1 //===-- aarch64 floating point env manipulation functions -------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENVIMPL_H
10 #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENVIMPL_H
11
12 #include "src/__support/macros/attributes.h" // LIBC_INLINE
13 #include "src/__support/macros/config.h"
14 #include "src/__support/macros/properties/architectures.h"
15
16 #if !defined(LIBC_TARGET_ARCH_IS_AARCH64) || defined(__APPLE__)
17 #error "Invalid include"
18 #endif
19
20 #include <arm_acle.h>
21 #include <stdint.h>
22
23 #include "hdr/fenv_macros.h"
24 #include "hdr/types/fenv_t.h"
25 #include "src/__support/FPUtil/FPBits.h"
26
27 namespace LIBC_NAMESPACE_DECL {
28 namespace fputil {
29
30 struct FEnv {
31 struct FPState {
32 uint32_t ControlWord;
33 uint32_t StatusWord;
34 };
35
36 static_assert(
37 sizeof(fenv_t) == sizeof(FPState),
38 "Internal floating point state does not match the public fenv_t type.");
39
40 static constexpr uint32_t TONEAREST = 0x0;
41 static constexpr uint32_t UPWARD = 0x1;
42 static constexpr uint32_t DOWNWARD = 0x2;
43 static constexpr uint32_t TOWARDZERO = 0x3;
44
45 static constexpr uint32_t INVALID = 0x1;
46 static constexpr uint32_t DIVBYZERO = 0x2;
47 static constexpr uint32_t OVERFLOW = 0x4;
48 static constexpr uint32_t UNDERFLOW = 0x8;
49 static constexpr uint32_t INEXACT = 0x10;
50
51 // Zero-th bit is the first bit.
52 static constexpr uint32_t RoundingControlBitPosition = 22;
53 static constexpr uint32_t ExceptionStatusFlagsBitPosition = 0;
54 static constexpr uint32_t ExceptionControlFlagsBitPosition = 8;
55
getStatusValueForExceptFEnv56 LIBC_INLINE static uint32_t getStatusValueForExcept(int excepts) {
57 return ((excepts & FE_INVALID) ? INVALID : 0) |
58 ((excepts & FE_DIVBYZERO) ? DIVBYZERO : 0) |
59 ((excepts & FE_OVERFLOW) ? OVERFLOW : 0) |
60 ((excepts & FE_UNDERFLOW) ? UNDERFLOW : 0) |
61 ((excepts & FE_INEXACT) ? INEXACT : 0);
62 }
63
exceptionStatusToMacroFEnv64 LIBC_INLINE static int exceptionStatusToMacro(uint32_t status) {
65 return ((status & INVALID) ? FE_INVALID : 0) |
66 ((status & DIVBYZERO) ? FE_DIVBYZERO : 0) |
67 ((status & OVERFLOW) ? FE_OVERFLOW : 0) |
68 ((status & UNDERFLOW) ? FE_UNDERFLOW : 0) |
69 ((status & INEXACT) ? FE_INEXACT : 0);
70 }
71
getControlWordFEnv72 static uint32_t getControlWord() {
73 #ifdef __clang__
74 // GCC does not currently support __arm_rsr.
75 return __arm_rsr("fpcr");
76 #else
77 return __builtin_aarch64_get_fpcr();
78 #endif
79 }
80
writeControlWordFEnv81 static void writeControlWord(uint32_t fpcr) {
82 #ifdef __clang__
83 // GCC does not currently support __arm_wsr.
84 __arm_wsr("fpcr", fpcr);
85 #else
86 __builtin_aarch64_set_fpcr(fpcr);
87 #endif
88 }
89
getStatusWordFEnv90 static uint32_t getStatusWord() {
91 #ifdef __clang__
92 return __arm_rsr("fpsr");
93 #else
94 return __builtin_aarch64_get_fpsr();
95 #endif
96 }
97
writeStatusWordFEnv98 static void writeStatusWord(uint32_t fpsr) {
99 #ifdef __clang__
100 __arm_wsr("fpsr", fpsr);
101 #else
102 __builtin_aarch64_set_fpsr(fpsr);
103 #endif
104 }
105 };
106
enable_except(int excepts)107 LIBC_INLINE int enable_except(int excepts) {
108 uint32_t newExcepts = FEnv::getStatusValueForExcept(excepts);
109 uint32_t controlWord = FEnv::getControlWord();
110 int oldExcepts =
111 (controlWord >> FEnv::ExceptionControlFlagsBitPosition) & 0x1F;
112 controlWord |= (newExcepts << FEnv::ExceptionControlFlagsBitPosition);
113 FEnv::writeControlWord(controlWord);
114 return FEnv::exceptionStatusToMacro(oldExcepts);
115 }
116
disable_except(int excepts)117 LIBC_INLINE int disable_except(int excepts) {
118 uint32_t disabledExcepts = FEnv::getStatusValueForExcept(excepts);
119 uint32_t controlWord = FEnv::getControlWord();
120 int oldExcepts =
121 (controlWord >> FEnv::ExceptionControlFlagsBitPosition) & 0x1F;
122 controlWord &= ~(disabledExcepts << FEnv::ExceptionControlFlagsBitPosition);
123 FEnv::writeControlWord(controlWord);
124 return FEnv::exceptionStatusToMacro(oldExcepts);
125 }
126
get_except()127 LIBC_INLINE int get_except() {
128 uint32_t controlWord = FEnv::getControlWord();
129 int enabledExcepts =
130 (controlWord >> FEnv::ExceptionControlFlagsBitPosition) & 0x1F;
131 return FEnv::exceptionStatusToMacro(enabledExcepts);
132 }
133
clear_except(int excepts)134 LIBC_INLINE int clear_except(int excepts) {
135 uint32_t statusWord = FEnv::getStatusWord();
136 uint32_t toClear = FEnv::getStatusValueForExcept(excepts);
137 statusWord &= ~(toClear << FEnv::ExceptionStatusFlagsBitPosition);
138 FEnv::writeStatusWord(statusWord);
139 return 0;
140 }
141
test_except(int excepts)142 LIBC_INLINE int test_except(int excepts) {
143 uint32_t toTest = FEnv::getStatusValueForExcept(excepts);
144 uint32_t statusWord = FEnv::getStatusWord();
145 return FEnv::exceptionStatusToMacro(
146 (statusWord >> FEnv::ExceptionStatusFlagsBitPosition) & toTest);
147 }
148
set_except(int excepts)149 LIBC_INLINE int set_except(int excepts) {
150 uint32_t statusWord = FEnv::getStatusWord();
151 uint32_t statusValue = FEnv::getStatusValueForExcept(excepts);
152 statusWord |= (statusValue << FEnv::ExceptionStatusFlagsBitPosition);
153 FEnv::writeStatusWord(statusWord);
154 return 0;
155 }
156
raise_except(int excepts)157 LIBC_INLINE int raise_except(int excepts) {
158 float zero = 0.0f;
159 float one = 1.0f;
160 float largeValue = FPBits<float>::max_normal().get_val();
161 float smallValue = FPBits<float>::min_normal().get_val();
162 auto divfunc = [](float a, float b) {
163 __asm__ __volatile__("ldr s0, %0\n\t"
164 "ldr s1, %1\n\t"
165 "fdiv s0, s0, s1\n\t"
166 : // No outputs
167 : "m"(a), "m"(b)
168 : "s0", "s1" /* s0 and s1 are clobbered */);
169 };
170
171 uint32_t toRaise = FEnv::getStatusValueForExcept(excepts);
172 int result = 0;
173
174 if (toRaise & FEnv::INVALID) {
175 divfunc(zero, zero);
176 uint32_t statusWord = FEnv::getStatusWord();
177 if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
178 FEnv::INVALID))
179 result = -1;
180 }
181
182 if (toRaise & FEnv::DIVBYZERO) {
183 divfunc(one, zero);
184 uint32_t statusWord = FEnv::getStatusWord();
185 if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
186 FEnv::DIVBYZERO))
187 result = -1;
188 }
189 if (toRaise & FEnv::OVERFLOW) {
190 divfunc(largeValue, smallValue);
191 uint32_t statusWord = FEnv::getStatusWord();
192 if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
193 FEnv::OVERFLOW))
194 result = -1;
195 }
196 if (toRaise & FEnv::UNDERFLOW) {
197 divfunc(smallValue, largeValue);
198 uint32_t statusWord = FEnv::getStatusWord();
199 if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
200 FEnv::UNDERFLOW))
201 result = -1;
202 }
203 if (toRaise & FEnv::INEXACT) {
204 float two = 2.0f;
205 float three = 3.0f;
206 // 2.0 / 3.0 cannot be represented exactly in any radix 2 floating point
207 // format.
208 divfunc(two, three);
209 uint32_t statusWord = FEnv::getStatusWord();
210 if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
211 FEnv::INEXACT))
212 result = -1;
213 }
214 return result;
215 }
216
get_round()217 LIBC_INLINE int get_round() {
218 uint32_t roundingMode =
219 (FEnv::getControlWord() >> FEnv::RoundingControlBitPosition) & 0x3;
220 switch (roundingMode) {
221 case FEnv::TONEAREST:
222 return FE_TONEAREST;
223 case FEnv::DOWNWARD:
224 return FE_DOWNWARD;
225 case FEnv::UPWARD:
226 return FE_UPWARD;
227 case FEnv::TOWARDZERO:
228 return FE_TOWARDZERO;
229 default:
230 return -1; // Error value.
231 }
232 }
233
set_round(int mode)234 LIBC_INLINE int set_round(int mode) {
235 uint16_t bitValue;
236 switch (mode) {
237 case FE_TONEAREST:
238 bitValue = FEnv::TONEAREST;
239 break;
240 case FE_DOWNWARD:
241 bitValue = FEnv::DOWNWARD;
242 break;
243 case FE_UPWARD:
244 bitValue = FEnv::UPWARD;
245 break;
246 case FE_TOWARDZERO:
247 bitValue = FEnv::TOWARDZERO;
248 break;
249 default:
250 return 1; // To indicate failure
251 }
252
253 uint32_t controlWord = FEnv::getControlWord();
254 controlWord &= ~(0x3 << FEnv::RoundingControlBitPosition);
255 controlWord |= (bitValue << FEnv::RoundingControlBitPosition);
256 FEnv::writeControlWord(controlWord);
257
258 return 0;
259 }
260
get_env(fenv_t * envp)261 LIBC_INLINE int get_env(fenv_t *envp) {
262 FEnv::FPState *state = reinterpret_cast<FEnv::FPState *>(envp);
263 state->ControlWord = FEnv::getControlWord();
264 state->StatusWord = FEnv::getStatusWord();
265 return 0;
266 }
267
set_env(const fenv_t * envp)268 LIBC_INLINE int set_env(const fenv_t *envp) {
269 if (envp == FE_DFL_ENV) {
270 // Default status and control words bits are all zeros so we just
271 // write zeros.
272 FEnv::writeStatusWord(0);
273 FEnv::writeControlWord(0);
274 return 0;
275 }
276 const FEnv::FPState *state = reinterpret_cast<const FEnv::FPState *>(envp);
277 FEnv::writeControlWord(state->ControlWord);
278 FEnv::writeStatusWord(state->StatusWord);
279 return 0;
280 }
281
282 } // namespace fputil
283 } // namespace LIBC_NAMESPACE_DECL
284
285 #endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENVIMPL_H
286