Fix an assertion failure in stack trace construction.

When constructing stack traces we interpret the deoptimization data for
optimized frames to find the receiver value.  This value could sometimes be
eliminated from the deoptimization data if we though it was unused.

BUG=v8:1118

Review URL: http://codereview.chromium.org/6465023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6694 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -900,17 +900,6 @@ void HPhi::AddInput(HValue* value) {
 }
 
 
-bool HPhi::HasReceiverOperand() {
-  for (int i = 0; i < OperandCount(); i++) {
-    if (OperandAt(i)->IsParameter() &&
-        HParameter::cast(OperandAt(i))->index() == 0) {
-      return true;
-    }
-  }
-  return false;
-}
-
-
 HValue* HPhi::GetRedundantReplacement() const {
   HValue* candidate = NULL;
   int count = OperandCount();

src/hydrogen-instructions.h

@@ -1702,7 +1702,7 @@ class HPhi: public HValue {
   HValue* GetRedundantReplacement() const;
   void AddInput(HValue* value);
 
-  bool HasReceiverOperand();
+  bool IsReceiver() { return merged_index_ == 0; }
 
   int merged_index() const { return merged_index_; }
 

src/hydrogen.cc

@@ -870,13 +870,11 @@ void HGraph::EliminateRedundantPhis() {
       }
       uses_to_replace.Rewind(0);
       block->RemovePhi(phi);
-    } else if (phi->HasNoUses() &&
-               !phi->HasReceiverOperand() &&
-               FLAG_eliminate_dead_phis) {
-      // We can't eliminate phis that have the receiver as an operand
-      // because in case of throwing an error we need the correct
-      // receiver value in the environment to construct a corrent
-      // stack trace.
+    } else if (FLAG_eliminate_dead_phis && phi->HasNoUses() &&
+               !phi->IsReceiver()) {
+      // We can't eliminate phis in the receiver position in the environment
+      // because in case of throwing an error we need this value to
+      // construct a stack trace.
       block->RemovePhi(phi);
       block->RecordDeletedPhi(phi->merged_index());
     }

test/mjsunit/regress/regress-1118.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.
+
+// An exception thrown in a function optimized by on-stack replacement (OSR)
+// should be able to construct a receiver from all optimized stack frames.
+
+function A() { }
+A.prototype.f = function() { }
+
+function B() { }
+
+var o = new A();
+
+// This function throws if o does not have an f property, and should not be
+// inlined.
+function g() { try { return o.f(); } finally { }}
+
+// This function should be optimized via OSR.
+function h() {
+  while(false) ;
+  for (var j = 0; j < 5000000; j++) g();
+}
+
+h();
+o = new B();
+assertThrows("h()");