[builtins] Make Math.ceil, Math.trunc and Math.round optimizable.

src/runtime/runtime-maths.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/assembler.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/bootstrapper.h"
@@ skipping 143 matching lines @@
   if (y == 0) {
     return Smi::FromInt(1);
   } else {
     double result = power_double_double(x, y);
     if (std::isnan(result)) return isolate->heap()->nan_value();
     return *isolate->factory()->NewNumber(result);
   }
 }
 
 
-RUNTIME_FUNCTION(Runtime_RoundNumber) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 1);
-  CONVERT_NUMBER_ARG_HANDLE_CHECKED(input, 0);
-  isolate->counters()->math_round_runtime()->Increment();
-
-  if (!input->IsHeapNumber()) {
-    DCHECK(input->IsSmi());
-    return *input;
-  }
-
-  Handle<HeapNumber> number = Handle<HeapNumber>::cast(input);
-
-  double value = number->value();
-  int exponent = number->get_exponent();
-  int sign = number->get_sign();
-
-  if (exponent < -1) {
-    // Number in range ]-0.5..0.5[. These always round to +/-zero.
-    if (sign) return isolate->heap()->minus_zero_value();
-    return Smi::FromInt(0);
-  }
-
-  // We compare with kSmiValueSize - 2 because (2^30 - 0.1) has exponent 29 and
-  // should be rounded to 2^30, which is not smi (for 31-bit smis, similar
-  // argument holds for 32-bit smis).
-  if (!sign && exponent < kSmiValueSize - 2) {
-    return Smi::FromInt(static_cast<int>(value + 0.5));
-  }
-
-  // If the magnitude is big enough, there's no place for fraction part. If we
-  // try to add 0.5 to this number, 1.0 will be added instead.
-  if (exponent >= 52) {
-    return *number;
-  }
-
-  if (sign && value >= -0.5) return isolate->heap()->minus_zero_value();
-
-  // Do not call NumberFromDouble() to avoid extra checks.
-  return *isolate->factory()->NewNumber(Floor(value + 0.5));
-}
-
-
 RUNTIME_FUNCTION(Runtime_GenerateRandomNumbers) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   if (isolate->serializer_enabled()) {
     // Random numbers in the snapshot are not really that random. And we cannot
     // return a typed array as it cannot be serialized. To make calling
     // Math.random possible when creating a custom startup snapshot, we simply
     // return a normal array with a single random number.
     Handle<HeapNumber> random_number = isolate->factory()->NewHeapNumber(
         isolate->random_number_generator()->NextDouble());
@@ skipping 37 matching lines @@
     base::RandomNumberGenerator::XorShift128(&state0, &state1);
     array[i] = base::RandomNumberGenerator::ToDouble(state0, state1);
   }
   // Persist current state.
   array[kState0Offset] = uint64_to_double(state0);
   array[kState1Offset] = uint64_to_double(state1);
   return *typed_array;
 }
 }  // namespace internal
 }  // namespace v8