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sdk/runtime/lib/double.cc
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Alexander Markov 7a20b6b8d8 Option to truncate integers to 64 bits, part 1 (core VM changes) 
This changeset revises --limit-ints-to-64-bits option to
change range of integers from unlimited to int64.
On overflow, integer arithmetic operations silently wrap around and
discard extra bits. No Bigints are allocated in case of overflow.

This changeset is the 1st part in the series of changes, it revises the implementation of integer arithmetic operations. More changes will follow.

R=regis@google.com, zra@google.com

Issue: https://github.com/dart-lang/sdk/issues/30103
Review-Url: https://codereview.chromium.org/2974633003 .
2017-07-10 15:16:40 -07:00

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// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/bootstrap_natives.h"
#include "platform/math.h"
#include "vm/dart_entry.h"
#include "vm/double_conversion.h"
#include "vm/double_internals.h"
#include "vm/exceptions.h"
#include "vm/native_entry.h"
#include "vm/object.h"
#include "vm/runtime_entry.h" // DartModulo.
#include "vm/symbols.h"
namespace dart {
DECLARE_FLAG(bool, trace_intrinsified_natives);
DEFINE_NATIVE_ENTRY(Double_doubleFromInteger, 2) {
ASSERT(TypeArguments::CheckedHandle(arguments->NativeArgAt(0)).IsNull());
const Integer& value = Integer::CheckedHandle(arguments->NativeArgAt(1));
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_doubleFromInteger %s\n", value.ToCString());
}
return Double::New(value.AsDoubleValue());
}
DEFINE_NATIVE_ENTRY(Double_add, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_add %f + %f\n", left, right);
}
return Double::New(left + right);
}
DEFINE_NATIVE_ENTRY(Double_sub, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_sub %f - %f\n", left, right);
}
return Double::New(left - right);
}
DEFINE_NATIVE_ENTRY(Double_mul, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_mul %f * %f\n", left, right);
}
return Double::New(left * right);
}
DEFINE_NATIVE_ENTRY(Double_div, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_div %f / %f\n", left, right);
}
return Double::New(left / right);
}
static RawInteger* DoubleToInteger(double val, const char* error_msg) {
if (isinf(val) || isnan(val)) {
const Array& args = Array::Handle(Array::New(1));
args.SetAt(0, String::Handle(String::New(error_msg)));
Exceptions::ThrowByType(Exceptions::kUnsupported, args);
}
if (FLAG_limit_ints_to_64_bits) {
// TODO(alexmarkov): decide on the double-to-integer conversion semantics
// in truncating mode.
int64_t ival = 0;
if (val <= static_cast<double>(kMinInt64)) {
ival = kMinInt64;
} else if (val >= static_cast<double>(kMaxInt64)) {
ival = kMaxInt64;
} else { // Representable in int64_t.
ival = static_cast<int64_t>(val);
}
return Integer::New(ival);
}
if ((-1.0 < val) && (val < 1.0)) {
return Smi::New(0);
}
DoubleInternals internals = DoubleInternals(val);
ASSERT(!internals.IsSpecial()); // Only Infinity and NaN are special.
uint64_t significand = internals.Significand();
intptr_t exponent = internals.Exponent();
if (exponent <= 0) {
significand >>= -exponent;
exponent = 0;
} else if (exponent <= 10) {
// A double significand has at most 53 bits. The following shift will
// hence not overflow, and yield an integer of at most 63 bits.
significand <<= exponent;
exponent = 0;
}
// A significand has at most 63 bits (after the shift above).
// The cast to int64_t is hence safe.
int64_t ival = static_cast<int64_t>(significand);
if (internals.Sign() < 0) {
ival = -ival;
}
if (exponent == 0) {
// The double fits in a Smi or Mint.
return Integer::New(ival);
}
Integer& result = Integer::Handle();
result = Bigint::NewFromShiftedInt64(ival, exponent);
return result.AsValidInteger();
}
DEFINE_NATIVE_ENTRY(Double_trunc_div, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_trunc_div %f ~/ %f\n", left, right);
}
return DoubleToInteger(trunc(left / right),
"Result of truncating division is Infinity or NaN");
}
DEFINE_NATIVE_ENTRY(Double_modulo, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
return Double::New(DartModulo(left, right));
}
DEFINE_NATIVE_ENTRY(Double_remainder, 2) {
double left = Double::CheckedHandle(arguments->NativeArgAt(0)).value();
GET_NON_NULL_NATIVE_ARGUMENT(Double, right_object, arguments->NativeArgAt(1));
double right = right_object.value();
return Double::New(fmod_ieee(left, right));
}
DEFINE_NATIVE_ENTRY(Double_greaterThan, 2) {
const Double& left = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Double, right, arguments->NativeArgAt(1));
bool result = right.IsNull() ? false : (left.value() > right.value());
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_greaterThan %s > %s\n", left.ToCString(),
right.ToCString());
}
return Bool::Get(result).raw();
}
DEFINE_NATIVE_ENTRY(Double_greaterThanFromInteger, 2) {
const Double& right = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Integer, left, arguments->NativeArgAt(1));
return Bool::Get(left.AsDoubleValue() > right.value()).raw();
}
DEFINE_NATIVE_ENTRY(Double_equal, 2) {
const Double& left = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Double, right, arguments->NativeArgAt(1));
bool result = right.IsNull() ? false : (left.value() == right.value());
if (FLAG_trace_intrinsified_natives) {
OS::Print("Double_equal %s == %s\n", left.ToCString(), right.ToCString());
}
return Bool::Get(result).raw();
}
DEFINE_NATIVE_ENTRY(Double_equalToInteger, 2) {
const Double& left = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Integer, right, arguments->NativeArgAt(1));
return Bool::Get(left.value() == right.AsDoubleValue()).raw();
}
DEFINE_NATIVE_ENTRY(Double_round, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return Double::New(round(arg.value()));
}
DEFINE_NATIVE_ENTRY(Double_floor, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return Double::New(floor(arg.value()));
}
DEFINE_NATIVE_ENTRY(Double_ceil, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return Double::New(ceil(arg.value()));
}
DEFINE_NATIVE_ENTRY(Double_truncate, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return Double::New(trunc(arg.value()));
}
#if defined(HOST_OS_MACOS)
// MAC OSX math library produces old style cast warning.
#pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
DEFINE_NATIVE_ENTRY(Double_toInt, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return DoubleToInteger(arg.value(), "Infinity or NaN toInt");
}
DEFINE_NATIVE_ENTRY(Double_parse, 3) {
GET_NON_NULL_NATIVE_ARGUMENT(String, value, arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Integer, startValue, arguments->NativeArgAt(1));
GET_NON_NULL_NATIVE_ARGUMENT(Integer, endValue, arguments->NativeArgAt(2));
const intptr_t start = startValue.AsTruncatedUint32Value();
const intptr_t end = endValue.AsTruncatedUint32Value();
const intptr_t len = value.Length();
// Indices should be inside the string, and 0 <= start < end <= len.
if (0 <= start && start < end && end <= len) {
double double_value;
if (String::ParseDouble(value, start, end, &double_value)) {
return Double::New(double_value);
}
}
return Object::null();
}
DEFINE_NATIVE_ENTRY(Double_toString, 1) {
const Number& number = Number::CheckedHandle(arguments->NativeArgAt(0));
return number.ToString(Heap::kNew);
}
DEFINE_NATIVE_ENTRY(Double_toStringAsFixed, 2) {
// The boundaries are exclusive.
static const double kLowerBoundary = -1e21;
static const double kUpperBoundary = 1e21;
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Smi, fraction_digits, arguments->NativeArgAt(1));
double d = arg.value();
intptr_t fraction_digits_value = fraction_digits.Value();
if (0 <= fraction_digits_value && fraction_digits_value <= 20 &&
kLowerBoundary < d && d < kUpperBoundary) {
return DoubleToStringAsFixed(d, static_cast<int>(fraction_digits_value));
} else {
Exceptions::ThrowArgumentError(String::Handle(
String::New("Illegal arguments to double.toStringAsFixed")));
return Object::null();
}
}
DEFINE_NATIVE_ENTRY(Double_toStringAsExponential, 2) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Smi, fraction_digits, arguments->NativeArgAt(1));
double d = arg.value();
intptr_t fraction_digits_value = fraction_digits.Value();
if (-1 <= fraction_digits_value && fraction_digits_value <= 20) {
return DoubleToStringAsExponential(d,
static_cast<int>(fraction_digits_value));
} else {
Exceptions::ThrowArgumentError(String::Handle(
String::New("Illegal arguments to double.toStringAsExponential")));
return Object::null();
}
}
DEFINE_NATIVE_ENTRY(Double_toStringAsPrecision, 2) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
GET_NON_NULL_NATIVE_ARGUMENT(Smi, precision, arguments->NativeArgAt(1));
double d = arg.value();
intptr_t precision_value = precision.Value();
if (1 <= precision_value && precision_value <= 21) {
return DoubleToStringAsPrecision(d, static_cast<int>(precision_value));
} else {
Exceptions::ThrowArgumentError(String::Handle(
String::New("Illegal arguments to double.toStringAsPrecision")));
return Object::null();
}
}
DEFINE_NATIVE_ENTRY(Double_getIsInfinite, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return Bool::Get(isinf(arg.value())).raw();
}
DEFINE_NATIVE_ENTRY(Double_getIsNaN, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
return Bool::Get(isnan(arg.value())).raw();
}
DEFINE_NATIVE_ENTRY(Double_getIsNegative, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
// Include negative zero, infinity.
double dval = arg.value();
return Bool::Get(signbit(dval) && !isnan(dval)).raw();
}
DEFINE_NATIVE_ENTRY(Double_flipSignBit, 1) {
const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
const double in_val = arg.value();
const int64_t bits = bit_cast<int64_t, double>(in_val) ^ kSignBitDouble;
return Double::New(bit_cast<double, int64_t>(bits));
}
// Add here only functions using/referring to old-style casts.
} // namespace dart
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