mirror of
https://github.com/golang/go
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e3e0122ae2
Replace various implementations of inlining prevention with "go:noinline" Change-Id: Iac90895c3a62d6f4b7a6c72e11e165d15a0abfa4 Reviewed-on: https://go-review.googlesource.com/16510 Reviewed-by: Keith Randall <khr@golang.org> Run-TryBot: Todd Neal <todd@tneal.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
79 lines
1.7 KiB
Go
79 lines
1.7 KiB
Go
// run
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// Copyright 2014 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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// The liveness code used to say that, in func g, s was live
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// starting at its declaration, because it appears to have its
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// address taken by the closure (different s, but the parser
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// gets slightly confused, a separate bug). The liveness analysis
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// saw s as having its address taken but the register optimizer
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// did not. This mismatch meant that s would be marked live
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// (and therefore initialized) at the call to f, but the register optimizer
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// would optimize away the initialization of s before f, causing the
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// garbage collector to use unused data.
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// The register optimizer has been changed to respect the
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// same "address taken" flag that the liveness analysis uses,
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// even if it cannot see any address being taken in the actual
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// machine code. This is conservative but keeps the two consistent,
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// which is the most important thing.
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package main
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import "runtime"
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//go:noinline
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func f() interface{} {
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runtime.GC()
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return nil
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}
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//go:noinline
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func g() {
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var s interface{}
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_ = func() {
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s := f()
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_ = s
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}
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s = f()
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useiface(s)
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useiface(s)
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}
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//go:noinline
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func useiface(x interface{}) {
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}
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//go:noinline
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func h() {
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var x [16]uintptr
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for i := range x {
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x[i] = 1
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}
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useint(x[0])
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useint(x[1])
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useint(x[2])
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useint(x[3])
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}
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//go:noinline
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func useint(x uintptr) {
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}
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func main() {
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// scribble non-zero values on stack
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h()
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// call function that used to let the garbage collector
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// see uninitialized stack values; it will see the
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// nonzero values.
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g()
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}
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func big(x int) {
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if x >= 0 {
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big(x - 1)
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}
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}
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