// 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)
}
}
// callInstruction translates function call instructions.
func (fr *frame) callInstruction(instr ssa.CallInstruction) []*govalue {
call := instr.Common()
if builtin, ok := call.Value.(*ssa.Builtin); ok {
var typ types.Type
if v := instr.Value(); v != nil {
typ = v.Type()
}
return fr.callBuiltin(typ, builtin, call.Args)
}
args := make([]*govalue, len(call.Args))
for i, arg := range call.Args {
args[i] = fr.value(arg)
}
var fn *govalue
if call.IsInvoke() {
var recv *govalue
fn, recv = fr.interfaceMethod(fr.llvmvalue(call.Value), call.Value.Type(), call.Method)
args = append([]*govalue{recv}, args...)
} else {
if ssafn, ok := call.Value.(*ssa.Function); ok {
llfn := fr.resolveFunctionGlobal(ssafn)
llfn = llvm.ConstBitCast(llfn, llvm.PointerType(llvm.Int8Type(), 0))
fn = newValue(llfn, ssafn.Type())
} else {
// First-class function values are stored as *{*fnptr}, so
// we must extract the function pointer. We must also
// call __go_set_closure, in case the function is a closure.
fn = fr.value(call.Value)
fr.runtime.setClosure.call(fr, fn.value)
fnptr := fr.builder.CreateBitCast(fn.value, llvm.PointerType(fn.value.Type(), 0), "")
fnptr = fr.builder.CreateLoad(fnptr, "")
fn = newValue(fnptr, fn.Type())
}
if recv := call.Signature().Recv(); recv != nil {
if _, ok := recv.Type().Underlying().(*types.Pointer); !ok {
recvalloca := fr.allocaBuilder.CreateAlloca(args[0].value.Type(), "")
fr.builder.CreateStore(args[0].value, recvalloca)
args[0] = newValue(recvalloca, types.NewPointer(args[0].Type()))
}
}
}
return fr.createCall(fn, args)
}
// 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.
}
}
// 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.Pkg
}
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)),
})
}
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
}
// createThunk creates a thunk from a
// given function and arguments, suitable for use with
// "defer" and "go".
func (fr *frame) createThunk(call ssa.CallInstruction) (thunk llvm.Value, arg llvm.Value) {
seenarg := make(map[ssa.Value]bool)
var args []ssa.Value
var argtypes []*types.Var
packArg := func(arg ssa.Value) {
switch arg.(type) {
case *ssa.Builtin, *ssa.Function, *ssa.Const, *ssa.Global:
// Do nothing: we can generate these in the thunk
default:
if !seenarg[arg] {
seenarg[arg] = true
args = append(args, arg)
field := types.NewField(0, nil, "_", arg.Type(), true)
argtypes = append(argtypes, field)
}
}
}
packArg(call.Common().Value)
for _, arg := range call.Common().Args {
packArg(arg)
}
var isRecoverCall bool
i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
var structllptr llvm.Type
if len(args) == 0 {
if builtin, ok := call.Common().Value.(*ssa.Builtin); ok {
isRecoverCall = builtin.Name() == "recover"
}
if isRecoverCall {
// When creating a thunk for recover(), we must pass fr.canRecover.
arg = fr.builder.CreateZExt(fr.canRecover, fr.target.IntPtrType(), "")
arg = fr.builder.CreateIntToPtr(arg, i8ptr, "")
} else {
arg = llvm.ConstPointerNull(i8ptr)
}
} else {
structtype := types.NewStruct(argtypes, nil)
arg = fr.createTypeMalloc(structtype)
structllptr = arg.Type()
for i, ssaarg := range args {
argptr := fr.builder.CreateStructGEP(arg, i, "")
fr.builder.CreateStore(fr.llvmvalue(ssaarg), argptr)
}
arg = fr.builder.CreateBitCast(arg, i8ptr, "")
}
thunkfntype := llvm.FunctionType(llvm.VoidType(), []llvm.Type{i8ptr}, false)
thunkfn := llvm.AddFunction(fr.module.Module, "", thunkfntype)
thunkfn.SetLinkage(llvm.InternalLinkage)
fr.addCommonFunctionAttrs(thunkfn)
thunkfr := newFrame(fr.unit, thunkfn)
defer thunkfr.dispose()
prologuebb := llvm.AddBasicBlock(thunkfn, "prologue")
thunkfr.builder.SetInsertPointAtEnd(prologuebb)
if isRecoverCall {
thunkarg := thunkfn.Param(0)
thunkarg = thunkfr.builder.CreatePtrToInt(thunkarg, fr.target.IntPtrType(), "")
thunkfr.canRecover = thunkfr.builder.CreateTrunc(thunkarg, llvm.Int1Type(), "")
} else if len(args) > 0 {
thunkarg := thunkfn.Param(0)
thunkarg = thunkfr.builder.CreateBitCast(thunkarg, structllptr, "")
for i, ssaarg := range args {
thunkargptr := thunkfr.builder.CreateStructGEP(thunkarg, i, "")
thunkarg := thunkfr.builder.CreateLoad(thunkargptr, "")
thunkfr.env[ssaarg] = newValue(thunkarg, ssaarg.Type())
}
}
_, isDefer := call.(*ssa.Defer)
entrybb := llvm.AddBasicBlock(thunkfn, "entry")
br := thunkfr.builder.CreateBr(entrybb)
thunkfr.allocaBuilder.SetInsertPointBefore(br)
thunkfr.builder.SetInsertPointAtEnd(entrybb)
var exitbb llvm.BasicBlock
if isDefer {
exitbb = llvm.AddBasicBlock(thunkfn, "exit")
thunkfr.runtime.setDeferRetaddr.call(thunkfr, llvm.BlockAddress(thunkfn, exitbb))
}
if isDefer && isRecoverCall {
thunkfr.callRecover(true)
} else {
thunkfr.callInstruction(call)
}
if isDefer {
thunkfr.builder.CreateBr(exitbb)
thunkfr.builder.SetInsertPointAtEnd(exitbb)
}
thunkfr.builder.CreateRetVoid()
thunk = fr.builder.CreateBitCast(thunkfn, i8ptr, "")
return
}
// 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.MethodValue(r.prog.MethodSets.MethodSet(C).Lookup(imethod.Pkg(), imethod.Name()))
r.addEdge(site, cmethod, true)
}