[hydrogen] optimize switch with string clauses

src/hydrogen.cc

 // 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
@@ skipping 2677 matching lines @@
   CHECK_ALIVE(VisitForValue(stmt->tag()));
   AddSimulate(stmt->EntryId());
   HValue* tag_value = Pop();
   HBasicBlock* first_test_block = current_block();
 
   // 1. Build all the tests, with dangling true branches.  Unconditionally
   // deoptimize if we encounter a non-smi comparison.
   for (int i = 0; i < clause_count; ++i) {
     CaseClause* clause = clauses->at(i);
     if (clause->is_default()) continue;
-    if (!clause->label()->IsSmiLiteral()) {
+    if (!clause->label()->IsSmiLiteral() &&
+        !clause->label()->IsStringLiteral()) {
       return Bailout("SwitchStatement: non-literal switch label");
     }
 
-    // Unconditionally deoptimize on the first non-smi compare.
     clause->RecordTypeFeedback(oracle());
-    if (!clause->IsSmiCompare()) {
-      // Finish with deoptimize and add uses of enviroment values to
-      // account for invisible uses.
-      current_block()->FinishExitWithDeoptimization(HDeoptimize::kUseAll);
-      set_current_block(NULL);
-      break;
+
+    // Generate a compare and branch.
+    CHECK_ALIVE(VisitForValue(clause->label()));
+    HValue* label_value = Pop();
+
+    HBasicBlock* next_test_block = graph()->CreateBasicBlock();
+    HBasicBlock* body_block = graph()->CreateBasicBlock();
+
+    if (clause->IsSmiCompare()) {
+      HCompareIDAndBranch* compare =
+          new(zone()) HCompareIDAndBranch(tag_value,
+                                          label_value,
+                                          Token::EQ_STRICT);
+      compare->SetInputRepresentation(Representation::Integer32());
+      compare->SetSuccessorAt(0, body_block);
+      compare->SetSuccessorAt(1, next_test_block);
+      current_block()->Finish(compare);
+    } else {
+      AddInstruction(new(zone()) HCheckNonSmi(tag_value));
+      AddInstruction(HCheckInstanceType::NewIsSymbol(tag_value));
+      HCompareObjectEqAndBranch* compare =
+          new(zone()) HCompareObjectEqAndBranch(tag_value, label_value);
+      compare->SetSuccessorAt(0, body_block);

[Vyacheslav Egorov (Chromium), 2011/10/24 09:37:19]

Can be moved outside of the if to avoid code duplication.

+      compare->SetSuccessorAt(1, next_test_block);
+      current_block()->Finish(compare);
     }
 
-    // Otherwise generate a compare and branch.
-    CHECK_ALIVE(VisitForValue(clause->label()));
-    HValue* label_value = Pop();
-    HCompareIDAndBranch* compare =
-        new(zone()) HCompareIDAndBranch(tag_value,
-                                        label_value,
-                                        Token::EQ_STRICT);
-    compare->SetInputRepresentation(Representation::Integer32());
-    HBasicBlock* body_block = graph()->CreateBasicBlock();
-    HBasicBlock* next_test_block = graph()->CreateBasicBlock();
-    compare->SetSuccessorAt(0, body_block);
-    compare->SetSuccessorAt(1, next_test_block);
-    current_block()->Finish(compare);
     set_current_block(next_test_block);
   }
 
   // Save the current block to use for the default or to join with the
   // exit.  This block is NULL if we deoptimized.
   HBasicBlock* last_block = current_block();
 
   // 2. Loop over the clauses and the linked list of tests in lockstep,
   // translating the clause bodies.
   HBasicBlock* curr_test_block = first_test_block;
@@ skipping 4278 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal