MSL: Add C API for querying automatic resource bindings.

CMakeLists.txt

@@ -287,7 +287,7 @@ if (SPIRV_CROSS_STATIC)
 endif()
 
 set(spirv-cross-abi-major 0)
-set(spirv-cross-abi-minor 13)
+set(spirv-cross-abi-minor 14)
 set(spirv-cross-abi-patch 0)
 
 if (SPIRV_CROSS_SHARED)

spirv_cross_c.cpp

@@ -1031,6 +1031,44 @@ spvc_result spvc_compiler_msl_set_fragment_output_components(spvc_compiler compi
 #endif
 }
 
+unsigned spvc_compiler_msl_get_automatic_resource_binding(spvc_compiler compiler, spvc_variable_id id)
+{
+#if SPIRV_CROSS_C_API_MSL
+	if (compiler->backend != SPVC_BACKEND_MSL)
+	{
+		compiler->context->report_error("MSL function used on a non-MSL backend.");
+		return uint32_t(-1);
+	}
+
+	auto &msl = *static_cast<CompilerMSL *>(compiler->compiler.get());
+	msl.get_automatic_msl_resource_binding(id);
+	return SPVC_SUCCESS;
+#else
+	(void)id;
+	compiler->context->report_error("MSL function used on a non-MSL backend.");
+	return uint32_t(-1);
+#endif
+}
+
+unsigned spvc_compiler_msl_get_automatic_resource_binding_secondary(spvc_compiler compiler, spvc_variable_id id)
+{
+#if SPIRV_CROSS_C_API_MSL
+	if (compiler->backend != SPVC_BACKEND_MSL)
+	{
+		compiler->context->report_error("MSL function used on a non-MSL backend.");
+		return uint32_t(-1);
+	}
+
+	auto &msl = *static_cast<CompilerMSL *>(compiler->compiler.get());
+	msl.get_automatic_msl_resource_binding_secondary(id);
+	return SPVC_SUCCESS;
+#else
+	(void)id;
+	compiler->context->report_error("MSL function used on a non-MSL backend.");
+	return uint32_t(-1);
+#endif
+}
+
 spvc_result spvc_compiler_compile(spvc_compiler compiler, const char **source)
 {
 	SPVC_BEGIN_SAFE_SCOPE

spirv_cross_c.h

@@ -33,7 +33,7 @@ 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 13
+#define SPVC_C_API_VERSION_MINOR 14
 /* Bumped if internal implementation details change. */
 #define SPVC_C_API_VERSION_PATCH 0
 
@@ -551,6 +551,9 @@ SPVC_PUBLIC_API spvc_result spvc_compiler_msl_remap_constexpr_sampler(spvc_compi
 SPVC_PUBLIC_API spvc_result spvc_compiler_msl_remap_constexpr_sampler_by_binding(spvc_compiler compiler, unsigned desc_set, unsigned binding, const spvc_msl_constexpr_sampler *sampler);
 SPVC_PUBLIC_API spvc_result spvc_compiler_msl_set_fragment_output_components(spvc_compiler compiler, unsigned location, unsigned components);
 
+SPVC_PUBLIC_API unsigned spvc_compiler_msl_get_automatic_resource_binding(spvc_compiler compiler, spvc_variable_id id);
+SPVC_PUBLIC_API unsigned spvc_compiler_msl_get_automatic_resource_binding_secondary(spvc_compiler compiler, spvc_variable_id id);
+
 /*
  * Reflect resources.
  * Maps almost 1:1 to C++ API.

spirv_msl.cpp

@@ -79,6 +79,16 @@ bool CompilerMSL::is_msl_resource_binding_used(ExecutionModel model, uint32_t de
 	return itr != end(resource_bindings) && itr->second.second;
 }
 
+uint32_t CompilerMSL::get_automatic_msl_resource_binding(uint32_t id) const
+{
+	return get_extended_decoration(id, SPIRVCrossDecorationResourceIndexPrimary);
+}
+
+uint32_t CompilerMSL::get_automatic_msl_resource_binding_secondary(uint32_t id) const
+{
+	return get_extended_decoration(id, SPIRVCrossDecorationResourceIndexSecondary);
+}
+
 void CompilerMSL::set_fragment_output_components(uint32_t location, uint32_t components)
 {
 	fragment_output_components[location] = components;

spirv_msl.hpp

@@ -314,6 +314,19 @@ public:
 	// by remap_constexpr_sampler(_by_binding).
 	bool is_msl_resource_binding_used(spv::ExecutionModel model, uint32_t set, uint32_t binding);
 
+	// This must only be called after a successful call to CompilerMSL::compile().
+	// For a variable resource ID obtained through reflection API, report the automatically assigned resource index.
+	// If the descriptor set was part of an argument buffer, report the [[id(N)]],
+	// or [[buffer/texture/sampler]] binding for other resources.
+	// If the resource was a combined image sampler, report the image binding here,
+	// use the _secondary version of this call to query the sampler half of the resource.
+	// If no binding exists, uint32_t(-1) is returned.
+	uint32_t get_automatic_msl_resource_binding(uint32_t id) const;
+
+	// Same as get_automatic_msl_resource_binding, but should only be used for combined image samplers, in which case the
+	// sampler's binding is returned instead. For any other resource type, -1 is returned.
+	uint32_t get_automatic_msl_resource_binding_secondary(uint32_t id) const;
+
 	// Compiles the SPIR-V code into Metal Shading Language.
 	std::string compile() override;