Make heap iterable in PrepareForBreakPoints.

When aborting incremental marking with compaction discard all slots collected on evacuation candidates.

R=ricow@chromium.org
BUG=v8:1700
TEST=inspector/debugger/debugger-step-in.html

Review URL: http://codereview.chromium.org/7977004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9360 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/debug.cc

@@ -1733,6 +1733,10 @@ void Debug::PrepareForBreakPoints() {
   if (!has_break_points_) {
     Deoptimizer::DeoptimizeAll();
 
+    // We are going to iterate heap to find all functions without
+    // debug break slots.
+    isolate_->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
+
     AssertNoAllocation no_allocation;
     Builtins* builtins = isolate_->builtins();
     Code* lazy_compile = builtins->builtin(Builtins::kLazyCompile);

src/mark-compact.cc

@@ -258,6 +258,22 @@ bool MarkCompactCollector::StartCompaction() {
 }
 
 
+void MarkCompactCollector::AbortCompaction() {
+  if (compacting_) {
+    int npages = evacuation_candidates_.length();
+    for (int i = 0; i < npages; i++) {
+      Page* p = evacuation_candidates_[i];
+      slots_buffer_allocator_.DeallocateChain(p->slots_buffer_address());
+      p->ClearEvacuationCandidate();
+      p->ClearFlag(MemoryChunk::RESCAN_ON_EVACUATION);
+    }
+    compacting_ = false;
+    evacuation_candidates_.Rewind(0);
+  }
+  ASSERT_EQ(0, evacuation_candidates_.length());
+}
+
+
 void MarkCompactCollector::CollectGarbage() {
   // Make sure that Prepare() has been called. The individual steps below will
   // update the state as they proceed.
@@ -478,6 +494,7 @@ void MarkCompactCollector::Prepare(GCTracer* tracer) {
   if (heap()->incremental_marking()->IsMarking() && PreciseSweepingRequired()) {
     heap()->incremental_marking()->Abort();
     ClearMarkbits(heap_);
+    AbortCompaction();
   }
 
   if (!FLAG_never_compact) StartCompaction();

src/mark-compact.h

@@ -449,6 +449,8 @@ class MarkCompactCollector {
 
   bool StartCompaction();
 
+  void AbortCompaction();
+
   // During a full GC, there is a stack-allocated GCTracer that is used for
   // bookkeeping information.  Return a pointer to that tracer.
   GCTracer* tracer() { return tracer_; }