Minor fixes and improvements.

Author: peter-hofer

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/compacting/PlanningVisitor.java

@@ -54,6 +54,11 @@ public final class PlanningVisitor implements AlignedHeapChunk.Visitor {
     public PlanningVisitor() {
     }
 
+    public void init(Space space) {
+        allocChunk = space.getFirstAlignedHeapChunk();
+        allocPointer = AlignedHeapChunk.getObjectsStart(allocChunk);
+    }
+
     @Override
     public boolean visitChunk(AlignedHeapChunk.AlignedHeader chunk) {
         boolean sweeping = chunk.getShouldSweepInsteadOfCompact();
@@ -71,26 +76,26 @@ public boolean visitChunk(AlignedHeapChunk.AlignedHeader chunk) {
 
         BrickTable.setEntry(chunk, brickIndex, objSeq);
 
-        Pointer p = AlignedHeapChunk.getObjectsStart(chunk);
+        Pointer p = objSeq;
         while (p.belowThan(initialTop)) {
             Word header = ObjectHeaderImpl.readHeaderFromPointer(p);
-            Object obj = p.toObject();
 
             UnsignedWord objSize;
             if (ObjectHeaderImpl.isForwardedHeader(header)) {
                 /*
                  * If an object was copied from a chunk that won't be swept and forwarding was put
-                 * in place, it was because we needed to add an identity hash code field.
+                 * in place, it was because we needed to add an identity hash code field to the
+                 * object, and we need the object's original size here.
                  */
                 assert !sweeping && ConfigurationValues.getObjectLayout().isIdentityHashFieldOptional();
                 Object forwardedObj = ObjectHeaderImpl.getObjectHeaderImpl().getForwardedObject(p, header);
                 objSize = LayoutEncoding.getSizeFromObjectWithoutOptionalIdHashFieldInGC(forwardedObj);
             } else {
-                objSize = LayoutEncoding.getSizeFromObjectInlineInGC(obj);
+                objSize = LayoutEncoding.getSizeFromObjectInlineInGC(p.toObject());
             }
 
             if (ObjectHeaderImpl.isMarkedHeader(header)) {
-                ObjectHeaderImpl.unsetMarkedAndKeepRememberedSetBit(obj);
+                ObjectHeaderImpl.unsetMarkedAndKeepRememberedSetBit(p.toObject());
 
                 /*
                  * Adding the optional identity hash field would increase an object's size, so we
@@ -174,9 +179,4 @@ private Pointer allocate(UnsignedWord size) {
         }
         return p;
     }
-
-    public void init(Space space) {
-        allocChunk = space.getFirstAlignedHeapChunk();
-        allocPointer = AlignedHeapChunk.getObjectsStart(allocChunk);
-    }
 }