const generics: emit inline asm directly to not rely on failing generic_const_exprs

Author: Firestar99

crates/spirv-std/nightly/src/arch.rs

@@ -11,18 +11,41 @@ pub use barrier::{control_barrier, memory_barrier};
 pub use spirv_std::arch::*;
 
 use crate::glam::UVec2;
+#[cfg(target_arch = "spirv")]
+use core::arch::asm;
 use spirv_std::memory::Scope;
 
 /// See [`spirv_std::arch::read_clock_khr`]
 #[spirv_std_macros::gpu_only]
 #[doc(alias = "OpReadClockKHR")]
 pub fn read_clock_khr<const SCOPE: Scope>() -> u64 {
-    spirv_std::arch::read_clock_khr::<{ SCOPE as u32 }>()
+    unsafe {
+        let mut result: u64;
+        asm! {
+            "%uint = OpTypeInt 32 0",
+            "%scope = OpConstant %uint {scope}",
+            "{result} = OpReadClockKHR typeof*{result} %scope",
+            result = out(reg) result,
+            scope = const SCOPE as u32,
+        };
+        result
+    }
 }
 
 /// See [`spirv_std::arch::read_clock_uvec2_khr`]
 #[spirv_std_macros::gpu_only]
 #[doc(alias = "OpReadClockKHR")]
 pub fn read_clock_uvec2_khr<const SCOPE: Scope>() -> UVec2 {
-    spirv_std::arch::read_clock_uvec2_khr::<{ SCOPE as u32 }>()
+    unsafe {
+        let mut result = UVec2::default();
+        asm! {
+            "%uint = OpTypeInt 32 0",
+            "%scope = OpConstant %uint {scope}",
+            "%result = OpReadClockKHR typeof*{result} %scope",
+            "OpStore {result} %result",
+            result = in(reg) &mut result,
+            scope = const SCOPE as u32,
+        };
+        result
+    }
 }