Replaced unary negation by multiplication with -1.

test/mjsunit/unary-minus-deopt.js

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 // Flags: --allow-natives-syntax
 
-var g1 = { a:1 }
+// This is a boiled-down example happening in the Epic Citadel demo:
+// After deopting, the multiplication for unary minus stayed in Smi
+// mode instead of going to double mode, leading to deopt loops.
 
-function load() {
-  return g1.a;
+function unaryMinusTest(x) {
+  var g = (1 << x) | 0;
+  // Optimized code will contain a LMulI with -1 as right operand.
+  return (g & -g) - 1 | 0;
 }
 
-assertEquals(1, load());
-assertEquals(1, load());
-%OptimizeFunctionOnNextCall(load);
-assertEquals(1, load());
-delete g1.a;
-assertEquals(undefined, load());
+unaryMinusTest(3);
+unaryMinusTest(3);
+%OptimizeFunctionOnNextCall(unaryMinusTest);
+unaryMinusTest(3);
+assertOptimized(unaryMinusTest);
 
-var g2 = { a:2 }
+// Deopt on kMinInt
+unaryMinusTest(31);
+// The following is normally true, but not with --stress-opt. :-/
+// assertUnoptimized(unaryMinusTest);
 
-function load2() {
-  return g2.a;
-}
-
-assertEquals(2, load2());
-assertEquals(2, load2());
-%OptimizeFunctionOnNextCall(load2);
-assertEquals(2, load2());
-g2.b = 10;
-g2.a = 5;
-assertEquals(5, load2());
-
-var g3 = { a:2, b:9, c:1 }
-
-function store(v) {
-  g3.a = v;
-  return g3.a;
-}
-
-assertEquals(5, store(5));
-assertEquals(8, store(8));
-%OptimizeFunctionOnNextCall(store);
-assertEquals(10, store(10));
-delete g3.c;
-store(7);
-assertEquals({a:7, b:9}, g3);
+// We should have learned something from the deopt.
+unaryMinusTest(31);
+%OptimizeFunctionOnNextCall(unaryMinusTest);
+unaryMinusTest(31);
+assertOptimized(unaryMinusTest);