--- old/src/share/vm/gc/shenandoah/shenandoahConnectionMatrix.cpp	2017-03-24 18:44:29.334390285 +0100
+++ new/src/share/vm/gc/shenandoah/shenandoahConnectionMatrix.cpp	2017-03-24 18:44:29.278390436 +0100
@@ -36,7 +36,9 @@
   _magic_offset( ((uintptr_t) _matrix) - ( ((uintptr_t) ShenandoahHeap::heap()->first_region_bottom()) >> _region_shift) * (_stride + 1))
 
 {
-  clear_all();
+  if (UseShenandoahMatrix) {
+    clear_all();
+  }
 }
 
 ShenandoahConnectionMatrix::~ShenandoahConnectionMatrix() {
@@ -44,18 +46,22 @@
 }
 
 size_t ShenandoahConnectionMatrix::index_of(size_t from_idx, size_t to_idx) const {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   return from_idx * _stride + to_idx;
 }
 
 bool ShenandoahConnectionMatrix::is_connected(size_t from_idx, size_t to_idx) const {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   return _matrix[index_of(from_idx, to_idx)] > 0;
 }
 
 void ShenandoahConnectionMatrix::clear_connected(size_t from_idx, size_t to_idx) {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   _matrix[index_of(from_idx, to_idx)] = 0;
 }
 
 void ShenandoahConnectionMatrix::clear_region(size_t idx) {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   for (uint i = 0; i < _stride; i++) {
     clear_connected(i, idx);
     clear_connected(idx, i);
@@ -63,17 +69,20 @@
 }
 
 void ShenandoahConnectionMatrix::clear_region_outbound(size_t idx) {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   for (uint i = 0; i < _stride; i++) {
     clear_connected(idx, i);
   }
 }
 
 void ShenandoahConnectionMatrix::clear_all() {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   size_t count = sizeof(char) * _stride * _stride;
   Copy::fill_to_bytes(_matrix, count, 0);
 }
 
 void ShenandoahConnectionMatrix::print_on(outputStream* st) const {
+  assert (UseShenandoahMatrix, "call only when matrix is enabled");
   st->print_cr("Connection Matrix:");
   st->print_cr("%8s, %10s, %10s, %10s, %8s, %s", "Region", "Live", "Used", "Garbage", "Refcnt", "Referenced by");
 
--- old/src/share/vm/gc/shenandoah/shenandoahHeap.cpp	2017-03-24 18:44:29.538389736 +0100
+++ new/src/share/vm/gc/shenandoah/shenandoahHeap.cpp	2017-03-24 18:44:29.482389887 +0100
@@ -1149,11 +1149,9 @@
 
     ensure_parsability(true);
 
-    if (UseShenandoahMatrix) {
-      if (PrintShenandoahMatrix) {
-        outputStream* log = Log(gc)::info_stream();
-        connection_matrix()->print_on(log);
-      }
+    if (UseShenandoahMatrix && PrintShenandoahMatrix) {
+      outputStream* log = Log(gc)::info_stream();
+      connection_matrix()->print_on(log);
     }
 
     if (ShenandoahVerify || (UseShenandoahMatrix && VerifyShenandoahMatrix)) {
--- old/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp	2017-03-24 18:44:29.754389155 +0100
+++ new/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp	2017-03-24 18:44:29.698389306 +0100
@@ -351,8 +351,10 @@
     assert(p->klass() == return_val->klass(), "Should have the same class p: "PTR_FORMAT", copy: "PTR_FORMAT,
                                               p2i((HeapWord*) p), p2i((HeapWord*) copy));
 
-    UpdateMatrixClosure cl;
-    copy_val->oop_iterate(&cl);
+    if (UseShenandoahMatrix) {
+      UpdateMatrixClosure cl;
+      copy_val->oop_iterate(&cl);
+    }
 #endif
   }  else {
     if (alloc_from_gclab) {
--- old/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp	2017-03-24 18:44:29.958388604 +0100
+++ new/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp	2017-03-24 18:44:29.902388756 +0100
@@ -291,7 +291,10 @@
   _heap->set_complete_top_at_mark_start(bottom(), bottom());
   // We can only safely reset the C-TAMS pointer if the bitmap is clear for that region.
   assert(_heap->is_complete_bitmap_clear_range(bottom(), end()), "must be clear");
-  _heap->connection_matrix()->clear_region(region_number());
+
+  if (UseShenandoahMatrix) {
+    _heap->connection_matrix()->clear_region(region_number());
+  }
 }
 
 HeapWord* ShenandoahHeapRegion::block_start_const(const void* p) const {
--- old/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp	2017-03-24 18:44:30.162388054 +0100
+++ new/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp	2017-03-24 18:44:30.106388205 +0100
@@ -231,11 +231,9 @@
 
   oopDesc::set_bs(old_bs);
 
-  if (UseShenandoahMatrix) {
-    if (PrintShenandoahMatrix) {
-      outputStream* log = Log(gc)::info_stream();
-      _heap->connection_matrix()->print_on(log);
-    }
+  if (UseShenandoahMatrix && PrintShenandoahMatrix) {
+    outputStream* log = Log(gc)::info_stream();
+    _heap->connection_matrix()->print_on(log);
   }
 }
 
@@ -315,11 +313,9 @@
 
   _heap->swap_mark_bitmaps();
 
-  if (UseShenandoahMatrix) {
-    if (PrintShenandoahMatrix) {
-      outputStream* log = Log(gc)::info_stream();
-      _heap->connection_matrix()->print_on(log);
-    }
+  if (UseShenandoahMatrix && PrintShenandoahMatrix) {
+    outputStream* log = Log(gc)::info_stream();
+    _heap->connection_matrix()->print_on(log);
   }
 
   if (ShenandoahVerify || (UseShenandoahMatrix && VerifyShenandoahMatrix)) {