Fix invalid layout handling

Cached cases always only contain valid layouts. Objects with invalid layout caused the caches to overflow, which in turn resulted in a lot of megamorphic reports and with that a lot of splitting. For the same reason, AbstractPointersObjectGuard is dropped.

src/de.hpi.swa.trufflesqueak/src/de/hpi/swa/trufflesqueak/model/AbstractPointersObject.java

@@ -137,13 +137,9 @@ public final ObjectLayout getLayout() {
         return layout;
     }
 
-    public final boolean matchesLayout(final ObjectLayout expectedLayout) {
-        if (!getLayout().isValid()) {
-            CompilerDirectives.transferToInterpreterAndInvalidate();
-            updateLayout();
-        }
-        assert layout.isValid() : "Should only ever match valid layout (invalid expectedLayout will be replaced in PIC)";
-        return layout == expectedLayout;
+    public final ObjectLayout getValidLayoutOrNull() {
+        CompilerAsserts.neverPartOfCompilation();
+        return layout.isValid() ? layout : null;
     }
 
     public final void changeClassTo(final ClassObject newClass) {
@@ -161,14 +157,15 @@ public final void updateLayout() {
     @TruffleBoundary
     public final ObjectLayout updateLayout(final long index, final Object value) {
         assert !layout.getLocation(index).canStore(value);
-        ObjectLayout latestLayout = getSqueakClass().getLayout();
+        final ClassObject squeakClass = getSqueakClass();
+        ObjectLayout latestLayout = squeakClass.getLayout();
         if (!latestLayout.getLocation(index).canStore(value)) {
-            latestLayout = latestLayout.evolveLocation(index, value);
+            latestLayout = latestLayout.evolveLocation(squeakClass, index, value);
         } else {
             assert !layout.isValid() && layout != latestLayout : "Layout must have changed";
         }
         migrateToLayout(latestLayout);
-        return getSqueakClass().getLayout(); /* Layout may have evolved again during migration. */
+        return squeakClass.getLayout(); /* Layout may have evolved again during migration. */
     }
 
     @TruffleBoundary
@@ -178,6 +175,7 @@ private void migrateToLayout(final ObjectLayout targetLayout) {
         final ObjectLayout oldLayout = layout;
         assert oldLayout.getInstSize() == newLayout.getInstSize();
         final int instSize = oldLayout.getInstSize();
+        final ClassObject squeakClass = getSqueakClass();
         final Object[] values = new Object[instSize];
         for (int i = 0; i < instSize; i++) {
             final SlotLocation oldLocation = oldLayout.getLocation(i);
@@ -186,7 +184,7 @@ private void migrateToLayout(final ObjectLayout targetLayout) {
                 final Object oldValue = oldLocation.read(this);
                 oldLocation.unset(this);
                 if (!newLocation.canStore(oldValue)) {
-                    newLayout = newLayout.evolveLocation(i, oldValue);
+                    newLayout = newLayout.evolveLocation(squeakClass, i, oldValue);
                 }
                 values[i] = oldValue;
             }

src/de.hpi.swa.trufflesqueak/src/de/hpi/swa/trufflesqueak/model/layout/ObjectLayout.java

@@ -21,7 +21,6 @@
 import de.hpi.swa.trufflesqueak.util.UnsafeUtils;
 
 public final class ObjectLayout {
-    private final ClassObject squeakClass;
     @CompilationFinal(dimensions = 1) private final SlotLocation[] locations;
     private final int numPrimitiveExtension;
     private final int numObjectExtension;
@@ -30,7 +29,6 @@ public final class ObjectLayout {
 
     public ObjectLayout(final ClassObject classObject, final int instSize) {
         slowPathOperation();
-        squeakClass = classObject;
         classObject.updateLayout(this);
         locations = new SlotLocation[instSize];
         Arrays.fill(locations, SlotLocation.UNINITIALIZED_LOCATION);
@@ -40,14 +38,13 @@ public ObjectLayout(final ClassObject classObject, final int instSize) {
 
     public ObjectLayout(final ClassObject classObject, final SlotLocation[] locations) {
         slowPathOperation();
-        squeakClass = classObject;
         classObject.updateLayout(this);
         this.locations = locations;
         numPrimitiveExtension = countPrimitiveExtension(locations);
         numObjectExtension = countObjectExtension(locations);
     }
 
-    public ObjectLayout evolveLocation(final long longIndex, final Object value) {
+    public ObjectLayout evolveLocation(final ClassObject squeakClass, final long longIndex, final Object value) {
         slowPathOperation();
         final int index = Math.toIntExact(longIndex);
         if (!isValid()) {
@@ -210,10 +207,6 @@ public boolean isValid() {
         return isValidAssumption.isValid();
     }
 
-    public ClassObject getSqueakClass() {
-        return squeakClass;
-    }
-
     public SlotLocation getLocation(final long index) {
         return (SlotLocation) UnsafeUtils.getObject(locations, index);
     }
@@ -268,6 +261,6 @@ private static int countObjectExtension(final SlotLocation[] locations) {
     @Override
     public String toString() {
         CompilerAsserts.neverPartOfCompilation();
-        return (isValid() ? "valid" : "invalid") + " ObjectLayout for " + squeakClass + " @" + Integer.toHexString(hashCode());
+        return (isValid() ? "valid" : "invalid") + " ObjectLayout @" + Integer.toHexString(hashCode());
     }
 }

src/de.hpi.swa.trufflesqueak/src/de/hpi/swa/trufflesqueak/nodes/CacheLimits.java

@@ -12,4 +12,6 @@ public final class CacheLimits {
     public static final int INLINE_BLOCK_CACHE_LIMIT = 4;
     public static final int INLINE_METHOD_CACHE_LIMIT = 4;
     public static final int PERFORM_SELECTOR_CACHE_LIMIT = 4;
+    public static final int POINTERS_LAYOUT_CACHE_LIMIT = 4;
+    public static final int POINTERS_VARIABLE_PART_CACHE_LIMIT = 3;
 }