Fix debugger stub patching on x64 architecture

runtime/vm/debugger_x64.cc

Index: runtime/vm/debugger_x64.cc
===================================================================
--- runtime/vm/debugger_x64.cc	(revision 31811)
+++ runtime/vm/debugger_x64.cc	(working copy)
@@ -8,7 +8,9 @@
 #include "vm/debugger.h"
 
 #include "vm/assembler.h"
+#include "vm/code_patcher.h"
 #include "vm/cpu.h"
+#include "vm/instructions.h"
 #include "vm/stub_code.h"
 
 namespace dart {
@@ -32,6 +34,80 @@
              *reinterpret_cast<uword*>(closure_addr));
 }
 
+
+uword CodeBreakpoint::OrigStubAddress() const {
+  const Code& code =
+      Code::Handle(Function::Handle(function_).unoptimized_code());
+  const Array& object_pool = Array::Handle(code.ObjectPool());
+  uword offset = saved_value_ + kHeapObjectTag;
+  ASSERT((offset % kWordSize) == 0);
+  const intptr_t index = (offset - Array::data_offset()) / kWordSize;
+  const uword stub_address = reinterpret_cast<uword>(object_pool.At(index));
+  ASSERT(stub_address % kWordSize == 0);
+  return stub_address;
+}
+
+
+void CodeBreakpoint::PatchCode() {
+  ASSERT(!is_enabled_);
+  switch (breakpoint_kind_) {
+    case PcDescriptors::kIcCall: {
+      int32_t offset = CodePatcher::GetPoolOffsetAt(pc_);
+      ASSERT((offset > 0) && ((offset % 8) == 7));
+      saved_value_ = static_cast<uword>(offset);
+      const int32_t stub_offset =
+          InstructionPattern::OffsetFromPPIndex(
+              Assembler::kBreakpointDynamicCPIndex);
+      CodePatcher::SetPoolOffsetAt(pc_, stub_offset);
+      break;
+    }
+    case PcDescriptors::kUnoptStaticCall: {
+      int32_t offset = CodePatcher::GetPoolOffsetAt(pc_);
+      ASSERT((offset > 0) && ((offset % 8) == 7));
+      saved_value_ = static_cast<uword>(offset);
+      const uint32_t stub_offset =
+          InstructionPattern::OffsetFromPPIndex(
+              Assembler::kBreakpointStaticCPIndex);
+      CodePatcher::SetPoolOffsetAt(pc_, stub_offset);
+      break;
+    }
+    case PcDescriptors::kRuntimeCall:
+    case PcDescriptors::kClosureCall:
+    case PcDescriptors::kReturn: {
+      int32_t offset = CodePatcher::GetPoolOffsetAt(pc_);
+      ASSERT((offset > 0) && ((offset % 8) == 7));
+      saved_value_ = static_cast<uword>(offset);
+      const uint32_t stub_offset =
+          InstructionPattern::OffsetFromPPIndex(
+              Assembler::kBreakpointRuntimeCPIndex);
+      CodePatcher::SetPoolOffsetAt(pc_, stub_offset);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  is_enabled_ = true;
+}
+
+
+void CodeBreakpoint::RestoreCode() {
+  ASSERT(is_enabled_);
+  switch (breakpoint_kind_) {
+    case PcDescriptors::kIcCall:
+    case PcDescriptors::kUnoptStaticCall:
+    case PcDescriptors::kClosureCall:
+    case PcDescriptors::kRuntimeCall:
+    case PcDescriptors::kReturn: {
+      CodePatcher::SetPoolOffsetAt(pc_, static_cast<int32_t>(saved_value_));
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  is_enabled_ = false;
+}
+
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64