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
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
//! This module implements minimal run-time feature detection for x86.
//!
//! The features are detected using the `detect_features` function below.
//! This function uses the CPUID instruction to read the feature flags from the
//! CPU and encodes them in an `usize` where each bit position represents
//! whether a feature is available (bit is set) or unavaiable (bit is cleared).
//!
//! The enum `Feature` is used to map bit positions to feature names, and the
//! the `__crate::detect::check_for!` macro is used to map string literals (e.g.
//! "avx") to these bit positions (e.g. `Feature::avx`).
//!
//!
//! The run-time feature detection is performed by the
//! `__crate::detect::check_for(Feature) -> bool` function. On its first call,
//! this functions queries the CPU for the available features and stores them
//! in a global `AtomicUsize` variable. The query is performed by just checking
//! whether the feature bit in this global variable is set or cleared.

/// A macro to test at *runtime* whether a CPU feature is available on
/// x86/x86-64 platforms.
///
/// This macro is provided in the standard library and will detect at runtime
/// whether the specified CPU feature is detected. This does *not* resolve at
/// compile time unless the specified feature is already enabled for the entire
/// crate. Runtime detection currently relies mostly on the `cpuid` instruction.
///
/// This macro only takes one argument which is a string literal of the feature
/// being tested for. The feature names supported are the lowercase versions of
/// the ones defined by Intel in [their documentation][docs].
///
/// ## Supported arguments
///
/// This macro supports the same names that `#[target_feature]` supports. Unlike
/// `#[target_feature]`, however, this macro does not support names separated
/// with a comma. Instead testing for multiple features must be done through
/// separate macro invocations for now.
///
/// Supported arguments are:
///
/// * `"aes"`
/// * `"pclmulqdq"`
/// * `"rdrand"`
/// * `"rdseed"`
/// * `"tsc"`
/// * `"mmx"`
/// * `"sse"`
/// * `"sse2"`
/// * `"sse3"`
/// * `"ssse3"`
/// * `"sse4.1"`
/// * `"sse4.2"`
/// * `"sse4a"`
/// * `"sha"`
/// * `"avx"`
/// * `"avx2"`
/// * `"avx512f"`
/// * `"avx512cd"`
/// * `"avx512er"`
/// * `"avx512pf"`
/// * `"avx512bw"`
/// * `"avx512dq"`
/// * `"avx512vl"`
/// * `"avx512ifma"`
/// * `"avx512vbmi"`
/// * `"avx512vpopcntdq"`
/// * `"fma"`
/// * `"bmi1"`
/// * `"bmi2"`
/// * `"abm"`
/// * `"lzcnt"`
/// * `"tbm"`
/// * `"popcnt"`
/// * `"fxsr"`
/// * `"xsave"`
/// * `"xsaveopt"`
/// * `"xsaves"`
/// * `"xsavec"`
///
/// [docs]: https://software.intel.com/sites/landingpage/IntrinsicsGuide
#[macro_export]
#[stable(feature = "simd_x86", since = "1.27.0")]
#[allow_internal_unstable(stdsimd_internal,stdsimd)]
macro_rules! is_x86_feature_detected {
    ("aes") => {
        cfg!(target_feature = "aes") || $crate::detect::check_for(
            $crate::detect::Feature::aes)  };
    ("pclmulqdq") => {
        cfg!(target_feature = "pclmulqdq") || $crate::detect::check_for(
            $crate::detect::Feature::pclmulqdq)  };
    ("rdrand") => {
        cfg!(target_feature = "rdrand") || $crate::detect::check_for(
            $crate::detect::Feature::rdrand)  };
    ("rdseed") => {
        cfg!(target_feature = "rdseed") || $crate::detect::check_for(
            $crate::detect::Feature::rdseed)  };
    ("tsc") => {
        cfg!(target_feature = "tsc") || $crate::detect::check_for(
            $crate::detect::Feature::tsc)  };
    ("mmx") => {
        cfg!(target_feature = "mmx") || $crate::detect::check_for(
            $crate::detect::Feature::mmx)  };
    ("sse") => {
        cfg!(target_feature = "sse") || $crate::detect::check_for(
            $crate::detect::Feature::sse)  };
    ("sse2") => {
        cfg!(target_feature = "sse2") || $crate::detect::check_for(
            $crate::detect::Feature::sse2)
    };
    ("sse3") => {
        cfg!(target_feature = "sse3") || $crate::detect::check_for(
            $crate::detect::Feature::sse3)
    };
    ("ssse3") => {
        cfg!(target_feature = "ssse3") || $crate::detect::check_for(
            $crate::detect::Feature::ssse3)
    };
    ("sse4.1") => {
        cfg!(target_feature = "sse4.1") || $crate::detect::check_for(
            $crate::detect::Feature::sse4_1)
    };
    ("sse4.2") => {
        cfg!(target_feature = "sse4.2") || $crate::detect::check_for(
            $crate::detect::Feature::sse4_2)
    };
    ("sse4a") => {
        cfg!(target_feature = "sse4a") || $crate::detect::check_for(
            $crate::detect::Feature::sse4a)
    };
    ("sha") => {
        cfg!(target_feature = "sha") || $crate::detect::check_for(
            $crate::detect::Feature::sha)
    };
    ("avx") => {
        cfg!(target_feature = "avx") || $crate::detect::check_for(
            $crate::detect::Feature::avx)
    };
    ("avx2") => {
        cfg!(target_feature = "avx2") || $crate::detect::check_for(
            $crate::detect::Feature::avx2)
    };
    ("avx512f") => {
        cfg!(target_feature = "avx512f") || $crate::detect::check_for(
            $crate::detect::Feature::avx512f)
    };
    ("avx512cd") => {
        cfg!(target_feature = "avx512cd") || $crate::detect::check_for(
            $crate::detect::Feature::avx512cd)
    };
    ("avx512er") => {
        cfg!(target_feature = "avx512er") || $crate::detect::check_for(
            $crate::detect::Feature::avx512er)
    };
    ("avx512pf") => {
        cfg!(target_feature = "avx512pf") || $crate::detect::check_for(
            $crate::detect::Feature::avx512pf)
    };
    ("avx512bw") => {
        cfg!(target_feature = "avx512bw") || $crate::detect::check_for(
            $crate::detect::Feature::avx512bw)
    };
    ("avx512dq") => {
        cfg!(target_feature = "avx512dq") || $crate::detect::check_for(
            $crate::detect::Feature::avx512dq)
    };
    ("avx512vl") => {
        cfg!(target_Feature = "avx512vl") || $crate::detect::check_for(
            $crate::detect::Feature::avx512vl)
    };
    ("avx512ifma") => {
        cfg!(target_feature = "avx512ifma") || $crate::detect::check_for(
            $crate::detect::Feature::avx512_ifma)
    };
    ("avx512vbmi") => {
        cfg!(target_feature = "avx512vbmi") || $crate::detect::check_for(
            $crate::detect::Feature::avx512_vbmi)
    };
    ("avx512vpopcntdq") => {
        cfg!(target_feature = "avx512vpopcntdq") || $crate::detect::check_for(
            $crate::detect::Feature::avx512_vpopcntdq)
    };
    ("fma") => {
        cfg!(target_feature = "fma") || $crate::detect::check_for(
            $crate::detect::Feature::fma)
    };
    ("bmi1") => {
        cfg!(target_feature = "bmi1") || $crate::detect::check_for(
            $crate::detect::Feature::bmi)
    };
    ("bmi2") => {
        cfg!(target_feature = "bmi2") || $crate::detect::check_for(
            $crate::detect::Feature::bmi2)
    };
    ("abm") => {
        cfg!(target_feature = "abm") || $crate::detect::check_for(
            $crate::detect::Feature::abm)
    };
    ("lzcnt") => {
        cfg!(target_feature = "lzcnt") || $crate::detect::check_for(
            $crate::detect::Feature::abm)
    };
    ("tbm") => {
        cfg!(target_feature = "tbm") || $crate::detect::check_for(
            $crate::detect::Feature::tbm)
    };
    ("popcnt") => {
        cfg!(target_feature = "popcnt") || $crate::detect::check_for(
            $crate::detect::Feature::popcnt)
    };
    ("fxsr") => {
        cfg!(target_feature = "fxsr") || $crate::detect::check_for(
            $crate::detect::Feature::fxsr)
    };
    ("xsave") => {
        cfg!(target_feature = "xsave") || $crate::detect::check_for(
            $crate::detect::Feature::xsave)
    };
    ("xsaveopt") => {
        cfg!(target_feature = "xsaveopt") || $crate::detect::check_for(
            $crate::detect::Feature::xsaveopt)
    };
    ("xsaves") => {
        cfg!(target_feature = "xsaves") || $crate::detect::check_for(
            $crate::detect::Feature::xsaves)
    };
    ("xsavec") => {
        cfg!(target_feature = "xsavec") || $crate::detect::check_for(
            $crate::detect::Feature::xsavec)
    };
    ("cmpxchg16b") => {
        cfg!(target_feature = "cmpxchg16b") || $crate::detect::check_for(
            $crate::detect::Feature::cmpxchg16b)
    };
    ("adx") => {
        cfg!(target_feature = "adx") || $crate::detect::check_for(
            $crate::detect::Feature::adx)
    };
    ($t:tt,) => {
        is_x86_feature_detected!($t);
    };
    ($t:tt) => {
        compile_error!(concat!("unknown target feature: ", $t))
    };
}

/// X86 CPU Feature enum. Each variant denotes a position in a bitset for a
/// particular feature.
///
/// This is an unstable implementation detail subject to change.
#[allow(non_camel_case_types)]
#[repr(u8)]
#[doc(hidden)]
#[unstable(feature = "stdsimd_internal", issue = "0")]
pub enum Feature {
    /// AES (Advanced Encryption Standard New Instructions AES-NI)
    aes,
    /// CLMUL (Carry-less Multiplication)
    pclmulqdq,
    /// RDRAND
    rdrand,
    /// RDSEED
    rdseed,
    /// TSC (Time Stamp Counter)
    tsc,
    /// MMX
    mmx,
    /// SSE (Streaming SIMD Extensions)
    sse,
    /// SSE2 (Streaming SIMD Extensions 2)
    sse2,
    /// SSE3 (Streaming SIMD Extensions 3)
    sse3,
    /// SSSE3 (Supplemental Streaming SIMD Extensions 3)
    ssse3,
    /// SSE4.1 (Streaming SIMD Extensions 4.1)
    sse4_1,
    /// SSE4.2 (Streaming SIMD Extensions 4.2)
    sse4_2,
    /// SSE4a (Streaming SIMD Extensions 4a)
    sse4a,
    /// SHA
    sha,
    /// AVX (Advanced Vector Extensions)
    avx,
    /// AVX2 (Advanced Vector Extensions 2)
    avx2,
    /// AVX-512 F (Foundation)
    avx512f,
    /// AVX-512 CD (Conflict Detection Instructions)
    avx512cd,
    /// AVX-512 ER (Exponential and Reciprocal Instructions)
    avx512er,
    /// AVX-512 PF (Prefetch Instructions)
    avx512pf,
    /// AVX-512 BW (Byte and Word Instructions)
    avx512bw,
    /// AVX-512 DQ (Doubleword and Quadword)
    avx512dq,
    /// AVX-512 VL (Vector Length Extensions)
    avx512vl,
    /// AVX-512 IFMA (Integer Fused Multiply Add)
    avx512_ifma,
    /// AVX-512 VBMI (Vector Byte Manipulation Instructions)
    avx512_vbmi,
    /// AVX-512 VPOPCNTDQ (Vector Population Count Doubleword and
    /// Quadword)
    avx512_vpopcntdq,
    /// FMA (Fused Multiply Add)
    fma,
    /// BMI1 (Bit Manipulation Instructions 1)
    bmi,
    /// BMI1 (Bit Manipulation Instructions 2)
    bmi2,
    /// ABM (Advanced Bit Manipulation) on AMD / LZCNT (Leading Zero
    /// Count) on Intel
    abm,
    /// TBM (Trailing Bit Manipulation)
    tbm,
    /// POPCNT (Population Count)
    popcnt,
    /// FXSR (Floating-point context fast save and restor)
    fxsr,
    /// XSAVE (Save Processor Extended States)
    xsave,
    /// XSAVEOPT (Save Processor Extended States Optimized)
    xsaveopt,
    /// XSAVES (Save Processor Extended States Supervisor)
    xsaves,
    /// XSAVEC (Save Processor Extended States Compacted)
    xsavec,
    /// CMPXCH16B, a 16-byte compare-and-swap instruction
    cmpxchg16b,
    /// ADX, Intel ADX (Multi-Precision Add-Carry Instruction Extensions)
    adx,
}