Check for phi-uses of arguments object before eliminating dead phi's.

HGraphBuilder::TryArgumentsAccess does not emit any uses for receiver and will generate incorrect code when receiver for a property access is defined by a phi that returns either arguments object or something else.
 
BUG=v8:1582
TEST=test/mjsunit/regress/regress-1582.js
Review URL: http://codereview.chromium.org/7553006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8774 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen.cc

@@ -840,6 +840,19 @@ void HGraph::EliminateUnreachablePhis() {
 }
 
 
+bool HGraph::CheckPhis() {
+  int block_count = blocks_.length();
+  for (int i = 0; i < block_count; ++i) {
+    for (int j = 0; j < blocks_[i]->phis()->length(); ++j) {
+      HPhi* phi = blocks_[i]->phis()->at(j);
+      // We don't support phi uses of arguments for now.
+      if (phi->CheckFlag(HValue::kIsArguments)) return false;
+    }
+  }
+  return true;
+}
+
+
 bool HGraph::CollectPhis() {
   int block_count = blocks_.length();
   phi_list_ = new ZoneList<HPhi*>(block_count);
@@ -847,8 +860,6 @@ bool HGraph::CollectPhis() {
     for (int j = 0; j < blocks_[i]->phis()->length(); ++j) {
       HPhi* phi = blocks_[i]->phis()->at(j);
       phi_list_->Add(phi);
-      // We don't support phi uses of arguments for now.
-      if (phi->CheckFlag(HValue::kIsArguments)) return false;
       // Check for the hole value (from an uninitialized const).
       for (int k = 0; k < phi->OperandCount(); k++) {
         if (phi->OperandAt(k) == GetConstantHole()) return false;
@@ -2300,10 +2311,14 @@ HGraph* HGraphBuilder::CreateGraph() {
   graph()->OrderBlocks();
   graph()->AssignDominators();
   graph()->PropagateDeoptimizingMark();
+  if (!graph()->CheckPhis()) {
+    Bailout("Unsupported phi use of arguments object");
+    return NULL;
+  }
   graph()->EliminateRedundantPhis();
   if (FLAG_eliminate_dead_phis) graph()->EliminateUnreachablePhis();
   if (!graph()->CollectPhis()) {
-    Bailout("Unsupported phi-use");
+    Bailout("Unsupported phi use of uninitialized constant");
     return NULL;
   }
 

src/hydrogen.h

@@ -242,6 +242,10 @@ class HGraph: public ZoneObject {
 
   // Returns false if there are phi-uses of the arguments-object
   // which are not supported by the optimizing compiler.
+  bool CheckPhis();
+
+  // Returns false if there are phi-uses of hole values comming
+  // from uninitialized consts.
   bool CollectPhis();
 
   Handle<Code> Compile(CompilationInfo* info);

test/mjsunit/regress/regress-1582.js

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// 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: --allow-natives-syntax
+
+function f(restIsArray, rest) {
+  var arr;
+  if (typeof rest === "object" && (rest instanceof Array)) {
+    arr = rest;
+  } else {
+    arr = arguments;
+  }
+  var i = arr.length;
+  while (--i >= 0) arr[i];
+  var arrIsArguments = (arr[1] !== rest);
+  assertEquals(restIsArray, arrIsArguments);
+}
+
+f(false, 'b', 'c');
+f(false, 'b', 'c');
+f(false, 'b', 'c');
+%OptimizeFunctionOnNextCall(f);
+f(true, ['b', 'c']);