Reorder switch clauses using newly-introduced execution counters in

src/x64/full-codegen-x64.cc

 // Copyright 2012 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 1008 matching lines @@
   __ bind(&next_test);
   __ Drop(1);  // Switch value is no longer needed.
   if (default_clause == NULL) {
     __ jmp(nested_statement.break_label());
   } else {
     __ jmp(default_clause->body_target());
   }
 
   // Compile all the case bodies.
   for (int i = 0; i < clauses->length(); i++) {
-    Comment cmnt(masm_, "[ Case body");
     CaseClause* clause = clauses->at(i);
     __ bind(clause->body_target());
     PrepareForBailoutForId(clause->EntryId(), NO_REGISTERS);
+
+    // Initialize counter
+    { Comment cmnt(masm_, "[ Case hit counter");
+      Handle<JSGlobalPropertyCell> cell =
+          isolate()->factory()->NewJSGlobalPropertyCell(
+              Handle<Object>(Smi::FromInt(0), isolate()));
+      RecordTypeFeedbackCell(clause->CounterId(), cell);
+
+      // Increment counter
+      Label ok;
+      Operand counter = FieldOperand(rbx, JSGlobalPropertyCell::kValueOffset);
+
+      __ LoadHeapObject(rbx, cell);
+      __ movq(rcx, counter);
+      __ AssertSmi(rcx);
+      __ SmiAddConstant(rcx, rcx, Smi::FromInt(1));
+      __ j(no_overflow, &ok, Label::kNear);
+
+      // Decrement on overflow
+      __ SmiAddConstant(rcx, rcx, Smi::FromInt(-1));
+      __ bind(&ok);
+      __ movq(counter, rcx);
+    }
+
+    Comment cmnt(masm_, "[ Case body");
     VisitStatements(clause->statements());
   }
 
   __ bind(nested_statement.break_label());
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
 }
 
 
 void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   Comment cmnt(masm_, "[ ForInStatement");
@@ skipping 3816 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64