[struct{ string }{string(bytes)}]
}
func LookupStringConversionArrayLit(m map[[2]string]int, bytes []byte) int {
// amd64:-`.*runtime\.slicebytetostring\(`
return m[[2]string{string(bytes), string(bytes)}]
}
func LookupStringConversionNestedLit(m map[[1]struct{ s [1]string }]int, bytes []byte) int {
// amd64:-`.*runtime\.slicebytetostring\(`
return m[[1]struct{ s [1]string }{struct{ s [1]string }{s: [1]string{string(bytes)}}}]
}
func LookupStringConversionKeyedArrayLit(m map[[2]string]int, bytes []byte) int {
// amd64:-`.*runtime\.slicebytetostring\(`
return m[[2]string{0: string(bytes)}]
}
// ------------------- //
// Map Clear //
// ------------------- //
// Optimization of map clear idiom (Issue #20138).
func MapClearReflexive(m map[int]int) {
// amd64:`.*runtime\.mapclear`
// amd64:-`.*runtime\.mapiterinit`
for k := range m {
delete(m, k)
}
}
func MapClearIndirect(m map[int]int) {
s := struct{ m map[int]int }{m: m}
// amd64:`.*runtime\.mapclear`
// amd64:-`.*runtime\.mapiterinit`
for k := range s.m {
delete(s.m, k)
}
}
func MapClearPointer(m map[*byte]int) {
// amd64:`.*runtime\.mapclear`
// amd64:-`.*runtime\.mapiterinit`
for k := range m {
delete(m, k)
}
}
func MapClearNotReflexive(m map[float64]int) {
// amd64:`.*runtime\.mapiterinit`
// amd64:-`.*runtime\.mapclear`
for k := range m {
delete(m, k)
}
}
func MapClearInterface(m map[interface{}]int) {
// amd64:`.*runtime\.mapiterinit`
// amd64:-`.*runtime\.mapclear`
for k := range m {
delete(m, k)
}
}
func MapClearSideEffect(m map[int]int) int {
k := 0
// amd64:`.*runtime\.mapiterinit`
// amd64:-`.*runtime\.mapclear`
for k = range m {
delete(m, k)
}
return k
}