remove unnecessary data from runtime if -tiny is passed
Fixes #127. Saves an additional ~1-2% binary size in my testing.pull/138/head
Andrew LeFevre
5 years ago
committed by
Daniel Martí
parent
d679944408
commit
0d182a3dbd
@ -1,146 +0,0 @@
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// Copyright (c) 2020, The Garble Authors.
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// See LICENSE for licensing information.
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package main
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import (
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"go/ast"
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"go/token"
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ah "mvdan.cc/garble/internal/asthelper"
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)
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// addRuntimeAPI exposes additional functions in the runtime
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// package that may be helpful when hiding information
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// during execution is required.
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func addRuntimeAPI(filename string, file *ast.File) {
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switchPanicPrints := func(node ast.Node) bool {
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call, ok := node.(*ast.CallExpr)
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if !ok {
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return true
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}
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id, ok := call.Fun.(*ast.Ident)
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if !ok {
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return true
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}
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switch id.Name {
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case "print":
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id.Name = "panicprint"
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return false
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case "println":
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id.Name = "panicprint"
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call.Args = append(call.Args, &ast.BasicLit{Kind: token.STRING, Value: `"\n"`})
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return false
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default:
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return true
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}
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}
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switch filename {
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case "debug.go":
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// Add hideFatalErrors function and internal fatalErrorsHidden variable
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file.Decls = append(file.Decls, hideFatalErrorsDecls...)
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case "error.go":
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// Add a function panicprint, that does nothing if panics are
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// hidden, otherwise forwards arguments to printany to print them
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// as normal. Although we add an if statement to printany to do
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// nothing if panics are hidden, printany only takes one argument,
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// and both print and printany are used to print panic messages.
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// panicprint's entire purpose is to act as a replacement to print
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// that respects hideFatalErrors, and print is variadic, so print
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// must be replaced by a variadic function, hence panicprint.
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//
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// We will also add two statements to printany:
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// 1. An if statement that returns early if panics are hidden
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// 2. An additional case statement that handles printing runtime.hex
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// values. Without this case statement, the default case will print
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// the runtime.hex values in a way not consistent with normal panic
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// outputs
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for _, decl := range file.Decls {
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decl, ok := decl.(*ast.FuncDecl)
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if !ok || decl.Name.Name != "printany" {
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continue
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}
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for _, stmt := range decl.Body.List {
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if stmt, ok := stmt.(*ast.TypeSwitchStmt); ok {
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stmt.Body.List = append(stmt.Body.List, printanyHexCase)
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break
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}
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}
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decl.Body.List = append([]ast.Stmt{fatalErrorsHiddenCheckStmt}, decl.Body.List...)
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break
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}
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file.Decls = append(file.Decls, panicprintDecl)
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default:
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// Change all calls to print, which we don't control, to
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// panicprint, which we do control and does the same thing.
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ast.Inspect(file, switchPanicPrints)
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}
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}
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var fatalErrorsHiddenCheckStmt = &ast.IfStmt{
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Cond: ah.Ident("fatalErrorsHidden"),
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Body: ah.BlockStmt(ah.ReturnStmt()),
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}
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var hideFatalErrorsDecls = []ast.Decl{
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&ast.GenDecl{
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Tok: token.VAR,
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Specs: []ast.Spec{&ast.ValueSpec{
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Names: []*ast.Ident{ah.Ident("fatalErrorsHidden")},
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Type: ah.Ident("bool"),
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}},
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},
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&ast.FuncDecl{
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Name: ah.Ident("hideFatalErrors"),
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Type: &ast.FuncType{Params: &ast.FieldList{
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List: []*ast.Field{{
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Names: []*ast.Ident{ah.Ident("hide")},
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Type: ah.Ident("bool"),
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}},
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}},
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Body: ah.BlockStmt(
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&ast.AssignStmt{
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Lhs: []ast.Expr{ah.Ident("fatalErrorsHidden")},
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Tok: token.ASSIGN,
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Rhs: []ast.Expr{ah.Ident("hide")},
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},
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),
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},
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}
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var printanyHexCase = &ast.CaseClause{
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List: []ast.Expr{ah.Ident("hex")},
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Body: []ast.Stmt{
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ah.ExprStmt(ah.CallExpr(ah.Ident("print"), ah.Ident("v"))),
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},
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}
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var panicprintDecl = &ast.FuncDecl{
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Name: ah.Ident("panicprint"),
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Type: &ast.FuncType{Params: &ast.FieldList{
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List: []*ast.Field{{
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Names: []*ast.Ident{{Name: "args"}},
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Type: &ast.Ellipsis{Elt: &ast.InterfaceType{
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Methods: &ast.FieldList{},
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}},
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}},
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}},
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Body: ah.BlockStmt(
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&ast.IfStmt{
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Cond: ah.Ident("fatalErrorsHidden"),
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Body: ah.BlockStmt(ah.ReturnStmt()),
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},
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&ast.RangeStmt{
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Key: ah.Ident("_"),
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Value: ah.Ident("arg"),
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Tok: token.DEFINE,
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X: ah.Ident("args"),
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Body: ah.BlockStmt(
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ah.ExprStmt(ah.CallExpr(ah.Ident("printany"), ah.Ident("arg"))),
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),
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},
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),
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}
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@ -0,0 +1,174 @@
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// Copyright (c) 2020, The Garble Authors.
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// See LICENSE for licensing information.
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package main
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import (
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"go/ast"
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"go/token"
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"strings"
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ah "mvdan.cc/garble/internal/asthelper"
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)
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// stripRuntime removes unnecessary code from the runtime,
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// such as panic and fatal error printing, and code that
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// prints trace/debug info of the runtime.
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func stripRuntime(filename string, file *ast.File) {
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stripPrints := func(node ast.Node) bool {
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call, ok := node.(*ast.CallExpr)
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if !ok {
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return true
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}
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id, ok := call.Fun.(*ast.Ident)
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if !ok {
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return true
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}
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switch id.Name {
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case "print", "println":
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id.Name = "hidePrint"
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return false
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default:
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return true
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}
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}
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for _, decl := range file.Decls {
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switch x := decl.(type) {
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case *ast.FuncDecl:
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switch filename {
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case "error.go":
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// only used in panics
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switch x.Name.Name {
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case "printany", "printanycustomtype":
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x.Body.List = nil
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}
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case "mgcscavenge.go":
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// used in tracing the scavenger
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if x.Name.Name == "printScavTrace" {
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x.Body.List = nil
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break
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}
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case "mprof.go":
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// remove all functions that print debug/tracing info
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// of the runtime
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if strings.HasPrefix(x.Name.Name, "trace") {
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x.Body.List = nil
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}
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case "panic.go":
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// used for printing panics
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switch x.Name.Name {
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case "preprintpanics", "printpanics":
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x.Body.List = nil
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}
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case "print.go":
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// only used in tracebacks
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if x.Name.Name == "hexdumpWords" {
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x.Body.List = nil
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break
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}
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case "proc.go":
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// used in tracing the scheduler
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if x.Name.Name == "schedtrace" {
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x.Body.List = nil
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break
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}
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case "runtime1.go":
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switch x.Name.Name {
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case "parsedebugvars":
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// set defaults for GODEBUG cgocheck and
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// invalidptr, remove code that reads in
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// GODEBUG
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x.Body = parsedebugvarsStmts
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case "setTraceback":
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// tracebacks are completely hidden, no
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// sense keeping this function
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x.Body.List = nil
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}
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case "traceback.go":
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// only used for printing tracebacks
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switch x.Name.Name {
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case "tracebackdefers", "traceback", "tracebacktrap", "traceback1",
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"goroutineheader", "tracebackothers", "tracebackHexdump":
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x.Body.List = nil
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case "printOneCgoTraceback":
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x.Body = ah.BlockStmt(ah.ReturnStmt(ah.IntLit(0)))
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default:
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if strings.HasPrefix(x.Name.Name, "print") {
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x.Body.List = nil
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}
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}
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default:
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break
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}
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case *ast.GenDecl:
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if x.Tok != token.IMPORT {
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continue
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}
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switch filename {
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case "print.go":
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// was used in hexdumpWords
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x.Specs = removeImport(`"runtime/internal/sys"`, x.Specs)
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case "traceback.go":
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// was used in traceback1
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x.Specs = removeImport(`"runtime/internal/atomic"`, x.Specs)
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}
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}
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}
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if filename == "print.go" {
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file.Decls = append(file.Decls, hidePrintDecl)
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}
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// replace all 'print' and 'println' statements in
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// the runtime with an empty func, which will be
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// optimized out by the compiler
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ast.Inspect(file, stripPrints)
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}
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func removeImport(importPath string, specs []ast.Spec) []ast.Spec {
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for i, spec := range specs {
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imp := spec.(*ast.ImportSpec)
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if imp.Path.Value == importPath {
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specs = append(specs[:i], specs[i+1:]...)
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break
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}
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}
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return specs
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}
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var hidePrintDecl = &ast.FuncDecl{
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Name: ah.Ident("hidePrint"),
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Type: &ast.FuncType{Params: &ast.FieldList{
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List: []*ast.Field{{
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Names: []*ast.Ident{{Name: "args"}},
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Type: &ast.Ellipsis{Elt: &ast.InterfaceType{
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Methods: &ast.FieldList{},
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}},
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}},
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}},
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Body: &ast.BlockStmt{},
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}
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var parsedebugvarsStmts = ah.BlockStmt(
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&ast.AssignStmt{
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Lhs: []ast.Expr{&ast.SelectorExpr{
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X: ah.Ident("debug"),
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Sel: ah.Ident("cgocheck"),
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}},
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Tok: token.ASSIGN,
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Rhs: []ast.Expr{ah.IntLit(1)},
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},
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&ast.AssignStmt{
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Lhs: []ast.Expr{&ast.SelectorExpr{
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X: ah.Ident("debug"),
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Sel: ah.Ident("invalidptr"),
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}},
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Tok: token.ASSIGN,
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Rhs: []ast.Expr{ah.IntLit(1)},
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},
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)
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@ -1,23 +0,0 @@
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env GOPRIVATE=test/main
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garble build
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! exec ./main
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cmp stderr main.stderr
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-- go.mod --
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module test/main
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-- main.go --
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package main
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import _ "unsafe"
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//go:linkname hideFatalErrors runtime.hideFatalErrors
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func hideFatalErrors(hide bool)
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func init() { hideFatalErrors(true) }
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func main() {
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panic("ya like jazz?")
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}
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-- main.stderr --
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