tint/uniformity: Violations are now errors

Switch the default severity for all uniformity violations to errors.

We now have an opt-out mechanism for deriviative operations (via
diagnostic filters), and a `workgroupUniformLoad()` builtin for
compute shaders.

Bug: tint:1809
Change-Id: I666c706d6195ca0d24ead14c4709e7f646bfcc64
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/117741
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/reader/spirv/parser_test.cc

@@ -64,8 +64,7 @@ TEST_F(ParserTest, AllowNonUniformDerivatives_False) {
     options.allow_non_uniform_derivatives = false;
     auto program = Parse(spv, options);
     auto errs = diag::Formatter().format(program.Diagnostics());
-    // TODO(jrprice): This will become EXPECT_FALSE.
+    EXPECT_FALSE(program.IsValid()) << errs;
-    EXPECT_TRUE(program.IsValid()) << errs;
     EXPECT_THAT(errs, ::testing::HasSubstr("'dpdx' must only be called from uniform control flow"));
 }
 

src/tint/resolver/resolver.cc

@@ -146,12 +146,10 @@ bool Resolver::Resolve() {
         // Run the uniformity analysis, which requires a complete semantic module.
         if (!enabled_extensions_.Contains(ast::Extension::kChromiumDisableUniformityAnalysis)) {
             if (!AnalyzeUniformity(builder_, dependencies_)) {
-                if (kUniformityFailuresAsError) {
                 return false;
             }
         }
     }
-    }
 
     return result;
 }

src/tint/resolver/uniformity.h

@@ -26,7 +26,7 @@ class ProgramBuilder;
 namespace tint::resolver {
 
 /// If true, uniformity analysis failures will be treated as an error, else as a warning.
-constexpr bool kUniformityFailuresAsError = false;
+constexpr bool kUniformityFailuresAsError = true;
 
 /// Analyze the uniformity of a program.
 /// @param builder the program to analyze

src/tint/resolver/validator.cc

@@ -169,7 +169,7 @@ Validator::Validator(
       valid_type_storage_layouts_(valid_type_storage_layouts) {
     // Set default severities for filterable diagnostic rules.
     diagnostic_filters_.Set(ast::DiagnosticRule::kDerivativeUniformity,
-                            ast::DiagnosticSeverity::kWarning);
+                            ast::DiagnosticSeverity::kError);
     diagnostic_filters_.Set(ast::DiagnosticRule::kChromiumUnreachableCode,
                             ast::DiagnosticSeverity::kWarning);
 }

src/tint/transform/demote_to_helper_test.cc

@@ -542,10 +542,10 @@ fn foo_discard(@location(0) in : f32, @location(1) coord : vec2<f32>) {
 
 @fragment
 fn foo_no_discard(@location(0) in : f32, @location(1) coord : vec2<f32>) {
+  let ret = bar_no_discard(in, coord);
   if (in == 0.0) {
     return;
   }
-  let ret = bar_no_discard(in, coord);
   v2 = ret;
 }
 )";
@@ -591,10 +591,10 @@ fn foo_discard(@location(0) in : f32, @location(1) coord : vec2<f32>) {
 
 @fragment
 fn foo_no_discard(@location(0) in : f32, @location(1) coord : vec2<f32>) {
+  let ret = bar_no_discard(in, coord);
   if ((in == 0.0)) {
     return;
   }
-  let ret = bar_no_discard(in, coord);
   v2 = ret;
 }
 )";
@@ -992,8 +992,9 @@ fn foo(@location(0) in : f32, @location(1) coord : vec2<f32>) -> @location(0) i3
   }
   var result = 0;
   for (var i = 0; i < 10; i = atomicAdd(&a, 1)) {
-    result += i32(textureSample(t, s, coord).x);
+    result += i;
   }
+  result += i32(textureSample(t, s, coord).x);
   return result;
 }
 )";
@@ -1020,7 +1021,7 @@ fn foo(@location(0) in : f32, @location(1) coord : vec2<f32>) -> @location(0) i3
         break;
       }
       {
-        result += i32(textureSample(t, s, coord).x);
+        result += i;
       }
 
       continuing {
@@ -1032,6 +1033,7 @@ fn foo(@location(0) in : f32, @location(1) coord : vec2<f32>) -> @location(0) i3
       }
     }
   }
+  result += i32(textureSample(t, s, coord).x);
   if (tint_discarded) {
     discard;
   }
@@ -1060,8 +1062,9 @@ fn foo(@location(0) in : f32, @location(1) coord : vec2<f32>) -> @location(0) i3
   var result = 0;
   if (!atomicCompareExchangeWeak(&a, i32(in), 42).exchanged) {
     let xchg = atomicCompareExchangeWeak(&a, i32(in), 42);
-    result = i32(textureSample(t, s, coord).x) * xchg.old_value;
+    result = xchg.old_value;
   }
+  result += i32(textureSample(t, s, coord).x);
   return result;
 }
 )";
@@ -1100,8 +1103,9 @@ fn foo(@location(0) in : f32, @location(1) coord : vec2<f32>) -> @location(0) i3
       tint_symbol_3.exchanged = tint_symbol_4.exchanged;
     }
     let xchg = tint_symbol_3;
-    result = (i32(textureSample(t, s, coord).x) * xchg.old_value);
+    result = xchg.old_value;
   }
+  result += i32(textureSample(t, s, coord).x);
   if (tint_discarded) {
     discard;
   }