[turbofan] compute arguments length in deoptimizer

test/mjsunit/arguments-deopt.js

 // Copyright 2017 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --allow-natives-syntax --turbo
 
 (function MaterializeStrictArguments() {
   "use strict"
 
   function f(x, y) {
@@ skipping 78 matching lines @@
   assertEquals(test4(1, 2, 3), 6);
 })();
 
 (function ArgumentsAccessStrict () {
   "use strict"
   function sum1(a,b,c) {
     var sum = 0;
     var rest = arguments;
     for (var i = 0; i < rest.length; ++i) {
       var j = i;
-      if (rest.length % 15 == 0 && i == 10) j += rest.length;
-      sum += rest[j] || rest[j-rest.length];
+      if (rest.length % 15 == 0 && i == 10) j += 10000;
+      sum += rest[j] || i+1;
     }
     return sum;
   };
 
   var args = []
   for (var i = 1; i < 30; ++i) {
     args.push(i);
     if (i%10 == 0) %OptimizeFunctionOnNextCall(sum1);
     assertEquals(i*(i+1)/2, sum1(...args));
   }
 })();
 
 (function ArgumentsAccessSloppy () {
   function sum2(a,b,c) {
     var sum = 0;
-    var rest = arguments;
-    for (var i = 0; i < rest.length; ++i) {
+    for (var i = 0; i < arguments.length; ++i) {
       var j = i;
-      if (rest.length % 15 == 0 && i == 10) j += rest.length;
-      sum += rest[j] || rest[j-rest.length];
+      if (arguments.length % 15 == 0 && i == 10) j += 10000;
+      sum += arguments[j] || i+1;
     }
     return sum;
   };
 
   var args = []
   for (var i = 1; i < 30; ++i) {
     args.push(i);
     if (i%10 == 0) %OptimizeFunctionOnNextCall(sum2);
     assertEquals(i*(i+1)/2, sum2(...args));
   }
 })();
 
 (function RestAccess0 () {
   function sum3(...rest) {
     var sum = 0;
     for (var i = 0; i < rest.length; ++i) {
       var j = i;
-      if (rest.length % 15 == 0 && i == 10) j += rest.length;
-      sum += rest[j] || rest[j-rest.length];
+      if (rest.length % 15 == 0 && i == 10) j += 10000;
+      sum += rest[j] || i+1;
     }
     return sum;
   };
 
   var args = []
   for (var i = 1; i < 30; ++i) {
     args.push(i);
     if (i%10 == 0) %OptimizeFunctionOnNextCall(sum3);
     assertEquals(i*(i+1)/2, sum3(...args));
   }
 })();
 
 (function RestAccess1 () {
   function sum4(a,...rest) {
     var sum = 0;
     for (var i = 0; i < rest.length; ++i) {
       var j = i;
-      if (rest.length % 15 == 0 && i == 10) j += rest.length;
-      sum += rest[j] || rest[j-rest.length];
+      if (rest.length % 15 == 0 && i == 10) j += 10000;
+      sum += rest[j] || i+2;
     }
     return sum;
   };
 
   var args = []
   for (var i = 1; i < 30; ++i) {
     args.push(i);
     if (i%10 == 0) %OptimizeFunctionOnNextCall(sum4);
     assertEquals(i*(i+1)/2-1, sum4(...args));
   }
 })();
+
+
+(function ReadArguments () {
+  function read() {
+    if (arguments.length % 10 == 5) %DeoptimizeNow();
+    return arguments[arguments.length-1];
+  };
+
+  var args = []
+  for (var i = 1; i < 30; ++i) {
+    args.push(i);
+    if (i%10 == 0) %OptimizeFunctionOnNextCall(read);
+    assertEquals(i, read(...args));
+  }
+})();