go issue29362b 源码
golang issue29362b 代码
文件路径：/test/fixedbugs/issue29362b.go
// run
// 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.
// Verify that we don't consider a Go'd function's
// arguments as pointers when they aren't.
package main
import (
"unsafe"
)
var badPtr uintptr
var sink []byte
func init() {
// Allocate large enough to use largeAlloc.
b := make([]byte, 1<<16-1)
sink = b // force heap allocation
// Any space between the object and the end of page is invalid to point to.
badPtr = uintptr(unsafe.Pointer(&b[len(b)-1])) + 1
}
var throttle = make(chan struct{}, 10)
// There are 2 arg bitmaps for this function, each with 2 bits.
// In the first, p and q are both live, so that bitmap is 11.
// In the second, only p is live, so that bitmap is 10.
// Bitmaps are byte aligned, so if the first bitmap is interpreted as
// extending across the entire argument area, we incorrectly concatenate
// the bitmaps and end up using 110000001. That bad bitmap causes a6
// to be considered a pointer.
func noPointerArgs(p, q *byte, a0, a1, a2, a3, a4, a5, a6 uintptr) {
sink = make([]byte, 4096)
sinkptr = q
<-throttle
sinkptr = p
}
var sinkptr *byte
func main() {
const N = 1000
for i := 0; i < N; i++ {
throttle <- struct{}{}
go noPointerArgs(nil, nil, badPtr, badPtr, badPtr, badPtr, badPtr, badPtr, badPtr)
sink = make([]byte, 4096)
}
}
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