Refactor exception handling for deoptimization

This CL refactors the exception handling (on the quick side) by isolating the
search of catch handler and the preparation of deoptimization.

We rename the CatchFinder class to QuickExceptionHandler so it's less specific
to catch handler search.

Finding catch handler happens in QuickExceptionHandler::FindCatch. Since the
CatchBlockStackVisitor resolves exception types, it may cause thread suspension
and breaks the assertion current thread can't be suspended. Therefore, we place
the exception in a SirtRef (while it is detached from the current thread) and
remove the thread suspension assertion.

Deoptimization now happens in QuickExceptionHandler::DeoptimizeStack. It uses
the new DeoptimizeStackVisitor class to create shadow frames.

We also add the Thread::GetDeoptimizationException method to get the definition
of the fake exception in only one place.

Change-Id: I01b19fa72af64329b5c3b6c7f0c3339d2d724978

1 files changed, 87 insertions, 0 deletions

diff --git a/runtime/deoptimize_stack_visitor.cc b/runtime/deoptimize_stack_visitor.cc
new file mode 100644
index 0000000..f2eaf00
--- /dev/null
+++ b/runtime/deoptimize_stack_visitor.cc
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "deoptimize_stack_visitor.h"
+
+#include "mirror/art_method-inl.h"
+#include "object_utils.h"
+#include "quick_exception_handler.h"
+#include "sirt_ref-inl.h"
+#include "verifier/method_verifier.h"
+
+namespace art {
+
+bool DeoptimizeStackVisitor::VisitFrame() {
+  exception_handler_->SetHandlerFrameId(GetFrameId());
+  mirror::ArtMethod* method = GetMethod();
+  if (method == nullptr) {
+    // This is the upcall, we remember the frame and last pc so that we may long jump to them.
+    exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
+    exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
+    return false;  // End stack walk.
+  } else if (method->IsRuntimeMethod()) {
+    // Ignore callee save method.
+    DCHECK(method->IsCalleeSaveMethod());
+    return true;
+  } else {
+    return HandleDeoptimization(method);
+  }
+}
+
+bool DeoptimizeStackVisitor::HandleDeoptimization(mirror::ArtMethod* m) {
+  MethodHelper mh(m);
+  const DexFile::CodeItem* code_item = mh.GetCodeItem();
+  CHECK(code_item != nullptr);
+  uint16_t num_regs = code_item->registers_size_;
+  uint32_t dex_pc = GetDexPc();
+  const Instruction* inst = Instruction::At(code_item->insns_ + dex_pc);
+  uint32_t new_dex_pc = dex_pc + inst->SizeInCodeUnits();
+  ShadowFrame* new_frame = ShadowFrame::Create(num_regs, nullptr, m, new_dex_pc);
+  SirtRef<mirror::DexCache> dex_cache(self_, mh.GetDexCache());
+  SirtRef<mirror::ClassLoader> class_loader(self_, mh.GetClassLoader());
+  verifier::MethodVerifier verifier(&mh.GetDexFile(), &dex_cache, &class_loader,
+                                    &mh.GetClassDef(), code_item, m->GetDexMethodIndex(), m,
+                                    m->GetAccessFlags(), false, true);
+  verifier.Verify();
+  std::vector<int32_t> kinds = verifier.DescribeVRegs(dex_pc);
+  for (uint16_t reg = 0; reg < num_regs; ++reg) {
+    VRegKind kind = static_cast<VRegKind>(kinds.at(reg * 2));
+    switch (kind) {
+      case kUndefined:
+        new_frame->SetVReg(reg, 0xEBADDE09);
+        break;
+      case kConstant:
+        new_frame->SetVReg(reg, kinds.at((reg * 2) + 1));
+        break;
+      case kReferenceVReg:
+        new_frame->SetVRegReference(reg,
+                                    reinterpret_cast<mirror::Object*>(GetVReg(m, reg, kind)));
+        break;
+      default:
+        new_frame->SetVReg(reg, GetVReg(m, reg, kind));
+        break;
+    }
+  }
+  if (prev_shadow_frame_ != nullptr) {
+    prev_shadow_frame_->SetLink(new_frame);
+  } else {
+    exception_handler_->SetTopShadowFrame(new_frame);
+  }
+  prev_shadow_frame_ = new_frame;
+  return true;
+}
+
+}  // namespace art