From 584cf5e42c4758a3f4d197655d861d31ee23db4e Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 24 Apr 2021 17:55:14 +0300
Subject: [PATCH] Handle function forward declarations in the SPIR-V generator

---
 source/glsl/spirv.cpp | 30 ++++++++++++++++++++++++++++--
 source/glsl/spirv.h   |  1 +
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/source/glsl/spirv.cpp b/source/glsl/spirv.cpp
index 7d6edf65..70d5fe78 100644
--- a/source/glsl/spirv.cpp
+++ b/source/glsl/spirv.cpp
@@ -237,8 +237,28 @@ SpirVGenerator::Id SpirVGenerator::get_id(Node &node) const
 
 SpirVGenerator::Id SpirVGenerator::allocate_id(Node &node, Id type_id)
 {
+	map<Node *, Declaration>::iterator i = declared_ids.find(&node);
+	if(i!=declared_ids.end())
+	{
+		if(i->second.type_id)
+			throw key_error(&node);
+		i->second.type_id = type_id;
+		return i->second.id;
+	}
+
+	Id id = next_id++;
+	declared_ids.insert(make_pair(&node, Declaration(id, type_id)));
+	return id;
+}
+
+SpirVGenerator::Id SpirVGenerator::allocate_forward_id(Node &node)
+{
+	map<Node *, Declaration>::iterator i = declared_ids.find(&node);
+	if(i!=declared_ids.end())
+		return i->second.id;
+
 	Id id = next_id++;
-	insert_unique(declared_ids, &node, Declaration(id, type_id));
+	declared_ids.insert(make_pair(&node, Declaration(id, 0)));
 	return id;
 }
 
@@ -1706,8 +1726,14 @@ void SpirVGenerator::visit_entry_point(FunctionDeclaration &func, Id func_id)
 
 void SpirVGenerator::visit(FunctionDeclaration &func)
 {
-	if(func.source==BUILTIN_SOURCE || func.definition!=&func)
+	if(func.source==BUILTIN_SOURCE)
 		return;
+	else if(func.definition!=&func)
+	{
+		if(func.definition)
+			allocate_forward_id(*func.definition);
+		return;
+	}
 
 	Id return_type_id = get_id(*func.return_type_declaration);
 	vector<unsigned> param_type_ids;
diff --git a/source/glsl/spirv.h b/source/glsl/spirv.h
index add5a967..26467bcd 100644
--- a/source/glsl/spirv.h
+++ b/source/glsl/spirv.h
@@ -113,6 +113,7 @@ private:
 	Id import_extension(const std::string &);
 	Id get_id(Node &) const;
 	Id allocate_id(Node &, Id);
+	Id allocate_forward_id(Node &);
 	Id write_constant(Id, Word, bool);
 	static ConstantKey get_constant_key(Id, const Variant &value);
 	Id get_constant_id(Id, const Variant &value);
-- 
2.43.0