Use PassMode::ByVal for Abi::Vector

Author: bjorn3

src/abi/pass_mode.rs

@@ -100,7 +100,13 @@ pub(super) fn get_pass_mode<'tcx>(tcx: TyCtxt<'tcx>, layout: TyAndLayout<'tcx>)
             }
 
             // FIXME implement Vector Abi in a cg_llvm compatible way
-            Abi::Vector { .. } => PassMode::ByRef { size: Some(layout.size) },
+            Abi::Vector { .. } => {
+                if let Some(vector_ty) = crate::intrinsics::clif_vector_type(tcx, layout) {
+                    PassMode::ByVal(vector_ty)
+                } else {
+                    PassMode::ByRef { size: Some(layout.size) }
+                }
+            }
 
             Abi::Aggregate { sized: true } => PassMode::ByRef { size: Some(layout.size) },
             Abi::Aggregate { sized: false } => PassMode::ByRef { size: None },

src/intrinsics/mod.rs

@@ -175,7 +175,7 @@ fn lane_type_and_count<'tcx>(
     (lane_layout, lane_count)
 }
 
-fn clif_vector_type<'tcx>(tcx: TyCtxt<'tcx>, layout: TyAndLayout<'tcx>) -> Option<Type> {
+pub(crate) fn clif_vector_type<'tcx>(tcx: TyCtxt<'tcx>, layout: TyAndLayout<'tcx>) -> Option<Type> {
     let (element, count) = match &layout.abi {
         Abi::Vector { element, count } => (element.clone(), *count),
         _ => unreachable!(),