// genCall generates constraints for call instruction instr.
func (a *analysis) genCall(caller *cgnode, instr ssa.CallInstruction) {
call := instr.Common()
// Intrinsic implementations of built-in functions.
if _, ok := call.Value.(*ssa.Builtin); ok {
a.genBuiltinCall(instr, caller)
return
}
var result nodeid
if v := instr.Value(); v != nil {
result = a.valueNode(v)
}
site := &callsite{instr: instr}
if call.StaticCallee() != nil {
a.genStaticCall(caller, site, call, result)
} else if call.IsInvoke() {
a.genInvoke(caller, site, call, result)
} else {
a.genDynamicCall(caller, site, call, result)
}
caller.sites = append(caller.sites, site)
if a.log != nil {
// TODO(adonovan): debug: improve log message.
fmt.Fprintf(a.log, "\t%s to targets %s from %s\n", site, site.targets, caller)
}
}
// addEdge adds the specified call graph edge, and marks it reachable.
// addrTaken indicates whether to mark the callee as "address-taken".
func (r *rta) addEdge(site ssa.CallInstruction, callee *ssa.Function, addrTaken bool) {
r.addReachable(callee, addrTaken)
if g := r.result.CallGraph; g != nil {
if site.Parent() == nil {
panic(site)
}
from := g.CreateNode(site.Parent())
to := g.CreateNode(callee)
callgraph.AddEdge(from, site, to)
}
}
// visitInvoke is called each time the algorithm encounters an "invoke"-mode call.
func (r *rta) visitInvoke(site ssa.CallInstruction) {
I := site.Common().Value.Type().Underlying().(*types.Interface)
// Record the invoke site.
sites, _ := r.invokeSites.At(I).([]ssa.CallInstruction)
r.invokeSites.Set(I, append(sites, site))
// Add callgraph edge for each existing
// address-taken concrete type implementing I.
for _, C := range r.implementations(I) {
r.addInvokeEdge(site, C)
}
}
// visitDynCall is called each time we encounter a dynamic "call"-mode call.
func (r *rta) visitDynCall(site ssa.CallInstruction) {
S := site.Common().Signature()
// Record the call site.
sites, _ := r.dynCallSites.At(S).([]ssa.CallInstruction)
r.dynCallSites.Set(S, append(sites, site))
// For each function of signature S that we know is address-taken,
// mark it reachable. We'll add the callgraph edges later.
funcs, _ := r.addrTakenFuncsBySig.At(S).(map[*ssa.Function]bool)
for g := range funcs {
r.addEdge(site, g, true)
}
}
// addCallees adds client data and links for the facts that site calls fns.
func (a *analysis) addCallees(site ssa.CallInstruction, fns []*ssa.Function) {
v := calleesJSON{
Descr: site.Common().Description(),
Callees: []anchorJSON{}, // (JS wants non-nil)
}
var this *types.Package // for relativizing names
if p := site.Parent().Package(); p != nil {
this = p.Object
}
for _, fn := range fns {
v.Callees = append(v.Callees, anchorJSON{
Text: prettyFunc(this, fn),
Href: a.posURL(funcToken(fn), len("func")),
})
}
fi, offset := a.fileAndOffset(site.Common().Pos())
fi.addLink(aLink{
start: offset,
end: offset + len("("),
title: fmt.Sprintf("%d callees", len(v.Callees)),
onclick: fmt.Sprintf("onClickCallees(%d)", fi.addData(v)),
})
}
// genBuiltinCall generates contraints for a call to a built-in.
func (a *analysis) genBuiltinCall(instr ssa.CallInstruction, cgn *cgnode) {
call := instr.Common()
switch call.Value.(*ssa.Builtin).Name() {
case "append":
// Safe cast: append cannot appear in a go or defer statement.
a.genAppend(instr.(*ssa.Call), cgn)
case "copy":
tElem := call.Args[0].Type().Underlying().(*types.Slice).Elem()
a.copyElems(cgn, tElem, call.Args[0], call.Args[1])
case "panic":
a.copy(a.panicNode, a.valueNode(call.Args[0]), 1)
case "recover":
if v := instr.Value(); v != nil {
a.copy(a.valueNode(v), a.panicNode, 1)
}
case "print":
// In the tests, the probe might be the sole reference
// to its arg, so make sure we create nodes for it.
if len(call.Args) > 0 {
a.valueNode(call.Args[0])
}
case "ssa:wrapnilchk":
a.copy(a.valueNode(instr.Value()), a.valueNode(call.Args[0]), 1)
default:
// No-ops: close len cap real imag complex print println delete.
}
}
func findCallees(o *Oracle, site ssa.CallInstruction) ([]*ssa.Function, error) {
// Avoid running the pointer analysis for static calls.
if callee := site.Common().StaticCallee(); callee != nil {
switch callee.String() {
case "runtime.SetFinalizer", "(reflect.Value).Call":
// The PTA treats calls to these intrinsics as dynamic.
// TODO(adonovan): avoid reliance on PTA internals.
default:
return []*ssa.Function{callee}, nil // singleton
}
}
// Dynamic call: use pointer analysis.
o.ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(o).CallGraph
cg.DeleteSyntheticNodes()
// Find all call edges from the site.
n := cg.Nodes[site.Parent()]
if n == nil {
return nil, fmt.Errorf("this call site is unreachable in this analysis")
}
calleesMap := make(map[*ssa.Function]bool)
for _, edge := range n.Out {
if edge.Site == site {
calleesMap[edge.Callee.Func] = true
}
}
// De-duplicate and sort.
funcs := make([]*ssa.Function, 0, len(calleesMap))
for f := range calleesMap {
funcs = append(funcs, f)
}
sort.Sort(byFuncPos(funcs))
return funcs, nil
}
// addInvokeEdge is called for each new pair (site, C) in the matrix.
func (r *rta) addInvokeEdge(site ssa.CallInstruction, C types.Type) {
// Ascertain the concrete method of C to be called.
imethod := site.Common().Method
cmethod := r.prog.Method(r.prog.MethodSets.MethodSet(C).Lookup(imethod.Pkg(), imethod.Name()))
r.addEdge(site, cmethod, true)
}