[naga glsl-out] Differentiate between support for std140 and std430 (#7579)

* [naga glsl-out] Differentiate between support for `std140` and `std430` layout, and emit `std140` in Uniforms when possible

* [naga glsl-out] Remove storage buffer std140 layout fallback, and error when we are unable to assign an explicit memory layout for uniform and storage globals

Co-authored-by: teoxoy <28601907+teoxoy@users.noreply.github.com>

---------

Co-authored-by: teoxoy <28601907+teoxoy@users.noreply.github.com>

CHANGELOG.md

@@ -46,6 +46,10 @@ Bottom level categories:
 
 - Add support for rendering to slices of 3D texture views and single layered 2D-Array texture views (this requires `VK_KHR_maintenance1` which should be widely available on newer drivers). By @teoxoy in [#7596](https://github.com/gfx-rs/wgpu/pull/7596)
 
+#### Naga
+
+- When emitting GLSL, Uniform and Storage Buffer memory layouts are now emitted even if no explicit binding is given. By @cloone8 in [#7579](https://github.com/gfx-rs/wgpu/pull/7579).
+
 ### Bug Fixes
 
 #### Naga

naga/src/back/glsl/mod.rs

@@ -211,6 +211,10 @@ impl Version {
         *self >= Version::Desktop(130) || *self >= Version::new_gles(310)
     }
 
+    fn supports_std140_layout(&self) -> bool {
+        *self >= Version::Desktop(140) || *self >= Version::new_gles(300)
+    }
+
     fn supports_std430_layout(&self) -> bool {
         *self >= Version::Desktop(430) || *self >= Version::new_gles(310)
     }
@@ -1186,6 +1190,68 @@ impl<'a, W: Write> Writer<'a, W> {
         Ok(())
     }
 
+    /// Helper method used by [Self::write_global] to write just the layout part of
+    /// a non image/sampler global variable, if applicable.
+    ///
+    /// # Notes
+    ///
+    /// Adds trailing whitespace if any layout qualifier is written
+    fn write_global_layout(&mut self, global: &crate::GlobalVariable) -> BackendResult {
+        // Determine which (if any) explicit memory layout to use, and whether we support it
+        let layout = match global.space {
+            crate::AddressSpace::Uniform => {
+                if !self.options.version.supports_std140_layout() {
+                    return Err(Error::Custom(
+                        "Uniform address space requires std140 layout support".to_string(),
+                    ));
+                }
+
+                Some("std140")
+            }
+            crate::AddressSpace::Storage { .. } => {
+                if !self.options.version.supports_std430_layout() {
+                    return Err(Error::Custom(
+                        "Storage address space requires std430 layout support".to_string(),
+                    ));
+                }
+
+                Some("std430")
+            }
+            _ => None,
+        };
+
+        // If our version supports explicit layouts, we can also output the explicit binding
+        // if we have it
+        if self.options.version.supports_explicit_locations() {
+            if let Some(ref br) = global.binding {
+                match self.options.binding_map.get(br) {
+                    Some(binding) => {
+                        write!(self.out, "layout(")?;
+
+                        if let Some(layout) = layout {
+                            write!(self.out, "{}, ", layout)?;
+                        }
+
+                        write!(self.out, "binding = {binding}) ")?;
+
+                        return Ok(());
+                    }
+                    None => {
+                        log::debug!("unassigned binding for {:?}", global.name);
+                    }
+                }
+            }
+        }
+
+        // Either no explicit bindings are supported or we didn't have any.
+        // Write just the memory layout.
+        if let Some(layout) = layout {
+            write!(self.out, "layout({}) ", layout)?;
+        }
+
+        Ok(())
+    }
+
     /// Helper method used to write non images/sampler globals
     ///
     /// # Notes
@@ -1198,34 +1264,7 @@ impl<'a, W: Write> Writer<'a, W> {
         handle: Handle<crate::GlobalVariable>,
         global: &crate::GlobalVariable,
     ) -> BackendResult {
-        if self.options.version.supports_explicit_locations() {
-            if let Some(ref br) = global.binding {
-                match self.options.binding_map.get(br) {
-                    Some(binding) => {
-                        let layout = match global.space {
-                            crate::AddressSpace::Storage { .. } => {
-                                if self.options.version.supports_std430_layout() {
-                                    "std430, "
-                                } else {
-                                    "std140, "
-                                }
-                            }
-                            crate::AddressSpace::Uniform => "std140, ",
-                            _ => "",
-                        };
-                        write!(self.out, "layout({layout}binding = {binding}) ")?
-                    }
-                    None => {
-                        log::debug!("unassigned binding for {:?}", global.name);
-                        if let crate::AddressSpace::Storage { .. } = global.space {
-                            if self.options.version.supports_std430_layout() {
-                                write!(self.out, "layout(std430) ")?
-                            }
-                        }
-                    }
-                }
-            }
-        }
+        self.write_global_layout(global)?;
 
         if let crate::AddressSpace::Storage { access } = global.space {
             self.write_storage_access(access)?;

naga/tests/out/glsl/wgsl-access.foo_vert.Vertex.glsl

@@ -39,11 +39,11 @@ layout(std430) buffer Bar_block_0Vertex {
     AlignedWrapper data[];
 } _group_0_binding_0_vs;
 
-uniform Baz_block_1Vertex { Baz _group_0_binding_1_vs; };
+layout(std140) uniform Baz_block_1Vertex { Baz _group_0_binding_1_vs; };
 
 layout(std430) buffer type_13_block_2Vertex { ivec2 _group_0_binding_2_vs; };
 
-uniform MatCx2InArray_block_3Vertex { MatCx2InArray _group_0_binding_3_vs; };
+layout(std140) uniform MatCx2InArray_block_3Vertex { MatCx2InArray _group_0_binding_3_vs; };
 
 
 void test_matrix_within_struct_accesses() {

naga/tests/out/glsl/wgsl-boids.main.Compute.glsl

@@ -20,7 +20,7 @@ struct SimParams {
 };
 const uint NUM_PARTICLES = 1500u;
 
-uniform SimParams_block_0Compute { SimParams _group_0_binding_0_cs; };
+layout(std140) uniform SimParams_block_0Compute { SimParams _group_0_binding_0_cs; };
 
 layout(std430) readonly buffer Particles_block_1Compute {
     Particle particles[];

naga/tests/out/glsl/wgsl-globals.main.Compute.glsl

@@ -19,15 +19,15 @@ layout(std430) buffer FooStruct_block_0Compute { FooStruct _group_0_binding_1_cs
 
 layout(std430) readonly buffer type_6_block_1Compute { vec2 _group_0_binding_2_cs[]; };
 
-uniform type_8_block_2Compute { vec4 _group_0_binding_3_cs[20]; };
+layout(std140) uniform type_8_block_2Compute { vec4 _group_0_binding_3_cs[20]; };
 
-uniform type_4_block_3Compute { vec3 _group_0_binding_4_cs; };
+layout(std140) uniform type_4_block_3Compute { vec3 _group_0_binding_4_cs; };
 
-uniform type_9_block_4Compute { mat3x2 _group_0_binding_5_cs; };
+layout(std140) uniform type_9_block_4Compute { mat3x2 _group_0_binding_5_cs; };
 
-uniform type_12_block_5Compute { mat2x4 _group_0_binding_6_cs[2][2]; };
+layout(std140) uniform type_12_block_5Compute { mat2x4 _group_0_binding_6_cs[2][2]; };
 
-uniform type_15_block_6Compute { mat4x2 _group_0_binding_7_cs[2][2]; };
+layout(std140) uniform type_15_block_6Compute { mat4x2 _group_0_binding_7_cs[2][2]; };
 
 
 void test_msl_packed_vec3_as_arg(vec3 arg) {

naga/tests/out/glsl/wgsl-padding.vertex.Vertex.glsl

@@ -18,11 +18,11 @@ struct Test3_ {
     mat4x3 a;
     float b;
 };
-uniform Test_block_0Vertex { Test _group_0_binding_0_vs; };
+layout(std140) uniform Test_block_0Vertex { Test _group_0_binding_0_vs; };
 
-uniform Test2_block_1Vertex { Test2_ _group_0_binding_1_vs; };
+layout(std140) uniform Test2_block_1Vertex { Test2_ _group_0_binding_1_vs; };
 
-uniform Test3_block_2Vertex { Test3_ _group_0_binding_2_vs; };
+layout(std140) uniform Test3_block_2Vertex { Test3_ _group_0_binding_2_vs; };
 
 
 void main() {

naga/tests/out/glsl/wgsl-phony_assignment.main.Compute.glsl

@@ -5,7 +5,7 @@ precision highp int;
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
 
-uniform type_block_0Compute { float _group_0_binding_0_cs; };
+layout(std140) uniform type_block_0Compute { float _group_0_binding_0_cs; };
 
 
 int five() {

naga/tests/out/glsl/wgsl-shadow.fs_main.Fragment.glsl

@@ -24,9 +24,9 @@ struct Light {
 const vec3 c_ambient = vec3(0.05, 0.05, 0.05);
 const uint c_max_lights = 10u;
 
-uniform Globals_block_0Fragment { Globals _group_0_binding_0_fs; };
+layout(std140) uniform Globals_block_0Fragment { Globals _group_0_binding_0_fs; };
 
-uniform Entity_block_1Fragment { Entity _group_1_binding_0_fs; };
+layout(std140) uniform Entity_block_1Fragment { Entity _group_1_binding_0_fs; };
 
 layout(std430) readonly buffer type_8_block_2Fragment { Light _group_0_binding_1_fs[]; };
 

naga/tests/out/glsl/wgsl-shadow.fs_main_without_storage.Fragment.glsl

@@ -24,11 +24,11 @@ struct Light {
 const vec3 c_ambient = vec3(0.05, 0.05, 0.05);
 const uint c_max_lights = 10u;
 
-uniform Globals_block_0Fragment { Globals _group_0_binding_0_fs; };
+layout(std140) uniform Globals_block_0Fragment { Globals _group_0_binding_0_fs; };
 
-uniform Entity_block_1Fragment { Entity _group_1_binding_0_fs; };
+layout(std140) uniform Entity_block_1Fragment { Entity _group_1_binding_0_fs; };
 
-uniform type_9_block_2Fragment { Light _group_0_binding_1_fs[10]; };
+layout(std140) uniform type_9_block_2Fragment { Light _group_0_binding_1_fs[10]; };
 
 uniform highp sampler2DArrayShadow _group_0_binding_2_fs;
 

naga/tests/out/glsl/wgsl-shadow.vs_main.Vertex.glsl

@@ -24,9 +24,9 @@ struct Light {
 const vec3 c_ambient = vec3(0.05, 0.05, 0.05);
 const uint c_max_lights = 10u;
 
-uniform Globals_block_0Vertex { Globals _group_0_binding_0_vs; };
+layout(std140) uniform Globals_block_0Vertex { Globals _group_0_binding_0_vs; };
 
-uniform Entity_block_1Vertex { Entity _group_1_binding_0_vs; };
+layout(std140) uniform Entity_block_1Vertex { Entity _group_1_binding_0_vs; };
 
 layout(location = 0) in ivec4 _p2vs_location0;
 layout(location = 1) in ivec4 _p2vs_location1;

naga/tests/out/glsl/wgsl-struct-layout.needs_padding_comp.Compute.glsl

@@ -14,7 +14,7 @@ struct NeedsPadding {
     vec3 v3_needs_padding;
     float f3_;
 };
-uniform NeedsPadding_block_0Compute { NeedsPadding _group_0_binding_2_cs; };
+layout(std140) uniform NeedsPadding_block_0Compute { NeedsPadding _group_0_binding_2_cs; };
 
 layout(std430) buffer NeedsPadding_block_1Compute { NeedsPadding _group_0_binding_3_cs; };
 

naga/tests/out/glsl/wgsl-struct-layout.no_padding_comp.Compute.glsl

@@ -14,7 +14,7 @@ struct NeedsPadding {
     vec3 v3_needs_padding;
     float f3_;
 };
-uniform NoPadding_block_0Compute { NoPadding _group_0_binding_0_cs; };
+layout(std140) uniform NoPadding_block_0Compute { NoPadding _group_0_binding_0_cs; };
 
 layout(std430) buffer NoPadding_block_1Compute { NoPadding _group_0_binding_1_cs; };