Add all the main machinery

Add functions size_shared, copy_shared_calculate and copy_shared_perform.
Add the infrastructure for making these communicate with each other.
Add debug information to other places in the VM, to watch interaction
with the sharing-preserving copy.

CAUTION: If you define the SHCOPY_DEBUG macro (after SHCOPY is actually
used in the VM) and make the whole OTP, there will be a lot of debugging
messages during make (it will also be enabled in erlc).  You have been
warned...

1 files changed, 10 insertions, 0 deletions

diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c
index 6cb37752bc..ec96a7563a 100644
--- a/erts/emulator/beam/erl_gc.c
+++ b/erts/emulator/beam/erl_gc.c
@@ -42,6 +42,8 @@
 #include "dtrace-wrapper.h"
 #include "erl_bif_unique.h"
 
+#undef SHCOPY_DEBUG
+
 #define ERTS_INACT_WR_PB_LEAVE_MUCH_LIMIT 1
 #define ERTS_INACT_WR_PB_LEAVE_MUCH_PERCENTAGE 20
 #define ERTS_INACT_WR_PB_LEAVE_LIMIT 10
@@ -1166,6 +1168,10 @@ do_minor(Process *p, ErlHeapFragment *live_hf_end,
     char* oh = (char *) OLD_HEAP(p);
     Uint oh_size = (char *) OLD_HTOP(p) - oh;
 
+#ifdef SHCOPY_DEBUG
+    VERBOSE_DEBUG("[pid=%T] MINOR GC: %p %p %p %p\n", p->common.id, HEAP_START(p), HEAP_END(p), OLD_HEAP(p), OLD_HEND(p));
+#endif
+
     n_htop = n_heap = (Eterm*) ERTS_HEAP_ALLOC(ERTS_ALC_T_HEAP,
 					       sizeof(Eterm)*new_sz);
 
@@ -1383,6 +1389,10 @@ major_collection(Process* p, ErlHeapFragment *live_hf_end,
     Uint new_sz, stk_sz;
     int adjusted;
 
+#ifdef SHCOPY_DEBUG
+    VERBOSE_DEBUG("[pid=%T] MAJOR GC: %p %p %p %p\n", p->common.id, HEAP_START(p), HEAP_END(p), OLD_HEAP(p), OLD_HEND(p));
+#endif
+
     /*
      * Do a fullsweep GC. First figure out the size of the heap
      * to receive all live data.