// genCall generates contraints 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 {
		fmt.Fprintf(a.log, "\t%s to targets %s from %s\n", site, site.targets, caller)
	}
}

// genCall generates contraints 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)
	}

	// The node whose pts(·) will contain all targets of the call.
	var targets nodeid
	switch {
	case call.StaticCallee() != nil:
		targets = a.genStaticCall(call, result)
	case call.IsInvoke():
		targets = a.genInvoke(call, result)
	default:
		targets = a.genDynamicCall(call, result)
	}

	site := &callsite{
		targets: targets,
		instr:   instr,
	}
	caller.sites = append(caller.sites, site)
	if a.log != nil {
		fmt.Fprintf(a.log, "\t%s to targets %s from %s\n", site, site.targets, caller)
	}
}

// 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).Object().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":
		// Analytically print is a no-op, but it's a convenient hook
		// for testing the pts of an expression, so we notify the client.
		// Existing uses in Go core libraries are few and harmless.
		if Print := a.config.Print; Print != nil {
			// Due to context-sensitivity, we may encounter
			// the same print() call in many contexts, so
			// we merge them to a canonical node.
			probe := a.probes[call]
			t := call.Args[0].Type()

			// First time?  Create the canonical probe node.
			if probe == 0 {
				probe = a.addNodes(t, "print")
				a.probes[call] = probe
				Print(call, ptr{a, nil, probe}) // notify client
			}

			a.copy(probe, a.valueNode(call.Args[0]), a.sizeof(t))
		}

	default:
		// No-ops: close len cap real imag complex 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
	callgraph := ptrAnalysis(o).CallGraph

	// Find all call edges from the site.
	calleesMap := make(map[*ssa.Function]bool)
	var foundCGNode bool
	for _, n := range callgraph.Nodes() {
		if n.Func() == site.Parent() {
			foundCGNode = true
			for _, edge := range n.Edges() {
				if edge.Site == site {
					calleesMap[edge.Callee.Func()] = true
				}
			}
		}
	}
	if !foundCGNode {
		return nil, fmt.Errorf("this call site is unreachable in this analysis")
	}

	// Discard context, 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
}

// prepareCall returns the evaluated function and arguments.
//
// For builtins that may not be used in go/defer, prepareCall
// will emits inline code. In this case, prepareCall returns
// nil for fn and args, and returns a non-nil value for result.
func (fr *frame) prepareCall(instr ssa.CallInstruction) (fn *LLVMValue, args []*LLVMValue, result *LLVMValue) {
	call := instr.Common()
	args = make([]*LLVMValue, len(call.Args))
	for i, arg := range call.Args {
		args[i] = fr.value(arg)
	}

	if call.IsInvoke() {
		fn := fr.interfaceMethod(fr.value(call.Value), call.Method)
		return fn, args, nil
	}

	switch v := call.Value.(type) {
	case *ssa.Builtin:
		// handled below
	case *ssa.Function:
		// Function handled specially; value() will convert
		// a function to one with a context argument.
		fn = fr.resolveFunction(v)
		pair := llvm.ConstNull(fr.llvmtypes.ToLLVM(fn.Type()))
		pair = llvm.ConstInsertValue(pair, fn.LLVMValue(), []uint32{0})
		fn = fr.NewValue(pair, fn.Type())
		return fn, args, nil
	default:
		fn = fr.value(call.Value)
		return fn, args, nil
	}

	// Builtins may only be used in calls (i.e. can't be assigned),
	// and only print[ln], panic and recover may be used in go/defer.
	builtin := call.Value.(*ssa.Builtin)
	switch builtin.Name() {
	case "print", "println":
		// print/println generates a call-site specific anonymous
		// function to print the values. It's not inline because
		// print/println may be deferred.
		params := make([]*types.Var, len(call.Args))
		for i, arg := range call.Args {
			// make sure to use args[i].Type(), not call.Args[i].Type(),
			// as the evaluated expression converts untyped.
			params[i] = types.NewParam(arg.Pos(), nil, arg.Name(), args[i].Type())
		}
		sig := types.NewSignature(nil, nil, types.NewTuple(params...), nil, false)
		llfntyp := fr.llvmtypes.ToLLVM(sig)
		llfnptr := llvm.AddFunction(fr.module.Module, "", llfntyp.StructElementTypes()[0].ElementType())
		currBlock := fr.builder.GetInsertBlock()
		entry := llvm.AddBasicBlock(llfnptr, "entry")
		fr.builder.SetInsertPointAtEnd(entry)
		internalArgs := make([]Value, len(args))
		for i, arg := range args {
			internalArgs[i] = fr.NewValue(llfnptr.Param(i), arg.Type())
		}
		fr.printValues(builtin.Name() == "println", internalArgs...)
		fr.builder.CreateRetVoid()
		fr.builder.SetInsertPointAtEnd(currBlock)
		return fr.NewValue(llfnptr, sig), args, nil

	case "panic":
		panic("TODO: panic")

	case "recover":
		// TODO(axw) determine number of frames to skip in pc check
		indirect := fr.NewValue(llvm.ConstNull(llvm.Int32Type()), types.Typ[types.Int32])
		return fr.runtime.recover_, []*LLVMValue{indirect}, nil

	case "append":
		return nil, nil, fr.callAppend(args[0], args[1])

	case "close":
		return fr.runtime.chanclose, args, nil

	case "cap":
		return nil, nil, fr.callCap(args[0])

	case "len":
		return nil, nil, fr.callLen(args[0])

	case "copy":
		return nil, nil, fr.callCopy(args[0], args[1])

	case "delete":
		fr.callDelete(args[0], args[1])
		return nil, nil, nil

	case "real":
		return nil, nil, args[0].extractComplexComponent(0)

	case "imag":
		return nil, nil, args[0].extractComplexComponent(1)

	case "complex":
		r := args[0].LLVMValue()
		i := args[1].LLVMValue()
		typ := instr.Value().Type()
		cmplx := llvm.Undef(fr.llvmtypes.ToLLVM(typ))
//.........这里部分代码省略.........