Fix issue 397 and issue 399.

Review URL: http://codereview.chromium.org/149247

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2372 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/date-delay.js

@@ -427,6 +427,19 @@ function TimeClip(time) {
 }
 
 
+// The Date cache is used to limit the cost of parsing the same Date
+// strings over and over again.
+var Date_cache = {
+  // Cached time value.
+  time: $NaN,
+  // Cached year when interpreting the time as a local time. Only
+  // valid when the time matches cached time.
+  year: $NaN,
+  // String input for which the cached time is valid.
+  string: null
+};
+
+
 %SetCode($Date, function(year, month, date, hours, minutes, seconds, ms) {
   if (!%_IsConstructCall()) {
     // ECMA 262 - 15.9.2
@@ -442,6 +455,20 @@ function TimeClip(time) {
   } else if (argc == 1) {
     if (IS_NUMBER(year)) {
       value = TimeClip(year);
+
+    } else if (IS_STRING(year)) {
+      // Probe the Date cache. If we already have a time value for the
+      // given time, we re-use that instead of parsing the string again.
+      var cache = Date_cache;
+      if (cache.string === year) {
+        value = cache.time;
+      } else {
+        value = DateParse(year);
+        cache.time = value;
+        cache.year = YearFromTime(LocalTimeNoCheck(value));
+        cache.string = year;
+      }
+
     } else {
       // According to ECMA 262, no hint should be given for this
       // conversion. However, ToPrimitive defaults to STRING_HINT for
@@ -537,8 +564,9 @@ function GetUTCHoursFrom(aDate) {
 function GetFullYearFrom(aDate) {
   var t = DATE_VALUE(aDate);
   if (NUMBER_IS_NAN(t)) return t;
-  // Ignore the DST offset for year computations.
-  return YearFromTime(t + local_time_offset);
+  var cache = Date_cache;
+  if (cache.time === t) return cache.year;
+  return YearFromTime(LocalTimeNoCheck(t));
 }
 
 
@@ -634,7 +662,7 @@ function DatePrintString(time) {
 
 // -------------------------------------------------------------------
 
-// Reused output buffer.
+// Reused output buffer. Used when parsing date strings.
 var parse_buffer = $Array(7);
 
 // ECMA 262 - 15.9.4.2

src/runtime.cc

@@ -4155,16 +4155,21 @@ static Object* Runtime_Math_pow(Arguments args) {
   }
 
   CONVERT_DOUBLE_CHECKED(y, args[1]);
-  if (y == 0.5) {
-    // It's not uncommon to use Math.pow(x, 0.5) to compute the square
-    // root of a number. To speed up such computations, we explictly
-    // check for this case and use the sqrt() function which is faster
-    // than pow().
-    return Heap::AllocateHeapNumber(sqrt(x));
-  } else if (y == -0.5) {
-    // Optimized using Math.pow(x, -0.5) == 1 / Math.pow(x, 0.5).
-    return Heap::AllocateHeapNumber(1.0 / sqrt(x));
-  } else if (y == 0) {
+
+  if (!isinf(x)) {
+    if (y == 0.5) {
+      // It's not uncommon to use Math.pow(x, 0.5) to compute the
+      // square root of a number. To speed up such computations, we
+      // explictly check for this case and use the sqrt() function
+      // which is faster than pow().
+      return Heap::AllocateHeapNumber(sqrt(x));
+    } else if (y == -0.5) {
+      // Optimized using Math.pow(x, -0.5) == 1 / Math.pow(x, 0.5).
+      return Heap::AllocateHeapNumber(1.0 / sqrt(x));
+    }
+  }
+
+  if (y == 0) {
     return Smi::FromInt(1);
   } else if (isnan(y) || ((x == 1 || x == -1) && isinf(y))) {
     return Heap::nan_value();

test/mjsunit/regress/regress-397.js

+// Copyright 2009 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.
+
+// See http://code.google.com/p/v8/issues/detail?id=397
+
+assertEquals("Infinity", String(Math.pow(Infinity, 0.5)));
+assertEquals(0, Math.pow(Infinity, -0.5));
+
+assertEquals("Infinity", String(Math.pow(-Infinity, 0.5)));
+assertEquals(0, Math.pow(-Infinity, -0.5));

test/mjsunit/regress/regress-399.js

+// Copyright 2009 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.
+
+// See http://code.google.com/p/v8/issues/detail?id=399
+
+var date = new Date(1.009804e12);
+var year = String(date).match(/.*(200\d)/)[1];
+assertEquals(year, date.getFullYear());