Merge #400

400: Validate bind group layouts by value r=kvark a=yanchith

This PR widens the comparisons done between two bind group layouts to also consider them equivalent if their vectors of `BindGroupLayoutBinding`s are equal. 

Tested on various modifications of the cube example from wgpu-rs. https://gist.github.com/yanchith/56e15fe35658b14587ff9bfcbd53116f

Fixes #335 

Co-authored-by: yanchith <yanchi.toth@gmail.com>

wgpu-core/src/binding_model.rs

@@ -7,6 +7,7 @@ use crate::{
     resource::TextureViewDimension,
     track::{DUMMY_SELECTOR, TrackerSet},
     BufferAddress,
+    FastHashMap,
     LifeGuard,
     RefCount,
     Stored,
@@ -41,7 +42,7 @@ pub enum BindingType {
 }
 
 #[repr(C)]
-#[derive(Clone, Debug, Hash)]
+#[derive(Clone, Debug, Hash, PartialEq)]
 pub struct BindGroupLayoutBinding {
     pub binding: u32,
     pub visibility: ShaderStage,
@@ -61,7 +62,7 @@ pub struct BindGroupLayoutDescriptor {
 #[derive(Debug)]
 pub struct BindGroupLayout<B: hal::Backend> {
     pub(crate) raw: B::DescriptorSetLayout,
-    pub(crate) bindings: Vec<BindGroupLayoutBinding>,
+    pub(crate) bindings: FastHashMap<u32, BindGroupLayoutBinding>,
     pub(crate) desc_ranges: DescriptorRanges,
     pub(crate) dynamic_count: usize,
 }

wgpu-core/src/device.rs

@@ -1181,6 +1181,23 @@ impl<F: IdentityFilter<BindGroupLayoutId>> Global<F> {
         let mut token = Token::root();
         let hub = B::hub(self);
         let bindings = unsafe { slice::from_raw_parts(desc.bindings, desc.bindings_length) };
+        let bindings_map: FastHashMap<_, _> = bindings
+            .iter()
+            .cloned()
+            .map(|b| (b.binding, b))
+            .collect();
+
+        {
+            let (bind_group_layout_guard, _) = hub.bind_group_layouts.read(&mut token);
+            let bind_group_layout =
+                bind_group_layout_guard
+                    .iter(device_id.backend())
+                    .find(|(_, bgl)| bgl.bindings == bindings_map);
+
+            if let Some((id, _)) = bind_group_layout {
+                return id;
+            }
+        }
 
         let raw_bindings = bindings
             .iter()
@@ -1203,7 +1220,7 @@ impl<F: IdentityFilter<BindGroupLayoutId>> Global<F> {
 
         let layout = binding_model::BindGroupLayout {
             raw,
-            bindings: bindings.to_vec(),
+            bindings: bindings_map,
             desc_ranges: DescriptorRanges::from_bindings(&raw_bindings),
             dynamic_count: bindings.iter().filter(|b| b.dynamic).count(),
         };
@@ -1299,7 +1316,9 @@ impl<F: IdentityFilter<BindGroupId>> Global<F> {
 
             //TODO: group writes into contiguous sections
             let mut writes = Vec::new();
-            for (b, decl) in bindings.iter().zip(&bind_group_layout.bindings) {
+            for b in bindings.iter() {
+                let decl = bind_group_layout.bindings.get(&b.binding)
+                    .expect("Failed to find binding declaration for binding");
                 let descriptor = match b.resource {
                     binding_model::BindingResource::Buffer(ref bb) => {
                         let (alignment, usage) = match decl.ty {

wgpu-core/src/hub.rs

@@ -136,8 +136,15 @@ impl<T, I: TypedId> Storage<T, I> {
                 value
             })
     }
-}
 
+    pub fn iter(&self, backend: Backend) -> impl Iterator<Item = (I, &T)> {
+        self.map
+            .iter()
+            .map(move |(index, (value, storage_epoch))| {
+                (I::zip(index as Index, *storage_epoch, backend), value)
+            })
+    }
+}
 
 /// Type system for enforcing the lock order on shared HUB structures.
 /// If type A implements `Access<B>`, that means we are allowed to proceed