Optimize branches in polymorphic equality operations.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 441 matching lines @@
   // 'temp' contains class-id of the left argument.
   ObjectStore* object_store = Isolate::Current()->object_store();
   Condition cond = TokenKindToSmiCondition(kind);
   Label done;
   const intptr_t len = ic_data.NumberOfChecks();
   for (intptr_t i = 0; i < len; i++) {
     // Assert that the Smi is at position 0, if at all.
     ASSERT((ic_data.GetReceiverClassIdAt(i) != kSmiCid) || (i == 0));
     Label next_test;
     __ cmpq(temp, Immediate(ic_data.GetReceiverClassIdAt(i)));
-    __ j(NOT_EQUAL, &next_test);
+    if (i < len - 1) {
+      __ j(NOT_EQUAL, &next_test);
+    } else {
+      __ j(NOT_EQUAL, deopt);
+    }
     const Function& target = Function::ZoneHandle(ic_data.GetTargetAt(i));
     if (target.Owner() == object_store->object_class()) {
       // Object.== is same as ===.
       __ Drop(2);
       __ cmpq(left, right);
       if (branch != NULL) {
         branch->EmitBranchOnCondition(compiler, cond);
       } else {
         // This case should be rare.
         Register result = locs->out().reg();
@@ skipping 15 matching lines @@
                                    locs);
       if (branch == NULL) {
         if (kind == Token::kNE) {
           Label false_label;
           __ CompareObject(RAX, Bool::True());
           __ j(EQUAL, &false_label, Assembler::kNearJump);
           __ LoadObject(RAX, Bool::True());
           __ jmp(&done);
           __ Bind(&false_label);
           __ LoadObject(RAX, Bool::False());
-          __ jmp(&done);
         }
       } else {
         if (branch->is_checked()) {
           EmitAssertBoolean(RAX, token_pos, deopt_id, locs, compiler);
         }
         __ CompareObject(RAX, Bool::True());
         branch->EmitBranchOnCondition(compiler, cond);
       }
     }
-    __ jmp(&done);
+    if (i < len - 1) {
+      __ jmp(&done);
+    }
     __ Bind(&next_test);
   }
-  // Fall through leads to deoptimization
-  __ jmp(deopt);
   __ Bind(&done);
 }
 
 
 // Emit code when ICData's targets are all Object == (which is ===).
 static void EmitCheckedStrictEqual(FlowGraphCompiler* compiler,
                                    const ICData& ic_data,
                                    const LocationSummary& locs,
                                    Token::Kind kind,
                                    BranchInstr* branch,
@@ skipping 2520 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64