Golang ssa.Program類代碼示例

// ssaValueForExpr returns the ssa.Value of the non-ast.Ident
// expression whose path to the root of the AST is path.
//
func ssaValueForExpr(prog *ssa.Program, qinfo *loader.PackageInfo, path []ast.Node) (value ssa.Value, isAddr bool, err error) {
	pkg := prog.Package(qinfo.Pkg)
	pkg.SetDebugMode(true)
	pkg.Build()

	fn := ssa.EnclosingFunction(pkg, path)
	if fn == nil {
		return nil, false, fmt.Errorf("no SSA function built for this location (dead code?)")
	}

	if v, addr := fn.ValueForExpr(path[0].(ast.Expr)); v != nil {
		return v, addr, nil
	}

	return nil, false, fmt.Errorf("can't locate SSA Value for expression in %s", fn)
}

func checkConstValue(t *testing.T, prog *ssa.Program, obj *types.Const) {
	c := prog.ConstValue(obj)
	// fmt.Printf("ConstValue(%s) = %s\n", obj, c) // debugging
	if c == nil {
		t.Errorf("ConstValue(%s) == nil", obj)
		return
	}
	if !types.Identical(c.Type(), obj.Type()) {
		t.Errorf("ConstValue(%s).Type() == %s", obj, c.Type())
		return
	}
	if obj.Name() != "nil" {
		if !exact.Compare(c.Value, token.EQL, obj.Val()) {
			t.Errorf("ConstValue(%s).Value (%s) != %s",
				obj, c.Value, obj.Val())
			return
		}
	}
}

func checkFuncValue(t *testing.T, prog *ssa.Program, obj *types.Func) {
	fn := prog.FuncValue(obj)
	// fmt.Printf("FuncValue(%s) = %s\n", obj, fn) // debugging
	if fn == nil {
		if obj.Name() != "interfaceMethod" {
			t.Errorf("FuncValue(%s) == nil", obj)
		}
		return
	}
	if fnobj := fn.Object(); fnobj != obj {
		t.Errorf("FuncValue(%s).Object() == %s; value was %s",
			obj, fnobj, fn.Name())
		return
	}
	if !types.Identical(fn.Type(), obj.Type()) {
		t.Errorf("FuncValue(%s).Type() == %s", obj, fn.Type())
		return
	}
}

// findVisibleConsts returns a mapping from each package-level constant assignable to type "error", to nil.
func findVisibleConsts(prog *ssa.Program, qpos *QueryPos) map[ssa.Const]*ssa.NamedConst {
	constants := make(map[ssa.Const]*ssa.NamedConst)
	for _, pkg := range prog.AllPackages() {
		for _, mem := range pkg.Members {
			obj, ok := mem.(*ssa.NamedConst)
			if !ok {
				continue
			}
			consttype := obj.Type()
			if !types.AssignableTo(consttype, builtinErrorType) {
				continue
			}
			if !isAccessibleFrom(obj.Object(), qpos.info.Pkg) {
				continue
			}
			constants[*obj.Value] = obj
		}
	}

	return constants
}

// findVisibleErrs returns a mapping from each package-level variable of type "error" to nil.
func findVisibleErrs(prog *ssa.Program, qpos *QueryPos) map[*ssa.Global]ssa.Value {
	globals := make(map[*ssa.Global]ssa.Value)
	for _, pkg := range prog.AllPackages() {
		for _, mem := range pkg.Members {
			gbl, ok := mem.(*ssa.Global)
			if !ok {
				continue
			}
			gbltype := gbl.Type()
			// globals are always pointers
			if !types.Identical(deref(gbltype), builtinErrorType) {
				continue
			}
			if !isAccessibleFrom(gbl.Object(), qpos.info.Pkg) {
				continue
			}
			globals[gbl] = nil
		}
	}
	return globals
}

func checkVarValue(t *testing.T, prog *ssa.Program, pkg *ssa.Package, ref []ast.Node, obj *types.Var, expKind string, wantAddr bool) {
	// The prefix of all assertions messages.
	prefix := fmt.Sprintf("VarValue(%s @ L%d)",
		obj, prog.Fset.Position(ref[0].Pos()).Line)

	v, gotAddr := prog.VarValue(obj, pkg, ref)

	// Kind is the concrete type of the ssa Value.
	gotKind := "nil"
	if v != nil {
		gotKind = fmt.Sprintf("%T", v)[len("*ssa."):]
	}

	// fmt.Printf("%s = %v (kind %q; expect %q) wantAddr=%t gotAddr=%t\n", prefix, v, gotKind, expKind, wantAddr, gotAddr) // debugging

	// Check the kinds match.
	// "nil" indicates expected failure (e.g. optimized away).
	if expKind != gotKind {
		t.Errorf("%s concrete type == %s, want %s", prefix, gotKind, expKind)
	}

	// Check the types match.
	// If wantAddr, the expected type is the object's address.
	if v != nil {
		expType := obj.Type()
		if wantAddr {
			expType = types.NewPointer(expType)
			if !gotAddr {
				t.Errorf("%s: got value, want address", prefix)
			}
		} else if gotAddr {
			t.Errorf("%s: got address, want value", prefix)
		}
		if !types.Identical(v.Type(), expType) {
			t.Errorf("%s.Type() == %s, want %s", prefix, v.Type(), expType)
		}
	}
}

// ssaValueForIdent returns the ssa.Value for the ast.Ident whose path
// to the root of the AST is path.  isAddr reports whether the
// ssa.Value is the address denoted by the ast.Ident, not its value.
//
func ssaValueForIdent(prog *ssa.Program, qinfo *loader.PackageInfo, obj types.Object, path []ast.Node) (value ssa.Value, isAddr bool, err error) {
	switch obj := obj.(type) {
	case *types.Var:
		pkg := prog.Package(qinfo.Pkg)
		pkg.Build()
		if v, addr := prog.VarValue(obj, pkg, path); v != nil {
			return v, addr, nil
		}
		return nil, false, fmt.Errorf("can't locate SSA Value for var %s", obj.Name())

	case *types.Func:
		fn := prog.FuncValue(obj)
		if fn == nil {
			return nil, false, fmt.Errorf("%s is an interface method", obj)
		}
		// TODO(adonovan): there's no point running PTA on a *Func ident.
		// Eliminate this feature.
		return fn, false, nil
	}
	panic(obj)
}