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_u32)
22#[inline]
23// LLVM BUG (should be mulxl): https://bugs.llvm.org/show_bug.cgi?id=34232
24#[cfg_attr(all(test, target_arch = "x86_64"), assert_instr(imul))]
25#[cfg_attr(all(test, target_arch = "x86"), assert_instr(mul))]
26#[target_feature(enable = "bmi2")]
27#[stable(feature = "simd_x86", since = "1.27.0")]
28pub fn _mulx_u32(a: u32, b: u32, hi: &mut u32) -> u32 {
29 let result: u64 = (a as u64) * (b as u64);
30 *hi = (result >> 32) as u32;
31 result as u32
32}
33
34/// Zeroes higher bits of `a` >= `index`.
35///
36/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_bzhi_u32)
37#[inline]
38#[target_feature(enable = "bmi2")]
39#[cfg_attr(test, assert_instr(bzhi))]
40#[stable(feature = "simd_x86", since = "1.27.0")]
41pub fn _bzhi_u32(a: u32, index: u32) -> u32 {
42 unsafe { x86_bmi2_bzhi_32(x:a, y:index) }
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_u32)
49#[inline]
50#[target_feature(enable = "bmi2")]
51#[cfg_attr(test, assert_instr(pdep))]
52#[stable(feature = "simd_x86", since = "1.27.0")]
53pub fn _pdep_u32(a: u32, mask: u32) -> u32 {
54 unsafe { x86_bmi2_pdep_32(x:a, y:mask) }
55}
56
57/// Gathers the bits of `x` specified by the `mask` into the contiguous low
58/// order bit positions of the result.
59///
60/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_pext_u32)
61#[inline]
62#[target_feature(enable = "bmi2")]
63#[cfg_attr(test, assert_instr(pext))]
64#[stable(feature = "simd_x86", since = "1.27.0")]
65pub fn _pext_u32(a: u32, mask: u32) -> u32 {
66 unsafe { x86_bmi2_pext_32(x:a, y:mask) }
67}
68
69unsafe extern "C" {
70 #[link_name = "llvm.x86.bmi.bzhi.32"]
71 unsafefn x86_bmi2_bzhi_32(x: u32, y: u32) -> u32;
72 #[link_name = "llvm.x86.bmi.pdep.32"]
73 unsafefn x86_bmi2_pdep_32(x: u32, y: u32) -> u32;
74 #[link_name = "llvm.x86.bmi.pext.32"]
75 unsafefn x86_bmi2_pext_32(x: u32, y: u32) -> u32;
76}
77
78#[cfg(test)]
79mod tests {
80 use stdarch_test::simd_test;
81
82 use crate::core_arch::x86::*;
83
84 #[simd_test(enable = "bmi2")]
85 unsafe fn test_pext_u32() {
86 let n = 0b1011_1110_1001_0011u32;
87
88 let m0 = 0b0110_0011_1000_0101u32;
89 let s0 = 0b0000_0000_0011_0101u32;
90
91 let m1 = 0b1110_1011_1110_1111u32;
92 let s1 = 0b0001_0111_0100_0011u32;
93
94 assert_eq!(_pext_u32(n, m0), s0);
95 assert_eq!(_pext_u32(n, m1), s1);
96 }
97
98 #[simd_test(enable = "bmi2")]
99 unsafe fn test_pdep_u32() {
100 let n = 0b1011_1110_1001_0011u32;
101
102 let m0 = 0b0110_0011_1000_0101u32;
103 let s0 = 0b0000_0010_0000_0101u32;
104
105 let m1 = 0b1110_1011_1110_1111u32;
106 let s1 = 0b1110_1001_0010_0011u32;
107
108 assert_eq!(_pdep_u32(n, m0), s0);
109 assert_eq!(_pdep_u32(n, m1), s1);
110 }
111
112 #[simd_test(enable = "bmi2")]
113 unsafe fn test_bzhi_u32() {
114 let n = 0b1111_0010u32;
115 let s = 0b0001_0010u32;
116 assert_eq!(_bzhi_u32(n, 5), s);
117 }
118
119 #[simd_test(enable = "bmi2")]
120 unsafe fn test_mulx_u32() {
121 let a: u32 = 4_294_967_200;
122 let b: u32 = 2;
123 let mut hi = 0;
124 let lo = _mulx_u32(a, b, &mut hi);
125 /*
126 result = 8589934400
127 = 0b0001_1111_1111_1111_1111_1111_1111_0100_0000u64
128 ^~hi ^~lo~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
129 */
130 assert_eq!(lo, 0b1111_1111_1111_1111_1111_1111_0100_0000u32);
131 assert_eq!(hi, 0b0001u32);
132 }
133}
134