add Primitive.pref_pos

Author: Dante-Broggi

src/librustc/ty/layout.rs

@@ -251,12 +251,15 @@ fn invert_mapping(map: &[u32]) -> Vec<u32> {
 impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
     fn scalar_pair(&self, a: Scalar, b: Scalar) -> LayoutDetails {
         let dl = self.data_layout();
-        let b_align = b.value.align(dl);
-        let align = a.value.align(dl).max(b_align).max(dl.aggregate_align);
-        let b_offset = a.value.size(dl).align_to(b_align.abi);
-        let size = (b_offset + b.value.size(dl)).align_to(align.abi);
 
-        let pref_pos = LayoutPositionPref::new(size, align);
+        let a_pref_pos = a.value.pref_pos(dl);
+        let b_pref_pos = b.value.pref_pos(dl);
+
+        let b_align = b_pref_pos.align;
+
+        let pref_pos = a_pref_pos.align_to(b_align).align_to(dl.aggregate_align);
+        let (pref_pos, b_offset) = pref_pos.extend(b_pref_pos);
+        let pref_pos = pref_pos.strided();
 
         // HACK(nox): We iter on `b` and then `a` because `max_by_key`
         // returns the last maximum.

src/librustc_target/abi/mod.rs

@@ -696,6 +696,17 @@ pub enum Primitive {
 }
 
 impl Primitive {
+    pub fn pref_pos<C: HasDataLayout>(self, cx: &C) -> LayoutPositionPref {
+        let dl = cx.data_layout();
+
+        match self {
+            Int(i, _) => LayoutPositionPref::new(i.size(), i.align(dl)),
+            F32 => LayoutPositionPref::new(Size::from_bits(32), dl.f32_align),
+            F64 => LayoutPositionPref::new(Size::from_bits(64), dl.f64_align),
+            Pointer => dl.pointer_pos
+        }
+    }
+
     pub fn size<C: HasDataLayout>(self, cx: &C) -> Size {
         let dl = cx.data_layout();
 
@@ -1069,9 +1080,7 @@ pub struct LayoutDetails {
 impl LayoutDetails {
     pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
         let largest_niche = Niche::from_scalar(cx, Size::ZERO, scalar.clone());
-        let size = scalar.value.size(cx);
-        let align = scalar.value.align(cx);
-        let pref_pos = LayoutPositionPref::new(size, align);
+        let pref_pos = scalar.value.pref_pos(cx);
         LayoutDetails {
             variants: Variants::Single { index: VariantIdx::new(0) },
             fields: FieldPlacement::Union(0),