Add const-eval support for SIMD types, insert, and extract

src/librustc_mir/interpret/intrinsics.rs

@@ -239,7 +239,57 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             "transmute" => {
                 self.copy_op_transmute(args[0], dest)?;
             }
+            "simd_insert" => {
+                let index = self.read_scalar(args[1])?.to_u32()? as u64;
+                let scalar = self.read_immediate(args[2])?;
+                let input = args[0];
+                let (len, e_ty) = self.read_vector_ty(input);
+                assert!(
+                    index < len,
+                    "index `{}` must be in bounds of vector type `{}`: `[0, {})`",
+                    index, e_ty, len
+                );
+                assert_eq!(
+                    args[0].layout, dest.layout,
+                    "Return type `{}` must match vector type `{}`",
+                    dest.layout.ty, input.layout.ty
+                );
+                assert_eq!(
+                    scalar.layout.ty, e_ty,
+                    "Scalar type `{}` must match vector element type `{}`",
+                    scalar.layout.ty, e_ty
+                );
 
+                for i in 0..len {
+                    let place = self.place_field(dest, index)?;
+                    if i == index {
+                        self.write_immediate(*scalar, place)?;
+                    } else {
+                        self.write_immediate(
+                            *self.read_immediate(self.operand_field(input, index)?)?,
+                            place
+                        )?;
+                    };
+                }
+            }
+            "simd_extract" => {
+                let index = self.read_scalar(args[1])?.to_u32()? as _;
+                let (len, e_ty) = self.read_vector_ty(args[0]);
+                assert!(
+                    index < len,
+                    "index `{}` must be in bounds of vector type `{}`: `[0, {})`",
+                    index, e_ty, len
+                );
+                assert_eq!(
+                    e_ty, dest.layout.ty,
+                    "Return type `{}` must match vector element type `{}`",
+                    dest.layout.ty, e_ty
+                );
+                self.write_immediate(
+                    *self.read_immediate(self.operand_field(args[0], index)?)?,
+                    dest
+                )?;
+            }
             _ => return Ok(false),
         }
 

src/librustc_mir/interpret/operand.rs

@@ -335,6 +335,18 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
+    /// Read vector length and element type
+    pub fn read_vector_ty(
+        &self, op: OpTy<'tcx, M::PointerTag>
+    )
+        -> (u64, &rustc::ty::TyS<'tcx>) {
+        if let layout::Abi::Vector { .. } = op.layout.abi {
+            (op.layout.ty.simd_size(*self.tcx) as _, op.layout.ty.simd_type(*self.tcx))
+        } else {
+            bug!("Type `{}` is not a SIMD vector type", op.layout.ty)
+        }
+    }
+
     /// Read a scalar from a place
     pub fn read_scalar(
         &self,

src/librustc_mir/interpret/terminator.rs

@@ -249,9 +249,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
         match instance.def {
             ty::InstanceDef::Intrinsic(..) => {
-                if caller_abi != Abi::RustIntrinsic {
-                    throw_unsup!(FunctionAbiMismatch(caller_abi, Abi::RustIntrinsic))
-                }
                 // The intrinsic itself cannot diverge, so if we got here without a return
                 // place... (can happen e.g., for transmute returning `!`)
                 let dest = match dest {

src/librustc_mir/transform/qualify_consts.rs

@@ -557,6 +557,8 @@ impl Qualif for IsNotPromotable {
                             | "saturating_add"
                             | "saturating_sub"
                             | "transmute"
+                            | "simd_insert"
+                            | "simd_extract"
                             => return true,
 
                             _ => {}

src/test/ui/consts/const-eval/simd/insert_extract-fail.rs

@@ -0,0 +1,27 @@
+#![feature(const_fn)]
+#![feature(repr_simd)]
+#![feature(platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+#[repr(simd)] struct i8x1(i8);
+
+extern "platform-intrinsic" {
+    fn simd_insert<T, U>(x: T, idx: u32, val: U) -> T;
+    fn simd_extract<T, U>(x: T, idx: u32) -> U;
+}
+
+const fn foo(x: i8x1) -> i8 {
+    // 42 is a i16 that does not fit in a i8
+    unsafe { simd_insert(x, 0_u32, 42_i16) }.0  //~ ERROR
+}
+
+const fn bar(x: i8x1) -> i16 {
+    // the i8 is not a i16:
+    unsafe { simd_extract(x, 0_u32) }  //~ ERROR
+}
+
+fn main() {
+    const V: i8x1 = i8x1(13);
+    const X: i8 = foo(V);
+    const Y: i16 = bar(V);
+}

src/test/ui/consts/const-eval/simd/insert_extract-fail.stderr

@@ -0,0 +1,16 @@
+error: any use of this value will cause an error
+  --> $DIR/insert_extract-fail.rs:14:14
+   |
+LL |     unsafe { simd_insert(x, 0_u32, 42_i16) }.0
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |              |
+   |              Inserting `i16` with size `2` to a vector element place of size `1`
+   |              inside call to `foo` at $DIR/insert_extract-fail.rs:19:19
+...
+LL |     const X: i8 = foo(V);
+   |     ---------------------
+   |
+   = note: `#[deny(const_err)]` on by default
+
+error: aborting due to previous error
+

src/test/ui/consts/const-eval/simd/insert_extract.rs

@@ -0,0 +1,53 @@
+// run-pass
+#![feature(const_fn)]
+#![feature(repr_simd)]
+#![feature(platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+#[repr(simd)] struct i8x1(i8);
+#[repr(simd)] struct u16x2(u16, u16);
+#[repr(simd)] struct f32x3(f32, f32, f32);
+
+extern "platform-intrinsic" {
+    fn simd_insert<T, U>(x: T, idx: u32, val: U) -> T;
+    fn simd_extract<T, U>(x: T, idx: u32) -> U;
+}
+
+fn main() {
+    {
+        const U: i8x1 = i8x1(13);
+        const V: i8x1 = unsafe { simd_insert(U, 0_u32, 42_i8) };
+        const X0: i8 = V.0;
+        const Y0: i8 = unsafe { simd_extract(V, 0) };
+        assert_eq!(X0, 42);
+        assert_eq!(Y0, 42);
+    }
+    {
+        const U: u16x2 = u16x2(13, 14);
+        const V: u16x2 = unsafe { simd_insert(U, 1_u32, 42_u16) };
+        const X0: u16 = V.0;
+        const X1: u16 = V.1;
+        const Y0: u16 = unsafe { simd_extract(V, 0) };
+        const Y1: u16 = unsafe { simd_extract(V, 1) };
+        assert_eq!(X0, 13);
+        assert_eq!(X1, 42);
+        assert_eq!(Y0, 13);
+        assert_eq!(Y1, 42);
+    }
+    {
+        const U: f32x3 = f32x3(13., 14., 15.);
+        const V: f32x3 = unsafe { simd_insert(U, 1_u32, 42_f32) };
+        const X0: f32 = V.0;
+        const X1: f32 = V.1;
+        const X2: f32 = V.2;
+        const Y0: f32 = unsafe { simd_extract(V, 0) };
+        const Y1: f32 = unsafe { simd_extract(V, 1) };
+        const Y2: f32 = unsafe { simd_extract(V, 2) };
+        assert_eq!(X0, 13.);
+        assert_eq!(X1, 42.);
+        assert_eq!(X2, 15.);
+        assert_eq!(Y0, 13.);
+        assert_eq!(Y1, 42.);
+        assert_eq!(Y2, 15.);
+    }
+}

src/test/ui/consts/const-eval/simd/read_fail.rs

@@ -0,0 +1,17 @@
+#![feature(const_fn)]
+#![feature(platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+extern "platform-intrinsic" {
+    fn simd_extract<T, U>(x: T, idx: u32) -> U;
+}
+
+const fn foo(x: i8) -> i8 {
+    // i8 is not a vector type:
+    unsafe { simd_extract(x, 0_u32) }  //~ ERROR
+}
+
+fn main() {
+    const V: i8 = 13;
+    const X: i8 = foo(V);
+}