Add flag —enable-debugger (default true) in order to disable debugger single stepping code.

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 11 matching lines @@
 #define __ assembler->
 
 namespace dart {
 
 DEFINE_FLAG(bool, inline_alloc, true, "Inline allocation of objects.");
 DEFINE_FLAG(bool, use_slow_path, false,
     "Set to true for debugging & verifying the slow paths.");
 DECLARE_FLAG(bool, trace_optimized_ic_calls);
 DEFINE_FLAG(bool, verify_incoming_contexts, false, "");
 
+DECLARE_FLAG(bool, enable_debugger);
 
 // Input parameters:
 //   ESP : points to return address.
 //   ESP + 4 : address of last argument in argument array.
 //   ESP + 4*EDX : address of first argument in argument array.
 //   ESP + 4*EDX + 4 : address of return value.
 //   ECX : address of the runtime function to call.
 //   EDX : number of arguments to the call.
 // Must preserve callee saved registers EDI and EBX.
 void StubCode::GenerateCallToRuntimeStub(Assembler* assembler) {
@@ skipping 1252 matching lines @@
     __ movl(EBX, FieldAddress(ECX, ICData::state_bits_offset()));
     ASSERT(ICData::NumArgsTestedShift() == 0);  // No shift needed.
     __ andl(EBX, Immediate(ICData::NumArgsTestedMask()));
     __ cmpl(EBX, Immediate(num_args));
     __ j(EQUAL, &ok, Assembler::kNearJump);
     __ Stop("Incorrect stub for IC data");
     __ Bind(&ok);
   }
 #endif  // DEBUG
 
-  // Check single stepping.
-  Label not_stepping;
-  __ movl(EAX, FieldAddress(CTX, Context::isolate_offset()));
-  __ movzxb(EAX, Address(EAX, Isolate::single_step_offset()));
-  __ cmpl(EAX, Immediate(0));
-  __ j(EQUAL, &not_stepping, Assembler::kNearJump);
+  if (FLAG_enable_debugger) {
+    // Check single stepping.
+    Label not_stepping;
+    __ movl(EAX, FieldAddress(CTX, Context::isolate_offset()));
+    __ movzxb(EAX, Address(EAX, Isolate::single_step_offset()));
+    __ cmpl(EAX, Immediate(0));
+    __ j(EQUAL, &not_stepping, Assembler::kNearJump);
 
-  __ EnterStubFrame();
-  __ pushl(ECX);
-  __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
-  __ popl(ECX);
-  __ LeaveFrame();
-  __ Bind(&not_stepping);
+    __ EnterStubFrame();
+    __ pushl(ECX);
+    __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
+    __ popl(ECX);
+    __ LeaveFrame();
+    __ Bind(&not_stepping);
+  }
 
   // ECX: IC data object (preserved).
   // Load arguments descriptor into EDX.
   __ movl(EDX, FieldAddress(ECX, ICData::arguments_descriptor_offset()));
   // Loop that checks if there is an IC data match.
   Label loop, update, test, found, get_class_id_as_smi;
   // ECX: IC data object (preserved).
   __ movl(EBX, FieldAddress(ECX, ICData::ic_data_offset()));
   // EBX: ic_data_array with check entries: classes and target functions.
   __ leal(EBX, FieldAddress(EBX, Array::data_offset()));
@@ skipping 580 matching lines @@
   const Register temp = ECX;
   __ movl(left, Address(ESP, 2 * kWordSize));
   __ movl(right, Address(ESP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32