From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 13 May 2014 16:43:31 +0000 (+0300)
Subject: Inline variables which are simple aliases, even if not optimizing
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=cdd4ca79e38325a482f007d5d271d08b2d9bec6c

Inline variables which are simple aliases, even if not optimizing

This fixes another problem with unoptimized legacy shaders, making them
work properly again.
---

diff --git a/source/programbuilder.cpp b/source/programbuilder.cpp
index 0f29675f..bf89e7db 100644
--- a/source/programbuilder.cpp
+++ b/source/programbuilder.cpp
@@ -292,11 +292,8 @@ void ProgramBuilder::add_shaders(Program &prog) const
 		}
 	}
 
-	if(optimize)
-	{
-		for(list<ShaderVariable *>::const_iterator i=resolved_vars.begin(); i!=resolved_vars.end(); ++i)
-			(*i)->check_inline(features.legacy);
-	}
+	for(list<ShaderVariable *>::const_iterator i=resolved_vars.begin(); i!=resolved_vars.end(); ++i)
+		(*i)->check_inline(features.legacy, !optimize);
 
 	prog.attach_shader_owned(new VertexShader(create_source(resolved_vars, VERTEX)));
 	prog.attach_shader_owned(new FragmentShader(create_source(resolved_vars, FRAGMENT)));
@@ -624,19 +621,39 @@ void ProgramBuilder::ShaderVariable::update_reference(ShaderVariable &from, Shad
 		resolve_space(to.resolved_space);
 }
 
-void ProgramBuilder::ShaderVariable::check_inline(bool allow_legacy)
+void ProgramBuilder::ShaderVariable::check_inline(bool allow_legacy, bool trivial_only)
 {
 	if(variable->expression)
 	{
 		if(!allow_legacy && !strncmp(variable->expression, "gl_", 3))
 			return;
 
+		// Never inline goal variables
 		unsigned total_refs = referenced_by.size();
+		if(!total_refs)
+			return;
+
+		// Inline an expression consisting of a single identifier
+		unsigned start, length;
+		if(parse_identifier(variable->expression, start, length))
+			if(start==0 && variable->expression[length]==0)
+			{
+				inlined = true;
+				return;
+			}
+
+		if(trivial_only)
+			return;
+
 		unsigned in_scope_refs = 0;
 		for(list<ShaderVariable *>::const_iterator i=referenced_by.begin(); i!=referenced_by.end(); ++i)
 			if((*i)->variable->scope==variable->scope)
 				++in_scope_refs;
-		if(total_refs==1 || (total_refs>0 && in_scope_refs==0))
+
+		/* Inline if there's only one ref, or if all refs are in other scopes.
+		In the latter case, the actual inlining will happen in the interface
+		variable assignment. */
+		if(total_refs==1 || in_scope_refs==0)
 		{
 			inlined = true;
 			unsigned level = 0;
diff --git a/source/programbuilder.h b/source/programbuilder.h
index 7840ecf0..8275e457 100644
--- a/source/programbuilder.h
+++ b/source/programbuilder.h
@@ -82,7 +82,7 @@ private:
 		void resolve_space(const std::string &);
 		void add_reference(ShaderVariable &);
 		void update_reference(ShaderVariable &, ShaderVariable &);
-		void check_inline(bool);
+		void check_inline(bool, bool);
 		bool is_referenced_from(VariableScope) const;
 		std::string get_expression() const;
 	};