VM: Clean up ARM/MIPS breakpoint patching

runtime/vm/debugger_mips.cc

Index: runtime/vm/debugger_mips.cc
diff --git a/runtime/vm/debugger_mips.cc b/runtime/vm/debugger_mips.cc
index e3918e6760c5b9a2bba950a3eb2cae27169f516a..96d463250b58de68910b4dd746ec431eea637be5 100644
--- a/runtime/vm/debugger_mips.cc
+++ b/runtime/vm/debugger_mips.cc
@@ -20,35 +20,25 @@ uword CodeBreakpoint::OrigStubAddress() const {
 
 void CodeBreakpoint::PatchCode() {
   ASSERT(!is_enabled_);
-  const Code& code = Code::Handle(code_);
-  const Instructions& instrs = Instructions::Handle(code.instructions());
-  Isolate* isolate = Isolate::Current();
-  {
-    WritableInstructionsScope writable(instrs.EntryPoint(), instrs.size());
-    switch (breakpoint_kind_) {
-      case RawPcDescriptors::kIcCall:
-      case RawPcDescriptors::kUnoptStaticCall: {
-        saved_value_ = CodePatcher::GetStaticCallTargetAt(pc_, code);
-        CodePatcher::PatchStaticCallAt(
-            pc_, code, isolate->stub_code()->ICCallBreakpointEntryPoint());
-        break;
-      }
-      case RawPcDescriptors::kClosureCall: {
-        saved_value_ = CodePatcher::GetStaticCallTargetAt(pc_, code);
-        CodePatcher::PatchStaticCallAt(
-            pc_, code, isolate->stub_code()->ClosureCallBreakpointEntryPoint());
-        break;
-      }
-      case RawPcDescriptors::kRuntimeCall: {
-        saved_value_ = CodePatcher::GetStaticCallTargetAt(pc_, code);
-        CodePatcher::PatchStaticCallAt(
-            pc_, code, isolate->stub_code()->RuntimeCallBreakpointEntryPoint());
-        break;
-      }
-      default:
-        UNREACHABLE();
-    }
+  StubCode* stub_code = Isolate::Current()->stub_code();
+  uword stub_target = 0;
+  switch (breakpoint_kind_) {
+    case RawPcDescriptors::kIcCall:
+    case RawPcDescriptors::kUnoptStaticCall:
+      stub_target = stub_code->ICCallBreakpointEntryPoint();
+      break;
+    case RawPcDescriptors::kClosureCall:
+      stub_target = stub_code->ClosureCallBreakpointEntryPoint();
+      break;
+    case RawPcDescriptors::kRuntimeCall:
+      stub_target = stub_code->RuntimeCallBreakpointEntryPoint();
+      break;
+    default:
+      UNREACHABLE();
   }
+  const Code& code = Code::Handle(code_);
+  saved_value_ = CodePatcher::GetStaticCallTargetAt(pc_, code);
+  CodePatcher::PatchStaticCallAt(pc_, code, stub_target);
   is_enabled_ = true;
 }
 
@@ -56,20 +46,16 @@ void CodeBreakpoint::PatchCode() {
 void CodeBreakpoint::RestoreCode() {
   ASSERT(is_enabled_);
   const Code& code = Code::Handle(code_);
-  const Instructions& instrs = Instructions::Handle(code.instructions());
-  {
-    WritableInstructionsScope writable(instrs.EntryPoint(), instrs.size());
-    switch (breakpoint_kind_) {
-      case RawPcDescriptors::kIcCall:
-      case RawPcDescriptors::kUnoptStaticCall:
-      case RawPcDescriptors::kClosureCall:
-      case RawPcDescriptors::kRuntimeCall: {
-        CodePatcher::PatchStaticCallAt(pc_, code, saved_value_);
-        break;
-      }
-      default:
-        UNREACHABLE();
+  switch (breakpoint_kind_) {
+    case RawPcDescriptors::kIcCall:
+    case RawPcDescriptors::kUnoptStaticCall:
+    case RawPcDescriptors::kClosureCall:
+    case RawPcDescriptors::kRuntimeCall: {
+      CodePatcher::PatchStaticCallAt(pc_, code, saved_value_);
+      break;
     }
+    default:
+      UNREACHABLE();
   }
   is_enabled_ = false;
 }