Merge pull request #2076 from billhollings/ios-tier2-writable-images

MSL: Add support for writable images in iOS Tier2 argument buffers.

CMakeLists.txt

@@ -332,7 +332,7 @@ if (SPIRV_CROSS_STATIC)
 endif()
 
 set(spirv-cross-abi-major 0)
-set(spirv-cross-abi-minor 53)
+set(spirv-cross-abi-minor 54)
 set(spirv-cross-abi-patch 0)
 
 if (SPIRV_CROSS_SHARED)

main.cpp

@@ -645,6 +645,7 @@ struct CLIArguments
 	bool msl_pad_fragment_output = false;
 	bool msl_domain_lower_left = false;
 	bool msl_argument_buffers = false;
+	uint32_t msl_argument_buffers_tier = 0;		// Tier 1
 	bool msl_texture_buffer_native = false;
 	bool msl_framebuffer_fetch = false;
 	bool msl_invariant_float_math = false;
@@ -856,8 +857,11 @@ static void print_help_msl()
 	                "\t[--msl-pad-fragment-output]:\n\t\tAlways emit color outputs as 4-component variables.\n"
 	                "\t\tIn Metal, the fragment shader must emit at least as many components as the render target format.\n"
 	                "\t[--msl-domain-lower-left]:\n\t\tUse a lower-left tessellation domain.\n"
-	                "\t[--msl-argument-buffers]:\n\t\tEmit Indirect Argument buffers instead of plain bindings.\n"
+	                "\t[--msl-argument-buffers]:\n\t\tEmit Metal argument buffers instead of discrete resource bindings.\n"
 	                "\t\tRequires MSL 2.0 to be enabled.\n"
+	                "\t[--msl-argument-buffers-tier]:\n\t\tWhen using Metal argument buffers, indicate the Metal argument buffer tier level supported by the Metal platform.\n"
+	                "\t\tUses same values as Metal MTLArgumentBuffersTier enumeration (0 = Tier1, 1 = Tier2).\n"
+	                "\t\tSetting this value also enables msl-argument-buffers.\n"
 	                "\t[--msl-texture-buffer-native]:\n\t\tEnable native support for texel buffers. Otherwise, it is emulated as a normal texture.\n"
 	                "\t[--msl-framebuffer-fetch]:\n\t\tImplement subpass inputs with frame buffer fetch.\n"
 	                "\t\tEmits [[color(N)]] inputs in fragment stage.\n"
@@ -1190,6 +1194,7 @@ static string compile_iteration(const CLIArguments &args, std::vector<uint32_t>
 		msl_opts.pad_fragment_output_components = args.msl_pad_fragment_output;
 		msl_opts.tess_domain_origin_lower_left = args.msl_domain_lower_left;
 		msl_opts.argument_buffers = args.msl_argument_buffers;
+		msl_opts.argument_buffers_tier = static_cast<CompilerMSL::Options::ArgumentBuffersTier>(args.msl_argument_buffers_tier);
 		msl_opts.texture_buffer_native = args.msl_texture_buffer_native;
 		msl_opts.multiview = args.msl_multiview;
 		msl_opts.multiview_layered_rendering = args.msl_multiview_layered_rendering;
@@ -1621,6 +1626,10 @@ static int main_inner(int argc, char *argv[])
 	cbs.add("--msl-pad-fragment-output", [&args](CLIParser &) { args.msl_pad_fragment_output = true; });
 	cbs.add("--msl-domain-lower-left", [&args](CLIParser &) { args.msl_domain_lower_left = true; });
 	cbs.add("--msl-argument-buffers", [&args](CLIParser &) { args.msl_argument_buffers = true; });
+	cbs.add("--msl-argument-buffer-tier", [&args](CLIParser &parser) {
+		args.msl_argument_buffers_tier = parser.next_uint();
+		args.msl_argument_buffers = true;
+	});
 	cbs.add("--msl-discrete-descriptor-set",
 	        [&args](CLIParser &parser) { args.msl_discrete_descriptor_sets.push_back(parser.next_uint()); });
 	cbs.add("--msl-device-argument-buffer",

spirv_cross_c.cpp

@@ -734,6 +734,10 @@ spvc_result spvc_compiler_options_set_uint(spvc_compiler_options options, spvc_c
 	case SPVC_COMPILER_OPTION_MSL_CHECK_DISCARDED_FRAG_STORES:
 		options->msl.check_discarded_frag_stores = value != 0;
 		break;
+
+	case SPVC_COMPILER_OPTION_MSL_ARGUMENT_BUFFERS_TIER:
+		options->msl.argument_buffers_tier = static_cast<CompilerMSL::Options::ArgumentBuffersTier>(value);
+		break;
 #endif
 
 	default:

spirv_cross_c.h

@@ -40,7 +40,7 @@ extern "C" {
 /* Bumped if ABI or API breaks backwards compatibility. */
 #define SPVC_C_API_VERSION_MAJOR 0
 /* Bumped if APIs or enumerations are added in a backwards compatible way. */
-#define SPVC_C_API_VERSION_MINOR 53
+#define SPVC_C_API_VERSION_MINOR 54
 /* Bumped if internal implementation details change. */
 #define SPVC_C_API_VERSION_PATCH 0
 
@@ -723,6 +723,8 @@ typedef enum spvc_compiler_option
 
 	SPVC_COMPILER_OPTION_GLSL_ENABLE_ROW_MAJOR_LOAD_WORKAROUND = 83 | SPVC_COMPILER_OPTION_GLSL_BIT,
 
+	SPVC_COMPILER_OPTION_MSL_ARGUMENT_BUFFERS_TIER = 84 | SPVC_COMPILER_OPTION_MSL_BIT,
+
 	SPVC_COMPILER_OPTION_INT_MAX = 0x7fffffff
 } spvc_compiler_option;
 

spirv_msl.cpp

@@ -11608,11 +11608,14 @@ string CompilerMSL::to_struct_member(const SPIRType &type, uint32_t member_type_
 		}
 	}
 
-	// Very specifically, image load-store in argument buffers are disallowed on MSL on iOS.
+	// iOS Tier 1 argument buffers do not support writable images.
-	if (msl_options.is_ios() && physical_type.basetype == SPIRType::Image && physical_type.image.sampled == 2)
+	if (physical_type.basetype == SPIRType::Image &&
+		physical_type.image.sampled == 2 &&
+		msl_options.is_ios() &&
+		msl_options.argument_buffers_tier <= Options::ArgumentBuffersTier::Tier1 &&
+		!has_decoration(orig_id, DecorationNonWritable))
 	{
-		if (!has_decoration(orig_id, DecorationNonWritable))
+		SPIRV_CROSS_THROW("Writable images are not allowed on Tier1 argument buffers on iOS.");
-			SPIRV_CROSS_THROW("Writable images are not allowed in argument buffers on iOS.");
 	}
 
 	// Array information is baked into these types.
@@ -16953,13 +16956,14 @@ bool CompilerMSL::descriptor_set_is_argument_buffer(uint32_t desc_set) const
 
 bool CompilerMSL::is_supported_argument_buffer_type(const SPIRType &type) const
 {
-	// Very specifically, image load-store in argument buffers are disallowed on MSL on iOS.
+	// iOS Tier 1 argument buffers do not support writable images.
-	// But we won't know when the argument buffer is encoded whether this image will have
+	// When the argument buffer is encoded, we don't know whether this image will have a
-	// a NonWritable decoration. So just use discrete arguments for all storage images
+	// NonWritable decoration, so just use discrete arguments for all storage images on iOS.
-	// on iOS.
+	bool is_supported_type = !(type.basetype == SPIRType::Image &&
-	bool is_storage_image = type.basetype == SPIRType::Image && type.image.sampled == 2;
+							   type.image.sampled == 2 &&
-	bool is_supported_type = !msl_options.is_ios() || !is_storage_image;
+							   msl_options.is_ios() &&
-	return !type_is_msl_framebuffer_fetch(type) && is_supported_type;
+							   msl_options.argument_buffers_tier <= Options::ArgumentBuffersTier::Tier1);
+	return is_supported_type && !type_is_msl_framebuffer_fetch(type);
 }
 
 void CompilerMSL::analyze_argument_buffers()

spirv_msl.hpp

@@ -339,10 +339,25 @@ public:
 		bool dispatch_base = false;
 		bool texture_1D_as_2D = false;
 
-		// Enable use of MSL 2.0 indirect argument buffers.
+		// Enable use of Metal argument buffers.
 		// MSL 2.0 must also be enabled.
 		bool argument_buffers = false;
 
+		// Defines Metal argument buffer tier levels.
+		// Uses same values as Metal MTLArgumentBuffersTier enumeration.
+		enum class ArgumentBuffersTier
+		{
+			Tier1 = 0,
+			Tier2 = 1,
+		};
+
+		// When using Metal argument buffers, indicates the Metal argument buffer tier level supported by the Metal platform.
+		// Ignored when Options::argument_buffers is disabled.
+		// - Tier1 supports writable images on macOS, but not on iOS.
+		// - Tier2 supports writable images on macOS and iOS, and higher resource count limits.
+		// Tier capabilities based on recommendations from Apple engineering.
+		ArgumentBuffersTier argument_buffers_tier = ArgumentBuffersTier::Tier1;
+
 		// Ensures vertex and instance indices start at zero. This reflects the behavior of HLSL with SV_VertexID and SV_InstanceID.
 		bool enable_base_index_zero = false;