[spv-in] Handle structs with no offset decorations

src/front/glsl/offset.rs

@@ -13,7 +13,7 @@ use super::{
     error::{Error, ErrorKind},
     SourceMetadata,
 };
-use crate::{Arena, Constant, Handle, Type, TypeInner};
+use crate::{front::align_up, Arena, Constant, Handle, Type, TypeInner};
 
 /// Struct with information needed for defining a struct member.
 ///
@@ -170,20 +170,3 @@ pub fn calculate_offset(
 
     TypeAlignSpan { ty, align, span }
 }
-
-/// Helper function used for aligning `value` to the next multiple of `align`
-///
-/// # Notes:
-/// - `align` must be a power of two.
-/// - The returned value will be greater or equal to `value`.
-/// # Examples:
-/// ```ignore
-/// assert_eq!(0, align_up(0, 16));
-/// assert_eq!(16, align_up(1, 16));
-/// assert_eq!(16, align_up(16, 16));
-/// assert_eq!(334, align_up(333, 2));
-/// assert_eq!(384, align_up(257, 128));
-/// ```
-pub fn align_up(value: u32, align: u32) -> u32 {
-    ((value.wrapping_sub(1)) & !(align - 1)).wrapping_add(align)
-}

src/front/glsl/parser/declarations.rs

@@ -597,7 +597,7 @@ impl<'source> ParsingContext<'source> {
                 &mut parser.errors,
             );
 
-            span = offset::align_up(span, info.align);
+            span = crate::front::align_up(span, info.align);
             align = align.max(info.align);
 
             members.push(StructMember {
@@ -614,7 +614,7 @@ impl<'source> ParsingContext<'source> {
             }
         }
 
-        span = offset::align_up(span, align);
+        span = crate::front::align_up(span, align);
 
         Ok(span)
     }

src/front/mod.rs

@@ -127,3 +127,20 @@ impl ops::Index<Handle<crate::Expression>> for Typifier {
         &self.resolutions[handle.index()]
     }
 }
+
+/// Helper function used for aligning `value` to the next multiple of `align`
+///
+/// # Notes:
+/// - `align` must be a power of two.
+/// - The returned value will be greater or equal to `value`.
+/// # Examples:
+/// ```ignore
+/// assert_eq!(0, align_up(0, 16));
+/// assert_eq!(16, align_up(1, 16));
+/// assert_eq!(16, align_up(16, 16));
+/// assert_eq!(334, align_up(333, 2));
+/// assert_eq!(384, align_up(257, 128));
+/// ```
+pub fn align_up(value: u32, align: u32) -> u32 {
+    ((value.wrapping_sub(1)) & !(align - 1)).wrapping_add(align)
+}

src/front/spv/mod.rs

@@ -40,7 +40,7 @@ use function::*;
 
 use crate::{
     arena::{Arena, Handle},
-    proc::{Alignment, Layouter},
+    proc::Layouter,
     FastHashMap,
 };
 
@@ -3245,10 +3245,11 @@ impl<I: Iterator<Item = u32>> Parser<I> {
             .update(&module.types, &module.constants)
             .unwrap();
 
-        let mut struct_alignment = Alignment::new(1).unwrap();
         let mut members = Vec::<crate::StructMember>::with_capacity(inst.wc as usize - 2);
         let mut member_lookups = Vec::with_capacity(members.capacity());
         let mut storage_access = crate::StorageAccess::empty();
+        let mut span = 0;
+        let mut alignment = 1;
         for i in 0..u32::from(inst.wc) - 2 {
             let type_id = self.next()?;
             let ty = self.lookup_type.lookup(type_id)?.handle;
@@ -3264,9 +3265,16 @@ impl<I: Iterator<Item = u32>> Parser<I> {
                 row_major: decor.matrix_major == Some(Majority::Row),
             });
 
+            span = crate::front::align_up(span, self.layouter[ty].alignment.get());
+            alignment = self.layouter[ty].alignment.get().max(alignment);
+
             let binding = decor.io_binding().ok();
-            // I/O structs don't have to have offsets, others do
-            let offset = decor.offset.unwrap_or(0);
+            if let Some(offset) = decor.offset {
+                span = offset;
+            }
+            let offset = span;
+
+            span += self.layouter[ty].size;
 
             if let crate::TypeInner::Matrix {
                 columns,
@@ -3292,8 +3300,6 @@ impl<I: Iterator<Item = u32>> Parser<I> {
                 }
             }
 
-            struct_alignment = struct_alignment.max(self.layouter[ty].alignment);
-
             members.push(crate::StructMember {
                 name: decor.name,
                 ty,
@@ -3302,16 +3308,11 @@ impl<I: Iterator<Item = u32>> Parser<I> {
             });
         }
 
+        span = crate::front::align_up(span, alignment);
+
         let inner = crate::TypeInner::Struct {
             top_level: block_decor.is_some(),
-            span: members
-                .iter()
-                .map(|member| {
-                    let end = member.offset + module.types[member.ty].inner.span(&module.constants);
-                    ((end - 1) | (struct_alignment.get() - 1)) + 1
-                })
-                .max()
-                .unwrap_or(4), //do we support this?
+            span,
             members,
         };