1 // Copyright 2013 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_ARM64_UTILS_ARM64_H_ 6 #define V8_ARM64_UTILS_ARM64_H_ 7 8 #include <cmath> 9 10 #include "src/arm64/constants-arm64.h" 11 12 namespace v8 { 13 namespace internal { 14 15 // These are global assumptions in v8. 16 STATIC_ASSERT((static_cast<int32_t>(-1) >> 1) == -1); 17 STATIC_ASSERT((static_cast<uint32_t>(-1) >> 1) == 0x7FFFFFFF); 18 19 // Floating point representation. 20 static inline uint32_t float_to_rawbits(float value) { 21 uint32_t bits = 0; 22 memcpy(&bits, &value, 4); 23 return bits; 24 } 25 26 27 static inline uint64_t double_to_rawbits(double value) { 28 uint64_t bits = 0; 29 memcpy(&bits, &value, 8); 30 return bits; 31 } 32 33 34 static inline float rawbits_to_float(uint32_t bits) { 35 float value = 0.0; 36 memcpy(&value, &bits, 4); 37 return value; 38 } 39 40 41 static inline double rawbits_to_double(uint64_t bits) { 42 double value = 0.0; 43 memcpy(&value, &bits, 8); 44 return value; 45 } 46 47 48 // Bit counting. 49 int CountLeadingZeros(uint64_t value, int width); 50 int CountLeadingSignBits(int64_t value, int width); 51 int CountTrailingZeros(uint64_t value, int width); 52 int CountSetBits(uint64_t value, int width); 53 uint64_t LargestPowerOf2Divisor(uint64_t value); 54 int MaskToBit(uint64_t mask); 55 56 57 template <typename T> 58 T ReverseBytes(T value, int block_bytes_log2) { 59 DCHECK((sizeof(value) == 4) || (sizeof(value) == 8)); 60 DCHECK((1U << block_bytes_log2) <= sizeof(value)); 61 // Split the 64-bit value into an 8-bit array, where b[0] is the least 62 // significant byte, and b[7] is the most significant. 63 uint8_t bytes[8]; 64 uint64_t mask = 0xff00000000000000; 65 for (int i = 7; i >= 0; i--) { 66 bytes[i] = (static_cast<uint64_t>(value) & mask) >> (i * 8); 67 mask >>= 8; 68 } 69 70 // Permutation tables for REV instructions. 71 // permute_table[0] is used by REV16_x, REV16_w 72 // permute_table[1] is used by REV32_x, REV_w 73 // permute_table[2] is used by REV_x 74 DCHECK((0 < block_bytes_log2) && (block_bytes_log2 < 4)); 75 static const uint8_t permute_table[3][8] = {{6, 7, 4, 5, 2, 3, 0, 1}, 76 {4, 5, 6, 7, 0, 1, 2, 3}, 77 {0, 1, 2, 3, 4, 5, 6, 7}}; 78 T result = 0; 79 for (int i = 0; i < 8; i++) { 80 result <<= 8; 81 result |= bytes[permute_table[block_bytes_log2 - 1][i]]; 82 } 83 return result; 84 } 85 86 87 // NaN tests. 88 inline bool IsSignallingNaN(double num) { 89 uint64_t raw = double_to_rawbits(num); 90 if (std::isnan(num) && ((raw & kDQuietNanMask) == 0)) { 91 return true; 92 } 93 return false; 94 } 95 96 97 inline bool IsSignallingNaN(float num) { 98 uint32_t raw = float_to_rawbits(num); 99 if (std::isnan(num) && ((raw & kSQuietNanMask) == 0)) { 100 return true; 101 } 102 return false; 103 } 104 105 106 template <typename T> 107 inline bool IsQuietNaN(T num) { 108 return std::isnan(num) && !IsSignallingNaN(num); 109 } 110 111 112 // Convert the NaN in 'num' to a quiet NaN. 113 inline double ToQuietNaN(double num) { 114 DCHECK(std::isnan(num)); 115 return rawbits_to_double(double_to_rawbits(num) | kDQuietNanMask); 116 } 117 118 119 inline float ToQuietNaN(float num) { 120 DCHECK(std::isnan(num)); 121 return rawbits_to_float(float_to_rawbits(num) | kSQuietNanMask); 122 } 123 124 125 // Fused multiply-add. 126 inline double FusedMultiplyAdd(double op1, double op2, double a) { 127 return fma(op1, op2, a); 128 } 129 130 131 inline float FusedMultiplyAdd(float op1, float op2, float a) { 132 return fmaf(op1, op2, a); 133 } 134 135 } // namespace internal 136 } // namespace v8 137 138 #endif // V8_ARM64_UTILS_ARM64_H_ 139
