From 634e3960c2bc322bbd51fccc7ff395d9f24e35dc Mon Sep 17 00:00:00 2001
From: Darren Wihandi <65404740+fairywreath@users.noreply.github.com>
Date: Mon, 19 May 2025 14:21:25 -0400
Subject: Map `SV_VertexID` to `gl_VertexIndex-gl_BaseVertex`, add
 `SV_Vulkan*ID` semantics (#7150)

* Map SV_VertexID to `gl_VertexIndex - gl_BaseVertex`, provide SV_Vulkan* SV semantics

* Fix docs

* Regenerate toc

* Fix affected pointer-2 test

* Add tests

---------

Co-authored-by: Yong He <yonghe@outlook.com>
---
 tests/spirv/pointer-2.slang                    |  2 +-
 tests/spirv/sv-vertex-id.slang                 | 16 ++++++++++
 tests/spirv/sv-vulkan-instance-vertex-id.slang | 42 ++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 tests/spirv/sv-vertex-id.slang
 create mode 100644 tests/spirv/sv-vulkan-instance-vertex-id.slang

(limited to 'tests')

diff --git a/tests/spirv/pointer-2.slang b/tests/spirv/pointer-2.slang
index 201d97001..1f2b2d0ea 100644
--- a/tests/spirv/pointer-2.slang
+++ b/tests/spirv/pointer-2.slang
@@ -44,7 +44,7 @@ ConstantBuffer<PushConstants> constantBuffer;
 // CHECK_SPV_VIA_GLSL: OpTypePointer PhysicalStorageBuffer
 
 [shader("vertex")]
-VSOutput vertexMain(int vertexIndex: SV_VertexID)
+VSOutput vertexMain(int vertexIndex: SV_VulkanVertexID)
 {
     //
     // Test field access chains.
diff --git a/tests/spirv/sv-vertex-id.slang b/tests/spirv/sv-vertex-id.slang
new file mode 100644
index 000000000..c92f0351e
--- /dev/null
+++ b/tests/spirv/sv-vertex-id.slang
@@ -0,0 +1,16 @@
+//TEST:SIMPLE(filecheck=GLSL): -target glsl -entry vertMain -stage vertex
+//TEST:SIMPLE(filecheck=CHECK): -target spirv
+//TEST:SIMPLE(filecheck=CHECK): -target spirv  -emit-spirv-via-glsl
+
+// CHECK-DAG: %[[BASE_VERTEX:[0-9]+|[a-zA-Z_][a-zA-Z0-9_]*]] = OpVariable {{.*}} BuiltIn BaseVertex
+// CHECK-DAG: %[[REG1:[0-9a-zA-Z_]+]] = OpLoad %int %[[BASE_VERTEX]]
+// CHECK-DAG: %[[REG2:[0-9a-zA-Z_]+]] = OpLoad %int %gl_VertexIndex
+// CHECK-DAG: OpISub %int %[[REG2]] %[[REG1]]
+
+// GLSL: gl_VertexIndex - gl_BaseVertex
+
+[shader("vertex")]
+float4 vertMain(int i : SV_VertexID) : SV_Position
+{
+    return i;
+}
diff --git a/tests/spirv/sv-vulkan-instance-vertex-id.slang b/tests/spirv/sv-vulkan-instance-vertex-id.slang
new file mode 100644
index 000000000..c8654c857
--- /dev/null
+++ b/tests/spirv/sv-vulkan-instance-vertex-id.slang
@@ -0,0 +1,42 @@
+//TEST:SIMPLE(filecheck=SPIRV): -entry main -stage vertex -target spirv -emit-spirv-directly
+//TEST:SIMPLE(filecheck=GLSL): -entry main -stage vertex -target glsl
+//TEST:SIMPLE(filecheck=METAL): -entry main -stage vertex -target metal
+//TEST:SIMPLE(filecheck=WGSL): -entry main -stage vertex -target wgsl
+
+struct VSInput
+{
+    uint vertexID : SV_VulkanVertexID;
+    uint instanceID : SV_VulkanInstanceID;
+};
+
+struct VSOutput
+{
+    float4 position : SV_POSITION;
+};
+
+[shader("vertex")]
+VSOutput main(VSInput input)
+{
+    VSOutput output;
+    output.position = float4(input.vertexID + input.instanceID);
+
+    // SPIRV-DAG: BuiltIn InstanceIndex
+    // SPIRV-DAG: BuiltIn VertexIndex
+    // SPIRV-NOT: BuiltIn BaseInstance
+    // SPIRV-NOT: BuiltIn BaseVertex
+
+    // GLSL-NOT: GL_ARB_shader_draw_parameters
+    // GLSL-DAG: gl_VertexIndex
+    // GLSL-NOT: gl_BaseVertex
+    // GLSL-DAG: gl_InstanceIndex
+    // GLSL-NOT: gl_BaseInstance
+
+    // METAL-DAG: vertex_id
+    // METAL-DAG: instance_id
+
+    // WGSL-DAG: vertex_index
+    // WGSL-DAG: instance_index
+
+    return output;
+}
+
-- 
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