Cache the results of slow math operations on machines that don't

have hardware fpu instructions to execute them.
Review URL: http://codereview.chromium.org/179059

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2790 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -257,6 +257,7 @@ void Heap::ReportStatisticsAfterGC() {
 
 
 void Heap::GarbageCollectionPrologue() {
+  TranscendentalCache::Clear();
   gc_count_++;
 #ifdef DEBUG
   ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
@@ -3986,4 +3987,30 @@ bool Heap::GarbageCollectionGreedyCheck() {
 }
 #endif
 
+
+TranscendentalCache::TranscendentalCache(TranscendentalCache::Type t)
+  : type_(t) {
+  uint32_t in0 = 0xffffffffu;  // Bit-pattern for a NaN that isn't
+  uint32_t in1 = 0xffffffffu;  // generated by the FPU.
+  for (int i = 0; i < kCacheSize; i++) {
+    elements_[i].in[0] = in0;
+    elements_[i].in[1] = in1;
+    elements_[i].output = NULL;
+  }
+}
+
+
+TranscendentalCache* TranscendentalCache::caches_[kNumberOfCaches];
+
+
+void TranscendentalCache::Clear() {
+  for (int i = 0; i < kNumberOfCaches; i++) {
+    if (caches_[i] != NULL) {
+      delete caches_[i];
+      caches_[i] = NULL;
+    }
+  }
+}
+
+
 } }  // namespace v8::internal

src/heap.h

@@ -28,8 +28,11 @@
 #ifndef V8_HEAP_H_
 #define V8_HEAP_H_
 
+#include <math.h>
+
 #include "zone-inl.h"
 
+
 namespace v8 {
 namespace internal {
 
@@ -1519,6 +1522,91 @@ class GCTracer BASE_EMBEDDED {
   int previous_marked_count_;
 };
 
+
+class TranscendentalCache {
+ public:
+  enum Type {ACOS, ASIN, ATAN, COS, EXP, LOG, SIN, TAN, kNumberOfCaches};
+
+  explicit TranscendentalCache(Type t);
+
+  // Returns a heap number with f(input), where f is a math function specified
+  // by the 'type' argument.
+  static inline Object* Get(Type type, double input) {
+    TranscendentalCache* cache = caches_[type];
+    if (cache == NULL) {
+      caches_[type] = cache = new TranscendentalCache(type);
+    }
+    return cache->Get(input);
+  }
+
+  // The cache contains raw Object pointers.  This method disposes of
+  // them before a garbage collection.
+  static void Clear();
+
+ private:
+  inline Object* Get(double input) {
+    Converter c;
+    c.dbl = input;
+    int hash = Hash(c);
+    Element e = elements_[hash];
+    if (e.in[0] == c.integers[0] &&
+        e.in[1] == c.integers[1]) {
+      ASSERT(e.output != NULL);
+      return e.output;
+    }
+    double answer = Calculate(input);
+    Object* heap_number = Heap::AllocateHeapNumber(answer);
+    if (!heap_number->IsFailure()) {
+      elements_[hash].in[0] = c.integers[0];
+      elements_[hash].in[1] = c.integers[1];
+      elements_[hash].output = heap_number;
+    }
+    return heap_number;
+  }
+
+  inline double Calculate(double input) {
+    switch (type_) {
+      case ACOS:
+        return acos(input);
+      case ASIN:
+        return asin(input);
+      case ATAN:
+        return atan(input);
+      case COS:
+        return cos(input);
+      case EXP:
+        return exp(input);
+      case LOG:
+        return log(input);
+      case SIN:
+        return sin(input);
+      case TAN:
+        return tan(input);
+      default:
+        return 0.0;  // Never happens.
+    }
+  }
+  static const int kCacheSize = 512;
+  struct Element {
+    uint32_t in[2];
+    Object* output;
+  };
+  union Converter {
+    double dbl;
+    uint32_t integers[2];
+  };
+  inline static int Hash(const Converter& c) {
+    uint32_t hash = (c.integers[0] ^ c.integers[1]);
+    hash ^= hash >> 16;
+    hash ^= hash >> 8;
+    return (hash & (kCacheSize - 1));
+  }
+  static TranscendentalCache* caches_[kNumberOfCaches];
+  Element elements_[kCacheSize];
+  Type type_;
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_

src/runtime.cc

@@ -4058,7 +4058,7 @@ static Object* Runtime_Math_acos(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(acos(x));
+  return TranscendentalCache::Get(TranscendentalCache::ACOS, x);
 }
 
 
@@ -4067,7 +4067,7 @@ static Object* Runtime_Math_asin(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(asin(x));
+  return TranscendentalCache::Get(TranscendentalCache::ASIN, x);
 }
 
 
@@ -4076,7 +4076,7 @@ static Object* Runtime_Math_atan(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(atan(x));
+  return TranscendentalCache::Get(TranscendentalCache::ATAN, x);
 }
 
 
@@ -4117,7 +4117,7 @@ static Object* Runtime_Math_cos(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(cos(x));
+  return TranscendentalCache::Get(TranscendentalCache::COS, x);
 }
 
 
@@ -4126,7 +4126,7 @@ static Object* Runtime_Math_exp(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(exp(x));
+  return TranscendentalCache::Get(TranscendentalCache::EXP, x);
 }
 
 
@@ -4144,7 +4144,7 @@ static Object* Runtime_Math_log(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(log(x));
+  return TranscendentalCache::Get(TranscendentalCache::LOG, x);
 }
 
 
@@ -4232,7 +4232,7 @@ static Object* Runtime_Math_sin(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(sin(x));
+  return TranscendentalCache::Get(TranscendentalCache::SIN, x);
 }
 
 
@@ -4250,7 +4250,7 @@ static Object* Runtime_Math_tan(Arguments args) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
-  return Heap::AllocateHeapNumber(tan(x));
+  return TranscendentalCache::Get(TranscendentalCache::TAN, x);
 }
 
 

test/mjsunit/transcendentals.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.
+
+
+// Two fp numbers that have the same hash value (see TranscendentalCache
+// in heap.h).
+var x = 0x123456789ABCD;
+var y = 0x1134567899BCD;
+
+assertEquals(-0.5582508193778007, Math.sin(x));
+assertEquals(-0.7367701055966746, Math.sin(y));
+
+assertEquals(-0.8296722380940645, Math.cos(x));
+assertEquals(-0.6761433365042245, Math.cos(y));
+
+assertEquals(0.6728570557696649, Math.tan(x));
+assertEquals(1.0896655573149632, Math.tan(y));
+
+assertEquals(33.400141709152514, Math.log(x));
+assertEquals(33.343643692997280, Math.log(y));
+
+// These also have the same hash value but they are < 1 so they can be
+// used for the asin and other functions.
+x = 0x123456789ABCD / 0x2000000000000;
+y = 0x1134567899BCD / 0x2000000000000;
+
+assertEquals(0.6051541873165459, Math.asin(x));
+assertEquals(0.5676343396849298, Math.asin(y));
+
+assertEquals(0.9656421394783508, Math.acos(x));
+assertEquals(1.0031619871099668, Math.acos(y));
+
+assertEquals(0.5172294898564562, Math.atan(x));
+assertEquals(0.4933034078249788, Math.atan(y));
+
+assertEquals(1.7663034013841883, Math.exp(x));
+assertEquals(1.7119599587777090, Math.exp(y));
+
+print("OK");