Fix premature deoptimization if the loop body isn't entered.

Add a test between initial_ and end_ to see if the loop body is entered.
If the loop body isn't entered at all, we jump to the loop header. Loop header is
still executed and is going to test the condition again and loop body won't be
entered. This makes sure no deoptimization is triggered if the loop body isn't
even entered.

Bug: 21034044

(cherry picked from commit 3584bce5b1f45e5741d3a6ca24884a36320ecb6b)

Change-Id: I2b6de1f22fbc4568ca419f76382ebd87806d9694

1 files changed, 143 insertions, 24 deletions

diff --git a/test/449-checker-bce/src/Main.java b/test/449-checker-bce/src/Main.java
index f90d85dac3..7a45ce357d 100644
--- a/test/449-checker-bce/src/Main.java
+++ b/test/449-checker-bce/src/Main.java
@@ -617,15 +617,21 @@ public class Main {
   // CHECK: ArrayGet
 
   // CHECK-START: void Main.foo1(int[], int, int) BCE (after)
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK-NOT: BoundsCheck
   // CHECK: ArraySet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
 
   void foo1(int[] array, int start, int end) {
     // Three HDeoptimize will be added. One for
@@ -646,15 +652,21 @@ public class Main {
   // CHECK: ArrayGet
 
   // CHECK-START: void Main.foo2(int[], int, int) BCE (after)
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK-NOT: BoundsCheck
   // CHECK: ArraySet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
 
   void foo2(int[] array, int start, int end) {
     // Three HDeoptimize will be added. One for
@@ -675,14 +687,20 @@ public class Main {
   // CHECK: ArrayGet
 
   // CHECK-START: void Main.foo3(int[], int) BCE (after)
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK-NOT: BoundsCheck
   // CHECK: ArraySet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
 
   void foo3(int[] array, int end) {
     // Two HDeoptimize will be added. One for end < array.length,
@@ -694,6 +712,7 @@ public class Main {
     }
   }
 
+
   // CHECK-START: void Main.foo4(int[], int) BCE (before)
   // CHECK: BoundsCheck
   // CHECK: ArraySet
@@ -701,14 +720,20 @@ public class Main {
   // CHECK: ArrayGet
 
   // CHECK-START: void Main.foo4(int[], int) BCE (after)
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK-NOT: BoundsCheck
   // CHECK: ArraySet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
 
   void foo4(int[] array, int end) {
     // Two HDeoptimize will be added. One for end <= array.length,
@@ -734,8 +759,6 @@ public class Main {
   // CHECK-START: void Main.foo5(int[], int) BCE (after)
   // CHECK-NOT: BoundsCheck
   // CHECK: ArraySet
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
@@ -743,6 +766,15 @@ public class Main {
   // CHECK: ArrayGet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  //  array.length is defined before the loop header so no phi is needed.
+  // CHECK-NOT: Phi
+  // CHECK: Goto
 
   void foo5(int[] array, int end) {
     // Bounds check in this loop can be eliminated without deoptimization.
@@ -774,10 +806,6 @@ public class Main {
   // CHECK: ArraySet
 
   // CHECK-START: void Main.foo6(int[], int, int) BCE (after)
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
@@ -791,6 +819,17 @@ public class Main {
   // CHECK: ArrayGet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArraySet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
+  // CHECK-NOT: Deoptimize
 
   void foo6(int[] array, int start, int end) {
     // Three HDeoptimize will be added. One for
@@ -810,15 +849,21 @@ public class Main {
   // CHECK: ArrayGet
 
   // CHECK-START: void Main.foo7(int[], int, int, boolean) BCE (after)
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK: Deoptimize
-  // CHECK-NOT: Deoptimize
   // CHECK: Phi
   // CHECK: BoundsCheck
   // CHECK: ArrayGet
   // CHECK-NOT: BoundsCheck
   // CHECK: ArrayGet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
 
   void foo7(int[] array, int start, int end, boolean lowEnd) {
     // Three HDeoptimize will be added. One for
@@ -837,6 +882,73 @@ public class Main {
   }
 
 
+  // CHECK-START: void Main.foo8(int[][], int, int) BCE (before)
+  // CHECK: BoundsCheck
+  // CHECK: ArrayGet
+  // CHECK: BoundsCheck
+  // CHECK: ArraySet
+
+  // CHECK-START: void Main.foo8(int[][], int, int) BCE (after)
+  // CHECK: Phi
+  // CHECK-NOT: BoundsCheck
+  // CHECK: ArrayGet
+  // CHECK: Phi
+  // CHECK-NOT: BoundsCheck
+  // CHECK: ArraySet
+  //  Added blocks for deoptimization.
+  // CHECK: If
+  // CHECK: Goto
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Goto
+  // CHECK: Phi
+  // CHECK: Goto
+
+  void foo8(int[][] matrix, int start, int end) {
+    // Three HDeoptimize will be added for the outer loop.
+    // start >= 0, end <= matrix.length, and null check on matrix.
+    // Three HDeoptimize will be added for the inner loop
+    // start >= 0 (TODO: this may be optimized away),
+    // end <= row.length, and null check on row.
+    for (int i = start; i < end; i++) {
+      int[] row = matrix[i];
+      for (int j = start; j < end; j++) {
+        row[j] = 1;
+      }
+    }
+  }
+
+
+  // CHECK-START: void Main.foo9(int[]) BCE (before)
+  // CHECK: NullCheck
+  // CHECK: BoundsCheck
+  // CHECK: ArrayGet
+
+  // CHECK-START: void Main.foo9(int[]) BCE (after)
+  //  The loop is guaranteed to be entered. No need to transform the
+  //  loop for loop body entry test.
+  // CHECK: Deoptimize
+  // CHECK: Deoptimize
+  // CHECK-NOT: Deoptimize
+  // CHECK: Phi
+  // CHECK-NOT: NullCheck
+  // CHECK-NOT: BoundsCheck
+  // CHECK: ArrayGet
+
+  void foo9(int[] array) {
+    // Two HDeoptimize will be added. One for
+    // 10 <= array.length, and one for null check on array.
+    for (int i = 0 ; i < 10; i++) {
+      sum += array[i];
+    }
+  }
+
+
   // CHECK-START: void Main.partialLooping(int[], int, int) BCE (before)
   // CHECK: BoundsCheck
   // CHECK: ArraySet
@@ -951,6 +1063,13 @@ public class Main {
     main.foo6(new int[10], 2, 7);
 
     main = new Main();
+    int[] array9 = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+    main.foo9(array9);
+    if (main.sum != 45) {
+      System.out.println("foo9 failed!");
+    }
+
+    main = new Main();
     int[] array = new int[4];
     main.partialLooping(new int[3], 0, 4);
     if ((array[0] != 1) && (array[1] != 1) &&