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If we call slicebytetostring immediately (with no intervening writes) before calling map access or delete functions with the resulting string as the key, then we can just use the ptr/len of the slicebytetostring argument as the key. This avoids an allocation. Fixes #44898 Update #71132 There's old code in cmd/compile/internal/walk/order.go that handles some of these cases. 1. m[string(b)] 2. s := string(b); m[s] 3. m[[2]string{string(b1),string(b2)}] The old code handled cases 1&3. The new code handles cases 1&2. We'll leave the old code around to keep 3 working, although it seems not terribly common. Case 2 happens particularly after inlining, so it is pretty common. Change-Id: I8913226ca79d2c65f4e2bd69a38ac8c976a57e43 Reviewed-on: https://go-review.googlesource.com/c/go/+/640656 Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Michael Pratt <mpratt@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
224 lines
4.3 KiB
Go
224 lines
4.3 KiB
Go
// asmcheck
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// Copyright 2018 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 codegen
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// This file contains code generation tests related to the handling of
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// map types.
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// ------------------- //
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// Access Const //
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// ------------------- //
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// Direct use of constants in fast map access calls (Issue #19015).
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func AccessInt1(m map[int]int) int {
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// amd64:"MOV[LQ]\t[$]5"
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return m[5]
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}
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func AccessInt2(m map[int]int) bool {
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// amd64:"MOV[LQ]\t[$]5"
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_, ok := m[5]
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return ok
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}
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func AccessString1(m map[string]int) int {
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// amd64:`.*"abc"`
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return m["abc"]
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}
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func AccessString2(m map[string]int) bool {
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// amd64:`.*"abc"`
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_, ok := m["abc"]
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return ok
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}
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// ------------------- //
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// String Conversion //
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// ------------------- //
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func LookupStringConversionSimple(m map[string]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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return m[string(bytes)]
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}
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func LookupStringConversionStructLit(m map[struct{ string }]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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return m[struct{ string }{string(bytes)}]
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}
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func LookupStringConversionArrayLit(m map[[2]string]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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return m[[2]string{string(bytes), string(bytes)}]
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}
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func LookupStringConversionNestedLit(m map[[1]struct{ s [1]string }]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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return m[[1]struct{ s [1]string }{struct{ s [1]string }{s: [1]string{string(bytes)}}}]
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}
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func LookupStringConversionKeyedArrayLit(m map[[2]string]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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return m[[2]string{0: string(bytes)}]
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}
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func LookupStringConversion1(m map[string]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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s := string(bytes)
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return m[s]
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}
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func LookupStringConversion2(m *map[string]int, bytes []byte) int {
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// amd64:-`.*runtime\.slicebytetostring\(`
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s := string(bytes)
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return (*m)[s]
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}
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func LookupStringConversion3(m map[string]int, bytes []byte) (int, bool) {
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// amd64:-`.*runtime\.slicebytetostring\(`
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s := string(bytes)
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r, ok := m[s]
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return r, ok
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}
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func DeleteStringConversion(m map[string]int, bytes []byte) {
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// amd64:-`.*runtime\.slicebytetostring\(`
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s := string(bytes)
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delete(m, s)
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}
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// ------------------- //
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// Map Clear //
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// ------------------- //
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// Optimization of map clear idiom (Issue #20138).
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func MapClearReflexive(m map[int]int) {
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// amd64:`.*runtime\.mapclear`
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// amd64:-`.*runtime\.(mapiterinit|mapIterStart)`
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for k := range m {
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delete(m, k)
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}
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}
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func MapClearIndirect(m map[int]int) {
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s := struct{ m map[int]int }{m: m}
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// amd64:`.*runtime\.mapclear`
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// amd64:-`.*runtime\.(mapiterinit|mapIterStart)`
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for k := range s.m {
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delete(s.m, k)
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}
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}
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func MapClearPointer(m map[*byte]int) {
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// amd64:`.*runtime\.mapclear`
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// amd64:-`.*runtime\.(mapiterinit|mapIterStart)`
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for k := range m {
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delete(m, k)
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}
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}
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func MapClearNotReflexive(m map[float64]int) {
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// amd64:`.*runtime\.(mapiterinit|mapIterStart)`
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// amd64:-`.*runtime\.mapclear`
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for k := range m {
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delete(m, k)
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}
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}
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func MapClearInterface(m map[interface{}]int) {
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// amd64:`.*runtime\.(mapiterinit|mapIterStart)`
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// amd64:-`.*runtime\.mapclear`
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for k := range m {
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delete(m, k)
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}
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}
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func MapClearSideEffect(m map[int]int) int {
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k := 0
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// amd64:`.*runtime\.(mapiterinit|mapIterStart)`
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// amd64:-`.*runtime\.mapclear`
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for k = range m {
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delete(m, k)
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}
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return k
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}
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func MapLiteralSizing(x int) (map[int]int, map[int]int) {
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// This is tested for internal/abi/maps.go:MapBucketCountBits={3,4,5}
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// amd64:"MOVL\t[$]33,"
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m := map[int]int{
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0: 0,
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1: 1,
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2: 2,
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3: 3,
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4: 4,
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5: 5,
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6: 6,
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7: 7,
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8: 8,
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9: 9,
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10: 10,
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11: 11,
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12: 12,
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13: 13,
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14: 14,
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15: 15,
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16: 16,
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17: 17,
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18: 18,
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19: 19,
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20: 20,
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21: 21,
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22: 22,
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23: 23,
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24: 24,
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25: 25,
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26: 26,
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27: 27,
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28: 28,
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29: 29,
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30: 30,
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31: 32,
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32: 32,
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}
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// amd64:"MOVL\t[$]33,"
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n := map[int]int{
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0: 0,
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1: 1,
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2: 2,
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3: 3,
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4: 4,
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5: 5,
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6: 6,
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7: 7,
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8: 8,
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9: 9,
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10: 10,
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11: 11,
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12: 12,
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13: 13,
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14: 14,
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15: 15,
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16: 16,
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17: 17,
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18: 18,
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19: 19,
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20: 20,
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21: 21,
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22: 22,
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23: 23,
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24: 24,
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25: 25,
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26: 26,
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27: 27,
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28: 28,
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29: 29,
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30: 30,
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31: 32,
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32: 32,
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}
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return m, n
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}
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