HLSL: Implement SM 6.8 BaseVertex/BaseInstance.

reference/shaders-hlsl-no-opt/vert/base-instance-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,25 @@
+static float4 gl_Position;
+static int gl_BaseInstanceARB;
+struct SPIRV_Cross_Input
+{
+    uint gl_BaseInstanceARB : SV_StartInstanceLocation;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : SV_Position;
+};
+
+void vert_main()
+{
+    gl_Position = float(gl_BaseInstanceARB).xxxx;
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    gl_BaseInstanceARB = stage_input.gl_BaseInstanceARB;
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    return stage_output;
+}

reference/shaders-hlsl-no-opt/vert/base-vertex-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,25 @@
+static float4 gl_Position;
+static int gl_BaseVertexARB;
+struct SPIRV_Cross_Input
+{
+    uint gl_BaseVertexARB : SV_StartVertexLocation;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : SV_Position;
+};
+
+void vert_main()
+{
+    gl_Position = float(gl_BaseVertexARB).xxxx;
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    gl_BaseVertexARB = stage_input.gl_BaseVertexARB;
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    return stage_output;
+}

reference/shaders-hlsl-no-opt/vert/instance-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,28 @@
+static float4 gl_Position;
+static int gl_InstanceIndex;
+static int gl_BaseInstanceARB;
+struct SPIRV_Cross_Input
+{
+    uint gl_InstanceIndex : SV_InstanceID;
+    uint gl_BaseInstanceARB : SV_StartInstanceLocation;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : SV_Position;
+};
+
+void vert_main()
+{
+    gl_Position = float(gl_InstanceIndex).xxxx;
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    gl_InstanceIndex = int(stage_input.gl_InstanceIndex + stage_input.gl_BaseInstanceARB);
+    gl_BaseInstanceARB = stage_input.gl_BaseInstanceARB;
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    return stage_output;
+}

reference/shaders-hlsl-no-opt/vert/vertex-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,28 @@
+static float4 gl_Position;
+static int gl_VertexIndex;
+static int gl_BaseVertexARB;
+struct SPIRV_Cross_Input
+{
+    uint gl_VertexIndex : SV_VertexID;
+    uint gl_BaseVertexARB : SV_StartVertexLocation;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : SV_Position;
+};
+
+void vert_main()
+{
+    gl_Position = float(gl_VertexIndex).xxxx;
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    gl_VertexIndex = int(stage_input.gl_VertexIndex + stage_input.gl_BaseVertexARB);
+    gl_BaseVertexARB = stage_input.gl_BaseVertexARB;
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    return stage_output;
+}

shaders-hlsl-no-opt/vert/base-instance-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,7 @@
+#version 450
+#extension GL_ARB_shader_draw_parameters : require
+
+void main()
+{
+	gl_Position = vec4(gl_BaseInstanceARB);
+}

shaders-hlsl-no-opt/vert/base-vertex-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,7 @@
+#version 450
+#extension GL_ARB_shader_draw_parameters : require
+
+void main()
+{
+	gl_Position = vec4(gl_BaseVertexARB);
+}

shaders-hlsl-no-opt/vert/instance-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,6 @@
+#version 450
+
+void main()
+{
+	gl_Position = vec4(gl_InstanceIndex);
+}

shaders-hlsl-no-opt/vert/vertex-index.sm68.nofxc.fxconly.vert

@@ -0,0 +1,6 @@
+#version 450
+
+void main()
+{
+	gl_Position = vec4(gl_VertexIndex);
+}

spirv_hlsl.cpp

@@ -849,11 +849,25 @@ void CompilerHLSL::emit_builtin_inputs_in_struct()
 		case BuiltInSubgroupLeMask:
 		case BuiltInSubgroupGtMask:
 		case BuiltInSubgroupGeMask:
-		case BuiltInBaseVertex:
-		case BuiltInBaseInstance:
 			// Handled specially.
 			break;
 
+		case BuiltInBaseVertex:
+			if (hlsl_options.shader_model >= 68)
+			{
+				type = "uint";
+				semantic = "SV_StartVertexLocation";
+			}
+			break;
+
+		case BuiltInBaseInstance:
+			if (hlsl_options.shader_model >= 68)
+			{
+				type = "uint";
+				semantic = "SV_StartInstanceLocation";
+			}
+			break;
+
 		case BuiltInHelperInvocation:
 			if (hlsl_options.shader_model < 50 || get_entry_point().model != ExecutionModelFragment)
 				SPIRV_CROSS_THROW("Helper Invocation input is only supported in PS 5.0 or higher.");
@@ -1231,7 +1245,7 @@ void CompilerHLSL::emit_builtin_variables()
 		case BuiltInVertexIndex:
 		case BuiltInInstanceIndex:
 			type = "int";
-			if (hlsl_options.support_nonzero_base_vertex_base_instance)
+			if (hlsl_options.support_nonzero_base_vertex_base_instance || hlsl_options.shader_model >= 68)
 				base_vertex_info.used = true;
 			break;
 
@@ -1353,7 +1367,7 @@ void CompilerHLSL::emit_builtin_variables()
 		}
 	});
 
-	if (base_vertex_info.used)
+	if (base_vertex_info.used && hlsl_options.shader_model < 68)
 	{
 		string binding_info;
 		if (base_vertex_info.explicit_binding)
@@ -3136,22 +3150,38 @@ void CompilerHLSL::emit_hlsl_entry_point()
 		case BuiltInVertexIndex:
 		case BuiltInInstanceIndex:
 			// D3D semantics are uint, but shader wants int.
-			if (hlsl_options.support_nonzero_base_vertex_base_instance)
+			if (hlsl_options.support_nonzero_base_vertex_base_instance || hlsl_options.shader_model >= 68)
+			{
+				if (hlsl_options.shader_model >= 68)
+				{
+					if (static_cast<BuiltIn>(i) == BuiltInInstanceIndex)
+						statement(builtin, " = int(stage_input.", builtin, " + stage_input.gl_BaseInstanceARB);");
+					else
+						statement(builtin, " = int(stage_input.", builtin, " + stage_input.gl_BaseVertexARB);");
+				}
+				else
 				{
 					if (static_cast<BuiltIn>(i) == BuiltInInstanceIndex)
 						statement(builtin, " = int(stage_input.", builtin, ") + SPIRV_Cross_BaseInstance;");
 					else
 						statement(builtin, " = int(stage_input.", builtin, ") + SPIRV_Cross_BaseVertex;");
 				}
+			}
 			else
 				statement(builtin, " = int(stage_input.", builtin, ");");
 			break;
 
 		case BuiltInBaseVertex:
+			if (hlsl_options.shader_model >= 68)
+				statement(builtin, " = stage_input.gl_BaseVertexARB;");
+			else
 				statement(builtin, " = SPIRV_Cross_BaseVertex;");
 			break;
 
 		case BuiltInBaseInstance:
+			if (hlsl_options.shader_model >= 68)
+				statement(builtin, " = stage_input.gl_BaseInstanceARB;");
+			else
 				statement(builtin, " = SPIRV_Cross_BaseInstance;");
 			break;
 
@@ -6714,6 +6744,15 @@ string CompilerHLSL::compile()
 	if (need_subpass_input)
 		active_input_builtins.set(BuiltInFragCoord);
 
+	// Need to offset by BaseVertex/BaseInstance in SM 6.8+.
+	if (hlsl_options.shader_model >= 68)
+	{
+		if (active_input_builtins.get(BuiltInVertexIndex))
+			active_input_builtins.set(BuiltInBaseVertex);
+		if (active_input_builtins.get(BuiltInInstanceIndex))
+			active_input_builtins.set(BuiltInBaseInstance);
+	}
+
 	uint32_t pass_count = 0;
 	do
 	{

test_shaders.py

@@ -494,6 +494,8 @@ def shader_to_sm(shader):
         return '62'
     elif '.sm60.' in shader:
         return '60'
+    elif '.sm68.' in shader:
+        return '68'
     elif '.sm51.' in shader:
         return '51'
     elif '.sm30.' in shader: