Merge pull request #1810 from billhollings/early-frag-tests-depth-out

MSL: Don't output depth and stencil values with explicit early fragment tests.

reference/opt/shaders-msl/frag/depth-out-early-frag-tests.frag

@@ -0,0 +1,19 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 color_out [[color(0)]];
+};
+
+[[ early_fragment_tests ]] fragment main0_out main0()
+{
+    float gl_FragDepth;
+    main0_out out = {};
+    out.color_out = float4(1.0, 0.0, 0.0, 1.0);
+    gl_FragDepth = 0.699999988079071044921875;
+    return out;
+}
+

reference/opt/shaders-msl/frag/depth-out-no-early-frag-tests.frag

@@ -0,0 +1,19 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 color_out [[color(0)]];
+    float gl_FragDepth [[depth(less)]];
+};
+
+fragment main0_out main0()
+{
+    main0_out out = {};
+    out.color_out = float4(1.0, 0.0, 0.0, 1.0);
+    out.gl_FragDepth = 0.699999988079071044921875;
+    return out;
+}
+

reference/shaders-msl/frag/depth-out-early-frag-tests.frag

@@ -0,0 +1,19 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 color_out [[color(0)]];
+};
+
+[[ early_fragment_tests ]] fragment main0_out main0()
+{
+    float gl_FragDepth;
+    main0_out out = {};
+    out.color_out = float4(1.0, 0.0, 0.0, 1.0);
+    gl_FragDepth = 0.699999988079071044921875;
+    return out;
+}
+

reference/shaders-msl/frag/depth-out-no-early-frag-tests.frag

@@ -0,0 +1,19 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 color_out [[color(0)]];
+    float gl_FragDepth [[depth(less)]];
+};
+
+fragment main0_out main0()
+{
+    main0_out out = {};
+    out.color_out = float4(1.0, 0.0, 0.0, 1.0);
+    out.gl_FragDepth = 0.699999988079071044921875;
+    return out;
+}
+

shaders-msl/frag/depth-out-early-frag-tests.frag

@@ -0,0 +1,11 @@
+#version 430
+layout(depth_less) out float gl_FragDepth;
+layout(early_fragment_tests) in;
+
+layout(location = 0) out vec4 color_out;
+
+void main()
+{
+    color_out = vec4(1.0, 0.0, 0.0, 1.0);
+    gl_FragDepth = 0.699999988079071044921875;
+}

shaders-msl/frag/depth-out-no-early-frag-tests.frag

@@ -0,0 +1,10 @@
+#version 430
+layout(depth_less) out float gl_FragDepth;
+
+layout(location = 0) out vec4 color_out;
+
+void main()
+{
+    color_out = vec4(1.0, 0.0, 0.0, 1.0);
+    gl_FragDepth = 0.699999988079071044921875;
+}

spirv_msl.cpp

@@ -3364,16 +3364,22 @@ uint32_t CompilerMSL::add_interface_block(StorageClass storage, bool patch)
 		// It's not enough to simply avoid marking fragment outputs if the pipeline won't
 		// accept them. We can't put them in the struct at all, or otherwise the compiler
 		// complains that the outputs weren't explicitly marked.
+		// Frag depth and stencil outputs are incompatible with explicit early fragment tests.
+		// In GLSL, depth and stencil outputs are just ignored when explicit early fragment tests are required.
+		// In Metal, it's a compilation error, so we need to exclude them from the output struct.
 		if (get_execution_model() == ExecutionModelFragment && storage == StorageClassOutput && !patch &&
-		    ((is_builtin && ((bi_type == BuiltInFragDepth && !msl_options.enable_frag_depth_builtin) ||
-		                     (bi_type == BuiltInFragStencilRefEXT && !msl_options.enable_frag_stencil_ref_builtin))) ||
+		    ((is_builtin && ((bi_type == BuiltInFragDepth && (!msl_options.enable_frag_depth_builtin || uses_explicit_early_fragment_test())) ||
+		                     (bi_type == BuiltInFragStencilRefEXT && (!msl_options.enable_frag_stencil_ref_builtin || uses_explicit_early_fragment_test())))) ||
 		     (!is_builtin && !(msl_options.enable_frag_output_mask & (1 << location)))))
 		{
 			hidden = true;
 			disabled_frag_outputs.push_back(var_id);
-			// If a builtin, force it to have the proper name.
+			// If a builtin, force it to have the proper name, and mark it as not part of the output struct.
 			if (is_builtin)
+			{
 				set_name(var_id, builtin_to_glsl(bi_type, StorageClassFunction));
+				mask_stage_output_by_builtin(bi_type);
+			}
 		}
 
 		// Barycentric inputs must be emitted in stage-in, because they can have interpolation arguments.
@@ -11156,10 +11162,7 @@ string CompilerMSL::func_type_decl(SPIRType &type)
 			                  execution.output_vertices, ") ]] vertex");
 		break;
 	case ExecutionModelFragment:
-		entry_type = execution.flags.get(ExecutionModeEarlyFragmentTests) ||
-		                     execution.flags.get(ExecutionModePostDepthCoverage) ?
-		                 "[[ early_fragment_tests ]] fragment" :
-		                 "fragment";
+		entry_type = uses_explicit_early_fragment_test() ? "[[ early_fragment_tests ]] fragment" : "fragment";
 		break;
 	case ExecutionModelTessellationControl:
 		if (!msl_options.supports_msl_version(1, 2))
@@ -11179,6 +11182,12 @@ string CompilerMSL::func_type_decl(SPIRType &type)
 	return entry_type + " " + return_type;
 }
 
+bool CompilerMSL::uses_explicit_early_fragment_test()
+{
+	auto &ep_flags = get_entry_point().flags;
+	return ep_flags.get(ExecutionModeEarlyFragmentTests) || ep_flags.get(ExecutionModePostDepthCoverage);
+}
+
 // In MSL, address space qualifiers are required for all pointer or reference variables
 string CompilerMSL::get_argument_address_space(const SPIRVariable &argument)
 {

spirv_msl.hpp

@@ -932,6 +932,8 @@ protected:
 	void build_implicit_builtins();
 	uint32_t build_constant_uint_array_pointer();
 	void emit_entry_point_declarations() override;
+	bool uses_explicit_early_fragment_test();
+
 	uint32_t builtin_frag_coord_id = 0;
 	uint32_t builtin_sample_id_id = 0;
 	uint32_t builtin_sample_mask_id = 0;