[Feat] (MG_Util/ShaderCompiler): extract global UBO offset from GL plain uniforms

MobileGL/MG_Test/Program/ProgramTest.cpp

@@ -287,6 +287,21 @@ TEST_F(ProgramTest, DecompProgram) {
         }
     }
 
-    auto ubo0 = sessions[0].GetShaderInterface(SPVC_RESOURCE_TYPE_UNIFORM_BUFFER);
-    auto ubo1 = sessions[1].GetShaderInterface(SPVC_RESOURCE_TYPE_UNIFORM_BUFFER);
+    auto& meta0 = sessions[0].GetMetadata();
+    auto& meta1 = sessions[1].GetMetadata();
+
+    for (auto& [name, offset] : meta0.plainUniformOffsetsInUBO) {
+        printf("%s: \t%u\n", name.c_str(), offset);
+    }
+
+    printf("\n");
+
+    for (auto& [name, offset] : meta1.plainUniformOffsetsInUBO) {
+        printf("%s: \t%u\n", name.c_str(), offset);
+    }
+
+    EXPECT_EQ(meta0.plainUniformOffsetsInUBO.size(), meta1.plainUniformOffsetsInUBO.size());
+    for (auto& [name, offset] : meta0.plainUniformOffsetsInUBO) {
+        EXPECT_EQ(offset, meta1.plainUniformOffsetsInUBO.at(name));
+    }
 }

MobileGL/MG_Util/ShaderTranspiler/ShaderCompiler.cpp

@@ -137,7 +137,7 @@ namespace MobileGL {
                 tshader->setAutoMapLocations(true);
                 tshader->setAutoMapBindings(true);
                 tshader->setEnvInputVulkanRulesRelaxed(); // using EXT_vulkan_glsl_relaxed for gl_VertexID and gl_InstanceID?
-                tshader->setGlobalUniformBlockName("MGL_GLOBAL_UBO");
+                tshader->setGlobalUniformBlockName(GLOBAL_UBO_NAME);
                 if (!tshader->parse(&GetTBuiltInResourceInstance(), 150, ECoreProfile,
                         /*forceDefaultVersionAndProfile: */false,
                         /*forwardCompatible: */true, EShMsgDefault)) {

MobileGL/MG_Util/ShaderTranspiler/SpvcSession.cpp

@@ -54,32 +54,52 @@ namespace ShaderTranspiler {
             var.name = list[i].name;
             var.location = spvc_compiler_get_decoration(compiler, list[i].id, SpvDecorationLocation);
             variables.push_back(var);
-
-            if (resource_type == SPVC_RESOURCE_TYPE_UNIFORM_BUFFER) {
-                spvc_type type = spvc_compiler_get_type_handle(compiler, list[i].base_type_id);
-                size_t num_members = spvc_type_get_num_member_types(type);
-                printf("uniform %s {\n", var.name.c_str());
-                for (size_t j = 0; j < num_members; ++j) {
-                    const char *memberName = spvc_compiler_get_member_name(compiler, list[i].base_type_id, j);
-                    // auto memberTypeId = spvc_type_get_member_type(type, j);
-                    // auto memberType = spvc_compiler_get_type_handle(compiler, memberTypeId);
-
-                    unsigned memberOffset = 0;
-                    spvc_compiler_type_struct_member_offset(compiler, type, j, &memberOffset);
-                    printf("\b%s; // %u\n", memberName, memberOffset);
-                }
-                printf("}\n");
-            }
         }
         std::sort(variables.begin(), variables.end());
         return variables;
     }
 
-    spvc_result SpvcSession::Compile(const char** result) const {
-        return spvc_compiler_compile(compiler, result);
+    spvc_result SpvcSession::Compile(const char** result) {
+        SPVC_CHK_INIT
+        SPVC_CHK_RESULT(spvc_compiler_compile(compiler, result));
+        SPVC_CHK_RESULT(ParseMetaData());
+        SPVC_CHK_RETURN
     }
 
+    spvc_result SpvcSession::ParseMetaData() {
+        SPVC_CHK_INIT
 
+        metadata = SpvcMetadata();
+
+        const spvc_reflected_resource *list = nullptr;
+        size_t count = 0;
+
+        SPVC_CHK_RESULT(
+            spvc_resources_get_resource_list_for_type(resources, SPVC_RESOURCE_TYPE_UNIFORM_BUFFER, &list, &count);
+        )
+        for (size_t i = 0; i < count; ++i) {
+            if (spvc_compiler_has_decoration(compiler, list[i].id, SpvDecorationBuiltIn)) {
+                continue;
+            }
+
+            if (strcmp(list[i].name, GLOBAL_UBO_NAME) == 0) {
+                spvc_type type = spvc_compiler_get_type_handle(compiler, list[i].base_type_id);
+                size_t num_members = spvc_type_get_num_member_types(type);
+                for (size_t j = 0; j < num_members; ++j) {
+                    const char *memberName = spvc_compiler_get_member_name(compiler, list[i].base_type_id, j);
+
+                    unsigned memberOffset = 0;
+                    SPVC_CHK_RESULT(spvc_compiler_type_struct_member_offset(compiler, type, j, &memberOffset);)
+                    metadata.plainUniformOffsetsInUBO[memberName] = memberOffset;
+                }
+            }
+        }
+        SPVC_CHK_RETURN
+    }
+
+    const SpvcMetadata& SpvcSession::GetMetadata() const {
+        return metadata;
+    }
 
     const char* SpvcSession::GetLastErrorString() const {
         return spvc_context_get_last_error_string(context);

MobileGL/MG_Util/ShaderTranspiler/SpvcSession.h

@@ -7,9 +7,25 @@
 
 #pragma once
 
+#define SPVC_CHK_INIT \
+    auto __r = SPVC_SUCCESS;
+
+#define SPVC_CHK_RESULT(res) \
+    __r = res; \
+    if (__r != SPVC_SUCCESS) { \
+        return __r; \
+    }
+
+#define SPVC_CHK_RETURN \
+    return __r;
+
 namespace MobileGL {
 namespace MG_Util {
 namespace ShaderTranspiler {
+    struct SpvcMetadata {
+        UnorderedMap<String, unsigned> plainUniformOffsetsInUBO;
+    };
+
     class SpvcSession {
     public:
         SpvcSession() {}
@@ -29,15 +45,21 @@ namespace ShaderTranspiler {
         spvc_result CreateOptions(spvc_compiler_options *options);
         spvc_result SetOptions(spvc_compiler_options options);
         Vector<InterfaceVariable> GetShaderInterface(spvc_resource_type resource_type) const;
-        spvc_result Compile(const char** result) const;
+        spvc_result Compile(const char** result);
+        const SpvcMetadata& GetMetadata() const;
         const char* GetLastErrorString() const;
 
     private:
+        // Should be called once, and only once, for every SPIR-V binary
+        spvc_result ParseMetaData();
+
         spvc_context context = nullptr;
         spvc_parsed_ir ir = nullptr;
         spvc_compiler compiler = nullptr;
         spvc_compiler_options compiler_options = nullptr;
         spvc_resources resources = nullptr;
+
+        SpvcMetadata metadata;
     };
 }
 }

MobileGL/MG_Util/ShaderTranspiler/Types.h

@@ -4,6 +4,8 @@
 namespace MobileGL {
     namespace MG_Util {
         namespace ShaderTranspiler {
+            inline const char* GLOBAL_UBO_NAME = "MGL_GLOBAL_UBO";
+
             struct EmptyType {};
 
             struct ShaderAttrib {