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7298a38552
sourceRevisionAtLastExport: 33f2fb0e53d135f0ee17cfccd9d993eb2a6f47de targetRevisionAtLastExport: 31340cbd9add103f586d501b0c3354b7b182abc0
68 lines
2.0 KiB
JavaScript
68 lines
2.0 KiB
JavaScript
// Copyright 2015 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --allow-natives-syntax --expose-gc --block-concurrent-recompilation
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function Inner() {
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this.property = "OK";
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this.prop2 = 1;
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}
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function Outer() {
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this.o = "u";
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}
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function KeepMapAlive(o) {
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return o.o;
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}
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function SetInner(o, i) {
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o.inner_field = i;
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}
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function Crash(o) {
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return o.inner_field.property;
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}
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var inner = new Inner();
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var outer = new Outer();
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// Collect type feedback.
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SetInner(new Outer(), inner);
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SetInner(outer, inner);
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// This function's only purpose is to stash away a Handle that keeps
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// outer's map alive during the gc() call below. We store this handle
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// on the compiler thread :-)
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KeepMapAlive(outer);
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KeepMapAlive(outer);
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%OptimizeFunctionOnNextCall(KeepMapAlive, "concurrent");
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KeepMapAlive(outer);
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// So far, all is well. Collect type feedback and optimize.
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print(Crash(outer));
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print(Crash(outer));
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%OptimizeFunctionOnNextCall(Crash);
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print(Crash(outer));
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// Null out references and perform GC. This will keep outer's map alive
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// (due to the handle created above), but will let inner's map die. Hence,
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// inner_field's field type stored in outer's map will get cleared.
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inner = undefined;
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outer = undefined;
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gc();
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// We could unblock the compiler thread now. But why bother?
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// Now optimize SetInner while inner_field's type is still cleared!
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// This will generate optimized code that stores arbitrary objects
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// into inner_field without checking their type against the field type.
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%OptimizeFunctionOnNextCall(SetInner);
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// Use the optimized code to store an arbitrary object into
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// o2's inner_field, without triggering any dependent code deopts...
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var o2 = new Outer();
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SetInner(o2, { invalid: 1.51, property: "OK" });
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// ...and then use the existing code expecting an Inner-class object to
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// read invalid data (in this case, a raw double).
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// We crash trying to convert the raw double into a printable string.
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print(Crash(o2));
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