1//! Bit Manipulation Instruction (BMI) Set 2.0.
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]:
11//! https://en.wikipedia.org/wiki/Bit_Manipulation_Instruction_Sets#ABM_.28Advanced_Bit_Manipulation.29
12
13#[cfg(test)]
14use stdarch_test::assert_instr;
15
16/// Unsigned multiply without affecting flags.
17///
18/// Unsigned multiplication of `a` with `b` returning a pair `(lo, hi)` with
19/// the low half and the high half of the result.
20///
21/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mulx_u64)
22#[inline]
23#[cfg_attr(test, assert_instr(mul))]
24#[target_feature(enable = "bmi2")]
25#[cfg(not(target_arch = "x86"))] // calls an intrinsic
26#[stable(feature = "simd_x86", since = "1.27.0")]
27pub unsafe fn _mulx_u64(a: u64, b: u64, hi: &mut u64) -> u64 {
28 let result: u128 = (a as u128) * (b as u128);
29 *hi = (result >> 64) as u64;
30 result as u64
31}
32
33/// Zeroes higher bits of `a` >= `index`.
34///
35/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_bzhi_u64)
36#[inline]
37#[target_feature(enable = "bmi2")]
38#[cfg_attr(test, assert_instr(bzhi))]
39#[cfg(not(target_arch = "x86"))]
40#[stable(feature = "simd_x86", since = "1.27.0")]
41pub unsafe fn _bzhi_u64(a: u64, index: u32) -> u64 {
42 x86_bmi2_bzhi_64(x:a, y:index as u64)
43}
44
45/// Scatter contiguous low order bits of `a` to the result at the positions
46/// specified by the `mask`.
47///
48/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_pdep_u64)
49#[inline]
50#[target_feature(enable = "bmi2")]
51#[cfg_attr(test, assert_instr(pdep))]
52#[cfg(not(target_arch = "x86"))]
53#[stable(feature = "simd_x86", since = "1.27.0")]
54pub unsafe fn _pdep_u64(a: u64, mask: u64) -> u64 {
55 x86_bmi2_pdep_64(x:a, y:mask)
56}
57
58/// Gathers the bits of `x` specified by the `mask` into the contiguous low
59/// order bit positions of the result.
60///
61/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_pext_u64)
62#[inline]
63#[target_feature(enable = "bmi2")]
64#[cfg_attr(test, assert_instr(pext))]
65#[cfg(not(target_arch = "x86"))]
66#[stable(feature = "simd_x86", since = "1.27.0")]
67pub unsafe fn _pext_u64(a: u64, mask: u64) -> u64 {
68 x86_bmi2_pext_64(x:a, y:mask)
69}
70
71extern "C" {
72 #[link_name = "llvm.x86.bmi.bzhi.64"]
73 fn x86_bmi2_bzhi_64(x: u64, y: u64) -> u64;
74 #[link_name = "llvm.x86.bmi.pdep.64"]
75 fn x86_bmi2_pdep_64(x: u64, y: u64) -> u64;
76 #[link_name = "llvm.x86.bmi.pext.64"]
77 fn x86_bmi2_pext_64(x: u64, y: u64) -> u64;
78}
79
80#[cfg(test)]
81mod tests {
82 use stdarch_test::simd_test;
83
84 use crate::core_arch::x86_64::*;
85
86 #[simd_test(enable = "bmi2")]
87 unsafe fn test_pext_u64() {
88 let n = 0b1011_1110_1001_0011u64;
89
90 let m0 = 0b0110_0011_1000_0101u64;
91 let s0 = 0b0000_0000_0011_0101u64;
92
93 let m1 = 0b1110_1011_1110_1111u64;
94 let s1 = 0b0001_0111_0100_0011u64;
95
96 assert_eq!(_pext_u64(n, m0), s0);
97 assert_eq!(_pext_u64(n, m1), s1);
98 }
99
100 #[simd_test(enable = "bmi2")]
101 unsafe fn test_pdep_u64() {
102 let n = 0b1011_1110_1001_0011u64;
103
104 let m0 = 0b0110_0011_1000_0101u64;
105 let s0 = 0b0000_0010_0000_0101u64;
106
107 let m1 = 0b1110_1011_1110_1111u64;
108 let s1 = 0b1110_1001_0010_0011u64;
109
110 assert_eq!(_pdep_u64(n, m0), s0);
111 assert_eq!(_pdep_u64(n, m1), s1);
112 }
113
114 #[simd_test(enable = "bmi2")]
115 unsafe fn test_bzhi_u64() {
116 let n = 0b1111_0010u64;
117 let s = 0b0001_0010u64;
118 assert_eq!(_bzhi_u64(n, 5), s);
119 }
120
121 #[simd_test(enable = "bmi2")]
122 #[rustfmt::skip]
123 unsafe fn test_mulx_u64() {
124 let a: u64 = 9_223_372_036_854_775_800;
125 let b: u64 = 100;
126 let mut hi = 0;
127 let lo = _mulx_u64(a, b, &mut hi);
128 /*
129result = 922337203685477580000 =
1300b00110001_1111111111111111_1111111111111111_1111111111111111_1111110011100000
131 ^~hi~~~~ ^~lo~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
132 */
133 assert_eq!(
134 lo,
135 0b11111111_11111111_11111111_11111111_11111111_11111111_11111100_11100000u64
136 );
137 assert_eq!(hi, 0b00110001u64);
138 }
139}
140