Eliminate redundant array bound checks (checks already performed earlier in the DT).

test/mjsunit/array-bounds-check-removal.js

Index: test/mjsunit/array-bounds-check-removal.js
diff --git a/test/mjsunit/array-bounds-check-removal.js b/test/mjsunit/array-bounds-check-removal.js
new file mode 100644
index 0000000000000000000000000000000000000000..81064aa2377ffcf6ba79a94b92f87eae89f31343
--- /dev/null
+++ b/test/mjsunit/array-bounds-check-removal.js
@@ -0,0 +1,145 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --allow-natives-syntax --expose-gc
+
+var a = new Int32Array(1024);
+
+function test_base(base,cond) {
+  a[base + 1] = 1;
+  a[base + 4] = 2;
+  a[base + 3] = 3;
+  a[base + 2] = 4;
+  a[base + 4] = base + 4;
+  if (cond) {
+    a[base + 1] = 1;
+    a[base + 2] = 2;
+    a[base + 2] = 3;
+    a[base + 2] = 4;
+    a[base + 4] = base + 4;
+  } else {
+    a[base + 6] = 1;
+    a[base + 4] = 2;
+    a[base + 3] = 3;
+    a[base + 2] = 4;
+    a[base + 4] = base - 4;
+  }
+}
+
+function check_test_base(base,cond) {
+  if (cond) {
+    assertEquals(1, a[base + 1]);
+    assertEquals(4, a[base + 2]);
+    assertEquals(base + 4, a[base + 4]);
+  } else {
+    assertEquals(1, a[base + 6]);
+    assertEquals(3, a[base + 3]);
+    assertEquals(4, a[base + 2]);
+    assertEquals(base - 4, a[base + 4]);
+  }
+}
+
+
+function test_minus(base,cond) {
+  a[base - 1] = 1;
+  a[base - 2] = 2;
+  a[base + 4] = 3;
+  a[base] = 4;
+  a[base + 4] = base + 4;
+  if (cond) {
+    a[base - 4] = 1;
+    a[base + 5] = 2;
+    a[base + 3] = 3;
+    a[base + 2] = 4;
+    a[base + 4] = base + 4;
+  } else {
+    a[base + 6] = 1;
+    a[base + 4] = 2;
+    a[base + 3] = 3;
+    a[base + 2] = 4;
+    a[base + 4] = base - 4;
+  }
+}
+
+function check_test_minus(base,cond) {
+  if (cond) {
+    assertEquals(2, a[base + 5]);
+    assertEquals(3, a[base + 3]);
+    assertEquals(4, a[base + 2]);
+    assertEquals(base + 4, a[base + 4]);
+  } else {
+    assertEquals(1, a[base + 6]);
+    assertEquals(3, a[base + 3]);
+    assertEquals(4, a[base + 2]);
+    assertEquals(base - 4, a[base + 4]);
+  }
+}
+
+test_base(1,true);
+test_base(2,true);
+test_base(1,false);
+test_base(2,false);
+%OptimizeFunctionOnNextCall(test_base);
+test_base(3,true);
+check_test_base(3,true);
+test_base(3,false);
+check_test_base(3,false);
+
+test_minus(5,true);
+test_minus(6,true);
+%OptimizeFunctionOnNextCall(test_minus);
+test_minus(7,true);
+check_test_minus(7,true);
+test_minus(7,false);
+check_test_minus(7,false);
+
+// Optimization status:
+// YES: 1
+// NO: 2
+// ALWAYS: 3
+// NEVER: 4
+
+if (false) {
+test_base(5,true);
+test_base(6,true);
+test_base(5,false);
+test_base(6,false);
+%OptimizeFunctionOnNextCall(test_base);
+test_base(-2,true);
+assertTrue(%GetOptimizationStatus(test_base) != 1);
+
+test_base(5,true);
+test_base(6,true);
+test_base(5,false);
+test_base(6,false);
+%OptimizeFunctionOnNextCall(test_base);
+test_base(2048,true);
+assertTrue(%GetOptimizationStatus(test_base) != 1);
+}
+
+gc();

[fschneider, 2012/04/26 09:35:50]

Why do you need --expose-gc and a call gc() here?

+