Rollup merge of rust-lang#88868 - calebzulawski:feature/simd_bitmask, r=workingjubilee

Allow simd_bitmask to return byte arrays

cc `@rust-lang/project-portable-simd` `@workingjubilee`

Author: matthiaskrgr

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -19,7 +19,7 @@ use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf};
 use rustc_middle::ty::{self, Ty};
 use rustc_middle::{bug, span_bug};
 use rustc_span::{sym, symbol::kw, Span, Symbol};
-use rustc_target::abi::{self, HasDataLayout, Primitive};
+use rustc_target::abi::{self, Align, HasDataLayout, Primitive};
 use rustc_target::spec::{HasTargetSpec, PanicStrategy};
 
 use std::cmp::Ordering;
@@ -857,28 +857,39 @@ fn generic_simd_intrinsic(
     let arg_tys = sig.inputs();
 
     if name == sym::simd_select_bitmask {
-        let in_ty = arg_tys[0];
-        let m_len = match in_ty.kind() {
-            // Note that this `.unwrap()` crashes for isize/usize, that's sort
-            // of intentional as there's not currently a use case for that.
-            ty::Int(i) => i.bit_width().unwrap(),
-            ty::Uint(i) => i.bit_width().unwrap(),
-            _ => return_error!("`{}` is not an integral type", in_ty),
-        };
         require_simd!(arg_tys[1], "argument");
-        let (v_len, _) = arg_tys[1].simd_size_and_type(bx.tcx());
-        require!(
-            // Allow masks for vectors with fewer than 8 elements to be
-            // represented with a u8 or i8.
-            m_len == v_len || (m_len == 8 && v_len < 8),
-            "mismatched lengths: mask length `{}` != other vector length `{}`",
-            m_len,
-            v_len
-        );
+        let (len, _) = arg_tys[1].simd_size_and_type(bx.tcx());
+
+        let expected_int_bits = (len.max(8) - 1).next_power_of_two();
+        let expected_bytes = len / 8 + ((len % 8 > 0) as u64);
+
+        let mask_ty = arg_tys[0];
+        let mask = match mask_ty.kind() {
+            ty::Int(i) if i.bit_width() == Some(expected_int_bits) => args[0].immediate(),
+            ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => args[0].immediate(),
+            ty::Array(elem, len)
+                if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
+                    && len.try_eval_usize(bx.tcx, ty::ParamEnv::reveal_all())
+                        == Some(expected_bytes) =>
+            {
+                let place = PlaceRef::alloca(bx, args[0].layout);
+                args[0].val.store(bx, place);
+                let int_ty = bx.type_ix(expected_bytes * 8);
+                let ptr = bx.pointercast(place.llval, bx.cx.type_ptr_to(int_ty));
+                bx.load(int_ty, ptr, Align::ONE)
+            }
+            _ => return_error!(
+                "invalid bitmask `{}`, expected `u{}` or `[u8; {}]`",
+                mask_ty,
+                expected_int_bits,
+                expected_bytes
+            ),
+        };
+
         let i1 = bx.type_i1();
-        let im = bx.type_ix(v_len);
-        let i1xn = bx.type_vector(i1, v_len);
-        let m_im = bx.trunc(args[0].immediate(), im);
+        let im = bx.type_ix(len);
+        let i1xn = bx.type_vector(i1, len);
+        let m_im = bx.trunc(mask, im);
         let m_i1s = bx.bitcast(m_im, i1xn);
         return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
     }
@@ -1056,16 +1067,16 @@ fn generic_simd_intrinsic(
 
     if name == sym::simd_bitmask {
         // The `fn simd_bitmask(vector) -> unsigned integer` intrinsic takes a
-        // vector mask and returns an unsigned integer containing the most
-        // significant bit (MSB) of each lane.
-
-        // If the vector has less than 8 lanes, a u8 is returned with zeroed
-        // trailing bits.
+        // vector mask and returns the most significant bit (MSB) of each lane in the form
+        // of either:
+        // * an unsigned integer
+        // * an array of `u8`
+        // If the vector has less than 8 lanes, a u8 is returned with zeroed trailing bits.
+        //
+        // The bit order of the result depends on the byte endianness, LSB-first for little
+        // endian and MSB-first for big endian.
         let expected_int_bits = in_len.max(8);
-        match ret_ty.kind() {
-            ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => (),
-            _ => return_error!("bitmask `{}`, expected `u{}`", ret_ty, expected_int_bits),
-        }
+        let expected_bytes = expected_int_bits / 8 + ((expected_int_bits % 8 > 0) as u64);
 
         // Integer vector <i{in_bitwidth} x in_len>:
         let (i_xn, in_elem_bitwidth) = match in_elem.kind() {
@@ -1095,8 +1106,34 @@ fn generic_simd_intrinsic(
         let i1xn = bx.trunc(i_xn_msb, bx.type_vector(bx.type_i1(), in_len));
         // Bitcast <i1 x N> to iN:
         let i_ = bx.bitcast(i1xn, bx.type_ix(in_len));
-        // Zero-extend iN to the bitmask type:
-        return Ok(bx.zext(i_, bx.type_ix(expected_int_bits)));
+
+        match ret_ty.kind() {
+            ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => {
+                // Zero-extend iN to the bitmask type:
+                return Ok(bx.zext(i_, bx.type_ix(expected_int_bits)));
+            }
+            ty::Array(elem, len)
+                if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
+                    && len.try_eval_usize(bx.tcx, ty::ParamEnv::reveal_all())
+                        == Some(expected_bytes) =>
+            {
+                // Zero-extend iN to the array lengh:
+                let ze = bx.zext(i_, bx.type_ix(expected_bytes * 8));
+
+                // Convert the integer to a byte array
+                let ptr = bx.alloca(bx.type_ix(expected_bytes * 8), Align::ONE);
+                bx.store(ze, ptr, Align::ONE);
+                let array_ty = bx.type_array(bx.type_i8(), expected_bytes);
+                let ptr = bx.pointercast(ptr, bx.cx.type_ptr_to(array_ty));
+                return Ok(bx.load(array_ty, ptr, Align::ONE));
+            }
+            _ => return_error!(
+                "cannot return `{}`, expected `u{}` or `[u8; {}]`",
+                ret_ty,
+                expected_int_bits,
+                expected_bytes
+            ),
+        }
     }
 
     fn simd_simple_float_intrinsic(

src/test/ui/simd/intrinsic/generic-bitmask.rs

@@ -51,19 +51,19 @@ fn main() {
         let _: u64 = simd_bitmask(m64);
 
         let _: u16 = simd_bitmask(m2);
-        //~^ ERROR bitmask `u16`, expected `u8`
+        //~^ ERROR invalid monomorphization of `simd_bitmask` intrinsic
 
         let _: u16 = simd_bitmask(m8);
-        //~^ ERROR bitmask `u16`, expected `u8`
+        //~^ ERROR invalid monomorphization of `simd_bitmask` intrinsic
 
         let _: u32 = simd_bitmask(m16);
-        //~^ ERROR bitmask `u32`, expected `u16`
+        //~^ ERROR invalid monomorphization of `simd_bitmask` intrinsic
 
         let _: u64 = simd_bitmask(m32);
-        //~^ ERROR bitmask `u64`, expected `u32`
+        //~^ ERROR invalid monomorphization of `simd_bitmask` intrinsic
 
         let _: u128 = simd_bitmask(m64);
-        //~^ ERROR bitmask `u128`, expected `u64`
+        //~^ ERROR invalid monomorphization of `simd_bitmask` intrinsic
 
    }
 }

src/test/ui/simd/intrinsic/generic-bitmask.stderr

@@ -1,28 +1,28 @@
-error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: bitmask `u16`, expected `u8`
+error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: cannot return `u16`, expected `u8` or `[u8; 1]`
   --> $DIR/generic-bitmask.rs:53:22
    |
 LL |         let _: u16 = simd_bitmask(m2);
    |                      ^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: bitmask `u16`, expected `u8`
+error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: cannot return `u16`, expected `u8` or `[u8; 1]`
   --> $DIR/generic-bitmask.rs:56:22
    |
 LL |         let _: u16 = simd_bitmask(m8);
    |                      ^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: bitmask `u32`, expected `u16`
+error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: cannot return `u32`, expected `u16` or `[u8; 2]`
   --> $DIR/generic-bitmask.rs:59:22
    |
 LL |         let _: u32 = simd_bitmask(m16);
    |                      ^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: bitmask `u64`, expected `u32`
+error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: cannot return `u64`, expected `u32` or `[u8; 4]`
   --> $DIR/generic-bitmask.rs:62:22
    |
 LL |         let _: u64 = simd_bitmask(m32);
    |                      ^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: bitmask `u128`, expected `u64`
+error[E0511]: invalid monomorphization of `simd_bitmask` intrinsic: cannot return `u128`, expected `u64` or `[u8; 8]`
   --> $DIR/generic-bitmask.rs:65:23
    |
 LL |         let _: u128 = simd_bitmask(m64);

src/test/ui/simd/intrinsic/generic-select.rs

@@ -20,8 +20,7 @@ struct b8x4(pub i8, pub i8, pub i8, pub i8);
 
 #[repr(simd)]
 #[derive(Copy, Clone, PartialEq)]
-struct b8x8(pub i8, pub i8, pub i8, pub i8,
-            pub i8, pub i8, pub i8, pub i8);
+struct b8x8(pub i8, pub i8, pub i8, pub i8, pub i8, pub i8, pub i8, pub i8);
 
 extern "platform-intrinsic" {
     fn simd_select<T, U>(x: T, a: U, b: U) -> U;
@@ -50,15 +49,15 @@ fn main() {
         //~^ ERROR found non-SIMD `u32`
 
         simd_select_bitmask(0u16, x, x);
-        //~^ ERROR mask length `16` != other vector length `4`
-        //
+        //~^ ERROR invalid bitmask `u16`, expected `u8` or `[u8; 1]`
+
         simd_select_bitmask(0u8, 1u32, 2u32);
         //~^ ERROR found non-SIMD `u32`
 
         simd_select_bitmask(0.0f32, x, x);
-        //~^ ERROR `f32` is not an integral type
+        //~^ ERROR invalid bitmask `f32`, expected `u8` or `[u8; 1]`
 
         simd_select_bitmask("x", x, x);
-        //~^ ERROR `&str` is not an integral type
+        //~^ ERROR invalid bitmask `&str`, expected `u8` or `[u8; 1]`
     }
 }

src/test/ui/simd/intrinsic/generic-select.stderr

@@ -1,47 +1,47 @@
 error[E0511]: invalid monomorphization of `simd_select` intrinsic: mismatched lengths: mask length `8` != other vector length `4`
-  --> $DIR/generic-select.rs:40:9
+  --> $DIR/generic-select.rs:39:9
    |
 LL |         simd_select(m8, x, x);
    |         ^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_select` intrinsic: mask element type is `u32`, expected `i_`
-  --> $DIR/generic-select.rs:43:9
+  --> $DIR/generic-select.rs:42:9
    |
 LL |         simd_select(x, x, x);
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_select` intrinsic: mask element type is `f32`, expected `i_`
-  --> $DIR/generic-select.rs:46:9
+  --> $DIR/generic-select.rs:45:9
    |
 LL |         simd_select(z, z, z);
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_select` intrinsic: expected SIMD argument type, found non-SIMD `u32`
-  --> $DIR/generic-select.rs:49:9
+  --> $DIR/generic-select.rs:48:9
    |
 LL |         simd_select(m4, 0u32, 1u32);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: mismatched lengths: mask length `16` != other vector length `4`
-  --> $DIR/generic-select.rs:52:9
+error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: invalid bitmask `u16`, expected `u8` or `[u8; 1]`
+  --> $DIR/generic-select.rs:51:9
    |
 LL |         simd_select_bitmask(0u16, x, x);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: expected SIMD argument type, found non-SIMD `u32`
-  --> $DIR/generic-select.rs:55:9
+  --> $DIR/generic-select.rs:54:9
    |
 LL |         simd_select_bitmask(0u8, 1u32, 2u32);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: `f32` is not an integral type
-  --> $DIR/generic-select.rs:58:9
+error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: invalid bitmask `f32`, expected `u8` or `[u8; 1]`
+  --> $DIR/generic-select.rs:57:9
    |
 LL |         simd_select_bitmask(0.0f32, x, x);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: `&str` is not an integral type
-  --> $DIR/generic-select.rs:61:9
+error[E0511]: invalid monomorphization of `simd_select_bitmask` intrinsic: invalid bitmask `&str`, expected `u8` or `[u8; 1]`
+  --> $DIR/generic-select.rs:60:9
    |
 LL |         simd_select_bitmask("x", x, x);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/simd/simd-bitmask.rs

@@ -0,0 +1,52 @@
+//run-pass
+//ignore-endian-big behavior of simd_select_bitmask is endian-specific
+#![feature(repr_simd, platform_intrinsics)]
+
+extern "platform-intrinsic" {
+    fn simd_bitmask<T, U>(v: T) -> U;
+    fn simd_select_bitmask<T, U>(m: T, a: U, b: U) -> U;
+}
+
+#[derive(Copy, Clone)]
+#[repr(simd)]
+struct Simd<T, const N: usize>([T; N]);
+
+fn main() {
+    unsafe {
+        let v = Simd::<i8, 4>([-1, 0, -1, 0]);
+        let i: u8 = simd_bitmask(v);
+        let a: [u8; 1] = simd_bitmask(v);
+
+        assert_eq!(i, 0b0101);
+        assert_eq!(a, [0b0101]);
+
+        let v = Simd::<i8, 16>([0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, -1, 0]);
+        let i: u16 = simd_bitmask(v);
+        let a: [u8; 2] = simd_bitmask(v);
+
+        assert_eq!(i, 0b0101000000001100);
+        assert_eq!(a, [0b1100, 0b01010000]);
+    }
+
+    unsafe {
+        let a = Simd::<i32, 8>([0, 1, 2, 3, 4, 5, 6, 7]);
+        let b = Simd::<i32, 8>([8, 9, 10, 11, 12, 13, 14, 15]);
+        let e = [0, 9, 2, 11, 12, 13, 14, 15];
+
+        let r = simd_select_bitmask(0b0101u8, a, b);
+        assert_eq!(r.0, e);
+
+        let r = simd_select_bitmask([0b0101u8], a, b);
+        assert_eq!(r.0, e);
+
+        let a = Simd::<i32, 16>([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
+        let b = Simd::<i32, 16>([16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]);
+        let e = [16, 17, 2, 3, 20, 21, 22, 23, 24, 25, 26, 27, 12, 29, 14, 31];
+
+        let r = simd_select_bitmask(0b0101000000001100u16, a, b);
+        assert_eq!(r.0, e);
+
+        let r = simd_select_bitmask([0b1100u8, 0b01010000u8], a, b);
+        assert_eq!(r.0, e);
+    }
+}