gotools/go/ssa/ssautil/visit.go

// AllFunctions finds and returns the set of functions potentially
// needed by program prog, as determined by a simple linker-style
// reachability algorithm starting from the members and method-sets of
// each package.  The result may include anonymous functions and
// synthetic wrappers.
//
// Precondition: all packages are built.
//
// TODO(adonovan): this function is underspecified. It doesn't
// actually work like a linker, which computes reachability from main
// using something like go/callgraph/cha (without materializing the
// call graph). In fact, it treats all public functions and all
// methods of public non-parameterized types as roots, even though
// they may be unreachable--but only in packages created from syntax.
//
// I think we should deprecate AllFunctions function in favor of two
// clearly defined ones:
//
//  1. The first would efficiently compute CHA reachability from a set
//     of main packages, making it suitable for a whole-program
//     analysis context with InstantiateGenerics, in conjunction with
//     Program.Build.
//
//  2. The second would return only the set of functions corresponding
//     to source Func{Decl,Lit} syntax, like SrcFunctions in
//     go/analysis/passes/buildssa; this is suitable for
//     package-at-a-time (or handful of packages) context.
//     ssa.Package could easily expose it as a field.
//
// We could add them unexported for now and use them via the linkname hack.
func AllFunctions(prog *ssa.Program) map[*ssa.Function]bool { … }

// MainPackages returns the subset of the specified packages
// named "main" that define a main function.
// The result may include synthetic "testmain" packages.
func MainPackages(pkgs []*ssa.Package) []*ssa.Package { … }

// TODO(adonovan): propose a principled API for this. One possibility
// is a new field, Package.SrcFunctions []*Function, which would
// contain the list of SrcFunctions described in point 2 of the
// AllFunctions doc comment, or nil if the package is not from syntax.
// But perhaps overloading nil vs empty slice is too subtle.
//
//go:linkname isSyntactic golang.org/x/tools/go/ssa.isSyntactic
func isSyntactic(pkg *ssa.Package) bool