Fixed type feedback in presence of negative lookups.

test/mjsunit/regress/regress-252797.js

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 // Flags: --allow-natives-syntax
 
-var a = new Array(2);
-a[0] = 1;
-assertTrue(%HasFastSmiElements(a));
-assertTrue(%HasFastHoleyElements(a));
+// The type feedback oracle had a bug when retrieving the map from an IC
+// starting with a negative lookup.
 
-function hole(i) {
-  return a[i] << 0;
+// Create a holder in fast mode.
+var holder = Object.create(null, {
+  holderMethod: {value: function() {}}
+});
+assertTrue(%HasFastProperties(holder));
+
+// Create a receiver into dictionary mode.
+var receiver = Object.create(holder, {
+  killMe: {value: 0, configurable: true},
+});
+delete receiver.killMe;
+assertFalse(%HasFastProperties(receiver));
+
+// The actual function to test, triggering the retrieval of the wrong map.
+function callConstantFunctionOnPrototype(obj) {
+  obj.holderMethod();
 }
 
-assertEquals(1, hole(0));
-assertEquals(1, hole(0));
-%OptimizeFunctionOnNextCall(hole);
-assertEquals(0, hole(1));
+callConstantFunctionOnPrototype(receiver);
+callConstantFunctionOnPrototype(receiver);
+%OptimizeFunctionOnNextCall(callConstantFunctionOnPrototype);
+callConstantFunctionOnPrototype(receiver);
+
+// Make sure that the function is still optimized.
+assertTrue(2 != %GetOptimizationStatus(callConstantFunctionOnPrototype));