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![David Chase](/assets/img/avatar_default.png)
Assignment between input parameters causes them to have more than
one "Name", and running this backwards from names to values can end
up confusing (conflating) parameter spill slots.
Around 105a6e9518
, this cases a stack overflow running
go test -race encoding/pem
because two slice parameters spill (incorrectly) into the same
stack slots (in the AB?I-defined parameter spill area).
This also tickles a failure in cue, which turned out to be
easier to isolate.
Fixes #45851.
Updates #40724.
Change-Id: I39c56815bd6abb652f1ccbe83c47f4f373a125c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/313212
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
69 lines
1.3 KiB
Go
69 lines
1.3 KiB
Go
// run
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// Copyright 2021 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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// This tickles a stack-allocation bug when the register ABI is enabled.
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// The original report was from cue, internal/core/adt/equality.go,
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// function equalVertex.
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// In the failing case, something bad gets passed to equalTerminal.
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package main
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import "fmt"
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type Kind uint16
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type Flag uint16
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const (
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allKinds Kind = 1
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TopKind Kind = (allKinds - 1)
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)
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type Value interface {
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Kind() Kind
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}
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type Vertex struct {
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BaseValue Value
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name string
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}
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func (v *Vertex) Kind() Kind {
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return TopKind
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}
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func main() {
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vA := &Vertex{name:"vA",}
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vB := &Vertex{name:"vB",}
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vX := &Vertex{name:"vX",}
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vA.BaseValue = vX
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vB.BaseValue = vX
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_ = equalVertex(vA, vB, Flag(1))
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}
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var foo string
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//go:noinline
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func (v *Vertex) IsClosedStruct() bool {
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return true
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}
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func equalVertex(x *Vertex, v Value, flags Flag) bool {
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y, ok := v.(*Vertex)
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if !ok {
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return false
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}
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v, ok1 := x.BaseValue.(Value)
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w, ok2 := y.BaseValue.(Value)
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if !ok1 && !ok2 {
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return true // both are struct or list.
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}
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return equalTerminal(v, w, flags)
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}
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//go:noinline
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func equalTerminal(x Value, y Value, flags Flag) bool {
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foo = fmt.Sprintf("EQclosed %s %s %d\n", x.(*Vertex).name, y.(*Vertex).name, flags)
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return true
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}
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