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master
test/fixedbugs/issue19078.go
42 строки
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khr
cmd/compile: zero return parameters earlier
13 мар 2017, 22:39
13 мар 2017, 22:39
a51e4cc
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// run // Copyright 2017 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. // Issue 19078: liveness & zero-initialization of results // when there is a defer. package main import "unsafe" func main() { // Construct an invalid pointer. We do this by // making a pointer which points to the unused space // between the last 48-byte object in a span and the // end of the span (there are 32 unused bytes there). p := new([48]byte) // make a 48-byte object sink = &p // escape it, so it allocates for real u := uintptr(unsafe.Pointer(p)) // get its address u = u >> 13 << 13 // round down to page size u += 1<<13 - 1 // add almost a page for i := 0; i < 1000000; i++ { _ = identity(u) // installs u at return slot _ = liveReturnSlot(nil) // incorrectly marks return slot as live } } //go:noinline func liveReturnSlot(x *int) *int { defer func() {}() // causes return slot to be marked live sink = &x // causes x to be moved to the heap, triggering allocation return x } //go:noinline func identity(x uintptr) uintptr { return x } var sink interface{}