Error if the uniformity requirements for a barrier aren't met

src/valid/analyzer.rs

@@ -775,13 +775,25 @@ impl FunctionInfo {
  ExitFlags::empty()
  },
  },
- S::Barrier(_) => FunctionUniformity {
- result: Uniformity {
- non_uniform_result: None,
- requirements: UniformityRequirements::WORK_GROUP_BARRIER,
- },
- exit: ExitFlags::empty(),
- },
+ S::Barrier(_) => {
+ #[cfg(feature = "validate")]
+ if self
+ .flags
+ .contains(super::ValidationFlags::CONTROL_FLOW_UNIFORMITY)
+ {
+ if let Some(cause) = disruptor {
+ return Err(FunctionError::NonUniformBarrier(cause)
+ .with_span_static(span, "Barrier creation"));
+ }
+ }
+ FunctionUniformity {
+ result: Uniformity {
+ non_uniform_result: None,
+ requirements: UniformityRequirements::WORK_GROUP_BARRIER,
+ },
+ exit: ExitFlags::empty(),
+ }
+ }
  S::Block(ref b) => {
  self.process_block(b, other_functions, disruptor, expression_arena)?
  }
@@ -1154,7 +1166,7 @@ fn uniform_control_flow() {
  assert_eq!(info[derivative_expr].ref_count, 1);
  assert_eq!(info[non_uniform_global], GlobalUse::READ);
 
- let stmt_emit3 = S::Emit(emit_range_globals);
+ let stmt_emit3 = S::Emit(emit_range_globals.clone());
  let stmt_return_non_uniform = S::Return {
  value: Some(non_uniform_global_expr),
  };
@@ -1201,4 +1213,25 @@ fn uniform_control_flow() {
  }),
  );
  assert_eq!(info[non_uniform_global], GlobalUse::READ | GlobalUse::WRITE);
+
+ let stmt_emit5 = S::Emit(emit_range_globals.clone());
+ let stmt_if_non_uniform = S::If {
+ condition: non_uniform_global_expr,
+ accept: vec![S::Barrier(crate::Barrier::empty())].into(),
+ reject: crate::Block::new(),
+ };
+ assert_eq!(
+ info.process_block(
+ &vec![stmt_emit5, stmt_if_non_uniform].into(),
+ &[],
+ None,
+ &expressions
+ ),
+ Err(
+ FunctionError::NonUniformBarrier(UniformityDisruptor::Expression(
+ non_uniform_global_expr
+ ))
+ .with_span()
+ ),
+ );
 }

src/valid/function.rs

@@ -139,6 +139,8 @@ pub enum FunctionError {
  Handle<crate::Expression>,
  UniformityDisruptor,
  ),
+ #[error("Required uniformity of barrier is not fulfilled because of {0:?}")]
+ NonUniformBarrier(UniformityDisruptor),
  #[error("Functions that are not entry points cannot have `@location` or `@builtin` attributes on their arguments: \"{name}\" has attributes")]
  PipelineInputRegularFunction { name: String },
  #[error("Functions that are not entry points cannot have `@location` or `@builtin` attributes on their return value types")]