Auto merge of #3086 - eduardosm:x86-sse3-intrinsics, r=RalfJung

Implement SSE3 and SSSE3 intrinsics

src/shims/x86/mod.rs

@@ -9,6 +9,8 @@ use shims::foreign_items::EmulateByNameResult;
 
 mod sse;
 mod sse2;
+mod sse3;
+mod ssse3;
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
 pub(super) trait EvalContextExt<'mir, 'tcx: 'mir>:
@@ -88,6 +90,16 @@ pub(super) trait EvalContextExt<'mir, 'tcx: 'mir>:
                     this, link_name, abi, args, dest,
                 );
             }
+            name if name.starts_with("sse3.") => {
+                return sse3::EvalContextExt::emulate_x86_sse3_intrinsic(
+                    this, link_name, abi, args, dest,
+                );
+            }
+            name if name.starts_with("ssse3.") => {
+                return ssse3::EvalContextExt::emulate_x86_ssse3_intrinsic(
+                    this, link_name, abi, args, dest,
+                );
+            }
             _ => return Ok(EmulateByNameResult::NotSupported),
         }
         Ok(EmulateByNameResult::NeedsJumping)
@@ -286,3 +298,44 @@ fn bin_op_simd_float_all<'tcx, F: rustc_apfloat::Float>(
 
     Ok(())
 }
+
+/// Horizontaly performs `which` operation on adjacent values of
+/// `left` and `right` SIMD vectors and stores the result in `dest`.
+fn horizontal_bin_op<'tcx>(
+    this: &mut crate::MiriInterpCx<'_, 'tcx>,
+    which: mir::BinOp,
+    saturating: bool,
+    left: &OpTy<'tcx, Provenance>,
+    right: &OpTy<'tcx, Provenance>,
+    dest: &PlaceTy<'tcx, Provenance>,
+) -> InterpResult<'tcx, ()> {
+    let (left, left_len) = this.operand_to_simd(left)?;
+    let (right, right_len) = this.operand_to_simd(right)?;
+    let (dest, dest_len) = this.place_to_simd(dest)?;
+
+    assert_eq!(dest_len, left_len);
+    assert_eq!(dest_len, right_len);
+    assert_eq!(dest_len % 2, 0);
+
+    let middle = dest_len / 2;
+    for i in 0..dest_len {
+        // `i` is the index in `dest`
+        // `j` is the index of the 2-item chunk in `src`
+        let (j, src) =
+            if i < middle { (i, &left) } else { (i.checked_sub(middle).unwrap(), &right) };
+        // `base_i` is the index of the first item of the 2-item chunk in `src`
+        let base_i = j.checked_mul(2).unwrap();
+        let lhs = this.read_immediate(&this.project_index(src, base_i)?)?;
+        let rhs = this.read_immediate(&this.project_index(src, base_i.checked_add(1).unwrap())?)?;
+
+        let res = if saturating {
+            Immediate::from(this.saturating_arith(which, &lhs, &rhs)?)
+        } else {
+            *this.wrapping_binary_op(which, &lhs, &rhs)?
+        };
+
+        this.write_immediate(res, &this.project_index(&dest, i)?)?;
+    }
+
+    Ok(())
+}

src/shims/x86/sse3.rs

@@ -0,0 +1,90 @@
+use rustc_middle::mir;
+use rustc_span::Symbol;
+use rustc_target::abi::Align;
+use rustc_target::spec::abi::Abi;
+
+use super::horizontal_bin_op;
+use crate::*;
+use shims::foreign_items::EmulateByNameResult;
+
+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_sse3_intrinsic(
+        &mut self,
+        link_name: Symbol,
+        abi: Abi,
+        args: &[OpTy<'tcx, Provenance>],
+        dest: &PlaceTy<'tcx, Provenance>,
+    ) -> InterpResult<'tcx, EmulateByNameResult<'mir, 'tcx>> {
+        let this = self.eval_context_mut();
+        // Prefix should have already been checked.
+        let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.sse3.").unwrap();
+
+        match unprefixed_name {
+            // Used to implement the _mm_addsub_ps and _mm_addsub_pd functions.
+            // Alternatingly add and subtract floating point (f32 or f64) from
+            // `left` and `right`
+            "addsub.ps" | "addsub.pd" => {
+                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.place_to_simd(dest)?;
+
+                assert_eq!(dest_len, left_len);
+                assert_eq!(dest_len, right_len);
+
+                for i in 0..dest_len {
+                    let left = this.read_immediate(&this.project_index(&left, i)?)?;
+                    let right = this.read_immediate(&this.project_index(&right, i)?)?;
+                    let dest = this.project_index(&dest, i)?;
+
+                    // Even elements are subtracted and odd elements are added.
+                    let op = if i % 2 == 0 { mir::BinOp::Sub } else { mir::BinOp::Add };
+                    let res = this.wrapping_binary_op(op, &left, &right)?;
+
+                    this.write_immediate(*res, &dest)?;
+                }
+            }
+            // Used to implement the _mm_h{add,sub}_p{s,d} functions.
+            // Horizontally add/subtract adjacent floating point values
+            // in `left` and `right`.
+            "hadd.ps" | "hadd.pd" | "hsub.ps" | "hsub.pd" => {
+                let [left, right] =
+                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
+
+                let which = match unprefixed_name {
+                    "hadd.ps" | "hadd.pd" => mir::BinOp::Add,
+                    "hsub.ps" | "hsub.pd" => mir::BinOp::Sub,
+                    _ => unreachable!(),
+                };
+
+                horizontal_bin_op(this, which, /*saturating*/ false, left, right, dest)?;
+            }
+            // Used to implement the _mm_lddqu_si128 function.
+            // Reads a 128-bit vector from an unaligned pointer. This intrinsic
+            // is expected to perform better than a regular unaligned read when
+            // the data crosses a cache line, but for Miri this is just a regular
+            // unaligned read.
+            "ldu.dq" => {
+                let [src_ptr] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
+                let src_ptr = this.read_pointer(src_ptr)?;
+                let dest = dest.force_mplace(this)?;
+
+                this.mem_copy(
+                    src_ptr,
+                    Align::ONE,
+                    dest.ptr(),
+                    Align::ONE,
+                    dest.layout.size,
+                    /*nonoverlapping*/ true,
+                )?;
+            }
+            _ => return Ok(EmulateByNameResult::NotSupported),
+        }
+        Ok(EmulateByNameResult::NeedsJumping)
+    }
+}

src/shims/x86/ssse3.rs

@@ -0,0 +1,199 @@
+use rustc_middle::mir;
+use rustc_span::Symbol;
+use rustc_target::spec::abi::Abi;
+
+use super::horizontal_bin_op;
+use crate::*;
+use shims::foreign_items::EmulateByNameResult;
+
+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: &PlaceTy<'tcx, Provenance>,
+    ) -> InterpResult<'tcx, EmulateByNameResult<'mir, 'tcx>> {
+        let this = self.eval_context_mut();
+        // 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)?;
+
+                let (op, op_len) = this.operand_to_simd(op)?;
+                let (dest, dest_len) = this.place_to_simd(dest)?;
+
+                assert_eq!(op_len, dest_len);
+
+                for i in 0..dest_len {
+                    let op = this.read_scalar(&this.project_index(&op, i)?)?;
+                    let dest = this.project_index(&dest, i)?;
+
+                    // Converting to a host "i128" works since the input is always signed.
+                    let res = op.to_int(dest.layout.size)?.unsigned_abs();
+
+                    this.write_scalar(Scalar::from_uint(res, dest.layout.size), &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.place_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.place_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)?;
+
+                let (left, left_len) = this.operand_to_simd(left)?;
+                let (right, right_len) = this.operand_to_simd(right)?;
+                let (dest, dest_len) = this.place_to_simd(dest)?;
+
+                assert_eq!(dest_len, left_len);
+                assert_eq!(dest_len, right_len);
+
+                for i in 0..dest_len {
+                    let left = this.read_scalar(&this.project_index(&left, i)?)?.to_i16()?;
+                    let right = this.read_scalar(&this.project_index(&right, i)?)?.to_i16()?;
+                    let dest = this.project_index(&dest, i)?;
+
+                    let res = (i32::from(left).checked_mul(right.into()).unwrap() >> 14)
+                        .checked_add(1)
+                        .unwrap()
+                        >> 1;
+
+                    // The result of this operation can overflow a signed 16-bit integer.
+                    // When `left` and `right` are -0x8000, the result is 0x8000.
+                    #[allow(clippy::cast_possible_truncation)]
+                    let res = res as i16;
+
+                    this.write_scalar(Scalar::from_i16(res), &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)?;
+
+                let (left, left_len) = this.operand_to_simd(left)?;
+                let (right, right_len) = this.operand_to_simd(right)?;
+                let (dest, dest_len) = this.place_to_simd(dest)?;
+
+                assert_eq!(dest_len, left_len);
+                assert_eq!(dest_len, right_len);
+
+                for i in 0..dest_len {
+                    let dest = this.project_index(&dest, i)?;
+                    let left = this.read_immediate(&this.project_index(&left, i)?)?;
+                    let right = this
+                        .read_scalar(&this.project_index(&right, i)?)?
+                        .to_int(dest.layout.size)?;
+
+                    let res = this.wrapping_binary_op(
+                        mir::BinOp::Mul,
+                        &left,
+                        &ImmTy::from_int(right.signum(), dest.layout),
+                    )?;
+
+                    this.write_immediate(*res, &dest)?;
+                }
+            }
+            _ => return Ok(EmulateByNameResult::NotSupported),
+        }
+        Ok(EmulateByNameResult::NeedsJumping)
+    }
+}