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Side by Side Diff: base/numerics/saturated_arithmetic.h

Issue 2533113003: Add back missing ALWAYS_INLINE to saturated math (Closed)
Patch Set: Created 4 years ago
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1 // Copyright 2016 The Chromium Authors. All rights reserved. 1 // Copyright 2016 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef BASE_NUMERICS_SATURATED_ARITHMETIC_H_ 5 #ifndef BASE_NUMERICS_SATURATED_ARITHMETIC_H_
6 #define BASE_NUMERICS_SATURATED_ARITHMETIC_H_ 6 #define BASE_NUMERICS_SATURATED_ARITHMETIC_H_
7 7
8 #include <stdint.h> 8 #include <stdint.h>
9 9
10 #include <limits> 10 #include <limits>
11 11
12 #include "base/compiler_specific.h" 12 #include "base/compiler_specific.h"
13 13
14 #if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS) && \ 14 #if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS) && \
15 defined(COMPILER_GCC) && !defined(OS_NACL) && __OPTIMIZE__ 15 defined(COMPILER_GCC) && !defined(OS_NACL) && __OPTIMIZE__
16 16
17 // If we're building ARM 32-bit on GCC we replace the C++ versions with some 17 // If we're building ARM 32-bit on GCC we replace the C++ versions with some
18 // native ARM assembly for speed. 18 // native ARM assembly for speed.
19 #include "base/numerics/saturated_arithmetic_arm.h" 19 #include "base/numerics/saturated_arithmetic_arm.h"
20 20
21 #else 21 #else
22 22
23 namespace base { 23 namespace base {
24 24
25 inline int32_t SaturatedAddition(int32_t a, int32_t b) { 25 ALWAYS_INLINE int32_t SaturatedAddition(int32_t a, int32_t b) {
26 uint32_t ua = a; 26 uint32_t ua = a;
27 uint32_t ub = b; 27 uint32_t ub = b;
28 uint32_t result = ua + ub; 28 uint32_t result = ua + ub;
29 29
30 // Can only overflow if the signed bit of the two values match. If the 30 // Can only overflow if the signed bit of the two values match. If the
31 // signed bit of the result and one of the values differ it overflowed. 31 // signed bit of the result and one of the values differ it overflowed.
32 // The branch compiles to a CMOVNS instruction on x86. 32 // The branch compiles to a CMOVNS instruction on x86.
33 if (~(ua ^ ub) & (result ^ ua) & (1 << 31)) 33 if (~(ua ^ ub) & (result ^ ua) & (1 << 31))
34 return std::numeric_limits<int>::max() + (ua >> 31); 34 return std::numeric_limits<int>::max() + (ua >> 31);
35 35
36 return result; 36 return result;
37 } 37 }
38 38
39 inline int32_t SaturatedSubtraction(int32_t a, int32_t b) { 39 ALWAYS_INLINE int32_t SaturatedSubtraction(int32_t a, int32_t b) {
40 uint32_t ua = a; 40 uint32_t ua = a;
41 uint32_t ub = b; 41 uint32_t ub = b;
42 uint32_t result = ua - ub; 42 uint32_t result = ua - ub;
43 43
44 // Can only overflow if the signed bit of the two input values differ. If 44 // Can only overflow if the signed bit of the two input values differ. If
45 // the signed bit of the result and the first value differ it overflowed. 45 // the signed bit of the result and the first value differ it overflowed.
46 // The branch compiles to a CMOVNS instruction on x86. 46 // The branch compiles to a CMOVNS instruction on x86.
47 if ((ua ^ ub) & (result ^ ua) & (1 << 31)) 47 if ((ua ^ ub) & (result ^ ua) & (1 << 31))
48 return std::numeric_limits<int>::max() + (ua >> 31); 48 return std::numeric_limits<int>::max() + (ua >> 31);
49 49
50 return result; 50 return result;
51 } 51 }
52 52
53 inline int32_t SaturatedNegative(int32_t a) { 53 ALWAYS_INLINE int32_t SaturatedNegative(int32_t a) {
54 if (UNLIKELY(a == std::numeric_limits<int>::min())) 54 if (UNLIKELY(a == std::numeric_limits<int>::min()))
55 return std::numeric_limits<int>::max(); 55 return std::numeric_limits<int>::max();
56 return -a; 56 return -a;
57 } 57 }
58 58
59 inline int GetMaxSaturatedSetResultForTesting(int fractional_shift) { 59 ALWAYS_INLINE int GetMaxSaturatedSetResultForTesting(int fractional_shift) {
60 // For C version the set function maxes out to max int, this differs from 60 // For C version the set function maxes out to max int, this differs from
61 // the ARM asm version, see saturated_arithmetic_arm.h for the equivalent asm 61 // the ARM asm version, see saturated_arithmetic_arm.h for the equivalent asm
62 // version. 62 // version.
63 return std::numeric_limits<int>::max(); 63 return std::numeric_limits<int>::max();
64 } 64 }
65 65
66 inline int GetMinSaturatedSetResultForTesting(int fractional_shift) { 66 ALWAYS_INLINE int GetMinSaturatedSetResultForTesting(int fractional_shift) {
67 return std::numeric_limits<int>::min(); 67 return std::numeric_limits<int>::min();
68 } 68 }
69 69
70 template <int fractional_shift> 70 template <int fractional_shift>
71 inline int SaturatedSet(int value) { 71 ALWAYS_INLINE int SaturatedSet(int value) {
72 const int kIntMaxForLayoutUnit = 72 const int kIntMaxForLayoutUnit =
73 std::numeric_limits<int>::max() >> fractional_shift; 73 std::numeric_limits<int>::max() >> fractional_shift;
74 74
75 const int kIntMinForLayoutUnit = 75 const int kIntMinForLayoutUnit =
76 std::numeric_limits<int>::min() >> fractional_shift; 76 std::numeric_limits<int>::min() >> fractional_shift;
77 77
78 if (value > kIntMaxForLayoutUnit) 78 if (value > kIntMaxForLayoutUnit)
79 return std::numeric_limits<int>::max(); 79 return std::numeric_limits<int>::max();
80 80
81 if (value < kIntMinForLayoutUnit) 81 if (value < kIntMinForLayoutUnit)
82 return std::numeric_limits<int>::min(); 82 return std::numeric_limits<int>::min();
83 83
84 return value << fractional_shift; 84 return value << fractional_shift;
85 } 85 }
86 86
87 template <int fractional_shift> 87 template <int fractional_shift>
88 inline int SaturatedSet(unsigned value) { 88 ALWAYS_INLINE int SaturatedSet(unsigned value) {
89 const unsigned kIntMaxForLayoutUnit = 89 const unsigned kIntMaxForLayoutUnit =
90 std::numeric_limits<int>::max() >> fractional_shift; 90 std::numeric_limits<int>::max() >> fractional_shift;
91 91
92 if (value >= kIntMaxForLayoutUnit) 92 if (value >= kIntMaxForLayoutUnit)
93 return std::numeric_limits<int>::max(); 93 return std::numeric_limits<int>::max();
94 94
95 return value << fractional_shift; 95 return value << fractional_shift;
96 } 96 }
97 97
98 } // namespace base 98 } // namespace base
99 99
100 #endif // CPU(ARM) && COMPILER(GCC) 100 #endif // CPU(ARM) && COMPILER(GCC)
101 #endif // BASE_NUMERICS_SATURATED_ARITHMETIC_H_ 101 #endif // BASE_NUMERICS_SATURATED_ARITHMETIC_H_
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