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

use rustc_middle::mir;
use rustc_span::Symbol;
use rustc_target::spec::abi::Abi;

use super::{horizontal_bin_op, int_abs, pmulhrsw, psign};
use crate::*;
use shims::foreign_items::EmulateForeignItemResult;

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
pub(super) trait EvalContextExt<'mir, 'tcx: 'mir>:
    crate::MiriInterpCxExt<'mir, 'tcx>
{
    fn emulate_x86_ssse3_intrinsic(
        &mut self,
        link_name: Symbol,
        abi: Abi,
        args: &[OpTy<'tcx, Provenance>],
        dest: &MPlaceTy<'tcx, Provenance>,
    ) -> InterpResult<'tcx, EmulateForeignItemResult> {
        let this = self.eval_context_mut();
        this.expect_target_feature_for_intrinsic(link_name, "ssse3")?;
        // Prefix should have already been checked.
        let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.ssse3.").unwrap();

        match unprefixed_name {
            // Used to implement the _mm_abs_epi{8,16,32} functions.
            // Calculates the absolute value of packed 8/16/32-bit integers.
            "pabs.b.128" | "pabs.w.128" | "pabs.d.128" => {
                let [op] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

                int_abs(this, op, dest)?;
            }
            // Used to implement the _mm_shuffle_epi8 intrinsic.
            // Shuffles bytes from `left` using `right` as pattern.
            // https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_shuffle_epi8
            "pshuf.b.128" => {
                let [left, right] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

                let (left, left_len) = this.operand_to_simd(left)?;
                let (right, right_len) = this.operand_to_simd(right)?;
                let (dest, dest_len) = this.mplace_to_simd(dest)?;

                assert_eq!(dest_len, left_len);
                assert_eq!(dest_len, right_len);

                for i in 0..dest_len {
                    let right = this.read_scalar(&this.project_index(&right, i)?)?.to_u8()?;
                    let dest = this.project_index(&dest, i)?;

                    let res = if right & 0x80 == 0 {
                        let j = right % 16; // index wraps around
                        this.read_scalar(&this.project_index(&left, j.into())?)?
                    } else {
                        // If the highest bit in `right` is 1, write zero.
                        Scalar::from_u8(0)
                    };

                    this.write_scalar(res, &dest)?;
                }
            }
            // Used to implement the _mm_h{add,adds,sub}_epi{16,32} functions.
            // Horizontally add / add with saturation / subtract adjacent 16/32-bit
            // integer values in `left` and `right`.
            "phadd.w.128" | "phadd.sw.128" | "phadd.d.128" | "phsub.w.128" | "phsub.sw.128"
            | "phsub.d.128" => {
                let [left, right] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

                let (which, saturating) = match unprefixed_name {
                    "phadd.w.128" | "phadd.d.128" => (mir::BinOp::Add, false),
                    "phadd.sw.128" => (mir::BinOp::Add, true),
                    "phsub.w.128" | "phsub.d.128" => (mir::BinOp::Sub, false),
                    "phsub.sw.128" => (mir::BinOp::Sub, true),
                    _ => unreachable!(),
                };

                horizontal_bin_op(this, which, saturating, left, right, dest)?;
            }
            // Used to implement the _mm_maddubs_epi16 function.
            // Multiplies packed 8-bit unsigned integers from `left` and packed
            // signed 8-bit integers from `right` into 16-bit signed integers. Then,
            // the saturating sum of the products with indices `2*i` and `2*i+1`
            // produces the output at index `i`.
            // https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_maddubs_epi16
            "pmadd.ub.sw.128" => {
                let [left, right] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

                let (left, left_len) = this.operand_to_simd(left)?;
                let (right, right_len) = this.operand_to_simd(right)?;
                let (dest, dest_len) = this.mplace_to_simd(dest)?;

                assert_eq!(left_len, right_len);
                assert_eq!(dest_len.checked_mul(2).unwrap(), left_len);

                for i in 0..dest_len {
                    let j1 = i.checked_mul(2).unwrap();
                    let left1 = this.read_scalar(&this.project_index(&left, j1)?)?.to_u8()?;
                    let right1 = this.read_scalar(&this.project_index(&right, j1)?)?.to_i8()?;

                    let j2 = j1.checked_add(1).unwrap();
                    let left2 = this.read_scalar(&this.project_index(&left, j2)?)?.to_u8()?;
                    let right2 = this.read_scalar(&this.project_index(&right, j2)?)?.to_i8()?;

                    let dest = this.project_index(&dest, i)?;

                    // Multiplication of a u8 and an i8 into an i16 cannot overflow.
                    let mul1 = i16::from(left1).checked_mul(right1.into()).unwrap();
                    let mul2 = i16::from(left2).checked_mul(right2.into()).unwrap();
                    let res = mul1.saturating_add(mul2);

                    this.write_scalar(Scalar::from_i16(res), &dest)?;
                }
            }
            // Used to implement the _mm_mulhrs_epi16 function.
            // Multiplies packed 16-bit signed integer values, truncates the 32-bit
            // product to the 18 most significant bits by right-shifting, and then
            // divides the 18-bit value by 2 (rounding to nearest) by first adding
            // 1 and then taking the bits `1..=16`.
            // https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_mulhrs_epi16
            "pmul.hr.sw.128" => {
                let [left, right] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

                pmulhrsw(this, left, right, dest)?;
            }
            // Used to implement the _mm_sign_epi{8,16,32} functions.
            // Negates elements from `left` when the corresponding element in
            // `right` is negative. If an element from `right` is zero, zero
            // is writen to the corresponding output element.
            // Basically, we multiply `left` with `right.signum()`.
            "psign.b.128" | "psign.w.128" | "psign.d.128" => {
                let [left, right] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

                psign(this, left, right, dest)?;
            }
            _ => return Ok(EmulateForeignItemResult::NotSupported),
        }
        Ok(EmulateForeignItemResult::NeedsJumping)
    }
}