1 files changed, 0 insertions, 346 deletions
diff --git a/tools/checklocks/state.go b/tools/checklocks/state.go
deleted file mode 100644
index aaf997d79..000000000
--- a/tools/checklocks/state.go
+++ /dev/null
@@ -1,346 +0,0 @@
-// Copyright 2020 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package checklocks
-
-import (
-	"fmt"
-	"go/token"
-	"go/types"
-	"strings"
-	"sync/atomic"
-
-	"golang.org/x/tools/go/ssa"
-)
-
-// lockState tracks the locking state and aliases.
-type lockState struct {
-	// lockedMutexes is used to track which mutexes in a given struct are
-	// currently locked. Note that most of the heavy lifting is done by
-	// valueAsString below, which maps to specific structure fields, etc.
-	//
-	// The value indicates whether this is an exclusive lock.
-	lockedMutexes map[string]bool
-
-	// stored stores values that have been stored in memory, bound to
-	// FreeVars or passed as Parameterse.
-	stored map[ssa.Value]ssa.Value
-
-	// used is a temporary map, used only for valueAsString. It prevents
-	// multiple use of the same memory location.
-	used map[ssa.Value]struct{}
-
-	// defers are the stack of defers that have been pushed.
-	defers []*ssa.Defer
-
-	// refs indicates the number of references on this structure. If it's
-	// greater than one, we will do copy-on-write.
-	refs *int32
-}
-
-// newLockState makes a new lockState.
-func newLockState() *lockState {
-	refs := int32(1) // Not shared.
-	return &lockState{
-		lockedMutexes: make(map[string]bool),
-		used:          make(map[ssa.Value]struct{}),
-		stored:        make(map[ssa.Value]ssa.Value),
-		defers:        make([]*ssa.Defer, 0),
-		refs:          &refs,
-	}
-}
-
-// fork forks the locking state. When a lockState is forked, any modifications
-// will cause maps to be copied.
-func (l *lockState) fork() *lockState {
-	if l == nil {
-		return newLockState()
-	}
-	atomic.AddInt32(l.refs, 1)
-	return &lockState{
-		lockedMutexes: l.lockedMutexes,
-		used:          make(map[ssa.Value]struct{}),
-		stored:        l.stored,
-		defers:        l.defers,
-		refs:          l.refs,
-	}
-}
-
-// modify indicates that this state will be modified.
-func (l *lockState) modify() {
-	if atomic.LoadInt32(l.refs) > 1 {
-		// Copy the lockedMutexes.
-		lm := make(map[string]bool)
-		for k, v := range l.lockedMutexes {
-			lm[k] = v
-		}
-		l.lockedMutexes = lm
-
-		// Copy the stored values.
-		s := make(map[ssa.Value]ssa.Value)
-		for k, v := range l.stored {
-			s[k] = v
-		}
-		l.stored = s
-
-		// Reset the used values.
-		l.used = make(map[ssa.Value]struct{})
-
-		// Copy the defers.
-		ds := make([]*ssa.Defer, len(l.defers))
-		copy(ds, l.defers)
-		l.defers = ds
-
-		// Drop our reference.
-		atomic.AddInt32(l.refs, -1)
-		newRefs := int32(1) // Not shared.
-		l.refs = &newRefs
-	}
-}
-
-// isHeld indicates whether the field is held is not.
-func (l *lockState) isHeld(rv resolvedValue, exclusiveRequired bool) (string, bool) {
-	if !rv.valid {
-		return rv.valueAsString(l), false
-	}
-	s := rv.valueAsString(l)
-	isExclusive, ok := l.lockedMutexes[s]
-	if !ok {
-		return s, false
-	}
-	// Accept a weaker lock if exclusiveRequired is false.
-	if exclusiveRequired && !isExclusive {
-		return s, false
-	}
-	return s, true
-}
-
-// lockField locks the given field.
-//
-// If false is returned, the field was already locked.
-func (l *lockState) lockField(rv resolvedValue, exclusive bool) (string, bool) {
-	if !rv.valid {
-		return rv.valueAsString(l), false
-	}
-	s := rv.valueAsString(l)
-	if _, ok := l.lockedMutexes[s]; ok {
-		return s, false
-	}
-	l.modify()
-	l.lockedMutexes[s] = exclusive
-	return s, true
-}
-
-// unlockField unlocks the given field.
-//
-// If false is returned, the field was not locked.
-func (l *lockState) unlockField(rv resolvedValue, exclusive bool) (string, bool) {
-	if !rv.valid {
-		return rv.valueAsString(l), false
-	}
-	s := rv.valueAsString(l)
-	wasExclusive, ok := l.lockedMutexes[s]
-	if !ok {
-		return s, false
-	}
-	if wasExclusive != exclusive {
-		return s, false
-	}
-	l.modify()
-	delete(l.lockedMutexes, s)
-	return s, true
-}
-
-// downgradeField downgrades the given field.
-//
-// If false was returned, the field was not downgraded.
-func (l *lockState) downgradeField(rv resolvedValue) (string, bool) {
-	if !rv.valid {
-		return rv.valueAsString(l), false
-	}
-	s := rv.valueAsString(l)
-	wasExclusive, ok := l.lockedMutexes[s]
-	if !ok {
-		return s, false
-	}
-	if !wasExclusive {
-		return s, false
-	}
-	l.modify()
-	l.lockedMutexes[s] = false // Downgraded.
-	return s, true
-}
-
-// store records an alias.
-func (l *lockState) store(addr ssa.Value, v ssa.Value) {
-	l.modify()
-	l.stored[addr] = v
-}
-
-// isSubset indicates other holds all the locks held by l.
-func (l *lockState) isSubset(other *lockState) bool {
-	for k, isExclusive := range l.lockedMutexes {
-		otherExclusive, otherOk := other.lockedMutexes[k]
-		if !otherOk {
-			return false
-		}
-		// Accept weaker locks as a subset.
-		if isExclusive && !otherExclusive {
-			return false
-		}
-	}
-	return true
-}
-
-// count indicates the number of locks held.
-func (l *lockState) count() int {
-	return len(l.lockedMutexes)
-}
-
-// isCompatible returns true if the states are compatible.
-func (l *lockState) isCompatible(other *lockState) bool {
-	return l.isSubset(other) && other.isSubset(l)
-}
-
-// elemType is a type that implements the Elem function.
-type elemType interface {
-	Elem() types.Type
-}
-
-// valueAsString returns a string for a given value.
-//
-// This decomposes the value into the simplest possible representation in terms
-// of parameters, free variables and globals. During resolution, stored values
-// may be transferred, as well as bound free variables.
-//
-// Nil may not be passed here.
-func (l *lockState) valueAsString(v ssa.Value) string {
-	switch x := v.(type) {
-	case *ssa.Parameter:
-		// Was this provided as a paramter for a local anonymous
-		// function invocation?
-		v, ok := l.stored[x]
-		if ok {
-			return l.valueAsString(v)
-		}
-		return fmt.Sprintf("{param:%s}", x.Name())
-	case *ssa.Global:
-		return fmt.Sprintf("{global:%s}", x.Name())
-	case *ssa.FreeVar:
-		// Attempt to resolve this, in case we are being invoked in a
-		// scope where all the variables are bound.
-		v, ok := l.stored[x]
-		if ok {
-			// The FreeVar is typically bound to a location, so we
-			// check what's been stored there. Note that the second
-			// may map to the same FreeVar, which we can check.
-			stored, ok := l.stored[v]
-			if ok {
-				return l.valueAsString(stored)
-			}
-		}
-		return fmt.Sprintf("{freevar:%s}", x.Name())
-	case *ssa.Convert:
-		// Just disregard conversion.
-		return l.valueAsString(x.X)
-	case *ssa.ChangeType:
-		// Ditto, disregard.
-		return l.valueAsString(x.X)
-	case *ssa.UnOp:
-		if x.Op != token.MUL {
-			break
-		}
-		// Is this loading a free variable? If yes, then this can be
-		// resolved in the original isAlias function.
-		if fv, ok := x.X.(*ssa.FreeVar); ok {
-			return l.valueAsString(fv)
-		}
-		// Should be try to resolve via a memory address? This needs to
-		// be done since a memory location can hold its own value.
-		if _, ok := l.used[x.X]; !ok {
-			// Check if we know what the accessed location holds.
-			// This is used to disambiguate memory locations.
-			v, ok := l.stored[x.X]
-			if ok {
-				l.used[x.X] = struct{}{}
-				defer func() { delete(l.used, x.X) }()
-				return l.valueAsString(v)
-			}
-		}
-		// x.X.Type is pointer. We must construct this type
-		// dynamically, since the ssa.Value could be synthetic.
-		return fmt.Sprintf("*(%s)", l.valueAsString(x.X))
-	case *ssa.Field:
-		structType, ok := resolveStruct(x.X.Type())
-		if !ok {
-			// This should not happen.
-			panic(fmt.Sprintf("structType not available for struct: %#v", x.X))
-		}
-		fieldObj := structType.Field(x.Field)
-		return fmt.Sprintf("%s.%s", l.valueAsString(x.X), fieldObj.Name())
-	case *ssa.FieldAddr:
-		structType, ok := resolveStruct(x.X.Type())
-		if !ok {
-			// This should not happen.
-			panic(fmt.Sprintf("structType not available for struct: %#v", x.X))
-		}
-		fieldObj := structType.Field(x.Field)
-		return fmt.Sprintf("&(%s.%s)", l.valueAsString(x.X), fieldObj.Name())
-	case *ssa.Index:
-		return fmt.Sprintf("%s[%s]", l.valueAsString(x.X), l.valueAsString(x.Index))
-	case *ssa.IndexAddr:
-		return fmt.Sprintf("&(%s[%s])", l.valueAsString(x.X), l.valueAsString(x.Index))
-	case *ssa.Lookup:
-		return fmt.Sprintf("%s[%s]", l.valueAsString(x.X), l.valueAsString(x.Index))
-	case *ssa.Extract:
-		return fmt.Sprintf("%s[%d]", l.valueAsString(x.Tuple), x.Index)
-	}
-
-	// In the case of any other type (e.g. this may be an alloc, a return
-	// value, etc.), just return the literal pointer value to the Value.
-	// This will be unique within the ssa graph, and so if two values are
-	// equal, they are from the same type.
-	return fmt.Sprintf("{%T:%p}", v, v)
-}
-
-// String returns the full lock state.
-func (l *lockState) String() string {
-	if l.count() == 0 {
-		return "no locks held"
-	}
-	keys := make([]string, 0, len(l.lockedMutexes))
-	for k, exclusive := range l.lockedMutexes {
-		// Include the exclusive status of each lock.
-		keys = append(keys, fmt.Sprintf("%s %s", k, exclusiveStr(exclusive)))
-	}
-	return strings.Join(keys, ",")
-}
-
-// pushDefer pushes a defer onto the stack.
-func (l *lockState) pushDefer(d *ssa.Defer) {
-	l.modify()
-	l.defers = append(l.defers, d)
-}
-
-// popDefer pops a defer from the stack.
-func (l *lockState) popDefer() *ssa.Defer {
-	// Does not technically modify the underlying slice.
-	count := len(l.defers)
-	if count == 0 {
-		return nil
-	}
-	d := l.defers[count-1]
-	l.defers = l.defers[:count-1]
-	return d
-}