cmd/objdump: print Go code alongside assembly

Added -S flag to print go source file line above corresponding disassembly:

$ go tool objdump -S -s main.main fmthello
TEXT main.main(SB) /home/rugginoso/Documents/src/go/src/cmd/objdump/testdata/fmthello.go
func main() {
  0x47d450		64488b0c25f8ffffff	FS MOVQ FS:0xfffffff8, CX
  0x47d459		483b6110		CMPQ 0x10(CX), SP
  0x47d45d		7631			JBE 0x47d490
  0x47d45f		4883ec18		SUBQ $0x18, SP
  0x47d463		48896c2410		MOVQ BP, 0x10(SP)
  0x47d468		488d6c2410		LEAQ 0x10(SP), BP
	Println("hello, world")
  0x47d46d		488d0563b00200		LEAQ 0x2b063(IP), AX
  0x47d474		48890424		MOVQ AX, 0(SP)
  0x47d478		48c74424080c000000	MOVQ $0xc, 0x8(SP)
  0x47d481		e81a000000		CALL main.Println(SB)
}
  0x47d486		488b6c2410		MOVQ 0x10(SP), BP
  0x47d48b		4883c418		ADDQ $0x18, SP
  0x47d48f		c3			RET
func main() {
  0x47d490		e8ebf1fcff		CALL runtime.morestack_noctxt(SB)
  0x47d495		ebb9			JMP main.main(SB)

Execution time:

$ time go tool objdump testdata/fmthello > /dev/null
real	0m0.430s
user	0m0.440s
sys	0m0.000s

$ time go tool objdump -S testdata/fmthello > /dev/null
real	0m0.471s
user	0m0.476s
sys	0m0.012s

Fixes #18245

Change-Id: I9b2f8338f9ee443c1352efd270d3ba85e3dd9b78
Reviewed-on: https://go-review.googlesource.com/37953
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 32 insertions, 11 deletions

diff --git a/src/cmd/objdump/objdump_test.go b/src/cmd/objdump/objdump_test.go
index 419be6717a..91adde3eb3 100644
--- a/src/cmd/objdump/objdump_test.go
+++ b/src/cmd/objdump/objdump_test.go
@@ -57,24 +57,18 @@ func buildObjdump() error {
 }
 
 var x86Need = []string{
-	"fmthello.go:6",
-	"TEXT main.main(SB)",
 	"JMP main.main(SB)",
 	"CALL main.Println(SB)",
 	"RET",
 }
 
 var armNeed = []string{
-	"fmthello.go:6",
-	"TEXT main.main(SB)",
 	//"B.LS main.main(SB)", // TODO(rsc): restore; golang.org/issue/9021
 	"BL main.Println(SB)",
 	"RET",
 }
 
 var ppcNeed = []string{
-	"fmthello.go:6",
-	"TEXT main.main(SB)",
 	"BR main.main(SB)",
 	"CALL main.Println(SB)",
 	"RET",
@@ -91,7 +85,7 @@ var target = flag.String("target", "", "test disassembly of `goos/goarch` binary
 // binary for the current system (only) and test that objdump
 // can handle that one.
 
-func testDisasm(t *testing.T, flags ...string) {
+func testDisasm(t *testing.T, printCode bool, flags ...string) {
 	goarch := runtime.GOARCH
 	if *target != "" {
 		f := strings.Split(*target, "/")
@@ -114,9 +108,15 @@ func testDisasm(t *testing.T, flags ...string) {
 		t.Fatalf("go build fmthello.go: %v\n%s", err, out)
 	}
 	need := []string{
-		"fmthello.go:6",
 		"TEXT main.main(SB)",
 	}
+
+	if printCode {
+		need = append(need, `	Println("hello, world")`)
+	} else {
+		need = append(need, "fmthello.go:6")
+	}
+
 	switch goarch {
 	case "amd64", "386":
 		need = append(need, x86Need...)
@@ -126,7 +126,16 @@ func testDisasm(t *testing.T, flags ...string) {
 		need = append(need, ppcNeed...)
 	}
 
-	out, err = exec.Command(exe, "-s", "main.main", hello).CombinedOutput()
+	args = []string{
+		"-s", "main.main",
+		hello,
+	}
+
+	if printCode {
+		args = append([]string{"-S"}, args...)
+	}
+
+	out, err = exec.Command(exe, args...).CombinedOutput()
 	if err != nil {
 		t.Fatalf("objdump fmthello.exe: %v\n%s", err, out)
 	}
@@ -153,7 +162,19 @@ func TestDisasm(t *testing.T) {
 	case "s390x":
 		t.Skipf("skipping on %s, issue 15255", runtime.GOARCH)
 	}
-	testDisasm(t)
+	testDisasm(t, false)
+}
+
+func TestDisasmCode(t *testing.T) {
+	switch runtime.GOARCH {
+	case "arm64":
+		t.Skipf("skipping on %s, issue 10106", runtime.GOARCH)
+	case "mips", "mipsle", "mips64", "mips64le":
+		t.Skipf("skipping on %s, issue 12559", runtime.GOARCH)
+	case "s390x":
+		t.Skipf("skipping on %s, issue 15255", runtime.GOARCH)
+	}
+	testDisasm(t, true)
 }
 
 func TestDisasmExtld(t *testing.T) {
@@ -178,5 +199,5 @@ func TestDisasmExtld(t *testing.T) {
 	if !build.Default.CgoEnabled {
 		t.Skip("skipping because cgo is not enabled")
 	}
-	testDisasm(t, "-ldflags=-linkmode=external")
+	testDisasm(t, false, "-ldflags=-linkmode=external")
 }