Fix shared function info code replacement.

src/mark-compact.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 867 matching lines @@
     next_candidate = GetNextCandidate(candidate);
     ClearNextCandidate(candidate, undefined);
 
     SharedFunctionInfo* shared = candidate->shared();
 
     Code* code = shared->code();
     MarkBit code_mark = Marking::MarkBitFrom(code);
     if (!code_mark.Get()) {
       shared->set_code(lazy_compile);
       candidate->set_code(lazy_compile);
-    } else if (code == lazy_compile) {
-      candidate->set_code(lazy_compile);
+    } else {
+      candidate->set_code(code);
     }
 
     // We are in the middle of a GC cycle so the write barrier in the code
     // setter did not record the slot update and we have to do that manually.
     Address slot = candidate->address() + JSFunction::kCodeEntryOffset;
     Code* target = Code::cast(Code::GetObjectFromEntryAddress(slot));
     isolate_->heap()->mark_compact_collector()->
         RecordCodeEntrySlot(slot, target);
 
     Object** shared_code_slot =
@@ skipping 28 matching lines @@
     isolate_->heap()->mark_compact_collector()->
         RecordSlot(code_slot, code_slot, *code_slot);
 
     candidate = next_candidate;
   }
 
   shared_function_info_candidates_head_ = NULL;
 }
 
 
+void CodeFlusher::EvictCandidate(SharedFunctionInfo* shared_info) {
+  ASSERT(shared_info->code()->gc_metadata() != NULL);
+
+  // The function is no longer a candidate, make sure it gets visited
+  // again so that previous flushing decisions are revisited.
+  isolate_->heap()->incremental_marking()->RecordWrites(shared_info);
+
+  SharedFunctionInfo* candidate = shared_function_info_candidates_head_;
+  SharedFunctionInfo* next_candidate;

[Hannes Payer (out of office), 2013/01/11 10:09:51]

Why is there a difference between shared_info being the head of the list and
being somewhere on the list? Moreover can you unify the code below?

[Michael Starzinger, 2013/01/11 12:27:22]

The head needs to be handles specially, because it is stored as a field inside
the code-flusher (i.e. in the shared_function_info_candidates_head_ field).

+  if (candidate == shared_info) {
+    next_candidate = GetNextCandidate(shared_info);
+    shared_function_info_candidates_head_ = next_candidate;
+    ClearNextCandidate(shared_info);
+  } else {
+    while (candidate != NULL) {
+      next_candidate = GetNextCandidate(candidate);
+
+      if (next_candidate == shared_info) {
+        next_candidate = GetNextCandidate(shared_info);
+        SetNextCandidate(candidate, next_candidate);
+        ClearNextCandidate(shared_info);

[Michael Starzinger, 2013/01/11 12:27:22]

As discussed offline, I added a break here.

+      }
+
+      candidate = next_candidate;
+    }
+  }
+}
+
+
 void CodeFlusher::EvictCandidate(JSFunction* function) {
   ASSERT(!function->next_function_link()->IsUndefined());
   Object* undefined = isolate_->heap()->undefined_value();
 
   // The function is no longer a candidate, make sure it gets visited
   // again so that previous flushing decisions are revisited.
   isolate_->heap()->incremental_marking()->RecordWrites(function);
 
   JSFunction* candidate = jsfunction_candidates_head_;
   JSFunction* next_candidate;
   if (candidate == function) {
     next_candidate = GetNextCandidate(function);
     jsfunction_candidates_head_ = next_candidate;
     ClearNextCandidate(function, undefined);
   } else {
     while (candidate != NULL) {
       next_candidate = GetNextCandidate(candidate);
 
       if (next_candidate == function) {
         next_candidate = GetNextCandidate(function);
         SetNextCandidate(candidate, next_candidate);
         ClearNextCandidate(function, undefined);

[Michael Starzinger, 2013/01/11 12:27:22]

Likewise.

       }
 
       candidate = next_candidate;
     }
   }
 }
 
 
 void CodeFlusher::EvictJSFunctionCandidates() {
   Object* undefined = isolate_->heap()->undefined_value();
@@ skipping 2842 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal