8331865: Consolidate size and alignment checks in LayoutPath

Reviewed-by: psandoz, jvernee

Author: mcimadamore

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

@@ -625,12 +625,12 @@ public sealed interface MemoryLayout
      *     (this layout), or an {@link IllegalArgumentException} is thrown. Note
      *     that the alignment constraint of the root layout can be more strict
      *     (but not less) than the alignment constraint of the selected value layout.</li>
-     *     <li>The offset of the access operation (computed as above) must fall inside
-     *     the spatial bounds of the accessed memory segment, or an
-     *     {@link IndexOutOfBoundsException} is thrown. This is the case when
-     *     {@code O + A <= S}, where {@code O} is the accessed offset (computed as above),
-     *     {@code A} is the size of the selected layout and {@code S} is the size of the
-     *     accessed memory segment.</li>
+     *     <li>The access operation must fall inside the spatial bounds of the accessed
+     *     memory segment, or an {@link IndexOutOfBoundsException} is thrown. This is the case
+     *     when {@code B + A <= S}, where {@code B} is the base offset (defined above),
+     *     {@code A} is the size of this layout and {@code S} is the size of the
+     *     accessed memory segment. Note that the size of this layout might be <em>bigger</em>
+     *     than the size of the accessed layout (e.g. when accessing a struct member).</li>
      *     <li>If the provided layout path has an open path element whose size is {@code S},
      *     its corresponding trailing {@code long} coordinate value {@code I} must be
      *     {@code 0 <= I < S}, or an {@link IndexOutOfBoundsException} is thrown.</li>
@@ -753,12 +753,12 @@ public sealed interface MemoryLayout
      *     (this layout), or an {@link IllegalArgumentException} is thrown. Note
      *     that the alignment constraint of the root layout can be more strict
      *     (but not less) than the alignment constraint of the selected value layout.</li>
-     *     <li>The offset of the access operation (computed as above) must fall inside
-     *     the spatial bounds of the accessed memory segment, or an
-     *     {@link IndexOutOfBoundsException} is thrown. This is the case when
-     *     {@code O + A <= S}, where {@code O} is the accessed offset (computed as above),
-     *     {@code A} is the size of the selected layout and {@code S} is the size of the
-     *     accessed memory segment.</li>
+     *     <li>The access operation must fall inside the spatial bounds of the accessed
+     *     memory segment, or an {@link IndexOutOfBoundsException} is thrown. This is the case
+     *     when {@code B + A <= S}, where {@code B} is the base offset (defined above),
+     *     {@code A} is the size of this layout and {@code S} is the size of the
+     *     accessed memory segment. Note that the size of this layout might be <em>bigger</em>
+     *     than the size of the accessed layout (e.g. when accessing a struct member).</li>
      *     <li>If the provided layout path has an open path element whose size is {@code S},
      *     its corresponding trailing {@code long} coordinate value {@code I} must be
      *     {@code 0 <= I < S}, or an {@link IndexOutOfBoundsException} is thrown.</li>
@@ -822,12 +822,12 @@ public sealed interface MemoryLayout
      *     (this layout), or an {@link IllegalArgumentException} will be issued. Note
      *     that the alignment constraint of the root layout can be more strict
      *     (but not less) than the alignment constraint of the selected layout.</li>
-     *     <li>The start offset of the slicing operation (computed as above) must fall
-     *     inside the spatial bounds of the accessed memory segment, or an
-     *     {@link IndexOutOfBoundsException} is thrown. This is the case when
-     *     {@code O + A <= S}, where {@code O} is the start offset of
-     *     the slicing operation (computed as above), {@code A} is the size of the
-     *     selected layout and {@code S} is the size of the accessed memory segment.</li>
+     *     <li>The slicing operation must fall inside the spatial bounds of the accessed
+     *     memory segment, or an {@link IndexOutOfBoundsException} is thrown. This is the case
+     *     when {@code B + A <= S}, where {@code B} is the base offset (defined above),
+     *     {@code A} is the size of this layout and {@code S} is the size of the
+     *     accessed memory segment. Note that the size of this layout might be <em>bigger</em>
+     *     than the size of the accessed layout (e.g. when accessing a struct member).</li>
      *     <li>If the provided layout path has an open path element whose size is {@code S},
      *     its corresponding trailing {@code long} coordinate value {@code I} must be
      *     {@code 0 <= I < S}, or an {@link IndexOutOfBoundsException} is thrown.</li>

src/java.base/share/classes/java/lang/invoke/VarHandleSegmentViewBase.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,8 +25,6 @@
 
 package java.lang.invoke;
 
-import jdk.internal.foreign.Utils;
-
 /**
  * Base class for memory segment var handle view implementations.
  */
@@ -42,23 +40,15 @@ abstract sealed class VarHandleSegmentViewBase extends VarHandle permits
     /** endianness **/
     final boolean be;
 
-    /** access size (in bytes, computed from var handle carrier type) **/
-    final long length;
-
     /** alignment constraint (in bytes, expressed as a bit mask) **/
     final long alignmentMask;
 
-    VarHandleSegmentViewBase(VarForm form, boolean be, long length, long alignmentMask, boolean exact) {
+    VarHandleSegmentViewBase(VarForm form, boolean be, long alignmentMask, boolean exact) {
         super(form, exact);
         this.be = be;
-        this.length = length;
         this.alignmentMask = alignmentMask;
     }
 
-    static IllegalArgumentException newIllegalArgumentExceptionForMisalignedAccess(long address) {
-        return new IllegalArgumentException("Misaligned access at address: " + Utils.toHexString(address));
-    }
-
     static UnsupportedOperationException newUnsupportedAccessModeForAlignment(long alignment) {
         return new UnsupportedOperationException("Unsupported access mode for alignment: " + alignment);
     }

src/java.base/share/classes/java/lang/invoke/VarHandles.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -306,6 +306,9 @@ else if (viewComponentType == float.class) {
      * The resulting var handle will take a memory segment as first argument (the segment to be dereferenced),
      * and a {@code long} as second argument (the offset into the segment).
      *
+     * Note: the returned var handle does not perform any size or alignment check. It is up to clients
+     * to adapt the returned var handle and insert the appropriate checks.
+     *
      * @param carrier the Java carrier type.
      * @param alignmentMask alignment requirement to be checked upon access. In bytes. Expressed as a mask.
      * @param byteOrder the byte order.
@@ -316,24 +319,23 @@ static VarHandle memorySegmentViewHandle(Class<?> carrier, long alignmentMask,
         if (!carrier.isPrimitive() || carrier == void.class || carrier == boolean.class) {
             throw new IllegalArgumentException("Invalid carrier: " + carrier.getName());
         }
-        long size = Utils.byteWidthOfPrimitive(carrier);
         boolean be = byteOrder == ByteOrder.BIG_ENDIAN;
         boolean exact = VAR_HANDLE_SEGMENT_FORCE_EXACT;
 
         if (carrier == byte.class) {
-            return maybeAdapt(new VarHandleSegmentAsBytes(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsBytes(be, alignmentMask, exact));
         } else if (carrier == char.class) {
-            return maybeAdapt(new VarHandleSegmentAsChars(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsChars(be, alignmentMask, exact));
         } else if (carrier == short.class) {
-            return maybeAdapt(new VarHandleSegmentAsShorts(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsShorts(be, alignmentMask, exact));
         } else if (carrier == int.class) {
-            return maybeAdapt(new VarHandleSegmentAsInts(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsInts(be, alignmentMask, exact));
         } else if (carrier == float.class) {
-            return maybeAdapt(new VarHandleSegmentAsFloats(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsFloats(be, alignmentMask, exact));
         } else if (carrier == long.class) {
-            return maybeAdapt(new VarHandleSegmentAsLongs(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsLongs(be, alignmentMask, exact));
         } else if (carrier == double.class) {
-            return maybeAdapt(new VarHandleSegmentAsDoubles(be, size, alignmentMask, exact));
+            return maybeAdapt(new VarHandleSegmentAsDoubles(be, alignmentMask, exact));
         } else {
             throw new IllegalStateException("Cannot get here");
         }