8dc2499aa6
gotools/ * Makefile.am (go_cmd_cgo_files): Add ast_go118.go (check-go-tool): Copy golang.org/x/tools directories. * Makefile.in: Regenerate. Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/384695
75 lines
1.6 KiB
Go
75 lines
1.6 KiB
Go
// Copyright 2019 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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"runtime"
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"runtime/debug"
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"sync/atomic"
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)
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func init() {
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register("AsyncPreempt", AsyncPreempt)
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}
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func AsyncPreempt() {
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// Run with just 1 GOMAXPROCS so the runtime is required to
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// use scheduler preemption.
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runtime.GOMAXPROCS(1)
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// Disable GC so we have complete control of what we're testing.
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debug.SetGCPercent(-1)
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// Out of an abundance of caution, also make sure that there are
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// no GCs actively in progress. The sweep phase of a GC cycle
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// for instance tries to preempt Ps at the very beginning.
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runtime.GC()
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// Start a goroutine with no sync safe-points.
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var ready, ready2 uint32
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go func() {
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for {
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atomic.StoreUint32(&ready, 1)
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dummy()
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dummy()
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}
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}()
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// Also start one with a frameless function.
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// This is an especially interesting case for
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// LR machines.
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go func() {
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atomic.AddUint32(&ready2, 1)
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frameless()
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}()
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// Also test empty infinite loop.
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go func() {
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atomic.AddUint32(&ready2, 1)
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for {
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}
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}()
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// Wait for the goroutine to stop passing through sync
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// safe-points.
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for atomic.LoadUint32(&ready) == 0 || atomic.LoadUint32(&ready2) < 2 {
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runtime.Gosched()
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}
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// Run a GC, which will have to stop the goroutine for STW and
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// for stack scanning. If this doesn't work, the test will
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// deadlock and timeout.
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runtime.GC()
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println("OK")
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}
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//go:noinline
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func frameless() {
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for i := int64(0); i < 1<<62; i++ {
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out += i * i * i * i * i * 12345
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}
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}
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var out int64
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//go:noinline
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func dummy() {}
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