Turn Runtime_MigrateInstance into Runtime_TryMigrateInstance

test/mjsunit/regress/regress-crbug-315252.js

 // Copyright 2014 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
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 //       notice, this list of conditions and the following disclaimer.
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 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --allow-natives-syntax
 
-function load(a, i) {
-  return a[i];
+function f(a, b, c) {
+ this.a = a;
+ this.b = b;
+ this.c = c;
 }
-load([1, 2, 3], "length");
-load(3);
-load([1, 2, 3], 3);
-load(0, 0);
-%OptimizeFunctionOnNextCall(load);
-assertEquals(2, load([1, 2, 3], 1));
-assertEquals(undefined, load(0, 0));
-
-function store(a, i, x) {
-  a[i] = x;
+var o3 = new f(1, 2, 3.5);
+var o4 = new f(1, 2.5, 3);
+var o1 = new f(1.5, 2, 3);
+var o2 = new f(1.5, 2, 3);
+function migrate(o) {
+ return o.a;
 }
-store([1, 2, 3], "length", 3);
-store(3);
-store([1, 2, 3], 3, 3);
-store(0, 0, 1);
-%OptimizeFunctionOnNextCall(store);
-var a = [1, 2, 3];
-store(a, 1, 1);
-assertEquals(1, a[1]);
-store(0, 0, 1);
+// Use migrate to stabilize o1, o2 and o4 in [double, double, smi].
+migrate(o4);
+migrate(o1);
+migrate(o2);
+function store_transition(o) {
+ o.d = 1;
+}
+// Optimize "store_transition" to transition from [double, double, smi] to
+// [double, double, smi, smi]. This adds a dependency on the
+// [double, double, smi] map.
+store_transition(o4);
+store_transition(o1);
+store_transition(o2);
+%OptimizeFunctionOnNextCall(store_transition);
+// Pass in a deprecated object of format [smi, smi, double]. This will migrate
+// the instance, forcing a merge with [double, double, smi], ending up with
+// [double, double, double], which deprecates [double, double, smi] and
+// deoptimizes all dependencies of [double, double, smi], including
+// store_transition itself.
+store_transition(o3);