mirror of
https://github.com/golang/go
synced 2024-11-24 12:20:17 -07:00
8462169b5a
There's a problem in liveness, where liveness of any part of an aggregate keeps the whole aggregate alive, but the not-live parts don't get spilled. The GC can observe those live-but-not-spilled slots, which can contain junk. A better fix is to change liveness to work pointer-by-pointer, but that is also a riskier, trickier fix. To avoid this, in the case of (1) an aggregate input parameter (2) containing pointers (3) passed in registers pre-spill the pointers. Updates #40724. Change-Id: I6beb8e0a353b1ae3c68c16072f56698061922c04 Reviewed-on: https://go-review.googlesource.com/c/go/+/307909 Trust: David Chase <drchase@google.com> Run-TryBot: David Chase <drchase@google.com> Reviewed-by: Cherry Zhang <cherryyz@google.com>
49 lines
823 B
Go
49 lines
823 B
Go
// run
|
|
|
|
// Copyright 2021 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.
|
|
|
|
// A test for partial liveness / partial spilling / compiler-induced GC failure
|
|
|
|
package main
|
|
|
|
import "runtime"
|
|
import "unsafe"
|
|
|
|
//go:registerparams
|
|
func F(s []int) {
|
|
for i, x := range s {
|
|
G(i, x)
|
|
}
|
|
GC()
|
|
G(len(s), cap(s))
|
|
GC()
|
|
}
|
|
|
|
//go:noinline
|
|
//go:registerparams
|
|
func G(int, int) {}
|
|
|
|
//go:registerparams
|
|
func GC() { runtime.GC(); runtime.GC() }
|
|
|
|
func main() {
|
|
s := make([]int, 3)
|
|
escape(s)
|
|
p := int(uintptr(unsafe.Pointer(&s[2])) + 42) // likely point to unallocated memory
|
|
poison([3]int{p, p, p})
|
|
F(s)
|
|
}
|
|
|
|
//go:noinline
|
|
//go:registerparams
|
|
func poison([3]int) {}
|
|
|
|
//go:noinline
|
|
//go:registerparams
|
|
func escape(s []int) {
|
|
g = s
|
|
}
|
|
var g []int
|