Multiple Vector.slice over each other slow things down (#11945)

Fixes #11859 by unwrapping results of previous `Vector.slice` before doing another `slice`.

Author: JaroslavTulach

engine/runtime-benchmarks/src/main/java/org/enso/interpreter/bench/benchmarks/semantic/VectorBenchmarks.java

@@ -20,8 +20,8 @@
 
 @BenchmarkMode(Mode.AverageTime)
 @Fork(1)
-@Warmup(iterations = 3)
-@Measurement(iterations = 5)
+@Warmup(iterations = 3, time = 3, timeUnit = TimeUnit.SECONDS)
+@Measurement(iterations = 5, time = 2, timeUnit = TimeUnit.SECONDS)
 @OutputTimeUnit(TimeUnit.MILLISECONDS)
 @State(Scope.Benchmark)
 public class VectorBenchmarks {
@@ -35,10 +35,8 @@ public void initializeBenchmark(BenchmarkParams params) throws Exception {
     var benchmarkName = SrcUtil.findName(params);
     var code =
         """
-        import Standard.Base.Data.Vector.Builder
-        import Standard.Base.Data.Vector.Vector
+        from Standard.Base import all
         import Standard.Base.Data.Array_Proxy.Array_Proxy
-        from Standard.Base.Data.Boolean import False
 
         avg arr =
             sum acc i =
@@ -62,7 +60,16 @@ public void initializeBenchmark(BenchmarkParams params) throws Exception {
 
         to_vector arr = Vector.from_polyglot_array arr
         to_array vec = vec.to_array
-        slice vec = vec.slice
+        slice n vec start end =
+            initial = vec.slice start end
+
+            complicate round v = if round != 0 then complicate round-1 (v.slice 1 v.length) else
+                Runtime.assert v==initial
+                v
+
+            if n==0 then initial else
+                complicate n (0.up_to n).to_vector+initial
+
         fill_proxy proxy vec =
           size v =
             _ = v
@@ -91,7 +98,17 @@ public void initializeBenchmark(BenchmarkParams params) throws Exception {
         }
       case "averageOverSlice":
         {
-          this.arrayOfFibNumbers = getMethod.apply("slice").execute(self, vec, 1, length);
+          this.arrayOfFibNumbers = getMethod.apply("slice").execute(self, 0, vec, 1, length);
+          break;
+        }
+      case "averageOverSliceWrapped10":
+        {
+          this.arrayOfFibNumbers = getMethod.apply("slice").execute(self, 10, vec, 1, length);
+          break;
+        }
+      case "averageOverSliceWrapped100":
+        {
+          this.arrayOfFibNumbers = getMethod.apply("slice").execute(self, 100, vec, 1, length);
           break;
         }
       case "averageOverArray":
@@ -149,11 +166,24 @@ public void averageOverVector(Blackhole matter) {
     performBenchmark(matter);
   }
 
+  /** Measures performance of a single {@code Vector.slice}. */
   @Benchmark
   public void averageOverSlice(Blackhole matter) {
     performBenchmark(matter);
   }
 
+  /** Measures performance of {@code Vector.slice} applied ten times on the same array. */
+  @Benchmark
+  public void averageOverSliceWrapped10(Blackhole matter) {
+    performBenchmark(matter);
+  }
+
+  /** Measures performance of {@code Vector.slice} applied hundred times on the same array. */
+  @Benchmark
+  public void averageOverSliceWrapped100(Blackhole matter) {
+    performBenchmark(matter);
+  }
+
   @Benchmark
   public void averageOverPolyglotVector(Blackhole matter) {
     performBenchmark(matter);

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/vector/ArraySlice.java

@@ -29,26 +29,34 @@ final class ArraySlice extends EnsoObject {
   private final long start;
   private final long end;
 
-  private ArraySlice(Object storage, long start, long end) {
-    if (storage instanceof ArraySlice slice) {
+  private ArraySlice(Object base, long start, long end) {
+    var s = findStorage(base);
+    if (s instanceof ArraySlice slice) {
       this.storage = slice.storage;
       this.start = slice.start + start;
       this.end = Math.min(slice.end, slice.start + end);
     } else {
       if (CompilerDirectives.inInterpreter()) {
-        if (!InteropLibrary.getUncached().hasArrayElements(storage)) {
+        if (!InteropLibrary.getUncached().hasArrayElements(s)) {
           throw EnsoContext.get(null)
               .raiseAssertionPanic(
-                  null, "ArraySlice needs array-like delegate, but got: " + storage, null);
+                  null, "ArraySlice needs array-like delegate, but got: " + s, null);
         }
       }
-
-      this.storage = storage;
+      this.storage = s;
       this.start = start;
       this.end = end;
     }
   }
 
+  private static Object findStorage(Object storage) {
+    return switch (storage) {
+      case Vector.Generic gen -> gen.toArray();
+      case ArraySlice slice -> slice;
+      default -> storage;
+    };
+  }
+
   static Vector createOrNull(Object storage, long start, long this_length, long end) {
     long slice_start = Math.max(0, start);
     long slice_end = Math.min(this_length, end);