From f438142c7589df7480aa640cf62b7a2c3d48bab2 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 10 Oct 2021 18:35:43 +0300
Subject: [PATCH] Allow redeclaring entire builtin interface blocks

---
 source/glsl/resolve.cpp           | 66 ++++++++++++++++++++++++-------
 source/glsl/resolve.h             |  1 +
 tests/glsl/redeclare_builtin.glsl | 23 +++++++++++
 3 files changed, 75 insertions(+), 15 deletions(-)
 create mode 100644 tests/glsl/redeclare_builtin.glsl

diff --git a/source/glsl/resolve.cpp b/source/glsl/resolve.cpp
index f72dedfd..b80ae217 100644
--- a/source/glsl/resolve.cpp
+++ b/source/glsl/resolve.cpp
@@ -390,6 +390,21 @@ void VariableResolver::merge_layouts(Layout &to_layout, const Layout &from_layou
 	}
 }
 
+void VariableResolver::redeclare_builtin(VariableDeclaration &existing, VariableDeclaration &var)
+{
+	if(var.layout)
+	{
+		if(existing.layout)
+			merge_layouts(*existing.layout, *var.layout);
+		else
+			existing.layout = var.layout;
+	}
+	if(var.array_size)
+		existing.array_size = var.array_size;
+
+	redeclared_builtins.push_back(&existing);
+}
+
 void VariableResolver::visit(VariableDeclaration &var)
 {
 	TraversingVisitor::visit(var);
@@ -422,17 +437,8 @@ void VariableResolver::visit(VariableDeclaration &var)
 	{
 		if(existing->source==BUILTIN_SOURCE)
 		{
-			if(var.layout)
-			{
-				if(existing->layout)
-					merge_layouts(*existing->layout, *var.layout);
-				else
-					existing->layout = var.layout;
-			}
-			if(var.array_size)
-				existing->array_size = var.array_size;
+			redeclare_builtin(*existing, var);
 
-			redeclared_builtins.push_back(existing);
 			if(block)
 			{
 				redeclared_builtins.push_back(block);
@@ -454,11 +460,41 @@ void VariableResolver::visit(VariableDeclaration &var)
 
 void VariableResolver::visit(InterfaceBlock &iface)
 {
-	/* Block names can be reused in different interfaces.  Prefix the name with
-	the first character of the interface to avoid conflicts. */
-	stage->interface_blocks.insert(make_pair(format("%s %s", iface.interface, iface.block_name), &iface));
-	if(!iface.instance_name.empty())
-		stage->interface_blocks.insert(make_pair(iface.instance_name, &iface));
+	string key = format("%s %s", iface.interface, iface.block_name);
+	auto i = stage->interface_blocks.find(key);
+	if(i!=stage->interface_blocks.end())
+	{
+		if(i->second->source==BUILTIN_SOURCE && iface.struct_declaration && i->second->struct_declaration)
+		{
+			const map<string, VariableDeclaration *> &vars = iface.struct_declaration->members.variables;
+			const map<string, VariableDeclaration *> &existing_vars = i->second->struct_declaration->members.variables;
+
+			bool found_all = true;
+			for(const auto &kvp: vars)
+			{
+				auto j = existing_vars.find(kvp.first);
+				if(j!=existing_vars.end() && j->second->type==kvp.second->type && j->second->array==kvp.second->array)
+					redeclare_builtin(*j->second, *kvp.second);
+				else
+					found_all = false;
+			}
+
+			if(found_all)
+			{
+				redeclared_builtins.push_back(i->second);
+				nodes_to_remove.insert(&iface);
+				nodes_to_remove.insert(iface.struct_declaration);
+			}
+		}
+	}
+	else
+	{
+		/* Block names can be reused in different interfaces.  Prepend the interface
+		to the name to avoid conflicts. */
+		stage->interface_blocks.insert(make_pair(key, &iface));
+		if(!iface.instance_name.empty())
+			stage->interface_blocks.insert(make_pair(iface.instance_name, &iface));
+	}
 
 	TraversingVisitor::visit(iface);
 }
diff --git a/source/glsl/resolve.h b/source/glsl/resolve.h
index 85611727..10322d49 100644
--- a/source/glsl/resolve.h
+++ b/source/glsl/resolve.h
@@ -78,6 +78,7 @@ private:
 	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
 	void merge_layouts(Layout &, const Layout &);
+	void redeclare_builtin(VariableDeclaration &, VariableDeclaration &);
 	virtual void visit(VariableDeclaration &);
 	virtual void visit(InterfaceBlock &);
 };
diff --git a/tests/glsl/redeclare_builtin.glsl b/tests/glsl/redeclare_builtin.glsl
new file mode 100644
index 00000000..c0b84c42
--- /dev/null
+++ b/tests/glsl/redeclare_builtin.glsl
@@ -0,0 +1,23 @@
+#pragma MSP stage(vertex)
+layout(location=0) in vec4 position;
+out float gl_ClipDistance[1];
+void main()
+{
+	gl_ClipDistance[0] = dot(position.xyz, vec3(0.0, 0.0, 1.0));
+	gl_Position = position;
+}
+
+/* Expected output: vertex
+out gl_PerVertex
+{
+	vec4 gl_Position;
+	float gl_PointSize;
+	float gl_ClipDistance[1];
+};
+layout(location=0) in vec4 position;
+void main()
+{
+	gl_ClipDistance[0] = dot(position.xyz, vec3(0.0, 0.0, 1.0));
+	gl_Position = position;
+}
+*/
-- 
2.43.0