[runtime][ic] Constant field tracking support.

test/mjsunit/smi-representation.js

 // Copyright 2013 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
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 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --track-fields --track-double-fields --allow-natives-syntax
 
 function smi_field() {
-  return {"smi":0};
+  // Assign twice to make the field non-constant.
+  // TODO(ishell): update test once constant field tracking is done.
+  var o = {smi: 1};
+  o.smi = 0;
+  return o;
 }
 
 function check_smi_repr(o, d1, d2) {
   var s = o.smi;
   var d = d1 - d2;
   s = s + d;
   o.smi = s;
   return o;
 }
 
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 }
 
 check_smi_repr_from_tagged(smi_field(), tagged_smi_field());
 check_smi_repr_from_tagged(smi_field(), tagged_smi_field());
 %OptimizeFunctionOnNextCall(check_smi_repr_from_tagged);
 var val = check_smi_repr_from_tagged(smi_field(), tagged_smi_field());
 assertTrue(%HaveSameMap(val, test));
 var overflow = tagged_smi_field();
 overflow.tag = 0x80000000;
 var val = check_smi_repr_from_tagged(smi_field(), overflow);