Combine offsets in loop-based dynamic BCE.

Rationale:
Similar to what I did recently for dom-based dynamic BCE, this
CL combines offsets for the tests generated for loop-based
dynamic BCE. For a set of n references, this reduces the
number of generated tests from 2*n+1 down to at most 4
(in some cases even less).

TEST: 530-checker-loops3

BUG=27430379

Change-Id: Ic80c2563eaae23f514c1fd52965dd83bccb9d190
diff --git a/test/530-checker-loops3/src/Main.java b/test/530-checker-loops3/src/Main.java
new file mode 100644
index 0000000..5ffcbe9
--- /dev/null
+++ b/test/530-checker-loops3/src/Main.java
@@ -0,0 +1,327 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Test on loop optimizations, in particular dynamic BCE. In all cases,
+// bounds check on a[] is resolved statically. Bounds checks on b[]
+// exercise various different scenarios. In all cases, loop-based
+// dynamic BCE is better than the dominator-based BCE, since it
+// generates the test outside the loop.
+//
+public class Main {
+
+  /// CHECK-START: void Main.oneConstantIndex(int[], int[]) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.oneConstantIndex(int[], int[]) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.oneConstantIndex(int[], int[]) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void oneConstantIndex(int[] a, int[] b) {
+    // Dynamic bce on b requires two deopts: one null and one bound.
+    for (int i = 0; i < a.length; i++) {
+      a[i] = b[1];
+    }
+  }
+
+  /// CHECK-START: void Main.multipleConstantIndices(int[], int[]) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.multipleConstantIndices(int[], int[]) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.multipleConstantIndices(int[], int[]) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void multipleConstantIndices(int[] a, int[] b) {
+    // Dynamic bce on b requires two deopts: one null and one bound.
+    for (int i = 0; i < a.length; i++) {
+      a[i] = b[0] + b[1] + b[2];
+    }
+  }
+
+  /// CHECK-START: void Main.oneInvariantIndex(int[], int[], int) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.oneInvariantIndex(int[], int[], int) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.oneInvariantIndex(int[], int[], int) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void oneInvariantIndex(int[] a, int[] b, int c) {
+    // Dynamic bce on b requires two deopts: one null and one bound.
+    for (int i = 0; i < a.length; i++) {
+      a[i] = b[c];
+    }
+  }
+
+  /// CHECK-START: void Main.multipleInvariantIndices(int[], int[], int) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.multipleInvariantIndices(int[], int[], int) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.multipleInvariantIndices(int[], int[], int) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void multipleInvariantIndices(int[] a, int[] b, int c) {
+    // Dynamic bce on b requires three deopts: one null and two bounds.
+    for (int i = 0; i < a.length; i++) {
+      a[i] = b[c-1] + b[c] + b[c+1];
+    }
+  }
+
+  /// CHECK-START: void Main.oneUnitStride(int[], int[]) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.oneUnitStride(int[], int[]) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.oneUnitStride(int[], int[]) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void oneUnitStride(int[] a, int[] b) {
+    // Dynamic bce on b requires three deopts: one null and two bounds.
+    for (int i = 0; i < a.length; i++) {
+      a[i] = b[i];
+    }
+  }
+
+  /// CHECK-START: void Main.multipleUnitStrides(int[], int[]) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.multipleUnitStrides(int[], int[]) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.multipleUnitStrides(int[], int[]) instruction_simplifier_after_bce (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.multipleUnitStrides(int[], int[]) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void multipleUnitStrides(int[] a, int[] b) {
+    // Dynamic bce on b requires four deopts: one null and three bounds.
+    // One redundant deopt is removed by simplifier.
+    // TODO: range information could remove another
+    for (int i = 1; i < a.length - 1; i++) {
+      a[i] = b[i-1] + b[i] + b[i+1];
+    }
+  }
+
+  /// CHECK-START: void Main.multipleUnitStridesConditional(int[], int[]) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.multipleUnitStridesConditional(int[], int[]) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.multipleUnitStridesConditional(int[], int[]) instruction_simplifier_after_bce (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.multipleUnitStridesConditional(int[], int[]) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void multipleUnitStridesConditional(int[] a, int[] b) {
+    // Dynamic bce on b requires four deopts: one null and three bounds.
+    // The two conditional references may be included, since they are in range.
+    // One redundant deopt is removed by simplifier.
+    for (int i = 2; i < a.length - 2; i++) {
+      int t = b[i-2] + b[i] + b[i+2] + (((i & 1) == 0) ? b[i+1] : b[i-1]);
+      a[i] = t;
+    }
+  }
+
+  /// CHECK-START: void Main.shifter(int[]) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.shifter(int[]) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.shifter(int[]) instruction_simplifier_after_bce (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.shifter(int[]) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void shifter(int[] x) {
+    // Real-life example: should have four deopts: one null and three bounds.
+    // Two redundant deopts are removed by simplifier.
+    for (int i = 16; i < 80; i++) {
+      int t = x[i - 3] ^ x[i - 8] ^ x[i - 14] ^ x[i - 16];
+      x[i] = t << 1 | t >>> 31;
+    }
+  }
+
+  /// CHECK-START: void Main.stencil(int[], int, int) BCE (before)
+  /// CHECK-DAG: BoundsCheck loop:<<Loop:B\d+>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  /// CHECK-DAG: BoundsCheck loop:<<Loop>>
+  //
+  /// CHECK-START: void Main.stencil(int[], int, int) BCE (after)
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-DAG: Deoptimize loop:none
+  /// CHECK-NOT: Deoptimize
+  //
+  /// CHECK-START: void Main.stencil(int[], int, int) BCE (after)
+  /// CHECK-NOT: BoundsCheck
+  public static void stencil(int[] array, int start, int end) {
+    // Real-life example: should have four deopts: one null and three bounds.
+    for (int i = end; i >= start; i--) {
+      array[i] = (array[i-2] + array[i-1] + array[i] + array[i+1] + array[i+2]) / 5;
+    }
+  }
+
+  //
+  // Verifier.
+  //
+
+  public static void main(String[] args) {
+    int[] a = new int[10];
+    int b[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+    int b1[] = { 100 };
+
+    oneConstantIndex(a, b);
+    for (int i = 0; i < a.length; i++) {
+      expectEquals(2, a[i]);;
+    }
+    try {
+      oneConstantIndex(a, b1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+    }
+
+    multipleConstantIndices(a, b);
+    for (int i = 0; i < a.length; i++) {
+      expectEquals(6, a[i]);;
+    }
+    try {
+      multipleConstantIndices(a, b1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+    }
+
+    oneInvariantIndex(a, b, 1);
+    for (int i = 0; i < a.length; i++) {
+      expectEquals(2, a[i]);;
+    }
+    try {
+      oneInvariantIndex(a, b1, 1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+    }
+
+    multipleInvariantIndices(a, b, 1);
+    for (int i = 0; i < a.length; i++) {
+      expectEquals(6, a[i]);;
+    }
+    try {
+      multipleInvariantIndices(a, b1, 1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+    }
+
+    oneUnitStride(a, b);
+    for (int i = 0; i < a.length; i++) {
+      expectEquals(i + 1, a[i]);;
+    }
+    try {
+      oneUnitStride(a, b1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+      expectEquals(100, a[0]);;
+    }
+
+    multipleUnitStrides(a, b);
+    for (int i = 1; i < a.length - 1; i++) {
+      expectEquals(3 * i + 3, a[i]);;
+    }
+    try {
+      multipleUnitStrides(a, b1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+    }
+
+    multipleUnitStridesConditional(a, b);
+    for (int i = 2; i < a.length - 2; i++) {
+      int e = 3 * i + 3 + (((i & 1) == 0) ? i + 2 : i);
+      expectEquals(e, a[i]);;
+    }
+    try {
+      multipleUnitStridesConditional(a, b1);
+      throw new Error("Should throw AIOOBE");
+    } catch (ArrayIndexOutOfBoundsException e) {
+    }
+
+    System.out.println("passed");
+  }
+
+  private static void expectEquals(int expected, int result) {
+    if (expected != result) {
+      throw new Error("Expected: " + expected + ", found: " + result);
+    }
+  }
+}