From 9978e2f62777795bf478b301aadffdd0ee8cbd41 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 8 Nov 2021 15:21:18 +0200
Subject: [PATCH] Recognize increment/decrement operators as modifying the
 target variable

---
 source/glsl/reflect.cpp | 35 ++++++++++++++++++++++++++++++++---
 source/glsl/reflect.h   |  9 +++++++--
 source/glsl/spirv.cpp   |  5 +++--
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/source/glsl/reflect.cpp b/source/glsl/reflect.cpp
index 6027acde..811679f3 100644
--- a/source/glsl/reflect.cpp
+++ b/source/glsl/reflect.cpp
@@ -1,4 +1,5 @@
 #include <msp/core/algorithm.h>
+#include <msp/core/raii.h>
 #include "reflect.h"
 
 using namespace std;
@@ -387,16 +388,44 @@ void DependencyCollector::visit(FunctionDeclaration &func)
 }
 
 
-set<VariableDeclaration *> AssignmentCollector::apply(Node &node)
+set<Node *> AssignmentCollector::apply(Node &node)
 {
 	node.visit(*this);
 	return assigned_variables;
 }
 
+void AssignmentCollector::visit(VariableReference &var)
+{
+	if(assignment_target)
+		assigned_variables.insert(var.declaration);
+}
+
+void AssignmentCollector::visit(InterfaceBlockReference &iface)
+{
+	if(assignment_target)
+		assigned_variables.insert(iface.declaration);
+}
+
+void AssignmentCollector::visit(UnaryExpression &unary)
+{
+	SetFlag set_assignment(assignment_target, (unary.oper->token[1]=='+' || unary.oper->token[1]=='-'));
+	TraversingVisitor::visit(unary);
+}
+
+void AssignmentCollector::visit(BinaryExpression &binary)
+{
+	binary.left->visit(*this);
+	SetFlag clear_assignment(assignment_target, false);
+	binary.right->visit(*this);
+}
+
 void AssignmentCollector::visit(Assignment &assign)
 {
-	if(VariableDeclaration *var = dynamic_cast<VariableDeclaration *>(assign.target.declaration))
-		assigned_variables.insert(var);
+	{
+		SetFlag set_assignment(assignment_target);
+		assign.left->visit(*this);
+	}
+	assign.right->visit(*this);
 }
 
 } // namespace SL
diff --git a/source/glsl/reflect.h b/source/glsl/reflect.h
index 5b4170a9..7c4d26c4 100644
--- a/source/glsl/reflect.h
+++ b/source/glsl/reflect.h
@@ -107,12 +107,17 @@ private:
 class AssignmentCollector: private TraversingVisitor
 {
 private:
-	std::set<VariableDeclaration *> assigned_variables;
+	bool assignment_target = false;
+	std::set<Node *> assigned_variables;
 
 public:
-	std::set<VariableDeclaration *> apply(Node &);
+	std::set<Node *> apply(Node &);
 
 private:
+	virtual void visit(VariableReference &);
+	virtual void visit(InterfaceBlockReference &);
+	virtual void visit(UnaryExpression &);
+	virtual void visit(BinaryExpression &);
 	virtual void visit(Assignment &);
 };
 
diff --git a/source/glsl/spirv.cpp b/source/glsl/spirv.cpp
index 7bec551b..2dcc285c 100644
--- a/source/glsl/spirv.cpp
+++ b/source/glsl/spirv.cpp
@@ -1873,8 +1873,9 @@ void SpirVGenerator::visit(Iteration &iter)
 	if(iter.init_statement)
 		iter.init_statement->visit(*this);
 
-	for(VariableDeclaration *v: AssignmentCollector().apply(iter))
-		variable_load_ids.erase(v);
+	for(Node *n: AssignmentCollector().apply(iter))
+		if(VariableDeclaration *var = dynamic_cast<VariableDeclaration *>(n))
+			variable_load_ids.erase(var);
 
 	Id header_id = next_id++;
 	Id continue_id = next_id++;
-- 
2.43.0