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Diffstat (limited to 'vendor/golang.org/x/tools/go/ssa/doc.go')
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diff --git a/vendor/golang.org/x/tools/go/ssa/doc.go b/vendor/golang.org/x/tools/go/ssa/doc.go new file mode 100644 index 0000000..3310b55 --- /dev/null +++ b/vendor/golang.org/x/tools/go/ssa/doc.go @@ -0,0 +1,122 @@ +// 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. +// +// 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 +// [golang.org/x/tools/go/ssa/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 [golang.org/x/tools/go/ssa/ssautil.Packages] helper function. +// (See the package-level Examples named LoadPackages and LoadWholeProgram.) +// 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 ✔ +// *MultiConvert ✔ ✔ +// *NamedConst ✔ (const) +// *Next ✔ ✔ +// *Panic ✔ +// *Parameter ✔ +// *Phi ✔ ✔ +// *Range ✔ ✔ +// *Return ✔ +// *RunDefers ✔ +// *Select ✔ ✔ +// *Send ✔ +// *Slice ✔ ✔ +// *SliceToArrayPointer ✔ ✔ +// *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: [types.Id] values, which 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 [golang.org/x/tools/go/ssa/ssautil] package provides various +// helper functions, for example to simplify loading a Go program into +// SSA form. +// +// 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" |