builtin: glsl equivalents

Author: Firestar99

crates/spirv-std/src/builtin.rs

@@ -1,16 +1,18 @@
 //! Query SPIR-V read-only global built-in values
 //!
 //! Reference links:
-//! * [WGSL specification describing these builtins](https://www.w3.org/TR/WGSL/#builtin-inputs-outputs)
+//! * [WGSL specification describing builtins](https://www.w3.org/TR/WGSL/#builtin-inputs-outputs)
 //! * [SPIR-V specification for builtins](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#_builtin)
-//! * [GLSL 4.x reference](https://registry.khronos.org/OpenGL-Refpages/gl4/)
+//! * [GLSL reference](https://registry.khronos.org/OpenGL-Refpages/gl4/)
+//!   * [GLSL reference source code](https://github.com/KhronosGroup/OpenGL-Refpages/tree/main/gl4)
+//!   * [GLSL extensions](https://github.com/KhronosGroup/GLSL/tree/main/extensions)
 
 #[cfg(target_arch = "spirv")]
 macro_rules! load_builtin {
     ($ty:ty, $name:ident) => {
         unsafe {
             let mut result = <$ty>::default();
-            asm! {
+            core::arch::asm! {
                 "%builtin = OpVariable typeof{result_ref} Input",
                 concat!("OpDecorate %builtin BuiltIn ", stringify!($name)),
                 "%result = OpLoad typeof*{result_ref} %builtin",
@@ -24,8 +26,6 @@ macro_rules! load_builtin {
 
 /// Compute shader built-ins
 pub mod compute {
-    #[cfg(target_arch = "spirv")]
-    use core::arch::asm;
     use glam::UVec3;
 
     // Local builtins (for this invocation's position in the workgroup).
@@ -70,10 +70,11 @@ pub mod compute {
 
     // Subgroup builtins
 
-    ///  The number of subgroups in the current invocation’s workgroup.
+    /// The number of subgroups in the current invocation’s workgroup.
     ///
+    /// GLSL: [`gl_NumSubgroups`](https://github.com/KhronosGroup/GLSL/blob/main/extensions/khr/GL_KHR_shader_subgroup.txt)
     /// WGSL: `num_subgroups`
-    /// No equivalent in GLSL.
+    #[doc(alias = "gl_NumSubgroups")]
     #[inline]
     #[gpu_only]
     pub fn num_subgroups() -> u32 {
@@ -82,8 +83,9 @@ pub mod compute {
 
     /// The subgroup ID of current invocation’s subgroup within the workgroup.
     ///
+    /// GLSL: [`gl_SubgroupID`](https://github.com/KhronosGroup/GLSL/blob/main/extensions/khr/GL_KHR_shader_subgroup.txt)
     /// WGSL: `subgroup_id`
-    /// No equivalent in GLSL.
+    #[doc(alias = "gl_SubgroupID")]
     #[inline]
     #[gpu_only]
     pub fn subgroup_id() -> u32 {
@@ -92,19 +94,20 @@ pub mod compute {
 
     /// This invocation's ID within its subgroup.
     ///
+    /// GLSL: [`gl_SubgroupInvocationID`](https://github.com/KhronosGroup/GLSL/blob/main/extensions/khr/GL_KHR_shader_subgroup.txt)
     /// WGSL: `subgroup_invocation_id`
-    /// No equivalent in GLSL.
-    #[doc(alias = "subgroup_invocation_id")]
+    #[doc(alias = "gl_SubgroupInvocationID")]
     #[inline]
     #[gpu_only]
-    pub fn subgroup_local_invocation_id() -> u32 {
+    pub fn subgroup_invocation_id() -> u32 {
         load_builtin!(u32, SubgroupLocalInvocationId)
     }
 
     ///  The subgroup size of current invocation’s subgroup.
     ///
+    /// GLSL: [`gl_SubgroupSize`](https://github.com/KhronosGroup/GLSL/blob/main/extensions/khr/GL_KHR_shader_subgroup.txt)
     /// WGSL: `subgroup_size`
-    /// No equivalent in GLSL.
+    #[doc(alias = "gl_SubgroupInvocationID")]
     #[inline]
     #[gpu_only]
     pub fn subgroup_size() -> u32 {