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 #include "src/utils.h" 12 13 namespace v8 { 14 namespace internal { 15 16 // These are global assumptions in v8. 17 STATIC_ASSERT((static_cast<int32_t>(-1) >> 1) == -1); 18 STATIC_ASSERT((static_cast<uint32_t>(-1) >> 1) == 0x7FFFFFFF); 19 20 uint32_t float_sign(float val); 21 uint32_t float_exp(float val); 22 uint32_t float_mantissa(float val); 23 uint32_t double_sign(double val); 24 uint32_t double_exp(double val); 25 uint64_t double_mantissa(double val); 26 27 float float_pack(uint32_t sign, uint32_t exp, uint32_t mantissa); 28 double double_pack(uint64_t sign, uint64_t exp, uint64_t mantissa); 29 30 // An fpclassify() function for 16-bit half-precision floats. 31 int float16classify(float16 value); 32 33 // Bit counting. 34 int CountLeadingZeros(uint64_t value, int width); 35 int CountLeadingSignBits(int64_t value, int width); 36 int CountTrailingZeros(uint64_t value, int width); 37 int CountSetBits(uint64_t value, int width); 38 int LowestSetBitPosition(uint64_t value); 39 int HighestSetBitPosition(uint64_t value); 40 uint64_t LargestPowerOf2Divisor(uint64_t value); 41 int MaskToBit(uint64_t mask); 42 43 44 template <typename T> 45 T ReverseBytes(T value, int block_bytes_log2) { 46 DCHECK((sizeof(value) == 4) || (sizeof(value) == 8)); 47 DCHECK((1U << block_bytes_log2) <= sizeof(value)); 48 // Split the 64-bit value into an 8-bit array, where b[0] is the least 49 // significant byte, and b[7] is the most significant. 50 uint8_t bytes[8]; 51 uint64_t mask = 0xff00000000000000; 52 for (int i = 7; i >= 0; i--) { 53 bytes[i] = (static_cast<uint64_t>(value) & mask) >> (i * 8); 54 mask >>= 8; 55 } 56 57 // Permutation tables for REV instructions. 58 // permute_table[0] is used by REV16_x, REV16_w 59 // permute_table[1] is used by REV32_x, REV_w 60 // permute_table[2] is used by REV_x 61 DCHECK((0 < block_bytes_log2) && (block_bytes_log2 < 4)); 62 static const uint8_t permute_table[3][8] = {{6, 7, 4, 5, 2, 3, 0, 1}, 63 {4, 5, 6, 7, 0, 1, 2, 3}, 64 {0, 1, 2, 3, 4, 5, 6, 7}}; 65 T result = 0; 66 for (int i = 0; i < 8; i++) { 67 result <<= 8; 68 result |= bytes[permute_table[block_bytes_log2 - 1][i]]; 69 } 70 return result; 71 } 72 73 74 // NaN tests. 75 inline bool IsSignallingNaN(double num) { 76 uint64_t raw = bit_cast<uint64_t>(num); 77 if (std::isnan(num) && ((raw & kDQuietNanMask) == 0)) { 78 return true; 79 } 80 return false; 81 } 82 83 84 inline bool IsSignallingNaN(float num) { 85 uint32_t raw = bit_cast<uint32_t>(num); 86 if (std::isnan(num) && ((raw & kSQuietNanMask) == 0)) { 87 return true; 88 } 89 return false; 90 } 91 92 inline bool IsSignallingNaN(float16 num) { 93 const uint16_t kFP16QuietNaNMask = 0x0200; 94 return (float16classify(num) == FP_NAN) && ((num & kFP16QuietNaNMask) == 0); 95 } 96 97 template <typename T> 98 inline bool IsQuietNaN(T num) { 99 return std::isnan(num) && !IsSignallingNaN(num); 100 } 101 102 103 // Convert the NaN in 'num' to a quiet NaN. 104 inline double ToQuietNaN(double num) { 105 DCHECK(std::isnan(num)); 106 return bit_cast<double>(bit_cast<uint64_t>(num) | kDQuietNanMask); 107 } 108 109 110 inline float ToQuietNaN(float num) { 111 DCHECK(std::isnan(num)); 112 return bit_cast<float>(bit_cast<uint32_t>(num) | 113 static_cast<uint32_t>(kSQuietNanMask)); 114 } 115 116 117 // Fused multiply-add. 118 inline double FusedMultiplyAdd(double op1, double op2, double a) { 119 return fma(op1, op2, a); 120 } 121 122 123 inline float FusedMultiplyAdd(float op1, float op2, float a) { 124 return fmaf(op1, op2, a); 125 } 126 127 } // namespace internal 128 } // namespace v8 129 130 #endif // V8_ARM64_UTILS_ARM64_H_ 131
