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_CODEGEN_ARM64_UTILS_ARM64_H_
6#define V8_CODEGEN_ARM64_UTILS_ARM64_H_
7
8#include <cmath>
9
10#include "src/codegen/arm64/constants-arm64.h"
11#include "src/utils/utils.h"
12
13namespace v8 {
14namespace internal {
15
16// These are global assumptions in v8.
17STATIC_ASSERT((static_cast<int32_t>(-1) >> 1) == -1);
18STATIC_ASSERT((static_cast<uint32_t>(-1) >> 1) == 0x7FFFFFFF);
19
20uint32_t float_sign(float val);
21uint32_t float_exp(float val);
22uint32_t float_mantissa(float val);
23uint32_t double_sign(double val);
24uint32_t double_exp(double val);
25uint64_t double_mantissa(double val);
26
27float float_pack(uint32_t sign, uint32_t exp, uint32_t mantissa);
28double double_pack(uint64_t sign, uint64_t exp, uint64_t mantissa);
29
30// An fpclassify() function for 16-bit half-precision floats.
31int float16classify(float16 value);
32
33// Bit counting.
34int CountLeadingZeros(uint64_t value, int width);
35int CountLeadingSignBits(int64_t value, int width);
36V8_EXPORT_PRIVATE int CountSetBits(uint64_t value, int width);
37int LowestSetBitPosition(uint64_t value);
38int HighestSetBitPosition(uint64_t value);
39uint64_t LargestPowerOf2Divisor(uint64_t value);
40int MaskToBit(uint64_t mask);
41
42template <typename T>
43T ReverseBytes(T value, int block_bytes_log2) {
44  DCHECK((sizeof(value) == 4) || (sizeof(value) == 8));
45  DCHECK((1ULL << block_bytes_log2) <= sizeof(value));
46  // Split the 64-bit value into an 8-bit array, where b[0] is the least
47  // significant byte, and b[7] is the most significant.
48  uint8_t bytes[8];
49  uint64_t mask = 0xff00000000000000;
50  for (int i = 7; i >= 0; i--) {
51    bytes[i] = (static_cast<uint64_t>(value) & mask) >> (i * 8);
52    mask >>= 8;
53  }
54
55  // Permutation tables for REV instructions.
56  //  permute_table[0] is used by REV16_x, REV16_w
57  //  permute_table[1] is used by REV32_x, REV_w
58  //  permute_table[2] is used by REV_x
59  DCHECK((0 < block_bytes_log2) && (block_bytes_log2 < 4));
60  static const uint8_t permute_table[3][8] = {{6, 7, 4, 5, 2, 3, 0, 1},
61                                              {4, 5, 6, 7, 0, 1, 2, 3},
62                                              {0, 1, 2, 3, 4, 5, 6, 7}};
63  typename std::make_unsigned<T>::type result = 0;
64  for (int i = 0; i < 8; i++) {
65    result <<= 8;
66    result |= bytes[permute_table[block_bytes_log2 - 1][i]];
67  }
68  return result;
69}
70
71// NaN tests.
72inline bool IsSignallingNaN(double num) {
73  uint64_t raw = bit_cast<uint64_t>(num);
74  if (std::isnan(num) && ((raw & kDQuietNanMask) == 0)) {
75    return true;
76  }
77  return false;
78}
79
80inline bool IsSignallingNaN(float num) {
81  uint32_t raw = bit_cast<uint32_t>(num);
82  if (std::isnan(num) && ((raw & kSQuietNanMask) == 0)) {
83    return true;
84  }
85  return false;
86}
87
88inline bool IsSignallingNaN(float16 num) {
89  const uint16_t kFP16QuietNaNMask = 0x0200;
90  return (float16classify(num) == FP_NAN) && ((num & kFP16QuietNaNMask) == 0);
91}
92
93template <typename T>
94inline bool IsQuietNaN(T num) {
95  return std::isnan(num) && !IsSignallingNaN(num);
96}
97
98// Convert the NaN in 'num' to a quiet NaN.
99inline double ToQuietNaN(double num) {
100  DCHECK(std::isnan(num));
101  return bit_cast<double>(bit_cast<uint64_t>(num) | kDQuietNanMask);
102}
103
104inline float ToQuietNaN(float num) {
105  DCHECK(std::isnan(num));
106  return bit_cast<float>(bit_cast<uint32_t>(num) |
107                         static_cast<uint32_t>(kSQuietNanMask));
108}
109
110// Fused multiply-add.
111inline double FusedMultiplyAdd(double op1, double op2, double a) {
112  return fma(op1, op2, a);
113}
114
115inline float FusedMultiplyAdd(float op1, float op2, float a) {
116  return fmaf(op1, op2, a);
117}
118
119}  // namespace internal
120}  // namespace v8
121
122#endif  // V8_CODEGEN_ARM64_UTILS_ARM64_H_
123