Prototype using const generic for simd_shuffle IDX array

Author: oli-obk

compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs

@@ -21,7 +21,7 @@ fn report_simd_type_validation_error(
 pub(super) fn codegen_simd_intrinsic_call<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
     intrinsic: Symbol,
-    _args: GenericArgsRef<'tcx>,
+    generic_args: GenericArgsRef<'tcx>,
     args: &[mir::Operand<'tcx>],
     ret: CPlace<'tcx>,
     target: BasicBlock,
@@ -117,6 +117,54 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
             });
         }
 
+        // simd_shuffle_generic<T, U, const I: &[u32]>(x: T, y: T) -> U
+        sym::simd_shuffle_generic => {
+            let [x, y] = args else {
+                bug!("wrong number of args for intrinsic {intrinsic}");
+            };
+            let x = codegen_operand(fx, x);
+            let y = codegen_operand(fx, y);
+
+            if !x.layout().ty.is_simd() {
+                report_simd_type_validation_error(fx, intrinsic, span, x.layout().ty);
+                return;
+            }
+
+            let idx = generic_args[2]
+                .expect_const()
+                .eval(fx.tcx, ty::ParamEnv::reveal_all(), Some(span))
+                .unwrap()
+                .unwrap_branch();
+
+            assert_eq!(x.layout(), y.layout());
+            let layout = x.layout();
+
+            let (lane_count, lane_ty) = layout.ty.simd_size_and_type(fx.tcx);
+            let (ret_lane_count, ret_lane_ty) = ret.layout().ty.simd_size_and_type(fx.tcx);
+
+            assert_eq!(lane_ty, ret_lane_ty);
+            assert_eq!(idx.len() as u64, ret_lane_count);
+
+            let total_len = lane_count * 2;
+
+            let indexes =
+                idx.iter().map(|idx| idx.unwrap_leaf().try_to_u16().unwrap()).collect::<Vec<u16>>();
+
+            for &idx in &indexes {
+                assert!(u64::from(idx) < total_len, "idx {} out of range 0..{}", idx, total_len);
+            }
+
+            for (out_idx, in_idx) in indexes.into_iter().enumerate() {
+                let in_lane = if u64::from(in_idx) < lane_count {
+                    x.value_lane(fx, in_idx.into())
+                } else {
+                    y.value_lane(fx, u64::from(in_idx) - lane_count)
+                };
+                let out_lane = ret.place_lane(fx, u64::try_from(out_idx).unwrap());
+                out_lane.write_cvalue(fx, in_lane);
+            }
+        }
+
         // simd_shuffle<T, I, U>(x: T, y: T, idx: I) -> U
         sym::simd_shuffle => {
             let (x, y, idx) = match args {

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -15,7 +15,7 @@ use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::*;
 use rustc_hir as hir;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf};
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, GenericArgsRef, Ty};
 use rustc_middle::{bug, span_bug};
 use rustc_span::{sym, symbol::kw, Span, Symbol};
 use rustc_target::abi::{self, Align, HasDataLayout, Primitive};
@@ -376,7 +376,9 @@ impl<'ll, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'_, 'll, 'tcx> {
             }
 
             _ if name.as_str().starts_with("simd_") => {
-                match generic_simd_intrinsic(self, name, callee_ty, args, ret_ty, llret_ty, span) {
+                match generic_simd_intrinsic(
+                    self, name, callee_ty, fn_args, args, ret_ty, llret_ty, span,
+                ) {
                     Ok(llval) => llval,
                     Err(()) => return,
                 }
@@ -911,6 +913,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
     bx: &mut Builder<'_, 'll, 'tcx>,
     name: Symbol,
     callee_ty: Ty<'tcx>,
+    fn_args: GenericArgsRef<'tcx>,
     args: &[OperandRef<'tcx, &'ll Value>],
     ret_ty: Ty<'tcx>,
     llret_ty: &'ll Type,
@@ -1030,6 +1033,56 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
         ));
     }
 
+    if name == sym::simd_shuffle_generic {
+        let idx = fn_args[2]
+            .expect_const()
+            .eval(tcx, ty::ParamEnv::reveal_all(), Some(span))
+            .unwrap()
+            .unwrap_branch();
+        let n = idx.len() as u64;
+
+        require_simd!(ret_ty, InvalidMonomorphization::SimdReturn { span, name, ty: ret_ty });
+        let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
+        require!(
+            out_len == n,
+            InvalidMonomorphization::ReturnLength { span, name, in_len: n, ret_ty, out_len }
+        );
+        require!(
+            in_elem == out_ty,
+            InvalidMonomorphization::ReturnElement { span, name, in_elem, in_ty, ret_ty, out_ty }
+        );
+
+        let total_len = in_len * 2;
+
+        let indices: Option<Vec<_>> = idx
+            .iter()
+            .enumerate()
+            .map(|(arg_idx, val)| {
+                let idx = val.unwrap_leaf().try_to_i32().unwrap();
+                if idx >= i32::try_from(total_len).unwrap() {
+                    bx.sess().emit_err(InvalidMonomorphization::ShuffleIndexOutOfBounds {
+                        span,
+                        name,
+                        arg_idx: arg_idx as u64,
+                        total_len: total_len.into(),
+                    });
+                    None
+                } else {
+                    Some(bx.const_i32(idx))
+                }
+            })
+            .collect();
+        let Some(indices) = indices else {
+            return Ok(bx.const_null(llret_ty));
+        };
+
+        return Ok(bx.shuffle_vector(
+            args[0].immediate(),
+            args[1].immediate(),
+            bx.const_vector(&indices),
+        ));
+    }
+
     if name == sym::simd_shuffle {
         // Make sure this is actually an array, since typeck only checks the length-suffixed
         // version of this intrinsic.

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -20,6 +20,7 @@ fn equate_intrinsic_type<'tcx>(
     it: &hir::ForeignItem<'_>,
     n_tps: usize,
     n_lts: usize,
+    n_cts: usize,
     sig: ty::PolyFnSig<'tcx>,
 ) {
     let (own_counts, span) = match &it.kind {
@@ -51,7 +52,7 @@ fn equate_intrinsic_type<'tcx>(
 
     if gen_count_ok(own_counts.lifetimes, n_lts, "lifetime")
         && gen_count_ok(own_counts.types, n_tps, "type")
-        && gen_count_ok(own_counts.consts, 0, "const")
+        && gen_count_ok(own_counts.consts, n_cts, "const")
     {
         let fty = Ty::new_fn_ptr(tcx, sig);
         let it_def_id = it.owner_id.def_id;
@@ -492,7 +493,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
     };
     let sig = tcx.mk_fn_sig(inputs, output, false, unsafety, Abi::RustIntrinsic);
     let sig = ty::Binder::bind_with_vars(sig, bound_vars);
-    equate_intrinsic_type(tcx, it, n_tps, n_lts, sig)
+    equate_intrinsic_type(tcx, it, n_tps, n_lts, 0, sig)
 }
 
 /// Type-check `extern "platform-intrinsic" { ... }` functions.
@@ -504,9 +505,9 @@ pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>)
 
     let name = it.ident.name;
 
-    let (n_tps, inputs, output) = match name {
+    let (n_tps, n_cts, inputs, output) = match name {
         sym::simd_eq | sym::simd_ne | sym::simd_lt | sym::simd_le | sym::simd_gt | sym::simd_ge => {
-            (2, vec![param(0), param(0)], param(1))
+            (2, 0, vec![param(0), param(0)], param(1))
         }
         sym::simd_add
         | sym::simd_sub
@@ -522,8 +523,8 @@ pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>)
         | sym::simd_fmax
         | sym::simd_fpow
         | sym::simd_saturating_add
-        | sym::simd_saturating_sub => (1, vec![param(0), param(0)], param(0)),
-        sym::simd_arith_offset => (2, vec![param(0), param(1)], param(0)),
+        | sym::simd_saturating_sub => (1, 0, vec![param(0), param(0)], param(0)),
+        sym::simd_arith_offset => (2, 0, vec![param(0), param(1)], param(0)),
         sym::simd_neg
         | sym::simd_bswap
         | sym::simd_bitreverse
@@ -541,25 +542,25 @@ pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>)
         | sym::simd_ceil
         | sym::simd_floor
         | sym::simd_round
-        | sym::simd_trunc => (1, vec![param(0)], param(0)),
-        sym::simd_fpowi => (1, vec![param(0), tcx.types.i32], param(0)),
-        sym::simd_fma => (1, vec![param(0), param(0), param(0)], param(0)),
-        sym::simd_gather => (3, vec![param(0), param(1), param(2)], param(0)),
-        sym::simd_scatter => (3, vec![param(0), param(1), param(2)], Ty::new_unit(tcx)),
-        sym::simd_insert => (2, vec![param(0), tcx.types.u32, param(1)], param(0)),
-        sym::simd_extract => (2, vec![param(0), tcx.types.u32], param(1)),
+        | sym::simd_trunc => (1, 0, vec![param(0)], param(0)),
+        sym::simd_fpowi => (1, 0, vec![param(0), tcx.types.i32], param(0)),
+        sym::simd_fma => (1, 0, vec![param(0), param(0), param(0)], param(0)),
+        sym::simd_gather => (3, 0, vec![param(0), param(1), param(2)], param(0)),
+        sym::simd_scatter => (3, 0, vec![param(0), param(1), param(2)], Ty::new_unit(tcx)),
+        sym::simd_insert => (2, 0, vec![param(0), tcx.types.u32, param(1)], param(0)),
+        sym::simd_extract => (2, 0, vec![param(0), tcx.types.u32], param(1)),
         sym::simd_cast
         | sym::simd_as
         | sym::simd_cast_ptr
         | sym::simd_expose_addr
-        | sym::simd_from_exposed_addr => (2, vec![param(0)], param(1)),
-        sym::simd_bitmask => (2, vec![param(0)], param(1)),
+        | sym::simd_from_exposed_addr => (2, 0, vec![param(0)], param(1)),
+        sym::simd_bitmask => (2, 0, vec![param(0)], param(1)),
         sym::simd_select | sym::simd_select_bitmask => {
-            (2, vec![param(0), param(1), param(1)], param(1))
+            (2, 0, vec![param(0), param(1), param(1)], param(1))
         }
-        sym::simd_reduce_all | sym::simd_reduce_any => (1, vec![param(0)], tcx.types.bool),
+        sym::simd_reduce_all | sym::simd_reduce_any => (1, 0, vec![param(0)], tcx.types.bool),
         sym::simd_reduce_add_ordered | sym::simd_reduce_mul_ordered => {
-            (2, vec![param(0), param(1)], param(1))
+            (2, 0, vec![param(0), param(1)], param(1))
         }
         sym::simd_reduce_add_unordered
         | sym::simd_reduce_mul_unordered
@@ -569,8 +570,9 @@ pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>)
         | sym::simd_reduce_min
         | sym::simd_reduce_max
         | sym::simd_reduce_min_nanless
-        | sym::simd_reduce_max_nanless => (2, vec![param(0)], param(1)),
-        sym::simd_shuffle => (3, vec![param(0), param(0), param(1)], param(2)),
+        | sym::simd_reduce_max_nanless => (2, 0, vec![param(0)], param(1)),
+        sym::simd_shuffle => (3, 0, vec![param(0), param(0), param(1)], param(2)),
+        sym::simd_shuffle_generic => (2, 1, vec![param(0), param(0)], param(1)),
         _ => {
             let msg = format!("unrecognized platform-specific intrinsic function: `{name}`");
             tcx.sess.struct_span_err(it.span, msg).emit();
@@ -580,5 +582,5 @@ pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>)
 
     let sig = tcx.mk_fn_sig(inputs, output, false, hir::Unsafety::Unsafe, Abi::PlatformIntrinsic);
     let sig = ty::Binder::dummy(sig);
-    equate_intrinsic_type(tcx, it, n_tps, 0, sig)
+    equate_intrinsic_type(tcx, it, n_tps, 0, n_cts, sig)
 }

compiler/rustc_span/src/symbol.rs

@@ -1465,6 +1465,7 @@ symbols! {
         simd_shl,
         simd_shr,
         simd_shuffle,
+        simd_shuffle_generic,
         simd_sub,
         simd_trunc,
         simd_xor,

src/tools/miri/src/shims/intrinsics/mod.rs

@@ -60,7 +60,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         }
 
         // The rest jumps to `ret` immediately.
-        this.emulate_intrinsic_by_name(intrinsic_name, args, dest)?;
+        this.emulate_intrinsic_by_name(intrinsic_name, instance.args, args, dest)?;
 
         trace!("{:?}", this.dump_place(dest));
         this.go_to_block(ret);
@@ -71,6 +71,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     fn emulate_intrinsic_by_name(
         &mut self,
         intrinsic_name: &str,
+        generic_args: ty::GenericArgsRef<'tcx>,
         args: &[OpTy<'tcx, Provenance>],
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx> {
@@ -80,7 +81,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             return this.emulate_atomic_intrinsic(name, args, dest);
         }
         if let Some(name) = intrinsic_name.strip_prefix("simd_") {
-            return this.emulate_simd_intrinsic(name, args, dest);
+            return this.emulate_simd_intrinsic(name, generic_args, args, dest);
         }
 
         match intrinsic_name {

src/tools/miri/src/shims/intrinsics/simd.rs

@@ -12,6 +12,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     fn emulate_simd_intrinsic(
         &mut self,
         intrinsic_name: &str,
+        generic_args: ty::GenericArgsRef<'tcx>,
         args: &[OpTy<'tcx, Provenance>],
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx> {
@@ -490,6 +491,38 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                     this.write_immediate(val, &dest)?;
                 }
             }
+            "shuffle_generic" => {
+                let [left, right] = check_arg_count(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)?;
+
+                let index = generic_args[2].expect_const().eval(*this.tcx, this.param_env(), Some(this.tcx.span)).unwrap().unwrap_branch();
+                let index_len = index.len();
+
+                assert_eq!(left_len, right_len);
+                assert_eq!(index_len as u64, dest_len);
+
+                for i in 0..dest_len {
+                    let src_index: u64 = index[i as usize].unwrap_leaf()
+                        .try_to_u32().unwrap()
+                        .into();
+                    let dest = this.project_index(&dest, i)?;
+
+                    let val = if src_index < left_len {
+                        this.read_immediate(&this.project_index(&left, src_index)?)?
+                    } else if src_index < left_len.checked_add(right_len).unwrap() {
+                        let right_idx = src_index.checked_sub(left_len).unwrap();
+                        this.read_immediate(&this.project_index(&right, right_idx)?)?
+                    } else {
+                        span_bug!(
+                            this.cur_span(),
+                            "simd_shuffle index {src_index} is out of bounds for 2 vectors of size {left_len}",
+                        );
+                    };
+                    this.write_immediate(*val, &dest)?;
+                }
+            }
             "shuffle" => {
                 let [left, right, index] = check_arg_count(args)?;
                 let (left, left_len) = this.operand_to_simd(left)?;

tests/ui/simd/intrinsic/generic-elements.rs

@@ -1,6 +1,7 @@
 // build-fail
 
-#![feature(repr_simd, platform_intrinsics, rustc_attrs)]
+#![feature(repr_simd, platform_intrinsics, rustc_attrs, adt_const_params)]
+#![allow(incomplete_features)]
 
 #[repr(simd)]
 #[derive(Copy, Clone)]
@@ -35,6 +36,7 @@ extern "platform-intrinsic" {
     fn simd_extract<T, E>(x: T, idx: u32) -> E;
 
     fn simd_shuffle<T, I, U>(x: T, y: T, idx: I) -> U;
+    fn simd_shuffle_generic<T, U, const IDX: &'static [u32]>(x: T, y: T) -> U;
 }
 
 fn main() {
@@ -71,5 +73,29 @@ fn main() {
         //~^ ERROR expected return type of length 4, found `i32x8` with length 8
         simd_shuffle::<_, _, i32x2>(x, x, IDX8);
         //~^ ERROR expected return type of length 8, found `i32x2` with length 2
+
+        const I2: &[u32] = &[0; 2];
+        simd_shuffle_generic::<i32, i32, I2>(0, 0);
+        //~^ ERROR expected SIMD input type, found non-SIMD `i32`
+        const I4: &[u32] = &[0; 4];
+        simd_shuffle_generic::<i32, i32, I4>(0, 0);
+        //~^ ERROR expected SIMD input type, found non-SIMD `i32`
+        const I8: &[u32] = &[0; 8];
+        simd_shuffle_generic::<i32, i32, I8>(0, 0);
+        //~^ ERROR expected SIMD input type, found non-SIMD `i32`
+
+        simd_shuffle_generic::<_, f32x2, I2>(x, x);
+//~^ ERROR element type `i32` (element of input `i32x4`), found `f32x2` with element type `f32`
+        simd_shuffle_generic::<_, f32x4, I4>(x, x);
+//~^ ERROR element type `i32` (element of input `i32x4`), found `f32x4` with element type `f32`
+        simd_shuffle_generic::<_, f32x8, I8>(x, x);
+//~^ ERROR element type `i32` (element of input `i32x4`), found `f32x8` with element type `f32`
+
+        simd_shuffle_generic::<_, i32x8, I2>(x, x);
+        //~^ ERROR expected return type of length 2, found `i32x8` with length 8
+        simd_shuffle_generic::<_, i32x8, I4>(x, x);
+        //~^ ERROR expected return type of length 4, found `i32x8` with length 8
+        simd_shuffle_generic::<_, i32x2, I8>(x, x);
+        //~^ ERROR expected return type of length 8, found `i32x2` with length 2
     }
 }