From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 25 Apr 2021 11:13:16 +0000 (+0300)
Subject: Refactor program stage management
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=7f0e08f04536bf42b8f64e7dff5cc3e18b916c7b

Refactor program stage management

There can't bee a huge number of stages in a program so a fixed-size
array takes less space than a vector.  It also allows accessing ids of
specific stages if needed.
---

diff --git a/source/core/program.cpp b/source/core/program.cpp
index 038c0313..d6bd5ee8 100644
--- a/source/core/program.cpp
+++ b/source/core/program.cpp
@@ -70,6 +70,7 @@ void Program::init()
 	static Require _req(ARB_shader_objects);
 
 	id = glCreateProgram();
+	fill(stage_ids, stage_ids+MAX_STAGES, 0);
 	module = 0;
 	transient = 0;
 	linked = false;
@@ -77,14 +78,15 @@ void Program::init()
 
 Program::~Program()
 {
-	for(vector<unsigned>::iterator i=stage_ids.begin(); i!=stage_ids.end(); ++i)
-		glDeleteShader(*i);
+	for(unsigned i=0; i<MAX_STAGES; ++i)
+		if(stage_ids[i])
+			glDeleteShader(stage_ids[i]);
 	glDeleteProgram(id);
 }
 
 void Program::add_stages(const Module &mod, const map<string, int> &spec_values)
 {
-	if(!stage_ids.empty())
+	if(has_stages())
 		throw invalid_operation("Program::add_stages");
 
 	switch(mod.get_format())
@@ -95,18 +97,30 @@ void Program::add_stages(const Module &mod, const map<string, int> &spec_values)
 	}
 }
 
-unsigned Program::add_stage(GLenum type)
+bool Program::has_stages() const
 {
+	for(unsigned i=0; i<MAX_STAGES; ++i)
+		if(stage_ids[i])
+			return true;
+	return false;
+}
+
+unsigned Program::add_stage(Stage type)
+{
+	GLenum gl_type;
 	switch(type)
 	{
-	case GL_VERTEX_SHADER: { static Require _req(ARB_vertex_shader); } break;
-	case GL_GEOMETRY_SHADER: { static Require _req(ARB_geometry_shader4); } break;
-	case GL_FRAGMENT_SHADER: { static Require _req(ARB_fragment_shader); } break;
+	case VERTEX: { static Require _req(ARB_vertex_shader); gl_type = GL_VERTEX_SHADER; } break;
+	case GEOMETRY: { static Require _req(ARB_geometry_shader4); gl_type = GL_GEOMETRY_SHADER; } break;
+	case FRAGMENT: { static Require _req(ARB_fragment_shader); gl_type = GL_FRAGMENT_SHADER; } break;
 	default: throw invalid_argument("Program::add_stage");
 	}
 
-	unsigned stage_id = glCreateShader(type);
-	stage_ids.push_back(stage_id);
+	if(stage_ids[type])
+		throw invalid_operation("Program::add_stage");
+
+	unsigned stage_id = glCreateShader(gl_type);
+	stage_ids[type] = stage_id;
 	glAttachShader(id, stage_id);
 
 	return stage_id;
@@ -132,9 +146,9 @@ void Program::add_glsl_stages(const GlslModule &mod, const map<string, int> &spe
 		unsigned stage_id = 0;
 		switch(*i)
 		{
-		case SL::Stage::VERTEX: stage_id = add_stage(GL_VERTEX_SHADER); break;
-		case SL::Stage::GEOMETRY: stage_id = add_stage(GL_GEOMETRY_SHADER); break;
-		case SL::Stage::FRAGMENT: stage_id = add_stage(GL_FRAGMENT_SHADER); break;
+		case SL::Stage::VERTEX: stage_id = add_stage(VERTEX); break;
+		case SL::Stage::GEOMETRY: stage_id = add_stage(GEOMETRY); break;
+		case SL::Stage::FRAGMENT: stage_id = add_stage(FRAGMENT); break;
 		default: throw invalid_operation("Program::add_glsl_stages");
 		}
 
@@ -194,25 +208,24 @@ void Program::add_spirv_stages(const SpirVModule &mod, const map<string, int> &s
 	module = &mod;
 
 	const vector<SpirVModule::EntryPoint> &entry_points = mod.get_entry_points();
-	std::set<SpirVModule::Stage> stages;
+	unsigned n_stages = 0;
+	unsigned used_stage_ids[MAX_STAGES];
 	for(vector<SpirVModule::EntryPoint>::const_iterator i=entry_points.begin(); i!=entry_points.end(); ++i)
 	{
-		if(stages.count(i->stage))
-			throw invalid_argument("Program::add_spirv_stages");
-
+		unsigned stage_id = 0;
 		switch(i->stage)
 		{
-		case SpirVModule::VERTEX: add_stage(GL_VERTEX_SHADER); break;
-		case SpirVModule::GEOMETRY: add_stage(GL_GEOMETRY_SHADER); break;
-		case SpirVModule::FRAGMENT: add_stage(GL_FRAGMENT_SHADER); break;
+		case SpirVModule::VERTEX: stage_id = add_stage(VERTEX); break;
+		case SpirVModule::GEOMETRY: stage_id = add_stage(GEOMETRY); break;
+		case SpirVModule::FRAGMENT: stage_id = add_stage(FRAGMENT); break;
 		default: throw invalid_operation("Program::add_spirv_stages");
 		}
 
-		stages.insert(i->stage);
+		used_stage_ids[n_stages++] = stage_id;
 	}
 
 	const vector<UInt32> &code = mod.get_code();
-	glShaderBinary(stage_ids.size(), &stage_ids[0], GL_SHADER_BINARY_FORMAT_SPIR_V, &code[0], code.size()*4);
+	glShaderBinary(n_stages, used_stage_ids, GL_SHADER_BINARY_FORMAT_SPIR_V, &code[0], code.size()*4);
 
 	if(!spec_values.empty() && !transient)
 		transient = new TransientData;
@@ -234,8 +247,9 @@ void Program::add_spirv_stages(const SpirVModule &mod, const map<string, int> &s
 	}
 
 	vector<SpirVModule::EntryPoint>::const_iterator j=entry_points.begin();
-	for(vector<unsigned>::const_iterator i=stage_ids.begin(); i!=stage_ids.end(); ++i, ++j)
-		glSpecializeShader(*i, j->name.c_str(), spec_id_array.size(), &spec_id_array[0], &spec_value_array[0]);
+	for(unsigned i=0; i<MAX_STAGES; ++i)
+		if(stage_ids[i])
+			glSpecializeShader(stage_ids[i], j->name.c_str(), spec_id_array.size(), &spec_id_array[0], &spec_value_array[0]);
 }
 
 #pragma GCC diagnostic push
@@ -245,7 +259,17 @@ void Program::attach_shader(Shader &shader)
 	unsigned shader_id = shader.steal_id();
 	if(!shader_id)
 		throw invalid_argument("Program::attach_shader");
-	stage_ids.push_back(shader_id);
+
+	int type;
+	glGetShaderiv(shader_id, GL_SHADER_TYPE, &type);
+	switch(type)
+	{
+	case GL_VERTEX_SHADER: stage_ids[VERTEX] = shader_id; break;
+	case GL_GEOMETRY_SHADER: stage_ids[GEOMETRY] = shader_id; break;
+	case GL_FRAGMENT_SHADER: stage_ids[FRAGMENT] = shader_id; break;
+	}
+
+	glAttachShader(id, shader_id);
 	compile_glsl_stage(shader_id);
 }
 
@@ -285,7 +309,7 @@ void Program::bind_fragment_data(unsigned index, const string &name)
 
 void Program::link()
 {
-	if(stage_ids.empty())
+	if(!has_stages())
 		throw invalid_operation("Program::link");
 
 	uniforms.clear();
diff --git a/source/core/program.h b/source/core/program.h
index 201d9270..090d8ed5 100644
--- a/source/core/program.h
+++ b/source/core/program.h
@@ -101,6 +101,14 @@ public:
 	};
 
 private:
+	enum Stage
+	{
+		VERTEX,
+		GEOMETRY,
+		FRAGMENT,
+		MAX_STAGES
+	};
+
 	struct TransientData
 	{
 		std::map<std::string, unsigned> textures;
@@ -109,7 +117,7 @@ private:
 	};
 
 	unsigned id;
-	std::vector<unsigned> stage_ids;
+	unsigned stage_ids[MAX_STAGES];
 	const Module *module;
 	TransientData *transient;
 	bool linked;
@@ -138,7 +146,8 @@ public:
 
 	void add_stages(const Module &, const std::map<std::string, int> & = std::map<std::string, int>());
 private:
-	unsigned add_stage(GLenum);
+	bool has_stages() const;
+	unsigned add_stage(Stage);
 	void add_glsl_stages(const GlslModule &, const std::map<std::string, int> &);
 	void compile_glsl_stage(unsigned);
 	void add_spirv_stages(const SpirVModule &, const std::map<std::string, int> &);