add simd_bswap and simd_bitreverse

Author: RalfJung

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

@@ -29,6 +29,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             | "fsqrt"
             | "ctlz"
             | "cttz"
+            | "bswap"
+            | "bitreverse"
             => {
                 let [op] = check_arg_count(args)?;
                 let (op, op_len) = this.operand_to_simd(op)?;
@@ -54,6 +56,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                     "trunc" => Op::Round(rustc_apfloat::Round::TowardZero),
                     "ctlz" => Op::Numeric(sym::ctlz),
                     "cttz" => Op::Numeric(sym::cttz),
+                    "bswap" => Op::Numeric(sym::bswap),
+                    "bitreverse" => Op::Numeric(sym::bitreverse),
                     _ => unreachable!(),
                 };
 
@@ -116,6 +120,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                             let bits_out = match name {
                                 sym::ctlz => u128::from(bits.leading_zeros()).checked_sub(extra).unwrap(),
                                 sym::cttz => u128::from((bits << extra).trailing_zeros()).checked_sub(extra).unwrap(),
+                                sym::bswap => (bits << extra).swap_bytes(),
+                                sym::bitreverse => (bits << extra).reverse_bits(),
                                 _ => unreachable!(),
                             };
                             Scalar::from_uint(bits_out, size)

src/tools/miri/tests/pass/portable-simd.rs

@@ -202,6 +202,19 @@ fn simd_ops_i32() {
     assert_eq!(b.trailing_zeros(), u32x4::from_array([0, 1, 0, 2]));
     assert_eq!(b.leading_ones(), u32x4::from_array([0, 0, 0, 30]));
     assert_eq!(b.trailing_ones(), u32x4::from_array([1, 0, 2, 0]));
+    assert_eq!(
+        b.swap_bytes(),
+        i32x4::from_array([0x01000000, 0x02000000, 0x03000000, 0xfcffffffu32 as i32])
+    );
+    assert_eq!(
+        b.reverse_bits(),
+        i32x4::from_array([
+            0x80000000u32 as i32,
+            0x40000000,
+            0xc0000000u32 as i32,
+            0x3fffffffu32 as i32
+        ])
+    );
 }
 
 fn simd_mask() {