Fix crash in arm conditional expression code generation.

src/arm/codegen-arm.cc

 // Copyright 2006-2009 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
@@ skipping 2406 matching lines @@
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope;
   Comment cmnt(masm_, "[ Conditional");
   JumpTarget then;
   JumpTarget else_;
   JumpTarget exit;
   LoadConditionAndSpill(node->condition(), NOT_INSIDE_TYPEOF,
                         &then, &else_, true);
-  Branch(false, &else_);
-  then.Bind();
-  LoadAndSpill(node->then_expression(), typeof_state());
-  exit.Jump();
-  else_.Bind();
-  LoadAndSpill(node->else_expression(), typeof_state());
-  exit.Bind();
+  if (frame_ != NULL) {
+    Branch(false, &else_);
+  }
+  if (frame_ != NULL || then.is_linked()) {
+    then.Bind();
+    LoadAndSpill(node->then_expression(), typeof_state());
+  }
+  if (frame_ != NULL) {

[Kevin Millikin (Chromium), 2009/07/09 01:20:31]

You only need to jump around the else part if you are going to emit it.  You
could write:

if (else_.is_linked()) {
  JumpTarget exit;
  if (has_valid_frame()) exit.Jump();
  LoadAndSpill(node->else_expression(), typeof_state());
  if (exit.is_linked()) exit.Bind();
}

[Mads Ager (chromium), 2009/07/09 04:11:08]

Done.  I left the binding of the else_ JumpTarget in there though.  :-)

+    exit.Jump();
+  }
+  if (else_.is_linked()) {
+    else_.Bind();
+    LoadAndSpill(node->else_expression(), typeof_state());
+  }
+  if (exit.is_linked()) {
+    exit.Bind();
+  }
   ASSERT(frame_->height() == original_height + 1);
 }
 
 
 void CodeGenerator::LoadFromSlot(Slot* slot, TypeofState typeof_state) {
   VirtualFrame::SpilledScope spilled_scope;
   if (slot->type() == Slot::LOOKUP) {
     ASSERT(slot->var()->is_dynamic());
 
     JumpTarget slow;
@@ skipping 3950 matching lines @@
 int CompareStub::MinorKey() {
   // Encode the two parameters in a unique 16 bit value.
   ASSERT(static_cast<unsigned>(cc_) >> 28 < (1 << 15));
   return (static_cast<unsigned>(cc_) >> 27) | (strict_ ? 1 : 0);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal