From b0112953006daa04fca65a922a5da1bf36533630 Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Thu, 5 Nov 2009 23:53:53 -0600
Subject: [PATCH] vm: fix 'become' when aging space is empty

---
 vm/bitwise_hacks.hpp     | 12 ++++++------
 vm/collector.hpp         | 22 +++++++++-------------
 vm/nursery_collector.cpp |  9 ++++++---
 3 files changed, 21 insertions(+), 22 deletions(-)

diff --git a/vm/bitwise_hacks.hpp b/vm/bitwise_hacks.hpp
index 8830e4f876..03a6ea5ad0 100644
--- a/vm/bitwise_hacks.hpp
+++ b/vm/bitwise_hacks.hpp
@@ -38,13 +38,13 @@ inline cell log2(cell x)
 #else
 	cell n = 0;
 #ifdef FACTOR_64
-	if (x >= (u64)1 << 32) { x >>= 32; n += 32; }
+	if (x >= (cell)1 << 32) { x >>= 32; n += 32; }
 #endif
-	if (x >= (u32)1 << 16) { x >>= 16; n += 16; }
-	if (x >= (u32)1 <<  8) { x >>=  8; n +=  8; }
-	if (x >= (u32)1 <<  4) { x >>=  4; n +=  4; }
-	if (x >= (u32)1 <<  2) { x >>=  2; n +=  2; }
-	if (x >= (u32)1 <<  1) {           n +=  1; }
+	if (x >= (cell)1 << 16) { x >>= 16; n += 16; }
+	if (x >= (cell)1 <<  8) { x >>=  8; n +=  8; }
+	if (x >= (cell)1 <<  4) { x >>=  4; n +=  4; }
+	if (x >= (cell)1 <<  2) { x >>=  2; n +=  2; }
+	if (x >= (cell)1 <<  1) {           n +=  1; }
 #endif
 	return n;
 }
diff --git a/vm/collector.hpp b/vm/collector.hpp
index 29711aeb9c..9b3faaf31f 100644
--- a/vm/collector.hpp
+++ b/vm/collector.hpp
@@ -196,14 +196,14 @@ template<typename TargetGeneration, typename Policy> struct collector {
 	{
 		card_deck *decks = data->decks;
 		card_deck *cards = data->cards;
-	
+
 		cell gen_start_card = addr_to_card(gen->start - data->start);
 
 		cell first_deck = card_deck_for_address(gen->start);
 		cell last_deck = card_deck_for_address(gen->end);
-	
+
 		cell start = 0, binary_start = 0, end = 0;
-	
+
 		for(cell deck_index = first_deck; deck_index < last_deck; deck_index++)
 		{
 			if(decks[deck_index] & mask)
@@ -212,7 +212,7 @@ template<typename TargetGeneration, typename Policy> struct collector {
 
 				cell first_card = first_card_in_deck(deck_index);
 				cell last_card = last_card_in_deck(deck_index);
-	
+
 				for(cell card_index = first_card; card_index < last_card; card_index++)
 				{
 					if(cards[card_index] & mask)
@@ -225,13 +225,9 @@ template<typename TargetGeneration, typename Policy> struct collector {
 							binary_start = start + ((object *)start)->binary_payload_start();
 							end = start + ((object *)start)->size();
 						}
-	
-#ifdef FACTOR_DEBUG
-						assert(addr_to_card(start - data->start) <= card_index);
-						assert(start < card_end_address(card_index));
-#endif
 
-scan_next_object:				{
+scan_next_object:				if(start < card_end_address(card_index))
+						{
 							trace_partial_objects(
 								start,
 								binary_start,
@@ -248,13 +244,13 @@ scan_next_object:				{
 								}
 							}
 						}
-	
+
 						unmarker(&cards[card_index]);
-	
+
 						if(!start) return;
 					}
 				}
-	
+
 				unmarker(&decks[deck_index]);
 			}
 		}
diff --git a/vm/nursery_collector.cpp b/vm/nursery_collector.cpp
index 155da243d4..5eb77fd763 100644
--- a/vm/nursery_collector.cpp
+++ b/vm/nursery_collector.cpp
@@ -22,9 +22,12 @@ void factor_vm::collect_nursery()
 	collector.trace_cards(data->tenured,
 		card_points_to_nursery,
 		simple_unmarker(card_points_to_nursery));
-	collector.trace_cards(data->aging,
-		card_points_to_nursery,
-		full_unmarker());
+	if(data->aging->here != data->aging->start)
+	{
+		collector.trace_cards(data->aging,
+			card_points_to_nursery,
+			full_unmarker());
+	}
 	current_gc->event->ended_card_scan(collector.cards_scanned,collector.decks_scanned);
 
 	current_gc->event->started_code_scan();