Accept [u8; N] bitmasks in simd_select_bitmask

Fixes #1446

Author: bjorn3

build_system/tests.rs

@@ -133,8 +133,8 @@ pub(crate) static REGEX: CargoProject = CargoProject::new(&REGEX_REPO.source_dir
 pub(crate) static PORTABLE_SIMD_REPO: GitRepo = GitRepo::github(
     "rust-lang",
     "portable-simd",
-    "4825b2a64d765317066948867e8714674419359b",
-    "9e67d07c00f5fb0b",
+    "97007cc2e70df8c97326ce896a79e2f0ce4dd98b",
+    "e54a16035cedf205",
     "portable-simd",
 );
 

patches/0001-portable-simd-Enable-the-exposed_provenance-feature.patch

@@ -822,7 +822,35 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
             let (lane_count, lane_ty) = a.layout().ty.simd_size_and_type(fx.tcx);
             let lane_layout = fx.layout_of(lane_ty);
 
-            let m = m.load_scalar(fx);
+            let expected_int_bits = lane_count.max(8);
+            let expected_bytes = expected_int_bits / 8 + ((expected_int_bits % 8 > 0) as u64);
+
+            let m = match m.layout().ty.kind() {
+                ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => m.load_scalar(fx),
+                ty::Array(elem, len)
+                    if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
+                        && len.try_eval_target_usize(fx.tcx, ty::ParamEnv::reveal_all())
+                            == Some(expected_bytes) =>
+                {
+                    m.force_stack(fx).0.load(
+                        fx,
+                        Type::int(expected_int_bits as u16).unwrap(),
+                        MemFlags::trusted(),
+                    )
+                }
+                _ => {
+                    fx.tcx.dcx().span_fatal(
+                        span,
+                        format!(
+                            "invalid monomorphization of `simd_select_bitmask` intrinsic: \
+                            cannot accept `{}` as mask, expected `u{}` or `[u8; {}]`",
+                            ret.layout().ty,
+                            expected_int_bits,
+                            expected_bytes
+                        ),
+                    );
+                }
+            };
 
             for lane in 0..lane_count {
                 let m_lane = fx.bcx.ins().ushr_imm(m, u64::from(lane) as i64);