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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_test
import (
"fmt"
"go/ast"
"go/importer"
"go/parser"
"go/token"
"go/types"
"log"
"os"
"golang.org/x/tools/go/packages"
"honnef.co/go/tools/ssa"
"honnef.co/go/tools/ssa/ssautil"
)
const hello = `
package main
import "fmt"
const message = "Hello, World!"
func main() {
fmt.Println(message)
}
`
// This program demonstrates how to run the SSA builder on a single
// package of one or more already-parsed files. Its dependencies are
// loaded from compiler export data. This is what you'd typically use
// for a compiler; it does not depend on golang.org/x/tools/go/loader.
//
// It shows the printed representation of packages, functions, and
// instructions. Within the function listing, the name of each
// BasicBlock such as ".0.entry" is printed left-aligned, followed by
// the block's Instructions.
//
// For each instruction that defines an SSA virtual register
// (i.e. implements Value), the type of that value is shown in the
// right column.
//
// Build and run the ssadump.go program if you want a standalone tool
// with similar functionality. It is located at
// golang.org/x/tools/cmd/ssadump.
//
func Example_buildPackage() {
// Parse the source files.
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "hello.go", hello, parser.ParseComments)
if err != nil {
fmt.Print(err) // parse error
return
}
files := []*ast.File{f}
// Create the type-checker's package.
pkg := types.NewPackage("hello", "")
// Type-check the package, load dependencies.
// Create and build the SSA program.
hello, _, err := ssautil.BuildPackage(
&types.Config{Importer: importer.Default()}, fset, pkg, files, ssa.SanityCheckFunctions)
if err != nil {
fmt.Print(err) // type error in some package
return
}
// Print out the package.
hello.WriteTo(os.Stdout)
// Print out the package-level functions.
hello.Func("init").WriteTo(os.Stdout)
hello.Func("main").WriteTo(os.Stdout)
// Output:
//
// package hello:
// func init func()
// var init$guard bool
// func main func()
// const message message = "Hello, World!":untyped string
//
// # Name: hello.init
// # Package: hello
// # Synthetic: package initializer
// func init():
// 0: entry P:0 S:2
// t0 = *init$guard bool
// if t0 goto 2 else 1
// 1: init.start P:1 S:1
// *init$guard = true:bool
// t1 = fmt.init() ()
// jump 2
// 2: init.done P:2 S:0
// return
//
// # Name: hello.main
// # Package: hello
// # Location: hello.go:8:6
// func main():
// 0: entry P:0 S:0
// t0 = new [1]interface{} (varargs) *[1]interface{}
// t1 = &t0[0:int] *interface{}
// t2 = make interface{} <- string ("Hello, World!":string) interface{}
// *t1 = t2
// t3 = slice t0[:] []interface{}
// t4 = fmt.Println(t3...) (n int, err error)
// return
}
// This example builds SSA code for a set of packages using the
// x/tools/go/packages API. This is what you would typically use for a
// analysis capable of operating on a single package.
func Example_loadPackages() {
// Load, parse, and type-check the initial packages.
cfg := &packages.Config{Mode: packages.LoadSyntax}
initial, err := packages.Load(cfg, "fmt", "net/http")
if err != nil {
log.Fatal(err)
}
// Stop if any package had errors.
// This step is optional; without it, the next step
// will create SSA for only a subset of packages.
if packages.PrintErrors(initial) > 0 {
log.Fatalf("packages contain errors")
}
// Create SSA packages for all well-typed packages.
prog, pkgs := ssautil.Packages(initial, ssa.PrintPackages)
_ = prog
// Build SSA code for the well-typed initial packages.
for _, p := range pkgs {
if p != nil {
p.Build()
}
}
}
// This example builds SSA code for a set of packages plus all their dependencies,
// using the x/tools/go/packages API.
// This is what you'd typically use for a whole-program analysis.
func Example_loadWholeProgram() {
// Load, parse, and type-check the whole program.
cfg := packages.Config{Mode: packages.LoadAllSyntax}
initial, err := packages.Load(&cfg, "fmt", "net/http")
if err != nil {
log.Fatal(err)
}
// Create SSA packages for well-typed packages and their dependencies.
prog, pkgs := ssautil.AllPackages(initial, ssa.PrintPackages)
_ = pkgs
// Build SSA code for the whole program.
prog.Build()
}