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+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ssa defines a representation of the elements of Go programs
+// (packages, types, functions, variables and constants) using a
+// static single-assignment (SSA) form intermediate representation
+// (IR) for the bodies of functions.
+//
+// THIS INTERFACE IS EXPERIMENTAL AND IS LIKELY TO CHANGE.
+//
+// For an introduction to SSA form, see
+// http://en.wikipedia.org/wiki/Static_single_assignment_form.
+// This page provides a broader reading list:
+// http://www.dcs.gla.ac.uk/~jsinger/ssa.html.
+//
+// The level of abstraction of the SSA form is intentionally close to
+// the source language to facilitate construction of source analysis
+// tools. It is not intended for machine code generation.
+//
+// All looping, branching and switching constructs are replaced with
+// unstructured control flow. Higher-level control flow constructs
+// such as multi-way branch can be reconstructed as needed; see
+// ssautil.Switches() for an example.
+//
+// The simplest way to create the SSA representation of a package is
+// to load typed syntax trees using golang.org/x/tools/go/packages, then
+// invoke the ssautil.Packages helper function. See ExampleLoadPackages
+// and ExampleWholeProgram for examples.
+// The resulting ssa.Program contains all the packages and their
+// members, but SSA code is not created for function bodies until a
+// subsequent call to (*Package).Build or (*Program).Build.
+//
+// The builder initially builds a naive SSA form in which all local
+// variables are addresses of stack locations with explicit loads and
+// stores. Registerisation of eligible locals and φ-node insertion
+// using dominance and dataflow are then performed as a second pass
+// called "lifting" to improve the accuracy and performance of
+// subsequent analyses; this pass can be skipped by setting the
+// NaiveForm builder flag.
+//
+// The primary interfaces of this package are:
+//
+// - Member: a named member of a Go package.
+// - Value: an expression that yields a value.
+// - Instruction: a statement that consumes values and performs computation.
+// - Node: a Value or Instruction (emphasizing its membership in the SSA value graph)
+//
+// A computation that yields a result implements both the Value and
+// Instruction interfaces. The following table shows for each
+// concrete type which of these interfaces it implements.
+//
+// Value? Instruction? Member?
+// *Alloc ✔ ✔
+// *BinOp ✔ ✔
+// *Builtin ✔
+// *Call ✔ ✔
+// *ChangeInterface ✔ ✔
+// *ChangeType ✔ ✔
+// *Const ✔
+// *Convert ✔ ✔
+// *DebugRef ✔
+// *Defer ✔
+// *Extract ✔ ✔
+// *Field ✔ ✔
+// *FieldAddr ✔ ✔
+// *FreeVar ✔
+// *Function ✔ ✔ (func)
+// *Global ✔ ✔ (var)
+// *Go ✔
+// *If ✔
+// *Index ✔ ✔
+// *IndexAddr ✔ ✔
+// *Jump ✔
+// *Lookup ✔ ✔
+// *MakeChan ✔ ✔
+// *MakeClosure ✔ ✔
+// *MakeInterface ✔ ✔
+// *MakeMap ✔ ✔
+// *MakeSlice ✔ ✔
+// *MapUpdate ✔
+// *NamedConst ✔ (const)
+// *Next ✔ ✔
+// *Panic ✔
+// *Parameter ✔
+// *Phi ✔ ✔
+// *Range ✔ ✔
+// *Return ✔
+// *RunDefers ✔
+// *Select ✔ ✔
+// *Send ✔
+// *Slice ✔ ✔
+// *Store ✔
+// *Type ✔ (type)
+// *TypeAssert ✔ ✔
+// *UnOp ✔ ✔
+//
+// Other key types in this package include: Program, Package, Function
+// and BasicBlock.
+//
+// The program representation constructed by this package is fully
+// resolved internally, i.e. it does not rely on the names of Values,
+// Packages, Functions, Types or BasicBlocks for the correct
+// interpretation of the program. Only the identities of objects and
+// the topology of the SSA and type graphs are semantically
+// significant. (There is one exception: Ids, used to identify field
+// and method names, contain strings.) Avoidance of name-based
+// operations simplifies the implementation of subsequent passes and
+// can make them very efficient. Many objects are nonetheless named
+// to aid in debugging, but it is not essential that the names be
+// either accurate or unambiguous. The public API exposes a number of
+// name-based maps for client convenience.
+//
+// The ssa/ssautil package provides various utilities that depend only
+// on the public API of this package.
+//
+// TODO(adonovan): Consider the exceptional control-flow implications
+// of defer and recover().
+//
+// TODO(adonovan): write a how-to document for all the various cases
+// of trying to determine corresponding elements across the four
+// domains of source locations, ast.Nodes, types.Objects,
+// ssa.Values/Instructions.
+//
+package ssa // import "golang.org/x/tools/go/ssa"
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