1 // Copyright 2016 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // This program generates a test to verify that a program can be 6 // successfully linked even when there are very large text 7 // sections present. 8 9 package main 10 11 import ( 12 "bytes" 13 "cmd/internal/obj" 14 "fmt" 15 "internal/testenv" 16 "io/ioutil" 17 "os" 18 "os/exec" 19 "testing" 20 ) 21 22 func TestLargeText(t *testing.T) { 23 if testing.Short() || (obj.GOARCH != "ppc64le" && obj.GOARCH != "ppc64" && obj.GOARCH != "arm") { 24 t.Skip("Skipping large text section test in short mode or on %s", obj.GOARCH) 25 } 26 testenv.MustHaveGoBuild(t) 27 28 var w bytes.Buffer 29 const FN = 4 30 tmpdir, err := ioutil.TempDir("", "bigtext") 31 32 defer os.RemoveAll(tmpdir) 33 34 // Generate the scenario where the total amount of text exceeds the 35 // limit for the jmp/call instruction, on RISC architectures like ppc64le, 36 // which is 2^26. When that happens the call requires special trampolines or 37 // long branches inserted by the linker where supported. 38 // Multiple .s files are generated instead of one. 39 instOnArch := map[string]string{ 40 "ppc64": "\tMOVD\tR0,R3\n", 41 "ppc64le": "\tMOVD\tR0,R3\n", 42 "arm": "\tMOVW\tR0,R1\n", 43 } 44 inst := instOnArch[obj.GOARCH] 45 for j := 0; j < FN; j++ { 46 testname := fmt.Sprintf("bigfn%d", j) 47 fmt.Fprintf(&w, "TEXT %s(SB),$0\n", testname) 48 for i := 0; i < 2200000; i++ { 49 fmt.Fprintf(&w, inst) 50 } 51 fmt.Fprintf(&w, "\tRET\n") 52 err := ioutil.WriteFile(tmpdir+"/"+testname+".s", w.Bytes(), 0666) 53 if err != nil { 54 t.Fatalf("can't write output: %v\n", err) 55 } 56 w.Reset() 57 } 58 fmt.Fprintf(&w, "package main\n") 59 fmt.Fprintf(&w, "\nimport (\n") 60 fmt.Fprintf(&w, "\t\"os\"\n") 61 fmt.Fprintf(&w, "\t\"fmt\"\n") 62 fmt.Fprintf(&w, ")\n\n") 63 64 for i := 0; i < FN; i++ { 65 fmt.Fprintf(&w, "func bigfn%d()\n", i) 66 } 67 fmt.Fprintf(&w, "\nfunc main() {\n") 68 69 // There are lots of dummy code generated in the .s files just to generate a lot 70 // of text. Link them in but guard their call so their code is not executed but 71 // the main part of the program can be run. 72 fmt.Fprintf(&w, "\tif os.Getenv(\"LINKTESTARG\") != \"\" {\n") 73 for i := 0; i < FN; i++ { 74 fmt.Fprintf(&w, "\t\tbigfn%d()\n", i) 75 } 76 fmt.Fprintf(&w, "\t}\n") 77 fmt.Fprintf(&w, "\tfmt.Printf(\"PASS\\n\")\n") 78 fmt.Fprintf(&w, "}") 79 err = ioutil.WriteFile(tmpdir+"/bigfn.go", w.Bytes(), 0666) 80 if err != nil { 81 t.Fatalf("can't write output: %v\n", err) 82 } 83 84 // Build and run with internal linking. 85 os.Chdir(tmpdir) 86 cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "bigtext") 87 out, err := cmd.CombinedOutput() 88 if err != nil { 89 t.Fatalf("Build failed for big text program with internal linking: %v, output: %s", err, out) 90 } 91 cmd = exec.Command(tmpdir + "/bigtext") 92 out, err = cmd.CombinedOutput() 93 if err != nil { 94 t.Fatalf("Program built with internal linking failed to run with err %v, output: %s", err, out) 95 } 96 97 // Build and run with external linking 98 os.Chdir(tmpdir) 99 cmd = exec.Command(testenv.GoToolPath(t), "build", "-o", "bigtext", "-ldflags", "'-linkmode=external'") 100 out, err = cmd.CombinedOutput() 101 if err != nil { 102 t.Fatalf("Build failed for big text program with external linking: %v, output: %s", err, out) 103 } 104 cmd = exec.Command(tmpdir + "/bigtext") 105 out, err = cmd.CombinedOutput() 106 if err != nil { 107 t.Fatalf("Program built with external linking failed to run with err %v, output: %s", err, out) 108 } 109 } 110
