Reviewers: iposva,
Description:
Add comments to test-log-stack-tracer.
Please review this at http://codereview.chromium.org/1181001
Affected files:
M test/cctest/test-log-stack-tracer.cc
Index: test/cctest/test-log-stack-tracer.cc
diff --git a/test/cctest/test-log-stack-tracer.cc
b/test/cctest/test-log-stack-tracer.cc
index
d96e5e787877081c115ce716f05d0000776a4698..532311bfbc212a31cccccacaf7e9674997f62615
100644
--- a/test/cctest/test-log-stack-tracer.cc
+++ b/test/cctest/test-log-stack-tracer.cc
@@ -284,12 +284,18 @@ static void CreateTraceCallerFunction(const char*
func_name,
}
+// This test verifies that stack tracing works when called during
+// execution of a native function called from JS code. In this case,
+// StackTracer uses Top::c_entry_fp as a starting point for stack
+// walking.
TEST(CFromJSStackTrace) {
TickSample sample;
InitTraceEnv(&sample);
InitializeVM();
v8::HandleScope scope;
+ // Create global function JSFuncDoTrace which calls
+ // extension function trace() with the current frame pointer value.
CreateTraceCallerFunction("JSFuncDoTrace", "trace");
Local<Value> result = CompileRun(
"function JSTrace() {"
@@ -298,8 +304,15 @@ TEST(CFromJSStackTrace) {
"JSTrace();\n"
"true;");
CHECK(!result.IsEmpty());
+ // When stack tracer is invoked, the stack should look as follows:
+ // script [JS]
+ // JSTrace() [JS]
+ // JSFuncDoTrace() [JS] [captures EBP value and encodes it as Smi]
+ // trace(EBP encoded as Smi) [native (extension)]
+ // DoTrace(EBP) [native]
+ // StackTracer::Trace
CHECK_GT(sample.frames_count, 1);
- // Stack sampling will start from the first JS function,
i.e. "JSFuncDoTrace"
+ // Stack tracing will start from the first JS function,
i.e. "JSFuncDoTrace"
CheckRetAddrIsInJSFunction("JSFuncDoTrace",
sample.stack[0]);
CheckRetAddrIsInJSFunction("JSTrace",
@@ -307,12 +320,19 @@ TEST(CFromJSStackTrace) {
}
+// This test verifies that stack tracing works when called during
+// execution of JS code. However, as calling StackTracer requires
+// entering native code, we can only emulate pure JS by erasing
+// Top::c_entry_fp value. In this case, StackTracer uses passed frame
+// pointer value as a starting point for stack walking.
TEST(PureJSStackTrace) {
TickSample sample;
InitTraceEnv(&sample);
InitializeVM();
v8::HandleScope scope;
+ // Create global function JSFuncDoTrace which calls
+ // extension function js_trace() with the current frame pointer value.
CreateTraceCallerFunction("JSFuncDoTrace", "js_trace");
Local<Value> result = CompileRun(
"function JSTrace() {"
@@ -324,7 +344,17 @@ TEST(PureJSStackTrace) {
"OuterJSTrace();\n"
"true;");
CHECK(!result.IsEmpty());
- // The last JS function called.
+ // When stack tracer is invoked, the stack should look as follows:
+ // script [JS]
+ // OuterJSTrace() [JS]
+ // JSTrace() [JS]
+ // JSFuncDoTrace() [JS] [captures EBP value and encodes it as Smi]
+ // js_trace(EBP encoded as Smi) [native (extension)]
+ // DoTraceHideCEntryFPAddress(EBP) [native]
+ // StackTracer::Trace
+ //
+ // The last JS function called. It is only visible through
+ // sample.function, as its return address is above captured EBP value.
CHECK_EQ(GetGlobalJSFunction("JSFuncDoTrace")->address(),
sample.function);
CHECK_GT(sample.frames_count, 1);
@@ -361,6 +391,9 @@ static int CFunc(int depth) {
}
+// This test verifies that stack tracing doesn't crash when called on
+// pure native code. StackTracer only unrolls JS code, so we can't
+// get any meaningful info here.
TEST(PureCStackTrace) {
TickSample sample;
InitTraceEnv(&sample);
--
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