tint: Fix SPIR-V validation around interpolation decorations

SPIRV-Val has tightended up validation around input / output interpolation decorations.
This change ensures that the parser and writer do the right thing.

Change-Id: I29c97fdcc48c62aa77b106c42e64fbc54204d607
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/96020
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/tint/reader/spirv/parser_impl.cc

@@ -1795,6 +1795,14 @@ bool ParserImpl::ConvertPipelineDecorations(const Type* store_type,
         }
     }
 
+    if (type == ast::InterpolationType::kFlat &&
+        !ast::HasAttribute<ast::LocationAttribute>(*attributes)) {
+        // WGSL requires that '@interpolate(flat)' needs to be paired with '@location', however
+        // SPIR-V requires all fragment shader integer Inputs are 'flat'. If the decorations do not
+        // contain a SpvDecorationLocation, then make this perspective.
+        type = ast::InterpolationType::kPerspective;
+    }
+
     // Apply interpolation.
     if (type == ast::InterpolationType::kPerspective &&
         sampling == ast::InterpolationSampling::kNone) {

src/tint/transform/canonicalize_entry_point_io.cc

@@ -159,14 +159,16 @@ struct CanonicalizeEntryPointIO::State {
                                     ast::AttributeList attributes) {
         auto* ast_type = CreateASTTypeFor(ctx, type);
         if (cfg.shader_style == ShaderStyle::kSpirv || cfg.shader_style == ShaderStyle::kGlsl) {
-            // Vulkan requires that integer user-defined fragment inputs are
+            // Vulkan requires that integer user-defined fragment inputs are always decorated with
-            // always decorated with `Flat`.
+            // `Flat`. See:
-            // TODO(crbug.com/tint/1224): Remove this once a flat interpolation
+            // https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/StandaloneSpirv.html#VUID-StandaloneSpirv-Flat-04744
-            // attribute is required for integers.
+            // TODO(crbug.com/tint/1224): Remove this once a flat interpolation attribute is
-            if (type->is_integer_scalar_or_vector() &&
+            // required for integers.
-                ast::HasAttribute<ast::LocationAttribute>(attributes) &&
+            if (func_ast->PipelineStage() == ast::PipelineStage::kFragment &&
+                type->is_integer_scalar_or_vector() &&
                 !ast::HasAttribute<ast::InterpolateAttribute>(attributes) &&
-                func_ast->PipelineStage() == ast::PipelineStage::kFragment) {
+                (ast::HasAttribute<ast::LocationAttribute>(attributes) ||
+                 cfg.shader_style == ShaderStyle::kSpirv)) {
                 attributes.push_back(ctx.dst->Interpolate(ast::InterpolationType::kFlat,
                                                           ast::InterpolationSampling::kNone));
             }
@@ -226,14 +228,15 @@ struct CanonicalizeEntryPointIO::State {
                    const sem::Type* type,
                    ast::AttributeList attributes,
                    const ast::Expression* value) {
-        // Vulkan requires that integer user-defined vertex outputs are
+        // Vulkan requires that integer user-defined vertex outputs are always decorated with
-        // always decorated with `Flat`.
+        // `Flat`.
-        // TODO(crbug.com/tint/1224): Remove this once a flat interpolation
+        // TODO(crbug.com/tint/1224): Remove this once a flat interpolation attribute is required
-        // attribute is required for integers.
+        // for integers.
-        if (cfg.shader_style == ShaderStyle::kSpirv && type->is_integer_scalar_or_vector() &&
+        if (cfg.shader_style == ShaderStyle::kSpirv &&
+            func_ast->PipelineStage() == ast::PipelineStage::kVertex &&
+            type->is_integer_scalar_or_vector() &&
             ast::HasAttribute<ast::LocationAttribute>(attributes) &&
-            !ast::HasAttribute<ast::InterpolateAttribute>(attributes) &&
+            !ast::HasAttribute<ast::InterpolateAttribute>(attributes)) {
-            func_ast->PipelineStage() == ast::PipelineStage::kVertex) {
             attributes.push_back(ctx.dst->Interpolate(ast::InterpolationType::kFlat,
                                                       ast::InterpolationSampling::kNone));
         }
@@ -262,15 +265,19 @@ struct CanonicalizeEntryPointIO::State {
     /// that will be passed to the original function.
     /// @param param the original function parameter
     void ProcessNonStructParameter(const sem::Parameter* param) {
+        // Do not add interpolation attributes on vertex input
+        bool do_interpolate = func_ast->PipelineStage() != ast::PipelineStage::kVertex;
         // Remove the shader IO attributes from the inner function parameter, and
         // attach them to the new object instead.
         ast::AttributeList attributes;
         for (auto* attr : param->Declaration()->attributes) {
             if (IsShaderIOAttribute(attr)) {
                 ctx.Remove(param->Declaration()->attributes, attr);
+                if ((do_interpolate || !attr->Is<ast::InterpolateAttribute>())) {
                     attributes.push_back(ctx.Clone(attr));
                 }
             }
+        }
 
         auto name = ctx.src->Symbols().NameFor(param->Declaration()->symbol);
         auto* input_expr = AddInput(name, param->Type(), std::move(attributes));
@@ -283,6 +290,9 @@ struct CanonicalizeEntryPointIO::State {
     /// the original function.
     /// @param param the original function parameter
     void ProcessStructParameter(const sem::Parameter* param) {
+        // Do not add interpolation attributes on vertex input
+        bool do_interpolate = func_ast->PipelineStage() != ast::PipelineStage::kVertex;
+
         auto* str = param->Type()->As<sem::Struct>();
 
         // Recreate struct members in the outer entry point and build an initializer
@@ -297,12 +307,6 @@ struct CanonicalizeEntryPointIO::State {
             auto* member_ast = member->Declaration();
             auto name = ctx.src->Symbols().NameFor(member_ast->symbol);
 
-            // In GLSL, do not add interpolation attributes on vertex input
-            bool do_interpolate = true;
-            if (cfg.shader_style == ShaderStyle::kGlsl &&
-                func_ast->PipelineStage() == ast::PipelineStage::kVertex) {
-                do_interpolate = false;
-            }
             auto attributes = CloneShaderIOAttributes(member_ast->attributes, do_interpolate);
             auto* input_expr = AddInput(name, member->Type(), std::move(attributes));
             inner_struct_values.push_back(input_expr);
@@ -319,12 +323,8 @@ struct CanonicalizeEntryPointIO::State {
     /// @param inner_ret_type the original function return type
     /// @param original_result the result object produced by the original function
     void ProcessReturnType(const sem::Type* inner_ret_type, Symbol original_result) {
-        bool do_interpolate = true;
+        // Do not add interpolation attributes on fragment output
-        // In GLSL, do not add interpolation attributes on fragment output
+        bool do_interpolate = func_ast->PipelineStage() != ast::PipelineStage::kFragment;
-        if (cfg.shader_style == ShaderStyle::kGlsl &&
-            func_ast->PipelineStage() == ast::PipelineStage::kFragment) {
-            do_interpolate = false;
-        }
         if (auto* str = inner_ret_type->As<sem::Struct>()) {
             for (auto* member : str->Members()) {
                 if (member->Type()->Is<sem::Struct>()) {

src/tint/transform/canonicalize_entry_point_io_test.cc

@@ -1978,13 +1978,13 @@ fn frag_main(inputs : FragmentInterface) -> FragmentInterface {
 
 @location(3) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<in> vu_3 : vec4<u32>;
 
-@location(0) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> i_4 : i32;
+@location(0) @internal(disable_validation__ignore_storage_class) var<out> i_4 : i32;
 
-@location(1) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> u_4 : u32;
+@location(1) @internal(disable_validation__ignore_storage_class) var<out> u_4 : u32;
 
-@location(2) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> vi_4 : vec4<i32>;
+@location(2) @internal(disable_validation__ignore_storage_class) var<out> vi_4 : vec4<i32>;
 
-@location(3) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> vu_4 : vec4<u32>;
+@location(3) @internal(disable_validation__ignore_storage_class) var<out> vu_4 : vec4<u32>;
 
 struct VertexIn {
   i : i32,
@@ -2108,13 +2108,13 @@ struct FragmentInterface {
 
 @location(3) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<in> vu_3 : vec4<u32>;
 
-@location(0) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> i_4 : i32;
+@location(0) @internal(disable_validation__ignore_storage_class) var<out> i_4 : i32;
 
-@location(1) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> u_4 : u32;
+@location(1) @internal(disable_validation__ignore_storage_class) var<out> u_4 : u32;
 
-@location(2) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> vi_4 : vec4<i32>;
+@location(2) @internal(disable_validation__ignore_storage_class) var<out> vi_4 : vec4<i32>;
 
-@location(3) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<out> vu_4 : vec4<u32>;
+@location(3) @internal(disable_validation__ignore_storage_class) var<out> vu_4 : vec4<u32>;
 
 fn vert_main_inner(in : VertexIn) -> VertexOut {
   return VertexOut(in.i, in.u, in.vi, in.vu, vec4<f32>());
@@ -2344,7 +2344,7 @@ struct tint_symbol_1 {
 }
 
 struct tint_symbol_2 {
-  @location(1) @interpolate(flat)
+  @location(1)
   value : f32,
 }
 
@@ -2397,7 +2397,7 @@ struct tint_symbol_1 {
 }
 
 struct tint_symbol_2 {
-  @location(1) @interpolate(flat)
+  @location(1)
   value : f32,
 }
 
@@ -3868,9 +3868,9 @@ fn main(@builtin(sample_index) sample_index : u32,
 )";
 
     auto* expect = R"(
-@builtin(sample_index) @internal(disable_validation__ignore_storage_class) var<in> sample_index_1 : u32;
+@builtin(sample_index) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<in> sample_index_1 : u32;
 
-@builtin(sample_mask) @internal(disable_validation__ignore_storage_class) var<in> mask_in_1 : array<u32, 1u>;
+@builtin(sample_mask) @interpolate(flat) @internal(disable_validation__ignore_storage_class) var<in> mask_in_1 : array<u32, 1u>;
 
 @builtin(sample_mask) @internal(disable_validation__ignore_storage_class) var<out> value : array<u32, 1u>;
 

src/tint/writer/spirv/builder_entry_point_test.cc

@@ -311,9 +311,12 @@ TEST_F(BuilderTest, SampleIndex_SampleRateShadingCapability) {
 
     // Make sure we generate the SampleRateShading capability.
     EXPECT_EQ(DumpInstructions(b.capabilities()),
-              "OpCapability Shader\n"
+              R"(OpCapability Shader
-              "OpCapability SampleRateShading\n");
+OpCapability SampleRateShading
-    EXPECT_EQ(DumpInstructions(b.annots()), "OpDecorate %1 BuiltIn SampleId\n");
+)");
+    EXPECT_EQ(DumpInstructions(b.annots()), R"(OpDecorate %1 BuiltIn SampleId
+OpDecorate %1 Flat
+)");
 }
 
 }  // namespace

test/tint/bug/tint/1076.wgsl.expected.spvasm

@@ -22,6 +22,7 @@
                OpDecorate %a_1 Location 0
                OpDecorate %_arr_uint_uint_1 ArrayStride 4
                OpDecorate %mask_1 BuiltIn SampleMask
+               OpDecorate %mask_1 Flat
                OpDecorate %b_1 Location 1
                OpDecorate %a_2 Location 0
                OpDecorate %mask_2 BuiltIn SampleMask

test/tint/shader_io/fragment_input_builtins.wgsl.expected.spvasm

@@ -21,8 +21,10 @@
                OpDecorate %position_1 BuiltIn FragCoord
                OpDecorate %front_facing_1 BuiltIn FrontFacing
                OpDecorate %sample_index_1 BuiltIn SampleId
+               OpDecorate %sample_index_1 Flat
                OpDecorate %_arr_uint_uint_1 ArrayStride 4
                OpDecorate %sample_mask_1 BuiltIn SampleMask
+               OpDecorate %sample_mask_1 Flat
       %float = OpTypeFloat 32
     %v4float = OpTypeVector %float 4
 %_ptr_Input_v4float = OpTypePointer Input %v4float

test/tint/shader_io/fragment_input_builtins_struct.wgsl.expected.spvasm

@@ -23,8 +23,10 @@
                OpDecorate %position_1 BuiltIn FragCoord
                OpDecorate %front_facing_1 BuiltIn FrontFacing
                OpDecorate %sample_index_1 BuiltIn SampleId
+               OpDecorate %sample_index_1 Flat
                OpDecorate %_arr_uint_uint_1 ArrayStride 4
                OpDecorate %sample_mask_1 BuiltIn SampleMask
+               OpDecorate %sample_mask_1 Flat
                OpMemberDecorate %FragmentInputs 0 Offset 0
                OpMemberDecorate %FragmentInputs 1 Offset 16
                OpMemberDecorate %FragmentInputs 2 Offset 20

test/tint/shader_io/fragment_input_mixed.wgsl.expected.spvasm

@@ -37,9 +37,11 @@
                OpDecorate %loc1_1 Location 1
                OpDecorate %loc1_1 Flat
                OpDecorate %sample_index_1 BuiltIn SampleId
+               OpDecorate %sample_index_1 Flat
                OpDecorate %loc3_1 Location 3
                OpDecorate %_arr_uint_uint_1 ArrayStride 4
                OpDecorate %sample_mask_1 BuiltIn SampleMask
+               OpDecorate %sample_mask_1 Flat
                OpDecorate %loc2_1 Location 2
                OpMemberDecorate %FragmentInputs0 0 Offset 0
                OpMemberDecorate %FragmentInputs0 1 Offset 16

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_EntryPointWrapping_IOLocations.spvasm

@@ -10,8 +10,10 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %5 "main" %1 %2 %3 %4
 OpExecutionMode %5 OriginUpperLeft
 OpDecorate %1 Location 0
+OpDecorate %1 Flat
 OpDecorate %2 Location 0
 OpDecorate %3 Location 30
+OpDecorate %3 Flat
 OpDecorate %4 Location 6
 %void = OpTypeVoid
 %7 = OpTypeFunction %void

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_EntryPointWrapping_Interpolation_Flat_Vertex_In.spvasm

@@ -1,67 +0,0 @@
-; Test: SpvModuleScopeVarParserTest_EntryPointWrapping_Interpolation_Flat_Vertex_In.spvasm
-; SPIR-V
-; Version: 1.0
-; Generator: Khronos SPIR-V Tools Assembler; 0
-; Bound: 42
-; Schema: 0
-OpCapability Shader
-OpCapability SampleRateShading
-OpMemoryModel Logical Simple
-OpEntryPoint Vertex %7 "main" %1 %2 %3 %4 %5 %6 %gl_Position
-OpDecorate %1 Location 1
-OpDecorate %2 Location 2
-OpDecorate %3 Location 3
-OpDecorate %4 Location 4
-OpDecorate %5 Location 5
-OpDecorate %6 Location 6
-OpDecorate %1 Flat
-OpDecorate %2 Flat
-OpDecorate %3 Flat
-OpDecorate %4 Flat
-OpDecorate %5 Flat
-OpDecorate %6 Flat
-OpDecorate %gl_Position BuiltIn Position
-%void = OpTypeVoid
-%9 = OpTypeFunction %void
-%bool = OpTypeBool
-%float = OpTypeFloat 32
-%uint = OpTypeInt 32 0
-%int = OpTypeInt 32 1
-%_ptr_Private_bool = OpTypePointer Private %bool
-%_ptr_Private_float = OpTypePointer Private %float
-%_ptr_Private_uint = OpTypePointer Private %uint
-%_ptr_Private_int = OpTypePointer Private %int
-%true = OpConstantTrue %bool
-%false = OpConstantFalse %bool
-%float_0 = OpConstant %float 0
-%float_1_5 = OpConstant %float 1.5
-%uint_1 = OpConstant %uint 1
-%int_n1 = OpConstant %int -1
-%int_14 = OpConstant %int 14
-%uint_2 = OpConstant %uint 2
-%v2bool = OpTypeVector %bool 2
-%v2uint = OpTypeVector %uint 2
-%v2int = OpTypeVector %int 2
-%v2float = OpTypeVector %float 2
-%v4float = OpTypeVector %float 4
-%mat3v2float = OpTypeMatrix %v2float 3
-%_arr_uint_uint_2 = OpTypeArray %uint %uint_2
-%_ptr_Input_uint = OpTypePointer Input %uint
-%_ptr_Input_v2uint = OpTypePointer Input %v2uint
-%_ptr_Input_int = OpTypePointer Input %int
-%_ptr_Input_v2int = OpTypePointer Input %v2int
-%_ptr_Input_float = OpTypePointer Input %float
-%_ptr_Input_v2float = OpTypePointer Input %v2float
-%1 = OpVariable %_ptr_Input_uint Input
-%2 = OpVariable %_ptr_Input_v2uint Input
-%3 = OpVariable %_ptr_Input_int Input
-%4 = OpVariable %_ptr_Input_v2int Input
-%5 = OpVariable %_ptr_Input_float Input
-%6 = OpVariable %_ptr_Input_v2float Input
-%_ptr_Output_v4float = OpTypePointer Output %v4float
-%gl_Position = OpVariable %_ptr_Output_v4float Output
-%7 = OpFunction %void None %9
-%41 = OpLabel
-OpReturn
-OpFunctionEnd
-

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_EntryPointWrapping_Interpolation_Flat_Vertex_In.spvasm.expected.glsl

@@ -1,52 +0,0 @@
-SKIP: FAILED
-
-#version 310 es
-
-layout(location = 1) flat in uint x_1_param_1;
-layout(location = 2) flat in uvec2 x_2_param_1;
-layout(location = 3) flat in int x_3_param_1;
-layout(location = 4) flat in ivec2 x_4_param_1;
-layout(location = 5) flat in float x_5_param_1;
-layout(location = 6) flat in vec2 x_6_param_1;
-uint x_1 = 0u;
-uvec2 x_2 = uvec2(0u, 0u);
-int x_3 = 0;
-ivec2 x_4 = ivec2(0, 0);
-float x_5 = 0.0f;
-vec2 x_6 = vec2(0.0f, 0.0f);
-vec4 x_8 = vec4(0.0f, 0.0f, 0.0f, 0.0f);
-void main_1() {
-  return;
-}
-
-struct main_out {
-  vec4 x_8_1;
-};
-
-main_out tint_symbol(uint x_1_param, uvec2 x_2_param, int x_3_param, ivec2 x_4_param, float x_5_param, vec2 x_6_param) {
-  x_1 = x_1_param;
-  x_2 = x_2_param;
-  x_3 = x_3_param;
-  x_4 = x_4_param;
-  x_5 = x_5_param;
-  x_6 = x_6_param;
-  main_1();
-  main_out tint_symbol_1 = main_out(x_8);
-  return tint_symbol_1;
-}
-
-void main() {
-  gl_PointSize = 1.0;
-  main_out inner_result = tint_symbol(x_1_param_1, x_2_param_1, x_3_param_1, x_4_param_1, x_5_param_1, x_6_param_1);
-  gl_Position = inner_result.x_8_1;
-  gl_Position.y = -(gl_Position.y);
-  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
-  return;
-}
-Error parsing GLSL shader:
-ERROR: 0:3: '' : vertex input cannot be further qualified 
-ERROR: 0:3: '' : compilation terminated 
-ERROR: 2 compilation errors.  No code generated.
-
-
-

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_EntryPointWrapping_Interpolation_Floating_Fragment_Out.spvasm

@@ -1,61 +0,0 @@
-; Test: SpvModuleScopeVarParserTest_EntryPointWrapping_Interpolation_Floating_Fragment_Out.spvasm
-; SPIR-V
-; Version: 1.0
-; Generator: Khronos SPIR-V Tools Assembler; 0
-; Bound: 35
-; Schema: 0
-OpCapability Shader
-OpCapability SampleRateShading
-OpMemoryModel Logical Simple
-OpEntryPoint Fragment %7 "main" %1 %2 %3 %4 %5 %6
-OpExecutionMode %7 OriginUpperLeft
-OpDecorate %1 Location 1
-OpDecorate %2 Location 2
-OpDecorate %3 Location 3
-OpDecorate %4 Location 4
-OpDecorate %5 Location 5
-OpDecorate %6 Location 6
-OpDecorate %2 Centroid
-OpDecorate %3 Sample
-OpDecorate %4 NoPerspective
-OpDecorate %5 NoPerspective
-OpDecorate %5 Centroid
-OpDecorate %6 NoPerspective
-OpDecorate %6 Sample
-%void = OpTypeVoid
-%9 = OpTypeFunction %void
-%bool = OpTypeBool
-%float = OpTypeFloat 32
-%uint = OpTypeInt 32 0
-%int = OpTypeInt 32 1
-%_ptr_Private_bool = OpTypePointer Private %bool
-%_ptr_Private_float = OpTypePointer Private %float
-%_ptr_Private_uint = OpTypePointer Private %uint
-%_ptr_Private_int = OpTypePointer Private %int
-%true = OpConstantTrue %bool
-%false = OpConstantFalse %bool
-%float_0 = OpConstant %float 0
-%float_1_5 = OpConstant %float 1.5
-%uint_1 = OpConstant %uint 1
-%int_n1 = OpConstant %int -1
-%int_14 = OpConstant %int 14
-%uint_2 = OpConstant %uint 2
-%v2bool = OpTypeVector %bool 2
-%v2uint = OpTypeVector %uint 2
-%v2int = OpTypeVector %int 2
-%v2float = OpTypeVector %float 2
-%v4float = OpTypeVector %float 4
-%mat3v2float = OpTypeMatrix %v2float 3
-%_arr_uint_uint_2 = OpTypeArray %uint %uint_2
-%_ptr_Output_float = OpTypePointer Output %float
-%1 = OpVariable %_ptr_Output_float Output
-%2 = OpVariable %_ptr_Output_float Output
-%3 = OpVariable %_ptr_Output_float Output
-%4 = OpVariable %_ptr_Output_float Output
-%5 = OpVariable %_ptr_Output_float Output
-%6 = OpVariable %_ptr_Output_float Output
-%7 = OpFunction %void None %9
-%34 = OpLabel
-OpReturn
-OpFunctionEnd
-

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_SampleId_I32_Load_AccessChain.spvasm

@@ -10,6 +10,7 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %3 "main" %gl_SampleID
 OpExecutionMode %3 OriginUpperLeft
 OpDecorate %gl_SampleID BuiltIn SampleId
+OpDecorate %gl_SampleID Flat
 %void = OpTypeVoid
 %5 = OpTypeFunction %void
 %float = OpTypeFloat 32

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_SampleId_I32_Load_CopyObject.spvasm

@@ -10,6 +10,7 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %3 "main" %gl_SampleID
 OpExecutionMode %3 OriginUpperLeft
 OpDecorate %gl_SampleID BuiltIn SampleId
+OpDecorate %gl_SampleID Flat
 %void = OpTypeVoid
 %5 = OpTypeFunction %void
 %float = OpTypeFloat 32

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_SampleId_I32_Load_Direct.spvasm

@@ -10,6 +10,7 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %3 "main" %gl_SampleID
 OpExecutionMode %3 OriginUpperLeft
 OpDecorate %gl_SampleID BuiltIn SampleId
+OpDecorate %gl_SampleID Flat
 %void = OpTypeVoid
 %5 = OpTypeFunction %void
 %float = OpTypeFloat 32

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_SampleId_U32_Load_AccessChain.spvasm

@@ -10,6 +10,7 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %3 "main" %gl_SampleID
 OpExecutionMode %3 OriginUpperLeft
 OpDecorate %gl_SampleID BuiltIn SampleId
+OpDecorate %gl_SampleID Flat
 %void = OpTypeVoid
 %5 = OpTypeFunction %void
 %float = OpTypeFloat 32

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_SampleId_U32_Load_CopyObject.spvasm

@@ -10,6 +10,7 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %3 "main" %gl_SampleID
 OpExecutionMode %3 OriginUpperLeft
 OpDecorate %gl_SampleID BuiltIn SampleId
+OpDecorate %gl_SampleID Flat
 %void = OpTypeVoid
 %5 = OpTypeFunction %void
 %float = OpTypeFloat 32

test/tint/unittest/reader/spirv/SpvModuleScopeVarParserTest_SampleId_U32_Load_Direct.spvasm

@@ -10,6 +10,7 @@ OpMemoryModel Logical Simple
 OpEntryPoint Fragment %3 "main" %gl_SampleID
 OpExecutionMode %3 OriginUpperLeft
 OpDecorate %gl_SampleID BuiltIn SampleId
+OpDecorate %gl_SampleID Flat
 %void = OpTypeVoid
 %5 = OpTypeFunction %void
 %float = OpTypeFloat 32