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// Copyright 2016 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.
// This program generates a test to verify that a program can be
// successfully linked even when there are very large text
// sections present.
package main
import (
"bytes"
"cmd/internal/obj"
"fmt"
"internal/testenv"
"io/ioutil"
"os"
"os/exec"
"testing"
)
func TestLargeText(t *testing.T) {
if testing.Short() || (obj.GOARCH != "ppc64le" && obj.GOARCH != "ppc64" && obj.GOARCH != "arm") {
t.Skipf("Skipping large text section test in short mode or on %s", obj.GOARCH)
}
testenv.MustHaveGoBuild(t)
var w bytes.Buffer
const FN = 4
tmpdir, err := ioutil.TempDir("", "bigtext")
defer os.RemoveAll(tmpdir)
// Generate the scenario where the total amount of text exceeds the
// limit for the jmp/call instruction, on RISC architectures like ppc64le,
// which is 2^26. When that happens the call requires special trampolines or
// long branches inserted by the linker where supported.
// Multiple .s files are generated instead of one.
instOnArch := map[string]string{
"ppc64": "\tMOVD\tR0,R3\n",
"ppc64le": "\tMOVD\tR0,R3\n",
"arm": "\tMOVW\tR0,R1\n",
}
inst := instOnArch[obj.GOARCH]
for j := 0; j < FN; j++ {
testname := fmt.Sprintf("bigfn%d", j)
fmt.Fprintf(&w, "TEXT ·%s(SB),$0\n", testname)
for i := 0; i < 2200000; i++ {
fmt.Fprintf(&w, inst)
}
fmt.Fprintf(&w, "\tRET\n")
err := ioutil.WriteFile(tmpdir+"/"+testname+".s", w.Bytes(), 0666)
if err != nil {
t.Fatalf("can't write output: %v\n", err)
}
w.Reset()
}
fmt.Fprintf(&w, "package main\n")
fmt.Fprintf(&w, "\nimport (\n")
fmt.Fprintf(&w, "\t\"os\"\n")
fmt.Fprintf(&w, "\t\"fmt\"\n")
fmt.Fprintf(&w, ")\n\n")
for i := 0; i < FN; i++ {
fmt.Fprintf(&w, "func bigfn%d()\n", i)
}
fmt.Fprintf(&w, "\nfunc main() {\n")
// There are lots of dummy code generated in the .s files just to generate a lot
// of text. Link them in but guard their call so their code is not executed but
// the main part of the program can be run.
fmt.Fprintf(&w, "\tif os.Getenv(\"LINKTESTARG\") != \"\" {\n")
for i := 0; i < FN; i++ {
fmt.Fprintf(&w, "\t\tbigfn%d()\n", i)
}
fmt.Fprintf(&w, "\t}\n")
fmt.Fprintf(&w, "\tfmt.Printf(\"PASS\\n\")\n")
fmt.Fprintf(&w, "}")
err = ioutil.WriteFile(tmpdir+"/bigfn.go", w.Bytes(), 0666)
if err != nil {
t.Fatalf("can't write output: %v\n", err)
}
// Build and run with internal linking.
os.Chdir(tmpdir)
cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "bigtext")
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("Build failed for big text program with internal linking: %v, output: %s", err, out)
}
cmd = exec.Command(tmpdir + "/bigtext")
out, err = cmd.CombinedOutput()
if err != nil {
t.Fatalf("Program built with internal linking failed to run with err %v, output: %s", err, out)
}
// Build and run with external linking
os.Chdir(tmpdir)
cmd = exec.Command(testenv.GoToolPath(t), "build", "-o", "bigtext", "-ldflags", "'-linkmode=external'")
out, err = cmd.CombinedOutput()
if err != nil {
t.Fatalf("Build failed for big text program with external linking: %v, output: %s", err, out)
}
cmd = exec.Command(tmpdir + "/bigtext")
out, err = cmd.CombinedOutput()
if err != nil {
t.Fatalf("Program built with external linking failed to run with err %v, output: %s", err, out)
}
}
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