Remove flag enable_debugger as current debugging code has a very minor influence on unoptimzied cod…

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
===================================================================
--- runtime/vm/stub_code_x64.cc	(revision 38736)
+++ runtime/vm/stub_code_x64.cc	(working copy)
@@ -27,8 +27,6 @@
     "Set to true for debugging & verifying the slow paths.");
 DECLARE_FLAG(bool, trace_optimized_ic_calls);
 
-DECLARE_FLAG(bool, enable_debugger);
-
 // Input parameters:
 //   RSP : points to return address.
 //   RSP + 8 : address of last argument in argument array.
@@ -1268,13 +1266,11 @@
 #endif  // DEBUG
 
   Label stepping, done_stepping;
-  if (FLAG_enable_debugger) {
-    // Check single stepping.
-    __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
-    __ cmpb(Address(RAX, Isolate::single_step_offset()), Immediate(0));
-    __ j(NOT_EQUAL, &stepping);
-    __ Bind(&done_stepping);
-  }
+  // Check single stepping.
+  __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
+  __ cmpb(Address(RAX, Isolate::single_step_offset()), Immediate(0));
+  __ j(NOT_EQUAL, &stepping);
+  __ Bind(&done_stepping);
 
   // Load arguments descriptor into R10.
   __ movq(R10, FieldAddress(RBX, ICData::arguments_descriptor_offset()));
@@ -1378,15 +1374,13 @@
   __ addq(RCX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ jmp(RCX);
 
-  if (FLAG_enable_debugger) {
-    __ Bind(&stepping);
-    __ EnterStubFrame();
-    __ pushq(RBX);
-    __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
-    __ popq(RBX);
-    __ LeaveStubFrame();
-    __ jmp(&done_stepping);
-  }
+  __ Bind(&stepping);
+  __ EnterStubFrame();
+  __ pushq(RBX);
+  __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
+  __ popq(RBX);
+  __ LeaveStubFrame();
+  __ jmp(&done_stepping);
 }
 
 
@@ -1481,20 +1475,18 @@
   }
 #endif  // DEBUG
 
-  if (FLAG_enable_debugger) {
-    // Check single stepping.
-    Label not_stepping;
-    __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
-    __ movzxb(RAX, Address(RAX, Isolate::single_step_offset()));
-    __ cmpq(RAX, Immediate(0));
-    __ j(EQUAL, &not_stepping, Assembler::kNearJump);
-    __ EnterStubFrame();
-    __ pushq(RBX);  // Preserve IC data object.
-    __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
-    __ popq(RBX);
-    __ LeaveStubFrame();
-    __ Bind(&not_stepping);
-  }
+  // Check single stepping.
+  Label not_stepping;
+  __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
+  __ movzxb(RAX, Address(RAX, Isolate::single_step_offset()));
+  __ cmpq(RAX, Immediate(0));
+  __ j(EQUAL, &not_stepping, Assembler::kNearJump);
+  __ EnterStubFrame();
+  __ pushq(RBX);  // Preserve IC data object.
+  __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
+  __ popq(RBX);
+  __ LeaveStubFrame();
+  __ Bind(&not_stepping);
 
   // RBX: IC data object (preserved).
   __ movq(R12, FieldAddress(RBX, ICData::ic_data_offset()));
@@ -1608,19 +1600,18 @@
 
 // Called only from unoptimized code.
 void StubCode::GenerateDebugStepCheckStub(Assembler* assembler) {
-  if (FLAG_enable_debugger) {
-    // Check single stepping.
-    Label not_stepping;
-    __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
-    __ movzxb(RAX, Address(RAX, Isolate::single_step_offset()));
-    __ cmpq(RAX, Immediate(0));
-    __ j(EQUAL, &not_stepping, Assembler::kNearJump);
+  // Check single stepping.
+  Label not_stepping;
+  __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
+  __ movzxb(RAX, Address(RAX, Isolate::single_step_offset()));
+  __ cmpq(RAX, Immediate(0));
+  __ j(EQUAL, &not_stepping, Assembler::kNearJump);
 
-    __ EnterStubFrame();
-    __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
-    __ LeaveStubFrame();
-    __ Bind(&not_stepping);
-  }
+  __ EnterStubFrame();
+  __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
+  __ LeaveStubFrame();
+  __ Bind(&not_stepping);
+
   __ ret();
 }
 
@@ -1875,18 +1866,16 @@
 // Returns ZF set.
 void StubCode::GenerateUnoptimizedIdenticalWithNumberCheckStub(
     Assembler* assembler) {
-  if (FLAG_enable_debugger) {
-    // Check single stepping.
-    Label not_stepping;
-    __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
-    __ movzxb(RAX, Address(RAX, Isolate::single_step_offset()));
-    __ cmpq(RAX, Immediate(0));
-    __ j(EQUAL, &not_stepping, Assembler::kNearJump);
-    __ EnterStubFrame();
-    __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
-    __ LeaveStubFrame();
-    __ Bind(&not_stepping);
-  }
+  // Check single stepping.
+  Label not_stepping;
+  __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
+  __ movzxb(RAX, Address(RAX, Isolate::single_step_offset()));
+  __ cmpq(RAX, Immediate(0));
+  __ j(EQUAL, &not_stepping, Assembler::kNearJump);
+  __ EnterStubFrame();
+  __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
+  __ LeaveStubFrame();
+  __ Bind(&not_stepping);
 
   const Register left = RAX;
   const Register right = RDX;