8318324: Drop redundant default methods from FFM API

Reviewed-by: jvernee

Author: mcimadamore

src/java.base/share/classes/java/lang/foreign/MemoryLayout.java

@@ -26,14 +26,9 @@
 package java.lang.foreign;
 
 import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.MethodType;
 import java.lang.invoke.VarHandle;
-import java.util.EnumSet;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.Set;
-import java.util.function.Function;
 import java.util.stream.Stream;
 
 import jdk.internal.foreign.LayoutPath;
@@ -44,7 +39,6 @@
 import jdk.internal.foreign.layout.SequenceLayoutImpl;
 import jdk.internal.foreign.layout.StructLayoutImpl;
 import jdk.internal.foreign.layout.UnionLayoutImpl;
-import jdk.internal.vm.annotation.ForceInline;
 
 /**
  * A memory layout describes the contents of a memory segment.
@@ -404,35 +398,12 @@ public sealed interface MemoryLayout permits SequenceLayout, GroupLayout, Paddin
      * @throws IllegalArgumentException if {@code offset} or {@code index} is negative
      * @throws ArithmeticException if either the addition or multiplication overflows
      */
-    @ForceInline
-    default long scale(long offset, long index) {
-        if (offset < 0) {
-            throw new IllegalArgumentException("Negative offset: " + offset);
-        }
-        if (index < 0) {
-            throw new IllegalArgumentException("Negative index: " + index);
-        }
-
-        return Math.addExact(offset, Math.multiplyExact(byteSize(), index));
-    }
+    long scale(long offset, long index);
 
     /**
      *{@return a method handle that can be used to invoke {@link #scale(long, long)} on this layout}
      */
-    default MethodHandle scaleHandle() {
-        class Holder {
-            static final MethodHandle MH_SCALE;
-            static {
-                try {
-                    MH_SCALE = MethodHandles.lookup().findVirtual(MemoryLayout.class, "scale",
-                            MethodType.methodType(long.class, long.class, long.class));
-                } catch (ReflectiveOperationException e) {
-                    throw new ExceptionInInitializerError(e);
-                }
-            }
-        }
-        return Holder.MH_SCALE.bindTo(this);
-    }
+    MethodHandle scaleHandle();
 
     /**
      * Computes the offset, in bytes, of the layout selected by the given layout path, where the initial layout in the
@@ -444,10 +415,7 @@ class Holder {
      * @throws IllegalArgumentException if the layout path contains one or more <a href=#open-path-elements>open path elements</a>.
      * @throws IllegalArgumentException if the layout path contains one or more <a href=#deref-path-elements>dereference path elements</a>.
      */
-    default long byteOffset(PathElement... elements) {
-        return computePathOp(LayoutPath.rootPath(this), LayoutPath::offset,
-                EnumSet.of(PathKind.SEQUENCE_ELEMENT, PathKind.SEQUENCE_RANGE, PathKind.DEREF_ELEMENT), elements);
-    }
+    long byteOffset(PathElement... elements);
 
     /**
      * Creates a method handle that computes the offset, in bytes, of the layout selected
@@ -482,10 +450,7 @@ default long byteOffset(PathElement... elements) {
      * @throws IllegalArgumentException if the layout path is not <a href="#well-formedness">well-formed</a> for this layout.
      * @throws IllegalArgumentException if the layout path contains one or more <a href=#deref-path-elements>dereference path elements</a>.
      */
-    default MethodHandle byteOffsetHandle(PathElement... elements) {
-        return computePathOp(LayoutPath.rootPath(this), LayoutPath::offsetHandle,
-                EnumSet.of(PathKind.DEREF_ELEMENT), elements);
-    }
+    MethodHandle byteOffsetHandle(PathElement... elements);
 
     /**
      * Creates a var handle that accesses a memory segment at the offset selected by the given layout path,
@@ -577,14 +542,7 @@ default MethodHandle byteOffsetHandle(PathElement... elements) {
      * @throws IllegalArgumentException if the layout path is not <a href="#well-formedness">well-formed</a> for this layout.
      * @throws IllegalArgumentException if the layout selected by the provided path is not a {@linkplain ValueLayout value layout}.
      */
-    default VarHandle varHandle(PathElement... elements) {
-        Objects.requireNonNull(elements);
-        if (this instanceof ValueLayout vl && elements.length == 0) {
-            return vl.varHandle(); // fast path
-        }
-        return computePathOp(LayoutPath.rootPath(this), LayoutPath::dereferenceHandle,
-                Set.of(), elements);
-    }
+    VarHandle varHandle(PathElement... elements);
 
     /**
      * Creates a method handle which, given a memory segment, returns a {@linkplain MemorySegment#asSlice(long,long) slice}
@@ -623,10 +581,7 @@ default VarHandle varHandle(PathElement... elements) {
      * @throws IllegalArgumentException if the layout path is not <a href="#well-formedness">well-formed</a> for this layout.
      * @throws IllegalArgumentException if the layout path contains one or more <a href=#deref-path-elements>dereference path elements</a>.
      */
-    default MethodHandle sliceHandle(PathElement... elements) {
-        return computePathOp(LayoutPath.rootPath(this), LayoutPath::sliceHandle,
-                Set.of(PathKind.DEREF_ELEMENT), elements);
-    }
+    MethodHandle sliceHandle(PathElement... elements);
 
     /**
      * Returns the layout selected from the provided path, where the initial layout in the path is this layout.
@@ -638,23 +593,7 @@ default MethodHandle sliceHandle(PathElement... elements) {
      * @throws IllegalArgumentException if the layout path contains one or more path elements that select one or more
      * sequence element indices, such as {@link PathElement#sequenceElement(long)} and {@link PathElement#sequenceElement(long, long)}).
      */
-    default MemoryLayout select(PathElement... elements) {
-        return computePathOp(LayoutPath.rootPath(this), LayoutPath::layout,
-                EnumSet.of(PathKind.SEQUENCE_ELEMENT_INDEX, PathKind.SEQUENCE_RANGE, PathKind.DEREF_ELEMENT), elements);
-    }
-
-    private static <Z> Z computePathOp(LayoutPath path, Function<LayoutPath, Z> finalizer,
-                                       Set<PathKind> badKinds, PathElement... elements) {
-        Objects.requireNonNull(elements);
-        for (PathElement e : elements) {
-            LayoutPath.PathElementImpl pathElem = (LayoutPath.PathElementImpl)Objects.requireNonNull(e);
-            if (badKinds.contains(pathElem.kind())) {
-                throw new IllegalArgumentException(String.format("Invalid %s selection in layout path", pathElem.kind().description()));
-            }
-            path = pathElem.apply(path);
-        }
-        return finalizer.apply(path);
-    }
+    MemoryLayout select(PathElement... elements);
 
     /**
      * An element in a <a href="MemoryLayout.html#layout-paths"><em>layout path</em></a>. There