1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
|
/*
* Copyright (C) 2011, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_DENORMAL_DISABLER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_DENORMAL_DISABLER_H_
#include <float.h>
#include "build/build_config.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
namespace blink {
// Deal with denormals. They can very seriously impact performance on x86.
// Define HAVE_DENORMAL if we support flushing denormals to zero.
#if BUILDFLAG(IS_WIN) && defined(COMPILER_MSVC)
// Windows compiled using MSVC with SSE2
#define HAVE_DENORMAL 1
#endif
#if defined(COMPILER_GCC) && defined(ARCH_CPU_X86_FAMILY)
// X86 chips can flush denormals
#define HAVE_DENORMAL 1
#endif
#if defined(ARCH_CPU_ARM_FAMILY)
#define HAVE_DENORMAL 1
#endif
#if defined(HAVE_DENORMAL)
class DenormalModifier {
public:
virtual ~DenormalModifier() = default;
#if defined(COMPILER_GCC) && defined(ARCH_CPU_X86_FAMILY)
public:
static void DisableDenormals() {
unsigned old_csr = GetCsr();
SetCsr(old_csr | 0x8040);
}
static void EnableDenormals() {
unsigned old_csr = GetCsr();
SetCsr(old_csr & (~0x8040));
}
protected:
static inline unsigned GetCsr() {
int result;
asm volatile("stmxcsr %0" : "=m"(result));
return result;
}
static inline void SetCsr(int a) {
int temp = a;
asm volatile("ldmxcsr %0" : : "m"(temp));
}
#elif BUILDFLAG(IS_WIN) && defined(COMPILER_MSVC)
public:
static void DisableDenormals() { SetCsr(_DN_FLUSH); }
static void EnableDenormals() { SetCsr(_DN_SAVE); }
protected:
static inline unsigned GetCsr() {
unsigned result;
_controlfp_s(&result, 0, 0);
return result;
}
static inline void SetCsr(unsigned a) {
// http://stackoverflow.com/questions/637175/possible-bug-in-controlfp-s-may-not-restore-control-word-correctly
unsigned unused;
_controlfp_s(&unused, a, _MCW_DN);
}
#elif defined(ARCH_CPU_ARM_FAMILY)
public:
static void DisableDenormals() {
unsigned old_csr = GetCsr();
// Bit 24 is the flush-to-zero mode control bit. Setting it to 1 flushes
// denormals to 0.
SetCsr(old_csr | (1 << 24));
}
static void EnableDenormals() {
unsigned old_csr = GetCsr();
SetCsr(old_csr & (~(1 << 24)));
}
protected:
static inline unsigned GetCsr() {
int result;
#if defined(ARCH_CPU_ARM64)
asm volatile("mrs %x[result], FPCR" : [result] "=r"(result));
#else
asm volatile("vmrs %[result], FPSCR" : [result] "=r"(result));
#endif
return result;
}
static inline void SetCsr(int a) {
#if defined(ARCH_CPU_ARM64)
asm volatile("msr FPCR, %x[src]" : : [src] "r"(a));
#else
asm volatile("vmsr FPSCR, %[src]" : : [src] "r"(a));
#endif
}
#endif
};
class DenormalDisabler final : public DenormalModifier {
DISALLOW_NEW();
public:
DenormalDisabler() {
// Save the current state, and set mode to flush denormals.
saved_csr_ = GetCsr();
DisableDenormals();
}
~DenormalDisabler() final { SetCsr(saved_csr_); }
// This is a nop if we can flush denormals to zero in hardware.
static inline float FlushDenormalFloatToZero(float f) { return f; }
private:
unsigned saved_csr_ = 0;
};
class DenormalEnabler final : public DenormalModifier {
DISALLOW_NEW();
public:
DenormalEnabler() {
saved_csr_ = GetCsr();
EnableDenormals();
}
~DenormalEnabler() final { SetCsr(saved_csr_); }
private:
unsigned saved_csr_ = 0;
};
#else
// FIXME: add implementations for other architectures and compilers
class DenormalModifier final {
public:
virtual ~DenormalModifier() = default;
static void DisableDenormals() {}
static void EnableDenormals() {}
};
class DenormalDisabler final {
STACK_ALLOCATED();
public:
DenormalDisabler() = default;
~DenormalDisabler() = default;
// Assume the worst case that other architectures and compilers
// need to flush denormals to zero manually.
static inline float FlushDenormalFloatToZero(float f) {
return (fabs(f) < FLT_MIN) ? 0.0f : f;
}
};
class DenormalEnabler final {
STACK_ALLOCATED();
public:
DenormalEnabler() = default;
~DenormalEnabler() = default;
};
#endif
} // namespace blink
#undef HAVE_DENORMAL
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_DENORMAL_DISABLER_H_
|
