Fix debugger stub patching on x64 architecture

runtime/vm/debugger_x64.cc

 // Copyright (c) 2011, 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_X64)
 
 #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 {
 
 RawInstance* ActivationFrame::GetInstanceCallReceiver(
                  intptr_t num_actual_args) {
   ASSERT(num_actual_args > 0);  // At minimum we have a receiver on the stack.
   // Stack pointer points to last argument that was pushed on the stack.
   uword receiver_addr = sp() + ((num_actual_args - 1) * kWordSize);
   return reinterpret_cast<RawInstance*>(
              *reinterpret_cast<uword*>(receiver_addr));
 }
 
 
 RawObject* ActivationFrame::GetClosureObject(intptr_t num_actual_args) {
   // At a minimum we have the closure object on the stack.
   ASSERT(num_actual_args > 0);
   // Stack pointer points to last argument that was pushed on the stack.
   uword closure_addr = sp() + ((num_actual_args - 1) * kWordSize);
   return reinterpret_cast<RawObject*>(
              *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);
+  intptr_t index = (offset - Array::data_offset()) / kWordSize;
+  return reinterpret_cast<uword>(object_pool.At(index));

[Ivan Posva, 2014/01/14 22:12:39]

There are some assertions that you can make about the saved_value_ and the
address we are loading here. Where should we make sure our assumptions are
correct?

[hausner, 2014/01/14 22:49:41]

Done.

+}
+
+
+void CodeBreakpoint::PatchCode() {
+  ASSERT(!is_enabled_);
+  switch (breakpoint_kind_) {
+    case PcDescriptors::kIcCall: {
+      saved_value_ = CodePatcher::GetPoolOffsetAt(pc_);
+      const uint32_t stub_offset =
+          InstructionPattern::OffsetFromPPIndex(
+              Assembler::kBreakpointDynamicCPIndex);
+      CodePatcher::SetPoolOffsetAt(pc_, stub_offset);
+//printf("XXX dynamic: patched offs %ld with %d at 0x%lx\n", saved_value_, stub_offset, pc_);
+      break;
+    }
+    case PcDescriptors::kUnoptStaticCall: {
+      saved_value_ = CodePatcher::GetPoolOffsetAt(pc_);
+      const uint32_t stub_offset =
+          InstructionPattern::OffsetFromPPIndex(
+              Assembler::kBreakpointStaticCPIndex);
+      CodePatcher::SetPoolOffsetAt(pc_, stub_offset);
+//printf("XXX static: patched offs %ld with %d at 0x%lx\n", saved_value_, stub_offset, pc_);
+      break;
+    }
+    case PcDescriptors::kRuntimeCall:
+    case PcDescriptors::kClosureCall:
+    case PcDescriptors::kReturn: {
+      saved_value_ = CodePatcher::GetPoolOffsetAt(pc_);
+      const uint32_t stub_offset =
+          InstructionPattern::OffsetFromPPIndex(
+              Assembler::kBreakpointRuntimeCPIndex);
+      CodePatcher::SetPoolOffsetAt(pc_, stub_offset);
+//printf("XXX runtime: patched offs %ld with %d at 0x%lx\n", saved_value_, stub_offset, pc_);
+      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_, saved_value_);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  is_enabled_ = false;
+}
+
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64