test/mjsunit/concurrent-initial-prototype-change-1.js

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// Flags: --allow-natives-syntax --concurrent-recompilation
// Flags: --no-stress-opt --no-always-opt
//
// --nostress-opt is in place because this particular optimization
// (guaranteeing that the Array prototype chain has no elements) is
// maintained isolate-wide. Once it's been "broken" by the change
// to the Object prototype below, future compiles will not use the
// optimization anymore, and the code will remain optimized despite
// additional changes to the prototype chain.

function f1(a, i) {
  return a[i] + 0.5;
}

%PrepareFunctionForOptimization(f1);
var arr = [0.0,,2.5];
assertEquals(0.5, f1(arr, 0));
assertEquals(0.5, f1(arr, 0));

// Optimized code of f1 depends on initial object and array maps.
%DisableOptimizationFinalization();
%OptimizeFunctionOnNextCall(f1, "concurrent");
// Kick off recompilation. Note that the NoElements protector is read by the
// compiler in the main-thread phase of compilation, i.e., before the store to
// Object.prototype below.
assertEquals(0.5, f1(arr, 0));
// Invalidate current initial object map after compile graph has been created.
%WaitForBackgroundOptimization();
Object.prototype[1] = 1.5;
assertEquals(2, f1(arr, 1));
assertUnoptimized(f1);
// Sync with background thread to conclude optimization, which bails out
// due to map dependency.
%FinalizeOptimization();
assertUnoptimized(f1, "sync");
// Clear type info for stress runs.
%ClearFunctionFeedback(f1);