From efc15ba03b9022b29f849ea11d8027b03905396d Mon Sep 17 00:00:00 2001
From: Erich Gubler <erichdongubler@gmail.com>
Date: Wed, 13 Nov 2024 07:03:16 -0500
Subject: [PATCH] chore: revert removal of
 `DISABLE_UNIFORMITY_REQ_FOR_FRAGMENT_STAGE` (#6534)

---
 naga/src/valid/analyzer.rs | 96 ++++++++++++++++++++------------------
 1 file changed, 51 insertions(+), 45 deletions(-)

diff --git a/naga/src/valid/analyzer.rs b/naga/src/valid/analyzer.rs
index e169ed1d0..b50238b97 100644
--- a/naga/src/valid/analyzer.rs
+++ b/naga/src/valid/analyzer.rs
@@ -16,6 +16,8 @@ use std::ops;
 
 pub type NonUniformResult = Option<Handle<crate::Expression>>;
 
+const DISABLE_UNIFORMITY_REQ_FOR_FRAGMENT_STAGE: bool = true;
+
 bitflags::bitflags! {
     /// Kinds of expressions that require uniform control flow.
     #[cfg_attr(feature = "serialize", derive(serde::Serialize))]
@@ -23,8 +25,8 @@ bitflags::bitflags! {
     #[derive(Clone, Copy, Debug, Eq, PartialEq)]
     pub struct UniformityRequirements: u8 {
         const WORK_GROUP_BARRIER = 0x1;
-        const DERIVATIVE = 0x2;
-        const IMPLICIT_LEVEL = 0x4;
+        const DERIVATIVE = if DISABLE_UNIFORMITY_REQ_FOR_FRAGMENT_STAGE { 0 } else { 0x2 };
+        const IMPLICIT_LEVEL = if DISABLE_UNIFORMITY_REQ_FOR_FRAGMENT_STAGE { 0 } else { 0x4 };
     }
 }
 
@@ -1350,52 +1352,56 @@ fn uniform_control_flow() {
             &expressions,
             &Arena::new(),
         );
-        assert_eq!(
-            block_info,
-            Err(FunctionError::NonUniformControlFlow(
-                UniformityRequirements::DERIVATIVE,
-                derivative_expr,
-                UniformityDisruptor::Expression(non_uniform_global_expr)
-            )
-            .with_span()),
-        );
-        assert_eq!(info[derivative_expr].ref_count, 1);
+        if DISABLE_UNIFORMITY_REQ_FOR_FRAGMENT_STAGE {
+            assert_eq!(info[derivative_expr].ref_count, 2);
+        } else {
+            assert_eq!(
+                block_info,
+                Err(FunctionError::NonUniformControlFlow(
+                    UniformityRequirements::DERIVATIVE,
+                    derivative_expr,
+                    UniformityDisruptor::Expression(non_uniform_global_expr)
+                )
+                .with_span()),
+            );
+            assert_eq!(info[derivative_expr].ref_count, 1);
 
-        // Test that the same thing passes when we disable the `derivative_uniformity`
-        let mut diagnostic_filters = Arena::new();
-        let diagnostic_filter_leaf = diagnostic_filters.append(
-            DiagnosticFilterNode {
-                inner: crate::diagnostic_filter::DiagnosticFilter {
-                    new_severity: crate::diagnostic_filter::Severity::Off,
-                    triggering_rule: FilterableTriggeringRule::DerivativeUniformity,
+            // Test that the same thing passes when we disable the `derivative_uniformity`
+            let mut diagnostic_filters = Arena::new();
+            let diagnostic_filter_leaf = diagnostic_filters.append(
+                DiagnosticFilterNode {
+                    inner: crate::diagnostic_filter::DiagnosticFilter {
+                        new_severity: crate::diagnostic_filter::Severity::Off,
+                        triggering_rule: FilterableTriggeringRule::DerivativeUniformity,
+                    },
+                    parent: None,
                 },
-                parent: None,
-            },
-            crate::Span::default(),
-        );
-        let mut info = FunctionInfo {
-            diagnostic_filter_leaf: Some(diagnostic_filter_leaf),
-            ..info.clone()
-        };
+                crate::Span::default(),
+            );
+            let mut info = FunctionInfo {
+                diagnostic_filter_leaf: Some(diagnostic_filter_leaf),
+                ..info.clone()
+            };
 
-        let block_info = info.process_block(
-            &vec![stmt_emit2, stmt_if_non_uniform].into(),
-            &[],
-            None,
-            &expressions,
-            &diagnostic_filters,
-        );
-        assert_eq!(
-            block_info,
-            Ok(FunctionUniformity {
-                result: Uniformity {
-                    non_uniform_result: None,
-                    requirements: UniformityRequirements::DERIVATIVE,
-                },
-                exit: ExitFlags::empty()
-            }),
-        );
-        assert_eq!(info[derivative_expr].ref_count, 2);
+            let block_info = info.process_block(
+                &vec![stmt_emit2, stmt_if_non_uniform].into(),
+                &[],
+                None,
+                &expressions,
+                &diagnostic_filters,
+            );
+            assert_eq!(
+                block_info,
+                Ok(FunctionUniformity {
+                    result: Uniformity {
+                        non_uniform_result: None,
+                        requirements: UniformityRequirements::DERIVATIVE,
+                    },
+                    exit: ExitFlags::empty()
+                }),
+            );
+            assert_eq!(info[derivative_expr].ref_count, 2);
+        }
     }
     assert_eq!(info[non_uniform_global], GlobalUse::READ);