core/stdarch/crates/core_arch/src/x86_64/
bmi.rs

1//! Bit Manipulation Instruction (BMI) Set 1.0.
2//!
3//! The reference is [Intel 64 and IA-32 Architectures Software Developer's
4//! Manual Volume 2: Instruction Set Reference, A-Z][intel64_ref].
5//!
6//! [Wikipedia][wikipedia_bmi] provides a quick overview of the instructions
7//! available.
8//!
9//! [intel64_ref]: http://www.intel.de/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf
10//! [wikipedia_bmi]: https://en.wikipedia.org/wiki/Bit_Manipulation_Instruction_Sets#ABM_.28Advanced_Bit_Manipulation.29
11
12#[cfg(test)]
13use stdarch_test::assert_instr;
14
15/// Extracts bits in range [`start`, `start` + `length`) from `a` into
16/// the least significant bits of the result.
17///
18/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_bextr_u64)
19#[inline]
20#[target_feature(enable = "bmi1")]
21#[cfg_attr(test, assert_instr(bextr))]
22#[cfg(not(target_arch = "x86"))]
23#[stable(feature = "simd_x86", since = "1.27.0")]
24pub fn _bextr_u64(a: u64, start: u32, len: u32) -> u64 {
25    _bextr2_u64(a, ((start & 0xff) | ((len & 0xff) << 8)) as u64)
26}
27
28/// Extracts bits of `a` specified by `control` into
29/// the least significant bits of the result.
30///
31/// Bits `[7,0]` of `control` specify the index to the first bit in the range
32/// to be extracted, and bits `[15,8]` specify the length of the range.
33///
34/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_bextr2_u64)
35#[inline]
36#[target_feature(enable = "bmi1")]
37#[cfg_attr(test, assert_instr(bextr))]
38#[cfg(not(target_arch = "x86"))]
39#[stable(feature = "simd_x86", since = "1.27.0")]
40pub fn _bextr2_u64(a: u64, control: u64) -> u64 {
41    unsafe { x86_bmi_bextr_64(a, control) }
42}
43
44/// Bitwise logical `AND` of inverted `a` with `b`.
45///
46/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_andn_u64)
47#[inline]
48#[target_feature(enable = "bmi1")]
49#[cfg_attr(test, assert_instr(andn))]
50#[stable(feature = "simd_x86", since = "1.27.0")]
51pub fn _andn_u64(a: u64, b: u64) -> u64 {
52    !a & b
53}
54
55/// Extracts lowest set isolated bit.
56///
57/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_blsi_u64)
58#[inline]
59#[target_feature(enable = "bmi1")]
60#[cfg_attr(test, assert_instr(blsi))]
61#[cfg(not(target_arch = "x86"))] // generates lots of instructions
62#[stable(feature = "simd_x86", since = "1.27.0")]
63pub fn _blsi_u64(x: u64) -> u64 {
64    x & x.wrapping_neg()
65}
66
67/// Gets mask up to lowest set bit.
68///
69/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_blsmsk_u64)
70#[inline]
71#[target_feature(enable = "bmi1")]
72#[cfg_attr(test, assert_instr(blsmsk))]
73#[cfg(not(target_arch = "x86"))] // generates lots of instructions
74#[stable(feature = "simd_x86", since = "1.27.0")]
75pub fn _blsmsk_u64(x: u64) -> u64 {
76    x ^ (x.wrapping_sub(1_u64))
77}
78
79/// Resets the lowest set bit of `x`.
80///
81/// If `x` is sets CF.
82///
83/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_blsr_u64)
84#[inline]
85#[target_feature(enable = "bmi1")]
86#[cfg_attr(test, assert_instr(blsr))]
87#[cfg(not(target_arch = "x86"))] // generates lots of instructions
88#[stable(feature = "simd_x86", since = "1.27.0")]
89pub fn _blsr_u64(x: u64) -> u64 {
90    x & (x.wrapping_sub(1))
91}
92
93/// Counts the number of trailing least significant zero bits.
94///
95/// When the source operand is `0`, it returns its size in bits.
96///
97/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_tzcnt_u64)
98#[inline]
99#[target_feature(enable = "bmi1")]
100#[cfg_attr(test, assert_instr(tzcnt))]
101#[stable(feature = "simd_x86", since = "1.27.0")]
102pub fn _tzcnt_u64(x: u64) -> u64 {
103    x.trailing_zeros() as u64
104}
105
106/// Counts the number of trailing least significant zero bits.
107///
108/// When the source operand is `0`, it returns its size in bits.
109///
110/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_tzcnt_64)
111#[inline]
112#[target_feature(enable = "bmi1")]
113#[cfg_attr(test, assert_instr(tzcnt))]
114#[stable(feature = "simd_x86", since = "1.27.0")]
115pub fn _mm_tzcnt_64(x: u64) -> i64 {
116    x.trailing_zeros() as i64
117}
118
119unsafe extern "C" {
120    #[link_name = "llvm.x86.bmi.bextr.64"]
121    fn x86_bmi_bextr_64(x: u64, y: u64) -> u64;
122}
123
124#[cfg(test)]
125mod tests {
126    use stdarch_test::simd_test;
127
128    use crate::core_arch::{x86::*, x86_64::*};
129
130    #[simd_test(enable = "bmi1")]
131    unsafe fn test_bextr_u64() {
132        let r = _bextr_u64(0b0101_0000u64, 4, 4);
133        assert_eq!(r, 0b0000_0101u64);
134    }
135
136    #[simd_test(enable = "bmi1")]
137    unsafe fn test_andn_u64() {
138        assert_eq!(_andn_u64(0, 0), 0);
139        assert_eq!(_andn_u64(0, 1), 1);
140        assert_eq!(_andn_u64(1, 0), 0);
141        assert_eq!(_andn_u64(1, 1), 0);
142
143        let r = _andn_u64(0b0000_0000u64, 0b0000_0000u64);
144        assert_eq!(r, 0b0000_0000u64);
145
146        let r = _andn_u64(0b0000_0000u64, 0b1111_1111u64);
147        assert_eq!(r, 0b1111_1111u64);
148
149        let r = _andn_u64(0b1111_1111u64, 0b0000_0000u64);
150        assert_eq!(r, 0b0000_0000u64);
151
152        let r = _andn_u64(0b1111_1111u64, 0b1111_1111u64);
153        assert_eq!(r, 0b0000_0000u64);
154
155        let r = _andn_u64(0b0100_0000u64, 0b0101_1101u64);
156        assert_eq!(r, 0b0001_1101u64);
157    }
158
159    #[simd_test(enable = "bmi1")]
160    unsafe fn test_blsi_u64() {
161        assert_eq!(_blsi_u64(0b1101_0000u64), 0b0001_0000u64);
162    }
163
164    #[simd_test(enable = "bmi1")]
165    unsafe fn test_blsmsk_u64() {
166        let r = _blsmsk_u64(0b0011_0000u64);
167        assert_eq!(r, 0b0001_1111u64);
168    }
169
170    #[simd_test(enable = "bmi1")]
171    unsafe fn test_blsr_u64() {
172        // TODO: test the behavior when the input is `0`.
173        let r = _blsr_u64(0b0011_0000u64);
174        assert_eq!(r, 0b0010_0000u64);
175    }
176
177    #[simd_test(enable = "bmi1")]
178    unsafe fn test_tzcnt_u64() {
179        assert_eq!(_tzcnt_u64(0b0000_0001u64), 0u64);
180        assert_eq!(_tzcnt_u64(0b0000_0000u64), 64u64);
181        assert_eq!(_tzcnt_u64(0b1001_0000u64), 4u64);
182    }
183}
core/stdarch/crates/core_arch/src/x86_64/bmi.rs

core/stdarch/crates/core_arch/src/x86_64/
bmi.rs
