src/jdk.incubator.vector/share/classes/jdk/incubator/vector/VectorIntrinsics.java

@@ -52,10 +52,20 @@
              case 2: return Objects.checkIndex(ix, length - (vlen - 1));
              default: throw new InternalError();
          }
      }
  
+     @ForceInline
+     static long checkFromIndexSize(long ix, long vlen, long length) {
+         switch (VectorIntrinsics.VECTOR_ACCESS_OOB_CHECK) {
+             case 0: return ix; // no range check
+             case 1: return Objects.checkFromIndexSize(ix, vlen, length);
+             case 2: return Objects.checkIndex(ix, length - (vlen - 1));
+             default: throw new InternalError();
+         }
+     }
+ 
      @ForceInline
      static IntVector checkIndex(IntVector vix, int length) {
          switch (VectorIntrinsics.VECTOR_ACCESS_OOB_CHECK) {
              case 0: return vix; // no range check
              case 1: // fall-through

@@ -90,13 +100,34 @@
      }
      private static int roundDownNPOT(int index, int size) {
          if (index >= 0) {
              return index - (index % size);
          } else {
-             return index - Math.floorMod(index, Math.abs(size));
+             return index - Math.floorMod(index, size);
          }
      }
+ 
+     // If the index is not already a multiple of size,
+     // round it down to the next smaller multiple of size.
+     // It is an error if size is less than zero.
+     @ForceInline
+     static long roundDown(long index, int size) {
+         if ((size & (size - 1)) == 0) {
+             // Size is zero or a power of two, so we got this.
+             return index & ~(size - 1);
+         } else {
+             return roundDownNPOT(index, size);
+         }
+     }
+     private static long roundDownNPOT(long index, int size) {
+         if (index >= 0) {
+             return index - (index % size);
+         } else {
+             return index - Math.floorMod(index, size);
+         }
+     }
+ 
      @ForceInline
      static int wrapToRange(int index, int size) {
          if ((size & (size - 1)) == 0) {
              // Size is zero or a power of two, so we got this.
              return index & (size - 1);