5.6 Unit Test
IR Tree 构建逻辑的 UT 比前面章节的要麻烦一些，因为其不仅依赖前面的词法分析、语法分析、类型检查等所有步骤，还要依赖整个编译器的全局环境初始化。
编译器的初始化工作在文件
cmd/compile/internal/gc/main.go 中的 Main 函数中完成，词法分析之前的所有逻辑都是在做初始化的工作，分割点如下所示：func Main(archInit func(*ssagen.ArchInfo)) {
// 初始化代码，此处省略
// 词法分析、语法分析、类型检查
noder.LoadPackage(flag.Args())
// 编译阶段后续步骤，此处省略
}
编译器的初始化工作涉及很多方面，例如与架构体系相关的初始化（例如 amd64, x86 等）、内置函数及类型、默认配置等，但也有很多代码是搭建 UT 环境不需要的，例如解析编译参数、对编译过程进行 profile 等。为了搭建 IR Tree 的 UT 环境，我们需要做如下工作：
- 精简后的初始化代码
- 语法解析、类型检查等步骤
- Dump IR Tree 的逻辑
我们创建 UT 文件
cmd/compile/internal/noder/irgen_test.go, 其内容如下：// file: cmd/compile/internal/noder/irgen_test.go
package noder
import (
"bufio"
"cmd/compile/internal/amd64"
"cmd/compile/internal/base"
"cmd/compile/internal/escape"
"cmd/compile/internal/inline"
"cmd/compile/internal/ir"
"cmd/compile/internal/reflectdata"
"cmd/compile/internal/ssa"
"cmd/compile/internal/ssagen"
"cmd/compile/internal/syntax"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/compile/internal/types2"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/src"
"fmt"
"os"
"strings"
"testing"
)
func parseSrc(path, src string) (*syntax.File, error) {
var mode syntax.Mode
mode = syntax.AllowGenerics | syntax.CheckBranches
errh := func(error) {} // dummy error handler so that parsing continues in presence of errors
return syntax.Parse(syntax.NewFileBase(path), strings.NewReader(src), errh, nil, mode)
}
func defaultImporter() *gcimports {
return &gcimports{
packages: map[string]*types2.Package{},
}
}
func init() {
amd64.Init(&ssagen.Arch)
base.Ctxt = obj.Linknew(ssagen.Arch.LinkArch)
base.Ctxt.DiagFunc = base.Errorf
base.Ctxt.DiagFlush = base.FlushErrors
base.Ctxt.Bso = bufio.NewWriter(os.Stdout)
base.Ctxt.UseBASEntries = base.Ctxt.Headtype != objabi.Hdarwin
types.LocalPkg = types.NewPkg("", "")
types.LocalPkg.Prefix = "\"\""
types.LocalPkg.Height = types.MaxPkgHeight
types.BuiltinPkg = types.NewPkg("go.builtin", "") // TODO(gri) name this package go.builtin?
types.BuiltinPkg.Prefix = "go.builtin" // not go%2ebuiltin
ir.Pkgs.Unsafe = types.NewPkg("unsafe", "unsafe")
ir.Pkgs.Runtime = types.NewPkg("go.runtime", "runtime")
ir.Pkgs.Runtime.Prefix = "runtime"
ir.Pkgs.Itab = types.NewPkg("go.itab", "go.itab")
ir.Pkgs.Itab.Prefix = "go.itab" // not go%2eitab
ir.Pkgs.Go = types.NewPkg("go", "")
base.DebugSSA = ssa.PhaseOption
ssagen.Arch.LinkArch.Init(base.Ctxt)
ir.EscFmt = escape.Fmt
ir.IsIntrinsicCall = ssagen.IsIntrinsicCall
inline.SSADumpInline = ssagen.DumpInline
ssagen.InitEnv()
ssagen.InitTables()
types.PtrSize = ssagen.Arch.LinkArch.PtrSize
types.RegSize = ssagen.Arch.LinkArch.RegSize
types.MaxWidth = ssagen.Arch.MAXWIDTH
typecheck.Target = new(ir.Package)
typecheck.NeedITab = func(t, iface *types.Type) { reflectdata.ITabAddr(t, iface) }
typecheck.NeedRuntimeType = reflectdata.NeedRuntimeType // TODO(rsc): TypeSym for lock?
base.AutogeneratedPos = base.Ctxt.PosTable.XPos(src.MakePos(src.NewFileBase("<autogenerated>", "<autogenerated>"), 1, 0))
typecheck.InitUniverse()
}
func dumpIrTree(nodes []ir.Node) {
for _, n := range nodes {
s := fmt.Sprintf("\nafter noder2 %v", n)
ir.Dump(s, n)
}
}
func TestIrTree(t *testing.T) {
code := `
package p
import "fmt"
func genericFun[T any](i, j T) {
fmt.Printf("i: %v, j: %v\n",i, j)
}
func main() {
genericFun(5,6)
genericFun[float32](10.5, 11.8)
}
`
f, err := parseSrc("generic_testTypecheckConst", code)
if err != nil {
panic(err)
}
var conf types2.Config
conf.Trace = false
conf.Importer = defaultImporter()
conf.Error = func(err error) {
fmt.Printf("Typecheck Error: %v\n", err)
}
info := types2.Info{
Types: make(map[syntax.Expr]types2.TypeAndValue),
Defs: make(map[*syntax.Name]types2.Object),
Uses: make(map[*syntax.Name]types2.Object),
Selections: make(map[*syntax.SelectorExpr]*types2.Selection),
Implicits: make(map[syntax.Node]types2.Object),
Scopes: make(map[syntax.Node]*types2.Scope),
Inferred: make(map[syntax.Expr]types2.Inferred),
}
pkg, err := conf.Check("<no package>", []*syntax.File{f}, &info)
if err != nil {
panic(err)
}
var m posMap
g := irgen{
target: typecheck.Target,
self: pkg,
info: &info,
posMap: m,
objs: make(map[types2.Object]*ir.Name),
typs: make(map[types2.Type]*types.Type),
}
p := &noder{
err: make(chan syntax.Error),
trackScopes: base.Flag.Dwarf,
file: f,
}
g.generate([]*noder{p})
dumpIrTree(typecheck.Target.Decls)
}
其中
init 为精简之后的编译器初始化逻辑， parseSrc 用来完成语法分析， defaultImporter 用来在类型检查时加载包。运行 TestIrTree 将会得到最终的 IR Tree 结构信息。