Merge pull request #3683 from amicic/CS_no_Nusery_movement

Prevent object movement in Nursery contract

gc/base/standard/PhysicalSubArenaVirtualMemorySemiSpace.cpp

@@ -547,6 +547,19 @@ MM_PhysicalSubArenaVirtualMemorySemiSpace::contract(MM_EnvironmentBase *env, uin
 
 		/* Check if the move location actually does in fact move any valid heap */
 		if(allocateSegmentBase > allocateLeadingFreeTop) {
+			if (extensions->isConcurrentScavengerEnabled()) {
+				/* Fixup logic does not account for possible object growth, which would be required for objects
+				 * that have been allocated and hashed during the last concurrent phase (hence, in hybrid Survivor-Allocate
+				 * that is subject to movement).
+				 */
+				if(debug) {
+					omrtty_printf("\tHeap movement (%p %p) to (%p %p) required, but not allowed with CS enabled.\n",
+						allocateLeadingFreeTop, allocateTrailingFreeBase,
+						allocateSegmentBase, ((uintptr_t)allocateSegmentBase) + heapSizeToMove);
+				}
+				return 0;
+			}
+
 			/* Adjust all fields that point to the refered to region */
 			struct Modron_psavmssMoveData psavmssMoveData;
 			psavmssMoveData.env = env;
@@ -716,6 +729,19 @@ MM_PhysicalSubArenaVirtualMemorySemiSpace::contract(MM_EnvironmentBase *env, uin
 
 		/* Check if the move location actually does in fact move any valid heap */
 		if(allocateSegmentBase > allocateLeadingFreeTop) {
+			if (extensions->isConcurrentScavengerEnabled()) {
+				/* Fixup logic does not account for possible object growth, which would be required for objects
+				 * that have been allocated and hashed during the last concurrent phase (hence, in hybrid Survivor-Allocate
+				 * that is subject to movement).
+				 */
+				if(debug) {
+					omrtty_printf("\tHeap movement (%p %p) to (%p %p) required, but not allowed with CS enabled.\n",
+						allocateLeadingFreeTop, allocateTrailingFreeBase,
+						allocateSegmentBase, ((uintptr_t)allocateSegmentBase) + heapSizeToMove);
+				}
+				return 0;
+			}
+
 			/* Adjust all fields that point to the refered to region */
 			struct Modron_psavmssMoveData psavmssMoveData;
 			psavmssMoveData.env = env;