test: improve runtime/pprof tests for gccgo

In the CPU profile tests for gccgo, check to make sure that the
runtime's sigprof handler itself doesn't appear in the profile. Add a
"skip if gccgo" guard to one testpoint.

Updates #26595

Change-Id: I92a44161d61f17b9305ce09532134edd229745a7
Reviewed-on: https://go-review.googlesource.com/126316
Run-TryBot: Than McIntosh <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: thanm

src/runtime/pprof/pprof_test.go

@@ -72,15 +72,24 @@ func cpuHog2(x int) int {
 	return foo
 }
 
+// Return a list of functions that we don't want to ever appear in CPU
+// profiles. For gccgo, that list includes the sigprof handler itself.
+func avoidFunctions() []string {
+	if runtime.Compiler == "gccgo" {
+		return []string{"runtime.sigprof"}
+	}
+	return nil
+}
+
 func TestCPUProfile(t *testing.T) {
-	testCPUProfile(t, stackContains, []string{"runtime/pprof.cpuHog1"}, func(dur time.Duration) {
+	testCPUProfile(t, stackContains, []string{"runtime/pprof.cpuHog1"}, avoidFunctions(), func(dur time.Duration) {
 		cpuHogger(cpuHog1, &salt1, dur)
 	})
 }
 
 func TestCPUProfileMultithreaded(t *testing.T) {
 	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
-	testCPUProfile(t, stackContains, []string{"runtime/pprof.cpuHog1", "runtime/pprof.cpuHog2"}, func(dur time.Duration) {
+	testCPUProfile(t, stackContains, []string{"runtime/pprof.cpuHog1", "runtime/pprof.cpuHog2"}, avoidFunctions(), func(dur time.Duration) {
 		c := make(chan int)
 		go func() {
 			cpuHogger(cpuHog1, &salt1, dur)
@@ -92,7 +101,7 @@ func TestCPUProfileMultithreaded(t *testing.T) {
 }
 
 func TestCPUProfileInlining(t *testing.T) {
-	testCPUProfile(t, stackContains, []string{"runtime/pprof.inlinedCallee", "runtime/pprof.inlinedCaller"}, func(dur time.Duration) {
+	testCPUProfile(t, stackContains, []string{"runtime/pprof.inlinedCallee", "runtime/pprof.inlinedCaller"}, avoidFunctions(), func(dur time.Duration) {
 		cpuHogger(inlinedCaller, &salt1, dur)
 	})
 }
@@ -132,7 +141,7 @@ func parseProfile(t *testing.T, valBytes []byte, f func(uintptr, []*profile.Loca
 
 // testCPUProfile runs f under the CPU profiler, checking for some conditions specified by need,
 // as interpreted by matches.
-func testCPUProfile(t *testing.T, matches matchFunc, need []string, f func(dur time.Duration)) {
+func testCPUProfile(t *testing.T, matches matchFunc, need []string, avoid []string, f func(dur time.Duration)) {
 	switch runtime.GOOS {
 	case "darwin":
 		switch runtime.GOARCH {
@@ -171,7 +180,7 @@ func testCPUProfile(t *testing.T, matches matchFunc, need []string, f func(dur t
 		f(duration)
 		StopCPUProfile()
 
-		if profileOk(t, need, matches, prof, duration) {
+		if profileOk(t, matches, need, avoid, prof, duration) {
 			return
 		}
 
@@ -218,11 +227,13 @@ func stackContains(spec string, count uintptr, stk []*profile.Location, labels m
 
 type matchFunc func(spec string, count uintptr, stk []*profile.Location, labels map[string][]string) bool
 
-func profileOk(t *testing.T, need []string, matches matchFunc, prof bytes.Buffer, duration time.Duration) (ok bool) {
+func profileOk(t *testing.T, matches matchFunc, need []string, avoid []string, prof bytes.Buffer, duration time.Duration) (ok bool) {
 	ok = true
 
-	// Check that profile is well formed and contains need.
+	// Check that profile is well formed, contains 'need', and does not contain
+	// anything from 'avoid'.
 	have := make([]uintptr, len(need))
+	avoidSamples := make([]uintptr, len(avoid))
 	var samples uintptr
 	var buf bytes.Buffer
 	parseProfile(t, prof.Bytes(), func(count uintptr, stk []*profile.Location, labels map[string][]string) {
@@ -234,6 +245,15 @@ func profileOk(t *testing.T, need []string, matches matchFunc, prof bytes.Buffer
 				have[i] += count
 			}
 		}
+		for i, name := range avoid {
+			for _, loc := range stk {
+				for _, line := range loc.Line {
+					if strings.Contains(line.Function.Name, name) {
+						avoidSamples[i] += count
+					}
+				}
+			}
+		}
 		fmt.Fprintf(&buf, "\n")
 	})
 	t.Logf("total %d CPU profile samples collected:\n%s", samples, buf.String())
@@ -256,6 +276,14 @@ func profileOk(t *testing.T, need []string, matches matchFunc, prof bytes.Buffer
 		ok = false
 	}
 
+	for i, name := range avoid {
+		bad := avoidSamples[i]
+		if bad != 0 {
+			t.Logf("found %d samples in avoid-function %s\n", bad, name)
+			ok = false
+		}
+	}
+
 	if len(need) == 0 {
 		return ok
 	}
@@ -323,6 +351,9 @@ func TestCPUProfileWithFork(t *testing.T) {
 // If it did, it would see inconsistent state and would either record an incorrect stack
 // or crash because the stack was malformed.
 func TestGoroutineSwitch(t *testing.T) {
+	if runtime.Compiler == "gccgo" {
+		t.Skip("not applicable for gccgo")
+	}
 	// How much to try. These defaults take about 1 seconds
 	// on a 2012 MacBook Pro. The ones in short mode take
 	// about 0.1 seconds.
@@ -382,7 +413,7 @@ func fprintStack(w io.Writer, stk []*profile.Location) {
 
 // Test that profiling of division operations is okay, especially on ARM. See issue 6681.
 func TestMathBigDivide(t *testing.T) {
-	testCPUProfile(t, nil, nil, func(duration time.Duration) {
+	testCPUProfile(t, nil, nil, nil, func(duration time.Duration) {
 		t := time.After(duration)
 		pi := new(big.Int)
 		for {
@@ -411,7 +442,7 @@ func stackContainsAll(spec string, count uintptr, stk []*profile.Location, label
 }
 
 func TestMorestack(t *testing.T) {
-	testCPUProfile(t, stackContainsAll, []string{"runtime.newstack,runtime/pprof.growstack"}, func(duration time.Duration) {
+	testCPUProfile(t, stackContainsAll, []string{"runtime.newstack,runtime/pprof.growstack"}, avoidFunctions(), func(duration time.Duration) {
 		t := time.After(duration)
 		c := make(chan bool)
 		for {
@@ -913,7 +944,7 @@ func stackContainsLabeled(spec string, count uintptr, stk []*profile.Location, l
 }
 
 func TestCPUProfileLabel(t *testing.T) {
-	testCPUProfile(t, stackContainsLabeled, []string{"runtime/pprof.cpuHogger;key=value"}, func(dur time.Duration) {
+	testCPUProfile(t, stackContainsLabeled, []string{"runtime/pprof.cpuHogger;key=value"}, avoidFunctions(), func(dur time.Duration) {
 		Do(context.Background(), Labels("key", "value"), func(context.Context) {
 			cpuHogger(cpuHog1, &salt1, dur)
 		})
@@ -924,7 +955,7 @@ func TestLabelRace(t *testing.T) {
 	// Test the race detector annotations for synchronization
 	// between settings labels and consuming them from the
 	// profile.
-	testCPUProfile(t, stackContainsLabeled, []string{"runtime/pprof.cpuHogger;key=value"}, func(dur time.Duration) {
+	testCPUProfile(t, stackContainsLabeled, []string{"runtime/pprof.cpuHogger;key=value"}, nil, func(dur time.Duration) {
 		start := time.Now()
 		var wg sync.WaitGroup
 		for time.Since(start) < dur {