v8/test/debugger/debug/debug-evaluate-shadowed-context-3.js
Simon Zünd 2e11dff7f2 Change debug-evaluate from a whitelist to a blacklist approach
This CL changes how variables are resolved during debug evaluate.
We now re-parse the whole script when creating a ScopeIterator.
This gives us accurate scope information for all parent scopes of the
closure in which we stopped. Using this information, we build
blacklists of stack-allocated variables. Each context on the chain
in between the closure context up to the original native context is
wrapped in a debug-evaluate context with such a blacklist attached.
Variable lookup for debug-evalute contexts then works as follows:

  1) Look up in the materialized stack variables (stayed the same).
  2) Check the blacklist to find out whether to abort further lookup.
  3) Look up in the original context.

Steps 1-3 is repeated for each debug-evaluate context, since they
mirror the original context chain.

R=ulan@chromium.org, yangguo@chromium.org

Change-Id: Ied8e5786772c70566da9627ee3b7eff066fba2b4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1795354
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63666}
2019-09-11 07:52:45 +00:00

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1011 B
JavaScript

// Copyright 2019 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.
// Test that debug-evaluate properly shadows stack-allocated variables.
Debug = debug.Debug
let exception = null;
function listener(event, exec_state, event_data, data) {
if (event != Debug.DebugEvent.Break) return;
try {
assertEquals(2, exec_state.frame(0).evaluate("b").value());
assertEquals(3, exec_state.frame(0).evaluate("c").value())
assertThrows(() => exec_state.frame(0).evaluate("a").value());
} catch (e) {
exception = e;
print(e + e.stack);
}
}
Debug.setListener(listener);
(function f() {
let a = 1;
let b = 2;
let c = 3;
() => a + c; // a and c are context-allocated
return function g() {
let a = 2; // a is stack-allocated
return function h() {
b; // b is allocated onto f's context.
debugger;
}
}
})()()();
Debug.setListener(null);
assertNull(exception);