Refactor back edge table related code into a new class.

src/deoptimizer.cc

Index: src/deoptimizer.cc
diff --git a/src/deoptimizer.cc b/src/deoptimizer.cc
index 0c9760e0fa09c4b44e50a21a75eed5b09accb3ca..9a1bb9d8efb97e2193051079321f3b59d9219444 100644
--- a/src/deoptimizer.cc
+++ b/src/deoptimizer.cc
@@ -2338,85 +2338,6 @@ void Deoptimizer::DoTranslateCommand(TranslationIterator* iterator,
 }
 
 
-void Deoptimizer::PatchInterruptCode(Isolate* isolate,
-                                     Code* unoptimized) {
-  DisallowHeapAllocation no_gc;
-  Code* replacement_code =
-      isolate->builtins()->builtin(Builtins::kOnStackReplacement);
-
-  // Iterate over the back edge table and patch every interrupt
-  // call to an unconditional call to the replacement code.
-  int loop_nesting_level = unoptimized->allow_osr_at_loop_nesting_level();
-
-  for (FullCodeGenerator::BackEdgeTableIterator back_edges(unoptimized, &no_gc);
-       !back_edges.Done();
-       back_edges.Next()) {
-    if (static_cast<int>(back_edges.loop_depth()) == loop_nesting_level) {
-      ASSERT_EQ(NOT_PATCHED, GetInterruptPatchState(isolate,
-                                                    unoptimized,
-                                                    back_edges.pc()));
-      PatchInterruptCodeAt(unoptimized,
-                           back_edges.pc(),
-                           replacement_code);
-    }
-  }
-
-  unoptimized->set_back_edges_patched_for_osr(true);
-  ASSERT(Deoptimizer::VerifyInterruptCode(
-             isolate, unoptimized, loop_nesting_level));
-}
-
-
-void Deoptimizer::RevertInterruptCode(Isolate* isolate,
-                                      Code* unoptimized) {
-  DisallowHeapAllocation no_gc;
-  Code* interrupt_code =
-      isolate->builtins()->builtin(Builtins::kInterruptCheck);
-
-  // Iterate over the back edge table and revert the patched interrupt calls.
-  ASSERT(unoptimized->back_edges_patched_for_osr());
-  int loop_nesting_level = unoptimized->allow_osr_at_loop_nesting_level();
-
-  for (FullCodeGenerator::BackEdgeTableIterator back_edges(unoptimized, &no_gc);
-       !back_edges.Done();
-       back_edges.Next()) {
-    if (static_cast<int>(back_edges.loop_depth()) <= loop_nesting_level) {
-      ASSERT_EQ(PATCHED_FOR_OSR, GetInterruptPatchState(isolate,
-                                                        unoptimized,
-                                                        back_edges.pc()));
-      RevertInterruptCodeAt(unoptimized, back_edges.pc(), interrupt_code);
-    }
-  }
-
-  unoptimized->set_back_edges_patched_for_osr(false);
-  unoptimized->set_allow_osr_at_loop_nesting_level(0);
-  // Assert that none of the back edges are patched anymore.
-  ASSERT(Deoptimizer::VerifyInterruptCode(isolate, unoptimized, -1));
-}
-
-
-#ifdef DEBUG
-bool Deoptimizer::VerifyInterruptCode(Isolate* isolate,
-                                      Code* unoptimized,
-                                      int loop_nesting_level) {
-  DisallowHeapAllocation no_gc;
-  for (FullCodeGenerator::BackEdgeTableIterator back_edges(unoptimized, &no_gc);
-       !back_edges.Done();
-       back_edges.Next()) {
-    uint32_t loop_depth = back_edges.loop_depth();
-    CHECK_LE(static_cast<int>(loop_depth), Code::kMaxLoopNestingMarker);
-    // Assert that all back edges for shallower loops (and only those)
-    // have already been patched.
-    CHECK_EQ((static_cast<int>(loop_depth) <= loop_nesting_level),
-             GetInterruptPatchState(isolate,
-                                    unoptimized,
-                                    back_edges.pc()) != NOT_PATCHED);
-  }
-  return true;
-}
-#endif  // DEBUG
-
-
 unsigned Deoptimizer::ComputeInputFrameSize() const {
   unsigned fixed_size = ComputeFixedSize(function_);
   // The fp-to-sp delta already takes the context and the function