- Wire the stack frame iterator to use stack maps for traversing objects if there are stack maps in…

vm/stack_frame.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/stack_frame.h"
 
-#include "vm/code_index_table.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/os.h"
 #include "vm/raw_object.h"
 #include "vm/stub_code.h"
 #include "vm/visitor.h"
 
 namespace dart {
 
+bool StackFrame::FindRawCodeVisitor::FindObject(RawObject* obj) {
+  return RawInstructions::ContainsPC(obj, pc_);
+}
+
+
 void StackFrame::Print() const {
   OS::Print("[%-8s : sp(%p) ]\n", GetName(), sp());
 }
 
 
+RawCode* StackFrame::LookupCode(Isolate* isolate, uword pc) {
+  // TODO(asiva): Need to add a data structure for storing a (pc, code
+  // object) map in order to do a quick lookup and avoid having to
+  // traverse the code heap.
+  ASSERT(isolate != NULL);
+  // We add a no gc scope to ensure that the code below does not trigger
+  // a GC as we are handling raw object references here. It is possible
+  // that the code is called while a GC is in progress, that is ok.
+  NoGCScope no_gc;
+  FindRawCodeVisitor visitor(pc);
+  RawObject* obj = isolate->heap()->FindObjectInCodeSpace(&visitor);
+  if (obj != Object::null()) {
+    RawInstructions* instr = reinterpret_cast<RawInstructions*>(obj);
+    return instr->ptr()->code_;
+  }
+  return Code::null();
+}
+
+
 void ExitFrame::VisitObjectPointers(ObjectPointerVisitor* visitor) {
   // There are no objects to visit in this frame.
 }
 
 
 void EntryFrame::VisitObjectPointers(ObjectPointerVisitor* visitor) {
   // Visit objects between SP and (FP - callee_save_area).
   ASSERT(visitor != NULL);
   RawObject** start = reinterpret_cast<RawObject**>(sp());
   RawObject** end = reinterpret_cast<RawObject**>(
       fp() - kWordSize + ExitLinkOffset());
   visitor->VisitPointers(start, end);
 }
 
 
 void DartFrame::VisitObjectPointers(ObjectPointerVisitor* visitor) {
-  // Visit objects between SP and FP.
-  ASSERT(visitor != NULL);
-  visitor->VisitPointers(reinterpret_cast<RawObject**>(sp()),
-                         reinterpret_cast<RawObject**>(fp() - kWordSize));
+  RawCode* code = LookupDartCode();
+  ASSERT(code != Code::null());
+  RawStackmap* map = code->GetStackmap(pc());
+
+  // First visit the code object corresponding to this frame.
+  visitor->VisitPointer(reinterpret_cast<RawObject**>(&code));
+
+  // Now visit all objects on the frame.
+  if (map == Stackmap::null()) {
+    // No stack maps are present in the code object which means this
+    // frame relies on tagged pointers and hence we visit each entry
+    // on the frame between SP and FP.
+    ASSERT(visitor != NULL);
+    visitor->VisitPointers(reinterpret_cast<RawObject**>(sp()),
+                           reinterpret_cast<RawObject**>(fp() - kWordSize));
+    return;
+  }
+  // A stack map is present in the code object, use the stack map to visit
+  // frame slots which are marked as having objects.

[srdjan, 2012/03/28 21:56:36]

Can this part be tested?

[siva, 2012/03/29 19:01:27]

Added a unit test case for this by generating a stackmap for   an unoptimized
code blob and adding it to the code object.
The unit test forces a GC and traverses the stack at that point using the stack
map.

On 2012/03/28 21:56:36, srdjan wrote:

+  intptr_t size_in_bits = map->SizeInBits();
+  intptr_t bit_offset = 0;
+  uword addr = (fp() + (bit_offset * kWordSize));
+  while (bit_offset < size_in_bits) {
+    ASSERT(addr <= sp());
+    if (map->IsObject(bit_offset)) {
+      visitor->VisitPointer(reinterpret_cast<RawObject**>(addr));
+    }
+    bit_offset += 1;
+    addr = (fp() + (bit_offset * kWordSize));
+  }
 }
 
 
 RawFunction* DartFrame::LookupDartFunction() const {
-  // Get access to the code index table.
-  ASSERT(Isolate::Current() != NULL);
-  CodeIndexTable* code_index_table = Isolate::Current()->code_index_table();
-  ASSERT(code_index_table != NULL);
-  return Code::Handle(code_index_table->LookupCode(pc())).function();
+  const Code& code = Code::Handle(LookupDartCode());
+  if (!code.IsNull()) {
+    return code.function();
+  }
+  return Function::null();
 }
 
 
 RawCode* DartFrame::LookupDartCode() const {
-  // Get access to the code index table.
-  ASSERT(Isolate::Current() != NULL);
-  CodeIndexTable* code_index_table = Isolate::Current()->code_index_table();
-  ASSERT(code_index_table != NULL);
-  return code_index_table->LookupCode(pc());
+  // We add a no gc scope to ensure that the code below does not trigger
+  // a GC as we are handling raw object references here. It is possible
+  // that the code is called while a GC is in progress, that is ok.
+  NoGCScope no_gc;
+  Isolate* isolate = Isolate::Current();
+  RawCode* code = StackFrame::LookupCode(isolate, pc());
+  ASSERT(code != Code::null() && code->ptr()->function_ != Function::null());
+  return code;
 }
 
 
 bool DartFrame::FindExceptionHandler(uword* handler_pc) const {
   const Code& code = Code::Handle(LookupDartCode());
   ASSERT(!code.IsNull());
 
   // First try to find pc descriptor for the current pc.
   intptr_t try_index = -1;
   const PcDescriptors& descriptors =
@@ skipping 15 matching lines @@
         *handler_pc = handlers.HandlerPC(j);
         return true;
       }
     }
   }
   return false;
 }
 
 
 bool StubFrame::IsValid() const {
-  // Get access to the code index table.
-  ASSERT(Isolate::Current() != NULL);
-  CodeIndexTable* code_index_table = Isolate::Current()->code_index_table();
-  ASSERT(code_index_table != NULL);
-  return Code::Handle(code_index_table->LookupCode(pc())).IsNull();
+  // We add a no gc scope to ensure that the code below does not trigger
+  // a GC as we are handling raw object references here. It is possible
+  // that the code is called while a GC is in progress, that is ok.
+  NoGCScope no_gc;
+  Isolate* isolate = Isolate::Current();
+  RawCode* code = StackFrame::LookupCode(isolate, pc());
+  return (code != Code::null() && code->ptr()->function_ == Function::null());
 }
 
 
 void StubFrame::VisitObjectPointers(ObjectPointerVisitor* visitor) {
   // Visit objects between SP and FP.
   ASSERT(visitor != NULL);
   visitor->VisitPointers(reinterpret_cast<RawObject**>(sp()),
                          reinterpret_cast<RawObject**>(fp() - kWordSize));
 }
 
@@ skipping 76 matching lines @@
 EntryFrame* StackFrameIterator::NextEntryFrame() {
   ASSERT(!frames_.HasNext());
   entry_.sp_ = frames_.sp_;
   entry_.fp_ = frames_.fp_;
   SetupNextExitFrameData();  // Setup data for next exit frame in chain.
   ASSERT(entry_.IsValid());
   return &entry_;
 }
 
 }  // namespace dart