MSL: Support stencil export.

reference/opt/shaders-msl/frag/stencil-export.msl21.frag

@@ -0,0 +1,22 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 MRT0 [[color(0)]];
+    float4 MRT1 [[color(1)]];
+    uint gl_FragStencilRefARB [[stencil]];
+};
+
+fragment main0_out main0()
+{
+    main0_out out = {};
+    out.MRT0 = float4(1.0);
+    out.MRT1 = float4(1.0, 0.0, 1.0, 1.0);
+    out.gl_FragStencilRefARB = uint(100);
+    out.gl_FragStencilRefARB = uint(int(out.gl_FragStencilRefARB) + 10);
+    return out;
+}
+

reference/shaders-msl/frag/stencil-export.msl21.frag

@@ -0,0 +1,29 @@
+#pragma clang diagnostic ignored "-Wmissing-prototypes"
+
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 MRT0 [[color(0)]];
+    float4 MRT1 [[color(1)]];
+    uint gl_FragStencilRefARB [[stencil]];
+};
+
+void update_stencil(thread uint& gl_FragStencilRefARB)
+{
+    gl_FragStencilRefARB = uint(int(gl_FragStencilRefARB) + 10);
+}
+
+fragment main0_out main0()
+{
+    main0_out out = {};
+    out.MRT0 = float4(1.0);
+    out.MRT1 = float4(1.0, 0.0, 1.0, 1.0);
+    out.gl_FragStencilRefARB = uint(100);
+    update_stencil(out.gl_FragStencilRefARB);
+    return out;
+}
+

shaders-msl/frag/stencil-export.msl21.frag

@@ -0,0 +1,17 @@
+#version 450
+#extension GL_ARB_shader_stencil_export : require
+
+layout(location = 0) out vec4 MRT0;
+layout(location = 1) out vec4 MRT1;
+void update_stencil()
+{
+	gl_FragStencilRefARB += 10;
+}
+
+void main()
+{
+	MRT0 = vec4(1.0);
+	MRT1 = vec4(1.0, 0.0, 1.0, 1.0);
+	gl_FragStencilRefARB = 100;
+	update_stencil();
+}

spirv_msl.cpp

@@ -1956,7 +1956,7 @@ uint32_t CompilerMSL::add_interface_block(StorageClass storage, bool patch)
 		bool is_interface_block_builtin =
 		    (bi_type == BuiltInPosition || bi_type == BuiltInPointSize || bi_type == BuiltInClipDistance ||
 		     bi_type == BuiltInCullDistance || bi_type == BuiltInLayer || bi_type == BuiltInViewportIndex ||
-		     bi_type == BuiltInFragDepth || bi_type == BuiltInSampleMask) ||
+		     bi_type == BuiltInFragDepth || bi_type == BuiltInFragStencilRefEXT || bi_type == BuiltInSampleMask) ||
 		    (get_execution_model() == ExecutionModelTessellationEvaluation &&
 		     (bi_type == BuiltInTessLevelOuter || bi_type == BuiltInTessLevelInner));
 
@@ -2090,7 +2090,7 @@ uint32_t CompilerMSL::add_interface_block(StorageClass storage, bool patch)
 	set_name(ib_type_id, to_name(ir.default_entry_point) + "_" + ib_var_ref);
 	set_name(ib_var_id, ib_var_ref);
 
-	for (auto p_var : vars)
+	for (auto *p_var : vars)
 	{
 		bool strip_array =
 		    (get_execution_model() == ExecutionModelTessellationControl ||
@@ -2188,7 +2188,8 @@ uint32_t CompilerMSL::ensure_correct_builtin_type(uint32_t type_id, BuiltIn buil
 	auto &type = get<SPIRType>(type_id);
 
 	if ((builtin == BuiltInSampleMask && is_array(type)) ||
-	    ((builtin == BuiltInLayer || builtin == BuiltInViewportIndex) && type.basetype != SPIRType::UInt))
+	    ((builtin == BuiltInLayer || builtin == BuiltInViewportIndex || builtin == BuiltInFragStencilRefEXT) &&
+	     type.basetype != SPIRType::UInt))
 	{
 		uint32_t next_id = ir.increase_bound_by(type.pointer ? 2 : 1);
 		uint32_t base_type_id = next_id++;
@@ -5632,6 +5633,11 @@ string CompilerMSL::member_attribute_qualifier(const SPIRType &type, uint32_t in
 		{
 			switch (builtin)
 			{
+			case BuiltInFragStencilRefEXT:
+				if (!msl_options.supports_msl_version(2, 1))
+					SPIRV_CROSS_THROW("Stencil export only supported in MSL 2.1 and up.");
+				return string(" [[") + builtin_qualifier(builtin) + "]]";
+
 			case BuiltInSampleMask:
 			case BuiltInFragDepth:
 				return string(" [[") + builtin_qualifier(builtin) + "]]";
@@ -7526,6 +7532,7 @@ string CompilerMSL::builtin_to_glsl(BuiltIn builtin, StorageClass storage)
 	case BuiltInCullDistance:
 	case BuiltInLayer:
 	case BuiltInFragDepth:
+	case BuiltInFragStencilRefEXT:
 	case BuiltInSampleMask:
 		if (get_execution_model() == ExecutionModelTessellationControl)
 			break;
@@ -7657,6 +7664,9 @@ string CompilerMSL::builtin_qualifier(BuiltIn builtin)
 		else
 			return "depth(any)";
 
+	case BuiltInFragStencilRefEXT:
+		return "stencil";
+
 	// Compute function in
 	case BuiltInGlobalInvocationId:
 		return "thread_position_in_grid";
@@ -7780,6 +7790,9 @@ string CompilerMSL::builtin_type_decl(BuiltIn builtin)
 	case BuiltInFragDepth:
 		return "float";
 
+	case BuiltInFragStencilRefEXT:
+		return "uint";
+
 	// Compute function in
 	case BuiltInGlobalInvocationId:
 	case BuiltInLocalInvocationId:
@@ -8339,6 +8352,7 @@ void CompilerMSL::bitcast_from_builtin_load(uint32_t source_id, std::string &exp
 	case BuiltInNumWorkgroups:
 	case BuiltInLayer:
 	case BuiltInViewportIndex:
+	case BuiltInFragStencilRefEXT:
 		expected_type = SPIRType::UInt;
 		break;
 
@@ -8379,6 +8393,7 @@ void CompilerMSL::bitcast_to_builtin_store(uint32_t target_id, std::string &expr
 	{
 	case BuiltInLayer:
 	case BuiltInViewportIndex:
+	case BuiltInFragStencilRefEXT:
 		expected_type = SPIRType::UInt;
 		break;