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Issue 1456173004: wtf: Eliminate inliner abuse in saturatedSet function. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 5 years, 1 month ago
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1 // Copyright 2014 The Chromium Authors. All rights reserved. 1 // Copyright 2014 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 SaturatedArithmeticARM_h 5 #ifndef SaturatedArithmeticARM_h
6 #define SaturatedArithmeticARM_h 6 #define SaturatedArithmeticARM_h
7 7
8 #include "wtf/CPU.h" 8 #include "wtf/CPU.h"
9 #include <limits> 9 #include <limits>
10 #include <stdint.h> 10 #include <stdint.h>
(...skipping 28 matching lines...) Expand all
39 // possible integer part with the fractional part zero'd out. 39 // possible integer part with the fractional part zero'd out.
40 // e.g. 0x7fffffc0. 40 // e.g. 0x7fffffc0.
41 return std::numeric_limits<int>::max() & ~((1 << FractionalShift)-1); 41 return std::numeric_limits<int>::max() & ~((1 << FractionalShift)-1);
42 } 42 }
43 43
44 inline int getMinSaturatedSetResultForTesting(int FractionalShift) 44 inline int getMinSaturatedSetResultForTesting(int FractionalShift)
45 { 45 {
46 return std::numeric_limits<int>::min(); 46 return std::numeric_limits<int>::min();
47 } 47 }
48 48
49 ALWAYS_INLINE int saturatedSet(int value, int FractionalShift) 49 template <int FractionalShift>
50 ALWAYS_INLINE int saturatedSet(int value)
50 { 51 {
51 // Figure out how many bits are left for storing the integer part of 52 // Figure out how many bits are left for storing the integer part of
52 // the fixed point number, and saturate our input to that 53 // the fixed point number, and saturate our input to that
53 const int saturate = 32 - FractionalShift; 54 enum { Saturate = 32 - FractionalShift };
54 55
55 int result; 56 int result;
56 57
57 // The following ARM code will Saturate the passed value to the number of 58 // The following ARM code will Saturate the passed value to the number of
58 // bits used for the whole part of the fixed point representation, then 59 // bits used for the whole part of the fixed point representation, then
59 // shift it up into place. This will result in the low <FractionShift> bits 60 // shift it up into place. This will result in the low <FractionShift> bits
60 // all being 0's. When the value saturates this gives a different result 61 // all being 0's. When the value saturates this gives a different result
61 // to from the C++ case; in the C++ code a saturated value has all the low 62 // to from the C++ case; in the C++ code a saturated value has all the low
62 // bits set to 1 (for a +ve number at least). This cannot be done rapidly 63 // bits set to 1 (for a +ve number at least). This cannot be done rapidly
63 // in ARM ... we live with the difference, for the sake of speed. 64 // in ARM ... we live with the difference, for the sake of speed.
64 65
65 asm("ssat %[output],%[saturate],%[value]\n\t" 66 asm("ssat %[output],%[saturate],%[value]\n\t"
66 "lsl %[output],%[shift]" 67 "lsl %[output],%[shift]"
67 : [output] "=r" (result) 68 : [output] "=r" (result)
68 : [value] "r" (value), 69 : [value] "r" (value),
69 [saturate] "n" (saturate), 70 [saturate] "n" (Saturate),
70 [shift] "n" (FractionalShift)); 71 [shift] "n" (FractionalShift));
71 72
72 return result; 73 return result;
73 } 74 }
74 75
75 76
76 ALWAYS_INLINE int saturatedSet(unsigned value, int FractionalShift) 77 template <int FractionalShift>
78 ALWAYS_INLINE int saturatedSet(unsigned value)
77 { 79 {
78 // Here we are being passed an unsigned value to saturate, 80 // Here we are being passed an unsigned value to saturate,
79 // even though the result is returned as a signed integer. The ARM 81 // even though the result is returned as a signed integer. The ARM
80 // instruction for unsigned saturation therefore needs to be given one 82 // instruction for unsigned saturation therefore needs to be given one
81 // less bit (i.e. the sign bit) for the saturation to work correctly; hence 83 // less bit (i.e. the sign bit) for the saturation to work correctly; hence
82 // the '31' below. 84 // the '31' below.
83 const int saturate = 31 - FractionalShift; 85 enum { Saturate = 31 - FractionalShift };
84 86
85 // The following ARM code will Saturate the passed value to the number of 87 // The following ARM code will Saturate the passed value to the number of
86 // bits used for the whole part of the fixed point representation, then 88 // bits used for the whole part of the fixed point representation, then
87 // shift it up into place. This will result in the low <FractionShift> bits 89 // shift it up into place. This will result in the low <FractionShift> bits
88 // all being 0's. When the value saturates this gives a different result 90 // all being 0's. When the value saturates this gives a different result
89 // to from the C++ case; in the C++ code a saturated value has all the low 91 // to from the C++ case; in the C++ code a saturated value has all the low
90 // bits set to 1. This cannot be done rapidly in ARM, so we live with the 92 // bits set to 1. This cannot be done rapidly in ARM, so we live with the
91 // difference, for the sake of speed. 93 // difference, for the sake of speed.
92 94
93 int result; 95 int result;
94 96
95 asm("usat %[output],%[saturate],%[value]\n\t" 97 asm("usat %[output],%[saturate],%[value]\n\t"
96 "lsl %[output],%[shift]" 98 "lsl %[output],%[shift]"
97 : [output] "=r" (result) 99 : [output] "=r" (result)
98 : [value] "r" (value), 100 : [value] "r" (value),
99 [saturate] "n" (saturate), 101 [saturate] "n" (Saturate),
100 [shift] "n" (FractionalShift)); 102 [shift] "n" (FractionalShift));
101 103
102 return result; 104 return result;
103 } 105 }
104 106
105 #endif // SaturatedArithmeticARM_h 107 #endif // SaturatedArithmeticARM_h
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