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

runtime/vm/stub_code_arm.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_ARM)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/cpu.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/heap.h"
 #include "vm/instructions.h"
 #include "vm/object_store.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/tags.h"
 
 #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);
 
+DECLARE_FLAG(bool, enable_debugger);
 
 // Input parameters:
 //   LR : return address.
 //   SP : address of last argument in argument array.
 //   SP + 4*R4 - 4 : address of first argument in argument array.
 //   SP + 4*R4 : address of return value.
 //   R5 : address of the runtime function to call.
 //   R4 : number of arguments to the call.
 void StubCode::GenerateCallToRuntimeStub(Assembler* assembler) {
   const intptr_t isolate_offset = NativeArguments::isolate_offset();
@@ skipping 1221 matching lines @@
     __ ldr(R6, FieldAddress(R5, ICData::state_bits_offset()));
     ASSERT(ICData::NumArgsTestedShift() == 0);  // No shift needed.
     __ and_(R6, R6, ShifterOperand(ICData::NumArgsTestedMask()));
     __ CompareImmediate(R6, num_args);
     __ b(&ok, EQ);
     __ Stop("Incorrect stub for IC data");
     __ Bind(&ok);
   }
 #endif  // DEBUG
 
-  // Check single stepping.
-  Label not_stepping;
-  __ ldr(R6, FieldAddress(CTX, Context::isolate_offset()));
-  __ ldrb(R6, Address(R6, Isolate::single_step_offset()));
-  __ CompareImmediate(R6, 0);
-  __ b(&not_stepping, EQ);
-  __ EnterStubFrame();
-  __ Push(R5);  // Preserve IC data.
-  __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
-  __ Pop(R5);
-  __ LeaveStubFrame();
-  __ Bind(&not_stepping);
+  if (FLAG_enable_debugger) {
+    // Check single stepping.
+    Label not_stepping;
+    __ ldr(R6, FieldAddress(CTX, Context::isolate_offset()));
+    __ ldrb(R6, Address(R6, Isolate::single_step_offset()));
+    __ CompareImmediate(R6, 0);
+    __ b(&not_stepping, EQ);
+    __ EnterStubFrame();
+    __ Push(R5);  // Preserve IC data.
+    __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
+    __ Pop(R5);
+    __ LeaveStubFrame();
+    __ Bind(&not_stepping);
+  }
 
   // Load arguments descriptor into R4.
   __ ldr(R4, FieldAddress(R5, ICData::arguments_descriptor_offset()));
   // Preserve return address, since LR is needed for subroutine call.
   __ mov(R8, ShifterOperand(LR));
   // Loop that checks if there is an IC data match.
   Label loop, update, test, found, get_class_id_as_smi;
   // R5: IC data object (preserved).
   __ ldr(R6, FieldAddress(R5, ICData::ic_data_offset()));
   // R6: ic_data_array with check entries: classes and target functions.
@@ skipping 184 matching lines @@
     ASSERT(ICData::NumArgsTestedShift() == 0);  // No shift needed.
     __ and_(R6, R6, ShifterOperand(ICData::NumArgsTestedMask()));
     __ CompareImmediate(R6, 0);
     __ b(&ok, EQ);
     __ Stop("Incorrect IC data for unoptimized static call");
     __ Bind(&ok);
   }
 #endif  // DEBUG
 
   // Check single stepping.
   Label not_stepping;

[hausner, 2014/05/22 23:28:08]

Check the runtime flag here too?

   __ ldr(R6, FieldAddress(CTX, Context::isolate_offset()));
   __ ldrb(R6, Address(R6, Isolate::single_step_offset()));
   __ CompareImmediate(R6, 0);
   __ b(&not_stepping, EQ);
   __ EnterStubFrame();
   __ Push(R5);  // Preserve IC data.
   __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
   __ Pop(R5);
   __ LeaveStubFrame();
   __ Bind(&not_stepping);
@@ skipping 68 matching lines @@
   __ PopList((1 << R0) | (1 << R4) | (1 << R5));
   __ LeaveStubFrame();
   __ bx(R0);
 }
 
 
 // Called only from unoptimized code. All relevant registers have been saved.
 void StubCode::GenerateDebugStepCheckStub(
     Assembler* assembler) {
   // Check single stepping.
   Label not_stepping;

[hausner, 2014/05/22 23:28:08]

ditto

[srdjan, 2014/05/22 23:38:27]

Done.

   __ ldr(R1, FieldAddress(CTX, Context::isolate_offset()));
   __ ldrb(R1, Address(R1, Isolate::single_step_offset()));
   __ CompareImmediate(R1, 0);
   __ b(&not_stepping, EQ);
   __ EnterStubFrame();
   __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
   __ LeaveStubFrame();
   __ Bind(&not_stepping);
   __ Ret();
 }
@@ skipping 228 matching lines @@
 
 
 // Called only from unoptimized code. All relevant registers have been saved.
 // LR: return address.
 // SP + 4: left operand.
 // SP + 0: right operand.
 // Return Zero condition flag set if equal.
 void StubCode::GenerateUnoptimizedIdenticalWithNumberCheckStub(
     Assembler* assembler) {
   // Check single stepping.
   Label not_stepping;

[hausner, 2014/05/22 23:28:08]

ditto

[srdjan, 2014/05/22 23:38:27]

Done.

   __ ldr(R1, FieldAddress(CTX, Context::isolate_offset()));
   __ ldrb(R1, Address(R1, Isolate::single_step_offset()));
   __ CompareImmediate(R1, 0);
   __ b(&not_stepping, EQ);
   __ EnterStubFrame();
   __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
   __ LeaveStubFrame();
   __ Bind(&not_stepping);
 
   const Register temp = R2;
@@ skipping 18 matching lines @@
   const Register right = R0;
   __ ldr(left, Address(SP, 1 * kWordSize));
   __ ldr(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM