Simplify the way we materialize boolean values that are not yet pushed...

src/codegen-ia32.cc

 // Copyright 2006-2008 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 456 matching lines @@
   }
   ASSERT(has_cc() || !force_cc);
 }
 
 
 void CodeGenerator::Load(Expression* x, TypeofState typeof_state) {
   Label true_target;
   Label false_target;
   LoadCondition(x, typeof_state, &true_target, &false_target, false);
 
+  // Materialize boolean values on the stack frame if necessary.
   if (has_cc()) {
-    // convert cc_reg_ into a bool
-
-    Label loaded, materialize_true;
-    __ j(cc_reg_, &materialize_true);
+    // The value we want is in the cc register.  Since complicated
+    // conditions can require more than one test, there may also be branches
+    // to true_target and false_target.
+    Label loaded;
+    __ j(cc_reg_, &true_target);
+    __ bind(&false_target);
     frame_->Push(Immediate(Factory::false_value()));
     __ jmp(&loaded);
-    __ bind(&materialize_true);
+    __ bind(&true_target);
     frame_->Push(Immediate(Factory::true_value()));
     __ bind(&loaded);
     cc_reg_ = no_condition;
-  }
+  } else {
+    // Optimization of boolean-valued expressions whose value is statically
+    // known may have generated an unconditional jump to either of the
+    // targets (but not both) and failed to leave a value in either the cc
+    // register or on top of the frame.
+    ASSERT(!(true_target.is_linked() && false_target.is_linked()));
 
-  if (true_target.is_linked() || false_target.is_linked()) {
-    // we have at least one condition value
-    // that has been "translated" into a branch,
-    // thus it needs to be loaded explicitly again
-    Label loaded;
-    __ jmp(&loaded);  // don't lose current TOS
-    bool both = true_target.is_linked() && false_target.is_linked();
-    // reincarnate "true", if necessary
     if (true_target.is_linked()) {
       __ bind(&true_target);
       frame_->Push(Immediate(Factory::true_value()));
     }
-    // if both "true" and "false" need to be reincarnated,
-    // jump across code for "false"
-    if (both)
-      __ jmp(&loaded);
-    // reincarnate "false", if necessary
+
     if (false_target.is_linked()) {
       __ bind(&false_target);
       frame_->Push(Immediate(Factory::false_value()));
     }
-    // everything is loaded at this point
-    __ bind(&loaded);
   }
-  ASSERT(!has_cc());
 }
 
 
 void CodeGenerator::LoadGlobal() {
   frame_->Push(GlobalObject());
 }
 
 
 void CodeGenerator::LoadGlobalReceiver(Register scratch) {
   __ mov(scratch, GlobalObject());
@@ skipping 4609 matching lines @@
 
   // Slow-case: Go through the JavaScript implementation.
   __ bind(&slow);
   __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal