Line data Source code
1 : // Copyright 2014 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 : #include "src/base/bits.h"
6 :
7 : #include <limits>
8 :
9 : #include "src/base/logging.h"
10 : #include "src/base/safe_math.h"
11 :
12 : namespace v8 {
13 : namespace base {
14 : namespace bits {
15 :
16 18827083 : uint32_t RoundUpToPowerOfTwo32(uint32_t value) {
17 : DCHECK_LE(value, 0x80000000u);
18 18827083 : value = value - 1;
19 18827083 : value = value | (value >> 1);
20 18827083 : value = value | (value >> 2);
21 18827083 : value = value | (value >> 4);
22 18827083 : value = value | (value >> 8);
23 18827083 : value = value | (value >> 16);
24 18827083 : return value + 1;
25 : }
26 :
27 :
28 1280 : int32_t SignedMulHigh32(int32_t lhs, int32_t rhs) {
29 2655 : int64_t const value = static_cast<int64_t>(lhs) * static_cast<int64_t>(rhs);
30 3935 : return bit_cast<int32_t, uint32_t>(bit_cast<uint64_t>(value) >> 32u);
31 : }
32 :
33 :
34 1375 : int32_t SignedMulHighAndAdd32(int32_t lhs, int32_t rhs, int32_t acc) {
35 1375 : return bit_cast<int32_t>(bit_cast<uint32_t>(acc) +
36 1375 : bit_cast<uint32_t>(SignedMulHigh32(lhs, rhs)));
37 : }
38 :
39 :
40 23231 : int32_t SignedDiv32(int32_t lhs, int32_t rhs) {
41 23231 : if (rhs == 0) return 0;
42 23180 : if (rhs == -1) return -lhs;
43 22758 : return lhs / rhs;
44 : }
45 :
46 :
47 42688 : int32_t SignedMod32(int32_t lhs, int32_t rhs) {
48 42688 : if (rhs == 0 || rhs == -1) return 0;
49 42486 : return lhs % rhs;
50 : }
51 :
52 :
53 0 : int64_t FromCheckedNumeric(const internal::CheckedNumeric<int64_t> value) {
54 245401 : if (value.IsValid())
55 : return value.ValueUnsafe();
56 :
57 : // We could return max/min but we don't really expose what the maximum delta
58 : // is. Instead, return max/(-max), which is something that clients can reason
59 : // about.
60 : // TODO(rvargas) crbug.com/332611: don't use internal values.
61 : int64_t limit = std::numeric_limits<int64_t>::max();
62 0 : if (value.validity() == internal::RANGE_UNDERFLOW)
63 : limit = -limit;
64 0 : return value.ValueOrDefault(limit);
65 : }
66 :
67 :
68 245401 : int64_t SignedSaturatedAdd64(int64_t lhs, int64_t rhs) {
69 : internal::CheckedNumeric<int64_t> rv(lhs);
70 : rv += rhs;
71 245401 : return FromCheckedNumeric(rv);
72 : }
73 :
74 :
75 0 : int64_t SignedSaturatedSub64(int64_t lhs, int64_t rhs) {
76 : internal::CheckedNumeric<int64_t> rv(lhs);
77 : rv -= rhs;
78 0 : return FromCheckedNumeric(rv);
79 : }
80 :
81 117814 : bool SignedMulOverflow32(int32_t lhs, int32_t rhs, int32_t* val) {
82 : internal::CheckedNumeric<int32_t> rv(lhs);
83 : rv *= rhs;
84 : int32_t limit = std::numeric_limits<int32_t>::max();
85 117814 : *val = rv.ValueOrDefault(limit);
86 117814 : return !rv.IsValid();
87 : }
88 :
89 0 : bool SignedMulOverflow64(int64_t lhs, int64_t rhs, int64_t* val) {
90 : internal::CheckedNumeric<int64_t> rv(lhs);
91 : rv *= rhs;
92 : int64_t limit = std::numeric_limits<int64_t>::max();
93 0 : *val = rv.ValueOrDefault(limit);
94 0 : return !rv.IsValid();
95 : }
96 :
97 : } // namespace bits
98 : } // namespace base
99 : } // namespace v8
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