// describePointer runs the pointer analysis of the selected SSA value.
func describePointer(o *Oracle, v ssa.Value, indirect bool) (ptrs []pointerResult, err error) {
buildSSA(o)
// TODO(adonovan): don't run indirect pointer analysis on non-ptr-ptrlike types.
o.config.Queries = map[ssa.Value]pointer.Indirect{v: pointer.Indirect(indirect)}
ptares := ptrAnalysis(o)
// Combine the PT sets from all contexts.
pointers := ptares.Queries[v]
if pointers == nil {
return nil, fmt.Errorf("PTA did not encounter this expression (dead code?)")
}
pts := pointer.PointsToCombined(pointers)
if pointer.CanHaveDynamicTypes(v.Type()) {
// Show concrete types for interface/reflect.Value expression.
if concs := pts.DynamicTypes(); concs.Len() > 0 {
concs.Iterate(func(conc types.Type, pta interface{}) {
combined := pointer.PointsToCombined(pta.([]pointer.Pointer))
labels := combined.Labels()
sort.Sort(byPosAndString(labels)) // to ensure determinism
ptrs = append(ptrs, pointerResult{conc, labels})
})
}
} else {
// Show labels for other expressions.
labels := pts.Labels()
sort.Sort(byPosAndString(labels)) // to ensure determinism
ptrs = append(ptrs, pointerResult{v.Type(), labels})
}
sort.Sort(byTypeString(ptrs)) // to ensure determinism
return ptrs, nil
}
// runPTA runs the pointer analysis of the selected SSA value or address.
func runPTA(o *Oracle, v ssa.Value, isAddr bool) (ptrs []pointerResult, err error) {
buildSSA(o)
if isAddr {
o.ptaConfig.AddIndirectQuery(v)
} else {
o.ptaConfig.AddQuery(v)
}
ptares := ptrAnalysis(o)
// Combine the PT sets from all contexts.
var pointers []pointer.Pointer
if isAddr {
pointers = ptares.IndirectQueries[v]
} else {
pointers = ptares.Queries[v]
}
if pointers == nil {
return nil, fmt.Errorf("pointer analysis did not find expression (dead code?)")
}
pts := pointer.PointsToCombined(pointers)
if pointer.CanHaveDynamicTypes(v.Type()) {
// Show concrete types for interface/reflect.Value expression.
if concs := pts.DynamicTypes(); concs.Len() > 0 {
concs.Iterate(func(conc types.Type, pta interface{}) {
combined := pointer.PointsToCombined(pta.([]pointer.Pointer))
labels := combined.Labels()
sort.Sort(byPosAndString(labels)) // to ensure determinism
ptrs = append(ptrs, pointerResult{conc, labels})
})
}
} else {
// Show labels for other expressions.
labels := pts.Labels()
sort.Sort(byPosAndString(labels)) // to ensure determinism
ptrs = append(ptrs, pointerResult{v.Type(), labels})
}
sort.Sort(byTypeString(ptrs)) // to ensure determinism
return ptrs, nil
}
// peers enumerates, for a given channel send (or receive) operation,
// the set of possible receives (or sends) that correspond to it.
//
// TODO(adonovan): support reflect.{Select,Recv,Send}.
// TODO(adonovan): permit the user to query based on a MakeChan (not send/recv),
// or the implicit receive in "for v := range ch".
//
func peers(o *Oracle, qpos *QueryPos) (queryResult, error) {
arrowPos := findArrow(qpos)
if arrowPos == token.NoPos {
return nil, fmt.Errorf("there is no send/receive here")
}
buildSSA(o)
var queryOp chanOp // the originating send or receive operation
var ops []chanOp // all sends/receives of opposite direction
// Look at all send/receive instructions in the whole ssa.Program.
// Build a list of those of same type to query.
allFuncs := ssautil.AllFunctions(o.prog)
for fn := range allFuncs {
for _, b := range fn.Blocks {
for _, instr := range b.Instrs {
for _, op := range chanOps(instr) {
ops = append(ops, op)
if op.pos == arrowPos {
queryOp = op // we found the query op
}
}
}
}
}
if queryOp.ch == nil {
return nil, fmt.Errorf("ssa.Instruction for send/receive not found")
}
// Discard operations of wrong channel element type.
// Build set of channel ssa.Values as query to pointer analysis.
// We compare channels by element types, not channel types, to
// ignore both directionality and type names.
queryType := queryOp.ch.Type()
queryElemType := queryType.Underlying().(*types.Chan).Elem()
o.ptaConfig.AddQuery(queryOp.ch)
i := 0
for _, op := range ops {
if types.IsIdentical(op.ch.Type().Underlying().(*types.Chan).Elem(), queryElemType) {
o.ptaConfig.AddQuery(op.ch)
ops[i] = op
i++
}
}
ops = ops[:i]
// Run the pointer analysis.
ptares := ptrAnalysis(o)
// Combine the PT sets from all contexts.
queryChanPts := pointer.PointsToCombined(ptares.Queries[queryOp.ch])
// Ascertain which make(chan) labels the query's channel can alias.
var makes []token.Pos
for _, label := range queryChanPts.Labels() {
makes = append(makes, label.Pos())
}
sort.Sort(byPos(makes))
// Ascertain which send/receive operations can alias the same make(chan) labels.
var sends, receives []token.Pos
for _, op := range ops {
for _, ptr := range ptares.Queries[op.ch] {
if ptr.PointsTo().Intersects(queryChanPts) {
if op.dir == types.SendOnly {
sends = append(sends, op.pos)
} else {
receives = append(receives, op.pos)
}
}
}
}
sort.Sort(byPos(sends))
sort.Sort(byPos(receives))
return &peersResult{
queryPos: arrowPos,
queryType: queryType,
makes: makes,
sends: sends,
receives: receives,
}, nil
}