Revert "Replacing TrySync with Metadata"

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index dcc9829f7ece0451ceb1d8386ba23baf136ba922..0ee20ad2f34ddbf796c25f926172cf0440938d47 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -10,9 +10,7 @@
 
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
-#include "vm/datastream.h"
 #include "vm/debugger.h"
-#include "vm/deopt_instructions.h"
 #include "vm/flags.h"
 #include "vm/log.h"
 #include "vm/longjump.h"
@@ -145,201 +143,50 @@ static void BuildStackTrace(StackTraceBuilder* builder) {
 }
 
 
-static RawObject** VariableAt(uword fp, int stack_slot) {
-#if defined(TARGET_ARCH_DBC)
-  return reinterpret_cast<RawObject**>(fp + stack_slot * kWordSize);
-#else
-  if (stack_slot < 0) {
-    return reinterpret_cast<RawObject**>(ParamAddress(fp, -stack_slot));
-  } else {
-    return reinterpret_cast<RawObject**>(
-        LocalVarAddress(fp, kFirstLocalSlotFromFp - stack_slot));
-  }
-#endif
-}
-
-
-class ExceptionHandlerFinder {
- public:
-  explicit ExceptionHandlerFinder(Thread* thread)
-      : thread_(thread), cache_(NULL), metadata_(NULL) {}
-
-  // Iterate through the stack frames and try to find a frame with an
-  // exception handler. Once found, set the pc, sp and fp so that execution
-  // can continue in that frame. Sets 'needs_stacktrace' if there is no
-  // cath-all handler or if a stack-trace is specified in the catch.
-  bool Find() {
-    StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
-    StackFrame* frame = frames.NextFrame();
-    if (frame == NULL) return false;  // No Dart frame.
-    handler_pc_set_ = false;
-    needs_stacktrace = false;
-    bool is_catch_all = false;
-    uword temp_handler_pc = kUwordMax;
-    bool is_optimized = false;
-    code_ = NULL;
-    cache_ = thread_->isolate()->catch_entry_state_cache();
-
-    while (!frame->IsEntryFrame()) {
-      if (frame->IsDartFrame()) {
-        if (frame->FindExceptionHandler(thread_, &temp_handler_pc,
-                                        &needs_stacktrace, &is_catch_all,
-                                        &is_optimized)) {
-          if (!handler_pc_set_) {
-            handler_pc_set_ = true;
-            handler_pc = temp_handler_pc;
-            handler_sp = frame->sp();
-            handler_fp = frame->fp();
-            if (is_optimized) {
-              pc_ = frame->pc();
-              code_ = &Code::Handle(frame->LookupDartCode());
-              cached_ = cache_->Lookup(pc_);
-#if !defined(DART_PRECOMPILED_RUNTIME) && !defined(DART_PRECOMPILER)
-              intptr_t num_vars = Smi::Value(code_->variables());
-              if (!cached_) GetMetaDataFromDeopt(num_vars, frame);
-#else
-              if (!cached_) ReadCompressedMetaData();
-#endif  // !defined(DART_PRECOMPILED_RUNTIME) && !defined(DART_PRECOMPILER)
-            }
-          }
-          if (needs_stacktrace || is_catch_all) {
-            return true;
-          }
-        }
-      }  // if frame->IsDartFrame
-      frame = frames.NextFrame();
-      ASSERT(frame != NULL);
-    }  // while !frame->IsEntryFrame
-    ASSERT(frame->IsEntryFrame());
-    if (!handler_pc_set_) {
-      handler_pc = frame->pc();
-      handler_sp = frame->sp();
-      handler_fp = frame->fp();
-    }
-    // No catch-all encountered, needs stacktrace.
-    needs_stacktrace = true;
-    return handler_pc_set_;
-  }
-
-  void TrySync() {
-    if (code_ == NULL || !code_->is_optimized()) {
-      return;
-    }
-    if (cached_) {
-      // Cache hit.
-      TrySyncCached(cached_);
-    } else {
-      // New cache entry.
-      CatchEntryState m(metadata_);
-      TrySyncCached(&m);
-    }
-  }
-
-  void TrySyncCached(CatchEntryState* md) {
-    uword fp = handler_fp;
-    ObjectPool* pool = NULL;
-    intptr_t pairs = md->Pairs();
-    for (int j = 0; j < pairs; j++) {
-      intptr_t src = md->Src(j);
-      intptr_t dest = md->Dest(j);
-      if (md->isMove(j)) {
-        *VariableAt(fp, dest) = *VariableAt(fp, src);
-      } else {
-        if (pool == NULL) {
-          pool = &ObjectPool::Handle(code_->object_pool());
-        }
-        RawObject* obj = pool->ObjectAt(src);
-        *VariableAt(fp, dest) = obj;
-      }
-    }
-  }
-
-#if defined(DART_PRECOMPILED_RUNTIME) || defined(DART_PRECOMPILER)
-  void ReadCompressedMetaData() {
-    intptr_t pc_offset = pc_ - code_->PayloadStart();
-    const TypedData& td = TypedData::Handle(code_->catch_entry_state_maps());
-    NoSafepointScope no_safepoint;
-    ReadStream stream(static_cast<uint8_t*>(td.DataAddr(0)), td.Length());
-
-    bool found_metadata = false;
-    while (stream.PendingBytes() > 0) {
-      intptr_t target_pc_offset = Reader::Read(&stream);
-      intptr_t variables = Reader::Read(&stream);
-      intptr_t suffix_length = Reader::Read(&stream);
-      intptr_t suffix_offset = Reader::Read(&stream);
-      if (pc_offset == target_pc_offset) {
-        metadata_ = new intptr_t[2 * (variables + suffix_length) + 1];
-        metadata_[0] = variables + suffix_length;
-        for (int j = 0; j < variables; j++) {
-          intptr_t src = Reader::Read(&stream);
-          intptr_t dest = Reader::Read(&stream);
-          metadata_[1 + 2 * j] = src;
-          metadata_[2 + 2 * j] = dest;
+// Iterate through the stack frames and try to find a frame with an
+// exception handler. Once found, set the pc, sp and fp so that execution
+// can continue in that frame. Sets 'needs_stacktrace' if there is no
+// cath-all handler or if a stack-trace is specified in the catch.
+static bool FindExceptionHandler(Thread* thread,
+                                 uword* handler_pc,
+                                 uword* handler_sp,
+                                 uword* handler_fp,
+                                 bool* needs_stacktrace) {
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrame* frame = frames.NextFrame();
+  if (frame == NULL) return false;  // No Dart frame.
+  bool handler_pc_set = false;
+  *needs_stacktrace = false;
+  bool is_catch_all = false;
+  uword temp_handler_pc = kUwordMax;
+  while (!frame->IsEntryFrame()) {
+    if (frame->IsDartFrame()) {
+      if (frame->FindExceptionHandler(thread, &temp_handler_pc,
+                                      needs_stacktrace, &is_catch_all)) {
+        if (!handler_pc_set) {
+          handler_pc_set = true;
+          *handler_pc = temp_handler_pc;
+          *handler_sp = frame->sp();
+          *handler_fp = frame->fp();
         }
-        ReadCompressedSuffix(&stream, suffix_offset, suffix_length, metadata_,
-                             2 * variables + 1);
-        found_metadata = true;
-        break;
-      } else {
-        for (intptr_t j = 0; j < 2 * variables; j++) {
-          Reader::Read(&stream);
+        if (*needs_stacktrace || is_catch_all) {
+          return true;
         }
       }
-    }
-    ASSERT(found_metadata);
-  }
-
-  void ReadCompressedSuffix(ReadStream* stream,
-                            intptr_t offset,
-                            intptr_t length,
-                            intptr_t* target,
-                            intptr_t target_offset) {
-    stream->SetPosition(offset);
-    Reader::Read(stream);  // skip pc_offset
-    Reader::Read(stream);  // skip variables
-    intptr_t suffix_length = Reader::Read(stream);
-    intptr_t suffix_offset = Reader::Read(stream);
-    intptr_t to_read = length - suffix_length;
-    for (int j = 0; j < to_read; j++) {
-      target[target_offset + 2 * j] = Reader::Read(stream);
-      target[target_offset + 2 * j + 1] = Reader::Read(stream);
-    }
-    if (suffix_length > 0) {
-      ReadCompressedSuffix(stream, suffix_offset, suffix_length, target,
-                           target_offset + to_read * 2);
-    }
-  }
-
-#else
-  void GetMetaDataFromDeopt(intptr_t num_vars, StackFrame* frame) {
-    Isolate* isolate = thread_->isolate();
-    DeoptContext* deopt_context =
-        new DeoptContext(frame, *code_, DeoptContext::kDestIsAllocated, NULL,
-                         NULL, true, false /* deoptimizing_code */);
-    isolate->set_deopt_context(deopt_context);
-
-    metadata_ = deopt_context->CatchEntryState(num_vars);
-
-    isolate->set_deopt_context(NULL);
-    delete deopt_context;
+    }  // if frame->IsDartFrame
+    frame = frames.NextFrame();
+    ASSERT(frame != NULL);
+  }  // while !frame->IsEntryFrame
+  ASSERT(frame->IsEntryFrame());
+  if (!handler_pc_set) {
+    *handler_pc = frame->pc();
+    *handler_sp = frame->sp();
+    *handler_fp = frame->fp();
   }
-#endif  // defined(DART_PRECOMPILED_RUNTIME) || defined(DART_PRECOMPILER)
-
-  bool needs_stacktrace;
-  uword handler_pc;
-  uword handler_sp;
-  uword handler_fp;
-
- private:
-  typedef ReadStream::Raw<sizeof(intptr_t), intptr_t> Reader;
-  Thread* thread_;
-  CatchEntryStateCache* cache_;
-  Code* code_;
-  bool handler_pc_set_;
-  intptr_t* metadata_;       // MetaData generated from deopt.
-  CatchEntryState* cached_;  // Value of per PC MetaData cache.
-  intptr_t pc_;              // Current pc in the handler frame.
-};
+  // No catch-all encountered, needs stacktrace.
+  *needs_stacktrace = true;
+  return handler_pc_set;
+}
 
 
 static void FindErrorHandler(uword* handler_pc,
@@ -544,15 +391,16 @@ static void ThrowExceptionHelper(Thread* thread,
              exception.raw() == isolate->object_store()->stack_overflow()) {
     use_preallocated_stacktrace = true;
   }
+  uword handler_pc = 0;
+  uword handler_sp = 0;
+  uword handler_fp = 0;
+  Instance& stacktrace = Instance::Handle(zone);
+  bool handler_exists = false;
+  bool handler_needs_stacktrace = false;
   // Find the exception handler and determine if the handler needs a
   // stacktrace.
-  ExceptionHandlerFinder finder(thread);
-  bool handler_exists = finder.Find();
-  uword handler_pc = finder.handler_pc;
-  uword handler_sp = finder.handler_sp;
-  uword handler_fp = finder.handler_fp;
-  bool handler_needs_stacktrace = finder.needs_stacktrace;
-  Instance& stacktrace = Instance::Handle(zone);
+  handler_exists = FindExceptionHandler(thread, &handler_pc, &handler_sp,
+                                        &handler_fp, &handler_needs_stacktrace);
   if (use_preallocated_stacktrace) {
     if (handler_pc == 0) {
       // No Dart frame.
@@ -607,7 +455,6 @@ static void ThrowExceptionHelper(Thread* thread,
     THR_Print("%s\n", stacktrace.ToCString());
   }
   if (handler_exists) {
-    finder.TrySync();
     // Found a dart handler for the exception, jump to it.
     JumpToExceptionHandler(thread, handler_pc, handler_sp, handler_fp,
                            exception, stacktrace);