1 // Copyright 2018 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_OBJECTS_HEAP_NUMBER_H_ 6 #define V8_OBJECTS_HEAP_NUMBER_H_ 7 8 #include "src/objects/primitive-heap-object.h" 9 10 // Has to be the last include (doesn't have include guards): 11 #include "src/objects/object-macros.h" 12 13 namespace v8 { 14 namespace internal { 15 16 #include "torque-generated/src/objects/heap-number-tq.inc" 17 18 // The HeapNumber class describes heap allocated numbers that cannot be 19 // represented in a Smi (small integer). 20 class HeapNumber 21 : public TorqueGeneratedHeapNumber<HeapNumber, PrimitiveHeapObject> { 22 public: 23 // Since the value is read from the compiler, and it can't be done 24 // atomically, we signal both to TSAN and ourselves that this is a 25 // relaxed load and store. 26 inline uint64_t value_as_bits(RelaxedLoadTag) const; 27 inline void set_value_as_bits(uint64_t bits, RelaxedStoreTag); 28 29 inline int get_exponent(); 30 inline int get_sign(); 31 32 // Layout description. 33 // IEEE doubles are two 32 bit words. The first is just mantissa, the second 34 // is a mixture of sign, exponent and mantissa. The offsets of two 32 bit 35 // words within double numbers are endian dependent and they are set 36 // accordingly. 37 #if defined(V8_TARGET_LITTLE_ENDIAN) 38 static const int kMantissaOffset = kValueOffset; 39 static const int kExponentOffset = kValueOffset + 4; 40 #elif defined(V8_TARGET_BIG_ENDIAN) 41 static const int kMantissaOffset = kValueOffset + 4; 42 static const int kExponentOffset = kValueOffset; 43 #else 44 #error Unknown byte ordering 45 #endif 46 47 static const uint32_t kSignMask = 0x80000000u; 48 static const uint32_t kExponentMask = 0x7ff00000u; 49 static const uint32_t kMantissaMask = 0xfffffu; 50 static const int kMantissaBits = 52; 51 static const int kExponentBits = 11; 52 static const int kExponentBias = 1023; 53 static const int kExponentShift = 20; 54 static const int kInfinityOrNanExponent = 55 (kExponentMask >> kExponentShift) - kExponentBias; 56 static const int kMantissaBitsInTopWord = 20; 57 static const int kNonMantissaBitsInTopWord = 12; 58 59 DECL_PRINTER(HeapNumber) 60 V8_EXPORT_PRIVATE void HeapNumberShortPrint(std::ostream& os); 61 62 class BodyDescriptor; 63 64 TQ_OBJECT_CONSTRUCTORS(HeapNumber) 65 }; 66 67 } // namespace internal 68 } // namespace v8 69 70 #include "src/objects/object-macros-undef.h" 71 72 #endif // V8_OBJECTS_HEAP_NUMBER_H_ 73