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Current Path: /opt/golang/1.22.0/src/runtime/testdata/testprogcgo

opt / golang / 1.22.0 / src / runtime / testdata / testprogcgo /

📁 ..
📄 aprof.go(1.14 KB)
📄 aprof_c.c(217 B)
📄 bigstack1_windows.c(379 B)
📄 bigstack_windows.c(1.2 KB)
📄 bigstack_windows.go(586 B)
📄 bindm.c(692 B)
📄 bindm.go(1.2 KB)
📄 callback.go(1.86 KB)
📄 catchpanic.go(993 B)
📄 cgo.go(1.82 KB)
📄 cgonocallback.c(236 B)
📄 cgonocallback.go(629 B)
📄 cgonoescape.go(1.84 KB)
📄 crash.go(743 B)
📄 deadlock.go(509 B)
📄 destructor.c(459 B)
📄 destructor.go(442 B)
📄 dll_windows.go(459 B)
📄 dropm.go(1.05 KB)
📄 dropm_stub.go(336 B)
📄 eintr.go(5.17 KB)
📄 exec.go(2.1 KB)
📄 gprof.go(868 B)
📄 gprof_c.c(700 B)
📄 issue29707.go(1.15 KB)
📄 lockosthread.c(301 B)
📄 lockosthread.go(2.52 KB)
📄 main.go(651 B)
📄 needmdeadlock.go(1.83 KB)
📄 numgoroutine.go(1.91 KB)
📄 panic.c(239 B)
📄 panic.go(312 B)
📄 pprof.go(1.67 KB)
📄 pprof_callback.go(1.82 KB)
📄 raceprof.go(1.67 KB)
📄 racesig.go(1.67 KB)
📄 segv.go(525 B)
📄 segv_linux.go(546 B)
📄 sigfwd.go(1.58 KB)
📄 sigpanic.go(484 B)
📄 sigstack.go(2.09 KB)
📄 sigthrow.go(312 B)
📄 stack_windows.go(1.1 KB)
📄 stackswitch.c(3.88 KB)
📄 stackswitch.go(1.07 KB)
📄 threadpanic.go(428 B)
📄 threadpanic_unix.c(435 B)
📄 threadpanic_windows.c(435 B)
📄 threadpprof.go(2.54 KB)
📄 threadprof.go(2.41 KB)
📄 trace.go(1.15 KB)
📄 trace_unix.c(688 B)
📄 trace_windows.c(777 B)
📄 traceback.go(949 B)
📄 traceback_c.c(1.21 KB)
📄 tracebackctxt.go(2.85 KB)
📄 tracebackctxt_c.c(2.33 KB)
📁 windows

Editing: cgonoescape.go

// Copyright 2023 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 main

// #cgo noescape annotations for a C function means its arguments won't escape to heap.

// We assume that there won't be 100 new allocated heap objects in other places,
// i.e. runtime.ReadMemStats or other runtime background works.
// So, the tests are:
// 1. at least 100 new allocated heap objects after invoking withoutNoEscape 100 times.
// 2. less than 100 new allocated heap objects after invoking withoutNoEscape 100 times.

/*
// TODO(#56378): #cgo noescape runCWithNoEscape

void runCWithNoEscape(void *p) {
}
void runCWithoutNoEscape(void *p) {
}
*/
import "C"

import (
	"fmt"
	"runtime"
	"runtime/debug"
	"unsafe"
)

const num = 100

func init() {
	register("CgoNoEscape", CgoNoEscape)
}

//go:noinline
func withNoEscape() {
	var str string
	C.runCWithNoEscape(unsafe.Pointer(&str))
}

//go:noinline
func withoutNoEscape() {
	var str string
	C.runCWithoutNoEscape(unsafe.Pointer(&str))
}

func CgoNoEscape() {
	// make GC stop to see the heap objects allocated
	debug.SetGCPercent(-1)

var stats runtime.MemStats
	runtime.ReadMemStats(&stats)
	preHeapObjects := stats.HeapObjects

for i := 0; i < num; i++ {
		withNoEscape()
	}

runtime.ReadMemStats(&stats)
	nowHeapObjects := stats.HeapObjects

if nowHeapObjects-preHeapObjects >= num {
		fmt.Printf("too many heap objects allocated, pre: %v, now: %v\n", preHeapObjects, nowHeapObjects)
	}

runtime.ReadMemStats(&stats)
	preHeapObjects = stats.HeapObjects

for i := 0; i < num; i++ {
		withoutNoEscape()
	}

runtime.ReadMemStats(&stats)
	nowHeapObjects = stats.HeapObjects

if nowHeapObjects-preHeapObjects < num {
		fmt.Printf("too few heap objects allocated, pre: %v, now: %v\n", preHeapObjects, nowHeapObjects)
	}

fmt.Println("OK")
}

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Editing: cgonoescape.go

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