v8/test/debugger/debug/es6/debug-stepin-microtasks.js
kozyatinskiy e27d18c943 [debugger] tuned StepNext and StepOut at return position
Proposed behaviour:
- StepNext at return position go into next function call (no changes with current behavior, but implemented in v8::Debug instead of hack on inspector side);
- StepOut at return position go into next non-current function call.

We need this to have better stepping in cases with native functions, blackboxed functions and/or different embedder calls (e.g. event listeners).

New behavior could be illustrated with two examples (for more see stepping-with-natives-and-frameworks test):
- let's assume that we've blackboxed callAll function, this function just takes its arguments and call one after another:
var foo = () => 1;
callAll(foo, foo, () => 2);
If we break inside of first call of function foo. Then on..
..StepNext - we're able to reach second call of function foo,
..StepOut - we're able to reach () => 2 call.

- let's consider case with native function:
[1,2,3].map(x => x * 2)
If we break inside of first callback call, then with StepNext we can iterate through all calls of callback, with StepOut we go to next statement after .map call.

Implementation details:
- when we request break we schedule step-in function call for any step action at return position and for step-in at any position,
- when we request StepOut at return position - we mark current function as needed-to-be-ignored inside of PrepareStepIn(function) call,
- when we request StepOut at not return position - we set break at return position and ask debugger to just repeat last step action on next stepping-related break.

Design doc: https://docs.google.com/document/d/1ihXHOIhP_q-fJCA0e2EiXz_Zr3B08KMjaPifcaqZ60Q/edit

BUG=v8:6118,chromium:583193
R=dgozman@chromium.org,yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2758483002
Cr-Commit-Position: refs/heads/master@{#44028}
2017-03-22 14:16:18 +00:00

77 lines
2.1 KiB
JavaScript

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
Debug = debug.Debug
var exception = null;
var break_count = 0;
const expected_breaks = 10;
function listener(event, exec_state, event_data, data) {
try {
if (event == Debug.DebugEvent.Break) {
assertTrue(exec_state.frameCount() != 0, "FAIL: Empty stack trace");
var source = exec_state.frame(0).sourceLineText();
print("paused at: " + source);
assertTrue(source.indexOf("// Break " + break_count + ".") > 0,
"Unexpected pause at: " + source + "\n" +
"Expected: // Break " + break_count + ".");
if (source.indexOf("StepOver.") !== -1) {
exec_state.prepareStep(Debug.StepAction.StepNext);
} else if (source.indexOf("StepOut.") !== -1) {
exec_state.prepareStep(Debug.StepAction.StepOut);
} else {
exec_state.prepareStep(Debug.StepAction.StepIn);
}
++break_count;
}
} catch (e) {
exception = e;
print(e, e.stack);
}
};
Debug.setListener(listener);
Promise.resolve(42)
.then(promise1)
.then(Object) // Should skip stepping into native.
.then(Boolean) // Should skip stepping into native.
.then(promise2)
.catch(promise3)
.then(promise4)
.catch(function(e) {
%AbortJS("FAIL: uncaught exception " + e);
});
function promise1() {
debugger; // Break 0.
return exception || 1; // Break 1.
} // Break 2. StepOver.
function promise2() {
throw new Error; // Break 3.
}
function promise3() {
return break_count; // Break 4.
} // Break 5.
function promise4() {
finalize(); // Break 6. StepOver.
return 0; // Break 7.
} // Break 8. StepOut.
function finalize() {
Promise.resolve().then(function() {
if (expected_breaks !== break_count) { // Break 9. StepOut.
%AbortJS("FAIL: expected <" + expected_breaks + "> breaks instead of <" +
break_count + ">");
}
if (exception !== null) {
%AbortJS("FAIL: exception: " + exception);
}
});
}