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cmd/link: increase the function call limit in stkcheck

There is real (albeit generated) code that exceeds the limit.

Fixes #33555

Change-Id: I668e85825d3d2a471970e869abe63f3492213cc1
Reviewed-on: https://go-review.googlesource.com/c/go/+/189697
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
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ianlancetaylor committed Aug 9, 2019
1 parent 3626252 commit 951143cf1425189965498cc32fc8dc132bf7c777
Showing with 82 additions and 1 deletion.
  1. +1 −1 src/cmd/link/internal/ld/lib.go
  2. +81 −0 test/fixedbugs/issue33555.go
@@ -2066,7 +2066,7 @@ func stkcheck(ctxt *Link, up *chain, depth int) int {
s.Attr |= sym.AttrStackCheck
}

if depth > 100 {
if depth > 500 {
Errorf(s, "nosplit stack check too deep")
stkbroke(ctxt, up, 0)
return -1
@@ -0,0 +1,81 @@
// +build !nacl,!js
// run

// Copyright 2019 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.

// Test that the linker permits long call sequences.
package main

import (
"bytes"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strconv"
)

const start = `
package main
func main() {
println(f0() + 1)
}
`

const fn = `
//go:noinline
func f%d() int {
return f%d() + 1
}`

const fnlast = `
//go:noinline
func f%d() int {
return 0
}
`

const count = 400

func main() {
if err := test(); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}

func test() error {
var buf bytes.Buffer
buf.WriteString(start)
for i := 0; i < count; i++ {
fmt.Fprintf(&buf, fn, i, i + 1)
}
fmt.Fprintf(&buf, fnlast, count)

dir, err := ioutil.TempDir("", "issue33555")
if err != nil {
return err
}
defer os.RemoveAll(dir)

fn := filepath.Join(dir, "x.go")
if err := ioutil.WriteFile(fn, buf.Bytes(), 0644); err != nil {
return err
}

out, err := exec.Command("go", "run", fn).CombinedOutput()
if err != nil {
return err
}

want := strconv.Itoa(count + 1)
if got := string(bytes.TrimSpace(out)); got != want {
return fmt.Errorf("got %q want %q", got, want)
}

return nil
}

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