Make return statements single steppable

runtime/vm/intermediate_language_x64.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"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 78 matching lines @@
         (kFirstLocalSlotFromFp + 1 - compiler->StackSize()) * kWordSize;
     ASSERT(fp_sp_dist <= 0);
     __ movq(RDI, RSP);
     __ subq(RDI, RBP);
     __ CompareImmediate(RDI, Immediate(fp_sp_dist), PP);
     __ j(EQUAL, &done, Assembler::kNearJump);
     __ int3();
     __ Bind(&done);
   }
 #endif
-
-  __ ReturnPatchable();
-  compiler->AddCurrentDescriptor(PcDescriptors::kReturn,
-                                 Isolate::kNoDeoptId,
-                                 token_pos());
+  __ LeaveDartFrame();
+  __ ret();
 }
 
 
 static Condition NegateCondition(Condition condition) {
   switch (condition) {
     case EQUAL:         return NOT_EQUAL;
     case NOT_EQUAL:     return EQUAL;
     case LESS:          return GREATER_EQUAL;
     case LESS_EQUAL:    return GREATER;
     case GREATER:       return LESS_EQUAL;
@@ skipping 519 matching lines @@
       (is_bootstrap_native()) ? &StubCode::CallBootstrapCFunctionLabel() :
                                 &StubCode::CallNativeCFunctionLabel();
   compiler->GenerateCall(token_pos(),
                          stub_entry,
                          PcDescriptors::kOther,
                          locs());
   __ popq(result);
 }
 
 
+LocationSummary* DebugStepCheckInstr::MakeLocationSummary(bool opt) const {
+  const intptr_t kNumInputs = 0;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* locs =
+      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kCall);
+  return locs;
+}
+
+
+void DebugStepCheckInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  if (!compiler->is_optimizing()) {
+    const ExternalLabel label("debug_step_check",
+                              StubCode::DebugStepCheckEntryPoint());
+    compiler->GenerateCall(token_pos(),
+                           &label,
+                           PcDescriptors::kReturn,
+                           locs());
+  }
+}
+
+
+Instruction* DebugStepCheckInstr::Canonicalize(FlowGraph* flow_graph) {
+  if (compiler->is_optimizing()) {
+    return NULL;
+  }
+}
+
+
 static bool CanBeImmediateIndex(Value* index, intptr_t cid) {
   if (!index->definition()->IsConstant()) return false;
   const Object& constant = index->definition()->AsConstant()->value();
   if (!constant.IsSmi()) return false;
   const Smi& smi_const = Smi::Cast(constant);
   const intptr_t scale = FlowGraphCompiler::ElementSizeFor(cid);
   const intptr_t data_offset = FlowGraphCompiler::DataOffsetFor(cid);
   const int64_t disp = smi_const.AsInt64Value() * scale + data_offset;
   return Utils::IsInt(32, disp);
 }
@@ skipping 4311 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64