Fix noperspective modifier for SV_Barycentrics in SPIRV and GLSL (#8067)

* Fix noperspective modifier for SV_Barycentrics in SPIRV and GLSL

- Added test case with both regular and noperspective SV_Barycentrics inputs

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: davli-nv <davli-nv@users.noreply.github.com>

* fixup format

* address review

https://github.com/shader-slang/slang/pull/8067#pullrequestreview-3090037501

* address review

https://github.com/shader-slang/slang/pull/8067#discussion_r2255818595

* add test case from review

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: davli-nv <davli-nv@users.noreply.github.com>

2 files changed, 55 insertions, 8 deletions

diff --git a/tests/pipeline/rasterization/get-attribute-at-vertex-struct.slang b/tests/pipeline/rasterization/get-attribute-at-vertex-struct.slang
new file mode 100644
index 000000000..a63be1718
--- /dev/null
+++ b/tests/pipeline/rasterization/get-attribute-at-vertex-struct.slang
@@ -0,0 +1,38 @@
+// get-attribute-at-vertex-struct.slang
+
+// Test GetAttributeAtVertex and SV_Barycentrics on struct members
+
+//TEST:SIMPLE(filecheck=CHECK-SPIRV):-target spirv -entry main -stage fragment -profile glsl_450+GL_EXT_fragment_shader_barycentric
+//TEST:SIMPLE(filecheck=CHECK-GLSL):-target glsl -entry main -stage fragment -profile glsl_450+GL_EXT_fragment_shader_barycentric
+
+// CHECK-SPIRV: OpCapability FragmentBarycentricKHR
+// CHECK-SPIRV: OpExtension "SPV_KHR_fragment_shader_barycentric"
+
+// CHECK-SPIRV: OpEntryPoint Fragment %main "main"
+// CHECK-SPIRV: OpDecorate %{{.*}} BuiltIn BaryCoordKHR
+// CHECK-SPIRV: OpDecorate %{{.*}} BuiltIn BaryCoordNoPerspKHR
+// CHECK-SPIRV: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_0
+// CHECK-SPIRV: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_1
+// CHECK-SPIRV: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_2
+
+// CHECK-GLSL: #extension GL_EXT_fragment_shader_barycentric : require
+// CHECK-GLSL-DAG: gl_BaryCoordEXT
+// CHECK-GLSL-DAG: gl_BaryCoordNoPerspEXT
+
+struct Input
+{
+    pervertex float4 color : COLOR;
+    float3 bary : SV_Barycentrics;
+    noperspective float3 baryNoPerspective : SV_Barycentrics;
+}
+
+[shader("fragment")]
+void main(
+    Input input,
+    out float4 result : SV_Target)
+{
+    result = input.bary.x * GetAttributeAtVertex(input.color, 0)
+        + input.bary.y * GetAttributeAtVertex(input.color, 1)
+        + input.bary.z * GetAttributeAtVertex(input.color, 2)
+        + input.baryNoPerspective.x * 0.1f;
+}
\ No newline at end of file
diff --git a/tests/pipeline/rasterization/get-attribute-at-vertex.slang b/tests/pipeline/rasterization/get-attribute-at-vertex.slang
index c334200fb..342796b90 100644
--- a/tests/pipeline/rasterization/get-attribute-at-vertex.slang
+++ b/tests/pipeline/rasterization/get-attribute-at-vertex.slang
@@ -2,23 +2,32 @@
 
 // Basic test for `GetAttributeAtVertex` function
 
-//TEST:SIMPLE(filecheck=CHECK):-emit-spirv-directly -target spirv -entry main -stage fragment -profile glsl_450+GL_EXT_fragment_shader_barycentric
+//TEST:SIMPLE(filecheck=CHECK-SPIRV):-target spirv -entry main -stage fragment -profile glsl_450+GL_EXT_fragment_shader_barycentric
+//TEST:SIMPLE(filecheck=CHECK-GLSL):-target glsl -entry main -stage fragment -profile glsl_450+GL_EXT_fragment_shader_barycentric
 
-// CHECK: OpCapability FragmentBarycentricKHR
-// CHECK: OpExtension "SPV_KHR_fragment_shader_barycentric"
+// CHECK-SPIRV: OpCapability FragmentBarycentricKHR
+// CHECK-SPIRV: OpExtension "SPV_KHR_fragment_shader_barycentric"
 
-// CHECK: OpEntryPoint Fragment %main "main"
-// CHECK: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_0
-// CHECK: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_1
-// CHECK: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_2
+// CHECK-SPIRV: OpEntryPoint Fragment %main "main"
+// CHECK-SPIRV: OpDecorate %{{.*}} BuiltIn BaryCoordKHR
+// CHECK-SPIRV: OpDecorate %{{.*}} BuiltIn BaryCoordNoPerspKHR
+// CHECK-SPIRV: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_0
+// CHECK-SPIRV: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_1
+// CHECK-SPIRV: %{{.*}} = OpAccessChain %_ptr_Input_{{.*}} %{{.*}} %uint_2
+
+// CHECK-GLSL: #extension GL_EXT_fragment_shader_barycentric : require
+// CHECK-GLSL-DAG: gl_BaryCoordEXT
+// CHECK-GLSL-DAG: gl_BaryCoordNoPerspEXT
 
 [shader("fragment")]
 void main(
     pervertex float4 color : COLOR,
     float3 bary : SV_Barycentrics,
+    noperspective float3 baryNoPerspective : SV_Barycentrics,
     out float4 result : SV_Target)
 {
     result = bary.x * GetAttributeAtVertex(color, 0)
            + bary.y * GetAttributeAtVertex(color, 1)
-           + bary.z * GetAttributeAtVertex(color, 2);
+           + bary.z * GetAttributeAtVertex(color, 2)
+           + baryNoPerspective.x * 0.1f;
 }