* String type inference using compiler framework.

src/codegen-ia32.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 789 matching lines @@
   Result right(generator());
   enter()->Bind(&left, &right);
   generator()->frame()->Push(&left);
   generator()->frame()->Push(&right);
   Result answer = generator()->frame()->CallStub(&stub_, 2);
   exit_.Jump(&answer);
 }
 
 
 void CodeGenerator::GenericBinaryOperation(Token::Value op,
-                                           StaticType* type,
+                                           SmiAnalysis* type,
                                            OverwriteMode overwrite_mode) {
   Comment cmnt(masm_, "[ BinaryOperation");
   Comment cmnt_token(masm_, Token::String(op));
 
   if (op == Token::COMMA) {
     // Simply discard left value.
     frame_->Nip(1);
     return;
   }
 
@@ skipping 17 matching lines @@
       // By default only inline the Smi check code for likely smis if this
       // operation is part of a loop.
       flags = ((loop_nesting() > 0) && type->IsLikelySmi())
               ? SMI_CODE_INLINED
               : SMI_CODE_IN_STUB;
       break;
   }
 
   Result right = frame_->Pop();
   Result left = frame_->Pop();
+
+  if (op == Token::ADD) {
+    bool left_is_string = left.static_type().is_jsstring();
+    bool right_is_string = right.static_type().is_jsstring();
+    if (left_is_string || right_is_string) {
+      frame_->Push(&left);
+      frame_->Push(&right);
+      Result answer(this);
+      if (left_is_string) {
+        if (right_is_string) {
+          // TODO(lrn): if (left.is_constant() && right.is_constant())
+          // -- do a compile time cons, if allocation during codegen is allowed.
+          answer = frame_->CallRuntime(Runtime::kStringAdd, 2);
+        } else {
+          answer =
+            frame_->InvokeBuiltin(Builtins::STRING_ADD_LEFT, CALL_FUNCTION, 2);
+        }
+      } else if (right_is_string) {
+        answer =
+          frame_->InvokeBuiltin(Builtins::STRING_ADD_RIGHT, CALL_FUNCTION, 2);
+      }
+      answer.set_static_type(StaticType::jsstring());
+      frame_->Push(&answer);
+      return;
+    }
+    // Neither operand is known to be a string.
+  }
+
   bool left_is_smi = left.is_constant() && left.handle()->IsSmi();
   bool left_is_non_smi = left.is_constant() && !left.handle()->IsSmi();
   bool right_is_smi = right.is_constant() && right.handle()->IsSmi();
   bool right_is_non_smi = right.is_constant() && !right.handle()->IsSmi();
   bool generate_no_smi_code = false;  // No smi code at all, inline or in stub.
 
   if (left_is_smi && right_is_smi) {
     // Compute the constant result at compile time, and leave it on the frame.
     int left_int = Smi::cast(*left.handle())->value();
     int right_int = Smi::cast(*right.handle())->value();
@@ skipping 324 matching lines @@
   generator()->frame()->Push(&right);
   GenericBinaryOpStub igostub(Token::SUB, overwrite_mode_, SMI_CODE_INLINED);
   Result answer = generator()->frame()->CallStub(&igostub, 2);
   exit_.Jump(&answer);
 }
 
 
 void CodeGenerator::ConstantSmiBinaryOperation(Token::Value op,
                                                Result* operand,
                                                Handle<Object> value,
-                                               StaticType* type,
+                                               SmiAnalysis* type,
                                                bool reversed,
                                                OverwriteMode overwrite_mode) {
   // NOTE: This is an attempt to inline (a bit) more of the code for
   // some possible smi operations (like + and -) when (at least) one
   // of the operands is a constant smi.
   // Consumes the argument "operand".
 
   // TODO(199): Optimize some special cases of operations involving a
   // smi literal (multiply by 2, shift by 0, etc.).
   if (IsUnsafeSmi(value)) {
@@ skipping 2289 matching lines @@
   } else {
     ASSERT(var->is_global());
     Reference ref(this, node);
     ref.GetValue(typeof_state());
   }
 }
 
 
 void CodeGenerator::VisitLiteral(Literal* node) {
   Comment cmnt(masm_, "[ Literal");
-    frame_->Push(node->handle());
-  }
+  frame_->Push(node->handle());
+}
 
 
 void CodeGenerator::LoadUnsafeSmi(Register target, Handle<Object> value) {
   ASSERT(target.is_valid());
   ASSERT(value->IsSmi());
   int bits = reinterpret_cast<int>(*value);
   __ Set(target, Immediate(bits & 0x0000FFFF));
   __ xor_(target, bits & 0xFFFF0000);
 }
 
@@ skipping 3572 matching lines @@
 
   // Slow-case: Go through the JavaScript implementation.
   __ bind(&slow);
   __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal