1 files changed, 109 insertions, 0 deletions
diff --git a/third_party/rust/naga/src/back/spv/helpers.rs b/third_party/rust/naga/src/back/spv/helpers.rs
new file mode 100644
index 0000000000..5b6226db85
--- /dev/null
+++ b/third_party/rust/naga/src/back/spv/helpers.rs
@@ -0,0 +1,109 @@
+use crate::{Handle, UniqueArena};
+use spirv::Word;
+
+pub(super) fn bytes_to_words(bytes: &[u8]) -> Vec<Word> {
+    bytes
+        .chunks(4)
+        .map(|chars| chars.iter().rev().fold(0u32, |u, c| (u << 8) | *c as u32))
+        .collect()
+}
+
+pub(super) fn string_to_words(input: &str) -> Vec<Word> {
+    let bytes = input.as_bytes();
+    let mut words = bytes_to_words(bytes);
+
+    if bytes.len() % 4 == 0 {
+        // nul-termination
+        words.push(0x0u32);
+    }
+
+    words
+}
+
+pub(super) const fn map_storage_class(space: crate::AddressSpace) -> spirv::StorageClass {
+    match space {
+        crate::AddressSpace::Handle => spirv::StorageClass::UniformConstant,
+        crate::AddressSpace::Function => spirv::StorageClass::Function,
+        crate::AddressSpace::Private => spirv::StorageClass::Private,
+        crate::AddressSpace::Storage { .. } => spirv::StorageClass::StorageBuffer,
+        crate::AddressSpace::Uniform => spirv::StorageClass::Uniform,
+        crate::AddressSpace::WorkGroup => spirv::StorageClass::Workgroup,
+        crate::AddressSpace::PushConstant => spirv::StorageClass::PushConstant,
+    }
+}
+
+pub(super) fn contains_builtin(
+    binding: Option<&crate::Binding>,
+    ty: Handle<crate::Type>,
+    arena: &UniqueArena<crate::Type>,
+    built_in: crate::BuiltIn,
+) -> bool {
+    if let Some(&crate::Binding::BuiltIn(bi)) = binding {
+        bi == built_in
+    } else if let crate::TypeInner::Struct { ref members, .. } = arena[ty].inner {
+        members
+            .iter()
+            .any(|member| contains_builtin(member.binding.as_ref(), member.ty, arena, built_in))
+    } else {
+        false // unreachable
+    }
+}
+
+impl crate::AddressSpace {
+    pub(super) const fn to_spirv_semantics_and_scope(
+        self,
+    ) -> (spirv::MemorySemantics, spirv::Scope) {
+        match self {
+            Self::Storage { .. } => (spirv::MemorySemantics::UNIFORM_MEMORY, spirv::Scope::Device),
+            Self::WorkGroup => (
+                spirv::MemorySemantics::WORKGROUP_MEMORY,
+                spirv::Scope::Workgroup,
+            ),
+            _ => (spirv::MemorySemantics::empty(), spirv::Scope::Invocation),
+        }
+    }
+}
+
+/// Return true if the global requires a type decorated with `Block`.
+///
+/// Vulkan spec v1.3 §15.6.2, "Descriptor Set Interface", says:
+///
+/// > Variables identified with the `Uniform` storage class are used to
+/// > access transparent buffer backed resources. Such variables must
+/// > be:
+/// >
+/// > -   typed as `OpTypeStruct`, or an array of this type,
+/// >
+/// > -   identified with a `Block` or `BufferBlock` decoration, and
+/// >
+/// > -   laid out explicitly using the `Offset`, `ArrayStride`, and
+/// >     `MatrixStride` decorations as specified in §15.6.4, "Offset
+/// >     and Stride Assignment."
+// See `back::spv::GlobalVariable::access_id` for details.
+pub fn global_needs_wrapper(ir_module: &crate::Module, var: &crate::GlobalVariable) -> bool {
+    match var.space {
+        crate::AddressSpace::Uniform
+        | crate::AddressSpace::Storage { .. }
+        | crate::AddressSpace::PushConstant => {}
+        _ => return false,
+    };
+    match ir_module.types[var.ty].inner {
+        crate::TypeInner::Struct {
+            ref members,
+            span: _,
+        } => match members.last() {
+            Some(member) => match ir_module.types[member.ty].inner {
+                // Structs with dynamically sized arrays can't be copied and can't be wrapped.
+                crate::TypeInner::Array {
+                    size: crate::ArraySize::Dynamic,
+                    ..
+                } => false,
+                _ => true,
+            },
+            None => false,
+        },
+        crate::TypeInner::BindingArray { .. } => false,
+        // if it's not a structure or a binding array, let's wrap it to be able to put "Block"
+        _ => true,
+    }
+}