Make breakpoints on == fire reliably

runtime/vm/stub_code_ia32.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"
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1690 matching lines @@
 }
 
 
 // Megamorphic call is currently implemented as IC call but through a stub
 // that does not check/count function invocations.
 void StubCode::GenerateMegamorphicCallStub(Assembler* assembler) {
   GenerateNArgsCheckInlineCacheStub(assembler, 1);
 }
 
 
-//  EDX: Arguments descriptor array.
+// ECX: ICData
+void StubCode::GenerateBreakpointEqNullStub(Assembler* assembler) {
+  __ EnterStubFrame();
+  __ pushl(ECX);
+  __ CallRuntime(kBreakpointEqualNullHandlerRuntimeEntry);
+  __ popl(ECX);
+  __ LeaveFrame();
+  __ jmp(&StubCode::EqualityWithNullArgLabel());
+}
+
+
+// EDX: Arguments descriptor array.
 void StubCode::GenerateBreakpointClosureStub(Assembler* assembler) {
   __ EnterStubFrame();
   __ pushl(EDX);  // Push arguments descriptor.
   __ CallRuntime(kBreakpointClosureHandlerRuntimeEntry);
   __ popl(EDX);  // Restore arguments descriptor.
   __ LeaveFrame();
   __ jmp(&StubCode::CallClosureFunctionLabel());
 }
 
 
-//  EDX: Arguments descriptor array.
-//  TOS(0): return address (Dart code).
+// EDX: Arguments descriptor array.
+// TOS(0): return address (Dart code).
 void StubCode::GenerateBreakpointStaticStub(Assembler* assembler) {
   // Create a stub frame as we are pushing some objects on the stack before
   // calling into the runtime.
   __ EnterStubFrame();
   __ pushl(EDX);  // Preserve arguments descriptor.
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   __ pushl(raw_null);  // Room for result.
   __ CallRuntime(kBreakpointStaticHandlerRuntimeEntry);
   __ popl(EAX);  // Code object.
@@ skipping 401 matching lines @@
   __ Bind(&done);
   __ popl(temp);
   __ popl(right);
   __ popl(left);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32