#[spirv(block)] for Block decorations on structs.

crates/rustc_codegen_spirv/src/abi.rs

@@ -229,6 +229,7 @@ impl<'tcx> ConvSpirvType<'tcx> for CastTarget {
             field_types: args,
             field_offsets,
             field_names: None,
+            is_block: false,
         }
         .def(span, cx)
     }
@@ -324,6 +325,35 @@ fn trans_type_impl<'tcx>(
 ) -> Word {
     if let TyKind::Adt(adt, _) = *ty.ty.kind() {
         for attr in parse_attrs(cx, cx.tcx.get_attrs(adt.did)) {
+            if matches!(attr, SpirvAttribute::Block) {
+                if !adt.is_struct() {
+                    cx.tcx.sess.span_err(
+                        span,
+                        &format!(
+                            "`#[spirv(block)]` can only be used on a `struct`, \
+                             but `{}` is a `{}`",
+                            ty.ty,
+                            adt.descr(),
+                        ),
+                    );
+                }
+
+                if !matches!(ty.abi, Abi::Aggregate { sized: true }) {
+                    cx.tcx.sess.span_err(
+                        span,
+                        &format!(
+                            "`#[spirv(block)]` can only be used for `Sized` aggregates, \
+                             but `{}` has `Abi::{:?}`",
+                            ty.ty, ty.abi,
+                        ),
+                    );
+                }
+
+                assert!(matches!(ty.fields, FieldsShape::Arbitrary { .. }));
+
+                return trans_struct(cx, span, ty, true);
+            }
+
             if let Some(image) = trans_image(cx, span, ty, attr) {
                 return image;
             }
@@ -340,6 +370,7 @@ fn trans_type_impl<'tcx>(
             field_types: Vec::new(),
             field_offsets: Vec::new(),
             field_names: None,
+            is_block: false,
         }
         .def(span, cx),
         Abi::Scalar(ref scalar) => trans_scalar(cx, span, ty, scalar, None, is_immediate),
@@ -359,6 +390,7 @@ fn trans_type_impl<'tcx>(
                 field_types: vec![one_spirv, two_spirv],
                 field_offsets: vec![one_offset, two_offset],
                 field_names: None,
+                is_block: false,
             }
             .def(span, cx)
         }
@@ -618,6 +650,7 @@ fn trans_aggregate<'tcx>(cx: &CodegenCx<'tcx>, span: Span, ty: TyAndLayout<'tcx>
                     field_types: Vec::new(),
                     field_offsets: Vec::new(),
                     field_names: None,
+                    is_block: false,
                 }
                 .def(span, cx)
             } else {
@@ -638,7 +671,7 @@ fn trans_aggregate<'tcx>(cx: &CodegenCx<'tcx>, span: Span, ty: TyAndLayout<'tcx>
         FieldsShape::Arbitrary {
             offsets: _,
             memory_index: _,
-        } => trans_struct(cx, span, ty),
+        } => trans_struct(cx, span, ty, false),
     }
 }
 
@@ -668,7 +701,12 @@ pub fn auto_struct_layout<'tcx>(
 }
 
 // see struct_llfields in librustc_codegen_llvm for implementation hints
-fn trans_struct<'tcx>(cx: &CodegenCx<'tcx>, span: Span, ty: TyAndLayout<'tcx>) -> Word {
+fn trans_struct<'tcx>(
+    cx: &CodegenCx<'tcx>,
+    span: Span,
+    ty: TyAndLayout<'tcx>,
+    is_block: bool,
+) -> Word {
     let name = name_of_struct(ty);
     if let TyKind::Foreign(_) = ty.ty.kind() {
         // "An unsized FFI type that is opaque to Rust", `extern type A;` (currently unstable)
@@ -718,6 +756,7 @@ fn trans_struct<'tcx>(cx: &CodegenCx<'tcx>, span: Span, ty: TyAndLayout<'tcx>) -
         field_types,
         field_offsets,
         field_names: Some(field_names),
+        is_block,
     }
     .def(span, cx)
 }

crates/rustc_codegen_spirv/src/codegen_cx/constant.rs

@@ -187,6 +187,7 @@ impl<'tcx> ConstMethods<'tcx> for CodegenCx<'tcx> {
             field_types,
             field_offsets,
             field_names: None,
+            is_block: false,
         }
         .def(DUMMY_SP, self);
         self.constant_composite(struct_ty, elts.iter().map(|f| f.def_cx(self)).collect())

crates/rustc_codegen_spirv/src/codegen_cx/type_.rs

@@ -150,6 +150,7 @@ impl<'tcx> BaseTypeMethods<'tcx> for CodegenCx<'tcx> {
             field_types: els.to_vec(),
             field_offsets,
             field_names: None,
+            is_block: false,
         }
         .def(DUMMY_SP, self)
     }

crates/rustc_codegen_spirv/src/lib.rs

@@ -118,6 +118,7 @@ use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_target::spec::abi::Abi;
 use rustc_target::spec::{LinkerFlavor, PanicStrategy, Target, TargetOptions, TargetTriple};
+pub use spirv_tools;
 use std::any::Any;
 use std::env;
 use std::fs::{create_dir_all, File};

crates/rustc_codegen_spirv/src/spirv_type.rs

@@ -10,7 +10,7 @@ use rustc_span::Span;
 use rustc_target::abi::{Align, Size};
 use std::cell::RefCell;
 use std::fmt;
-use std::iter::once;
+use std::iter;
 use std::lazy::SyncLazy;
 use std::sync::Mutex;
 
@@ -34,6 +34,7 @@ pub enum SpirvType {
         field_types: Vec<Word>,
         field_offsets: Vec<Size>,
         field_names: Option<Vec<String>>,
+        is_block: bool,
     },
     Opaque {
         name: String,
@@ -126,6 +127,7 @@ impl SpirvType {
                 ref field_types,
                 ref field_offsets,
                 ref field_names,
+                is_block,
             } => {
                 let mut emit = cx.emit_global();
                 // Ensure a unique struct is emitted each time, due to possibly having different OpMemberDecorates
@@ -151,6 +153,9 @@ impl SpirvType {
                         emit.member_name(result, index as u32, field_name);
                     }
                 }
+                if is_block {
+                    emit.decorate(result, Decoration::Block, iter::empty());
+                }
                 result
             }
             Self::Opaque { ref name } => cx.emit_global().type_opaque(name),
@@ -168,7 +173,7 @@ impl SpirvType {
                     cx.emit_global().decorate(
                         result,
                         Decoration::ArrayStride,
-                        once(Operand::LiteralInt32(element_size as u32)),
+                        iter::once(Operand::LiteralInt32(element_size as u32)),
                     );
                 }
                 result
@@ -344,6 +349,7 @@ impl fmt::Debug for SpirvTypePrinter<'_, '_> {
                 ref field_types,
                 ref field_offsets,
                 ref field_names,
+                is_block,
             } => {
                 let fields = field_types
                     .iter()
@@ -357,6 +363,7 @@ impl fmt::Debug for SpirvTypePrinter<'_, '_> {
                     .field("field_types", &fields)
                     .field("field_offsets", field_offsets)
                     .field("field_names", field_names)
+                    .field("is_block", &is_block)
                     .finish()
             }
             SpirvType::Opaque { ref name } => f
@@ -485,7 +492,11 @@ impl SpirvTypePrinter<'_, '_> {
                 ref field_types,
                 field_offsets: _,
                 ref field_names,
+                is_block,
             } => {
+                if is_block {
+                    write!(f, "#[spirv(block)] ")?;
+                }
                 write!(f, "struct {} {{ ", name)?;
                 for (index, &field) in field_types.iter().enumerate() {
                     let suffix = if index + 1 == field_types.len() {

crates/rustc_codegen_spirv/src/symbols.rs

@@ -336,6 +336,7 @@ impl Symbols {
                 SpirvAttribute::ReallyUnsafeIgnoreBitcasts,
             ),
             ("sampler", SpirvAttribute::Sampler),
+            ("block", SpirvAttribute::Block),
         ]
         .iter()
         .cloned();
@@ -451,6 +452,7 @@ pub enum SpirvAttribute {
         access_qualifier: Option<AccessQualifier>,
     },
     Sampler,
+    Block,
 }
 
 // Note that we could mark the attr as used via cx.tcx.sess.mark_attr_used(attr), but unused

crates/spirv-builder/src/test/basic.rs

@@ -1,4 +1,4 @@
-use super::{dis_fn, val};
+use super::{dis_fn, val, val_vulkan};
 
 #[test]
 fn hello_world() {
@@ -126,3 +126,52 @@ pub fn main() {
 }
 "#);
 }
+
+// NOTE(eddyb) this won't pass Vulkan validation (see `push_constant_vulkan`),
+// but should still pass the basline SPIR-V validation.
+#[test]
+fn push_constant() {
+    val(r#"
+#[derive(Copy, Clone)]
+pub struct ShaderConstants {
+    pub width: u32,
+    pub height: u32,
+    pub time: f32,
+}
+
+#[allow(unused_attributes)]
+#[spirv(fragment)]
+pub fn main(
+    #[spirv(push_constant)] constants: PushConstant<ShaderConstants>,
+) {
+    let _constants = constants.load();
+}
+"#);
+}
+
+// NOTE(eddyb) we specifically run Vulkan validation here, as the default
+// validation rules are more lax and don't require a `Block` decoration
+// (`#[spirv(block)]` here) on `struct ShaderConstants`.
+#[test]
+fn push_constant_vulkan() {
+    val_vulkan(
+        r#"
+#[derive(Copy, Clone)]
+#[allow(unused_attributes)]
+#[spirv(block)]
+pub struct ShaderConstants {
+    pub width: u32,
+    pub height: u32,
+    pub time: f32,
+}
+
+#[allow(unused_attributes)]
+#[spirv(fragment)]
+pub fn main(
+    #[spirv(push_constant)] constants: PushConstant<ShaderConstants>,
+) {
+    let _constants = constants.load();
+}
+"#,
+    );
+}

crates/spirv-builder/src/test/mod.rs

@@ -90,6 +90,25 @@ fn val(src: &str) {
     build(src);
 }
 
+/// While `val` runs baseline SPIR-V validation, for some tests we want the
+/// stricter Vulkan validation (`vulkan1.2` specifically), which may produce
+/// additional errors (such as missing Vulkan-specific decorations).
+fn val_vulkan(src: &str) {
+    use rustc_codegen_spirv::spirv_tools::{
+        util::to_binary,
+        val::{self, Validator},
+        TargetEnv,
+    };
+
+    let validator = val::create(Some(TargetEnv::Vulkan_1_2));
+
+    let _lock = global_lock();
+    let bytes = std::fs::read(build(src)).unwrap();
+    if let Err(e) = validator.validate(to_binary(&bytes).unwrap(), None) {
+        panic!("Vulkan validation failed:\n{}", e.to_string());
+    }
+}
+
 fn assert_str_eq(expected: &str, result: &str) {
     let expected = expected
         .split('\n')

examples/shaders/shared/src/lib.rs

@@ -14,6 +14,8 @@ use spirv_std::glam::Vec3;
 use spirv_std::num_traits::Float;
 
 #[derive(Copy, Clone)]
+#[allow(unused_attributes)]
+#[spirv(block)]
 pub struct ShaderConstants {
     pub width: u32,
     pub height: u32,