Add some test cases with dead loops.

BUG=
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/98323004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18242 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/compiler/dead-loops-neg.js

+// Copyright 2013 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
+
+// Presents negative opportunities for dead loop removal.
+
+function loop1() {
+  while (true) return;
+}
+
+function loop2() {
+  var i = 0;
+  while (i++ < 10) ;
+  return i;  // value of {i} escapes.
+  // can only remove the loop with induction variable analysis.
+}
+
+function loop3() {
+  var i = 0;
+  for (; i < 10; i++) ;
+  return i;  // value of {i} escapes.
+  // can only remove the loop with induction variable analysis.
+}
+
+function loop4() {
+  var a = 0;
+  for (var i = 0; i < 10; i++) a++;
+  return a;  // value of {a} escapes.
+  // can only remove the loop with induction variable analysis.
+}
+
+function loop5() {
+  var a = new Int32Array(4), sum = 0;
+  for (var i = 0; i < a.length; i++) {
+    sum += a[i];
+  }
+  return sum;  // {sum} escapes.
+  // can only remove the loop by figuring out that all elements of {a} are 0.
+}
+
+function loop6(a) {
+  for (var i = 0; i < a; i++) ;  // implicit a.valueOf().
+  // can only remove the loop by guarding on the type of a.
+}
+
+function loop7(a) {
+  for (var i = 0; i < 10; i++) a.toString();  // unknown side-effect on a.
+  // can only remove the loop by guarding on the type of a.
+}
+
+function loop8(a) {
+  for (var i = 0; i < 10; i++) a.valueOf();  // unknown side-effect on a.
+  // can only remove the loop by guarding on the type of a.
+}
+
+var no_params_loops = [loop1, loop2, loop3, loop4, loop5, loop6];
+var params_loops = [loop6, loop7, loop8];
+
+for (var i = 0; i < no_params_loops.length; i++) {
+  var f = no_params_loops[i];
+  f();
+  f();
+  f();
+  %OptimizeFunctionOnNextCall(f);
+  f();
+}
+
+for (var i = 0; i < params_loops.length; i++) {
+  var f = params_loops[i];
+  f(3);
+  f(7);
+  f(11);
+  %OptimizeFunctionOnNextCall(f);
+  f(9);
+}

test/mjsunit/compiler/dead-loops.js

+// Copyright 2013 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
+
+// Presents opportunities for dead loop removal.
+
+function loop1() {
+  while (false) ;  // doesn't even loop.
+}
+
+function loop2() {
+  var i = 0;
+  while (i++ < 10) ;  // nothing in the body.
+}
+
+function loop3() {
+  for (var i = 0; i < 10; i++) ;  // nothing in the body.
+}
+
+function loop4() {
+  var a = 0;
+  for (var i = 0; i < 10; i++) a++;  // {a} is dead after the loop.
+}
+
+function loop5() {
+  var a = new Int32Array(4), sum = 0;
+  for (var i = 0; i < a.length; i++) {
+    // Involves only reads on typed arrays, and {i} doesn't overflow.
+    sum += a[i];
+  }
+}
+
+function loop6() {
+  var a = new Array(4), sum = 0;
+  for (var i = 0; i < a.length; i++) {
+    // Involves only in-bounds read on the array {a}.
+    // Have to prove that {a} doesn't have getters...?
+    sum += a[i];
+  }
+}
+
+function loop7() {
+  for (var i = 0; i < 10; i++) {
+    new Object();  // Have to prove the allocation doesn't escape.
+  }
+}
+
+function loop8() {
+  for (var i = 0; i < 10; i++) {
+    var x = {};  // Have to prove the allocation doesn't escape.
+  }
+}
+
+var loops = [loop1, loop2, loop3, loop4, loop5, loop6, loop7, loop8];
+
+for (var i = 0; i < loops.length; i++) {
+  var f = loops[i];
+  f();
+  f();
+  %OptimizeFunctionOnNextCall(f);
+  f();
+}