From c849969d056972dd976cfa616363f1bc8cbc6291 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 8 Nov 2021 02:03:54 +0200
Subject: [PATCH] Refactor assignment target overlap check into a function

---
 source/glsl/optimize.cpp | 26 +-------------------------
 source/glsl/syntax.cpp   | 26 ++++++++++++++++++++++++++
 source/glsl/syntax.h     |  1 +
 3 files changed, 28 insertions(+), 25 deletions(-)

diff --git a/source/glsl/optimize.cpp b/source/glsl/optimize.cpp
index 8008465e..a7f29a16 100644
--- a/source/glsl/optimize.cpp
+++ b/source/glsl/optimize.cpp
@@ -1284,36 +1284,12 @@ void UnusedVariableRemover::referenced(const Assignment::Target &target, Node &n
 	{
 		bool loop_external = false;
 		for(AssignmentInfo *a: var_info.assignments)
-		{
-			bool covered = true;
-			for(unsigned j=0; (covered && j<a->target.chain_len && j<target.chain_len); ++j)
-			{
-				Assignment::Target::ChainType type1 = static_cast<Assignment::Target::ChainType>(a->target.chain[j]&0xC0);
-				Assignment::Target::ChainType type2 = static_cast<Assignment::Target::ChainType>(target.chain[j]&0xC0);
-				unsigned index1 = a->target.chain[j]&0x3F;
-				unsigned index2 = target.chain[j]&0x3F;
-				if(type1==Assignment::Target::SWIZZLE || type2==Assignment::Target::SWIZZLE)
-				{
-					if(type1==Assignment::Target::SWIZZLE && type2==Assignment::Target::SWIZZLE)
-						covered = index1&index2;
-					else if(type1==Assignment::Target::ARRAY && index1<4)
-						covered = index2&(1<<index1);
-					else if(type2==Assignment::Target::ARRAY && index2<4)
-						covered = index1&(1<<index2);
-					/* If it's some other combination (shouldn't happen), leave
-					covered as true */
-				}
-				else
-					covered = (type1==type2 && (index1==index2 || index1==0x3F || index2==0x3F));
-			}
-
-			if(covered)
+			if(targets_overlap(a->target, target))
 			{
 				a->used_by.push_back(&node);
 				if(a->in_loop<in_loop)
 					loop_external = true;
 			}
-		}
 
 		if(loop_external)
 			loop_ext_refs.push_back(&node);
diff --git a/source/glsl/syntax.cpp b/source/glsl/syntax.cpp
index 8b00e82e..ccdb7197 100644
--- a/source/glsl/syntax.cpp
+++ b/source/glsl/syntax.cpp
@@ -414,6 +414,32 @@ void add_to_chain(Assignment::Target &target, Assignment::Target::ChainType type
 	++target.chain_len;
 }
 
+bool targets_overlap(const Assignment::Target &target1, const Assignment::Target &target2)
+{
+	bool overlap = (target1.declaration==target2.declaration);
+	for(unsigned i=0; (overlap && i<target1.chain_len && i<target2.chain_len); ++i)
+	{
+		Assignment::Target::ChainType type1 = static_cast<Assignment::Target::ChainType>(target1.chain[i]&0xC0);
+		Assignment::Target::ChainType type2 = static_cast<Assignment::Target::ChainType>(target2.chain[i]&0xC0);
+		unsigned index1 = target1.chain[i]&0x3F;
+		unsigned index2 = target2.chain[i]&0x3F;
+		if(type1==Assignment::Target::SWIZZLE || type2==Assignment::Target::SWIZZLE)
+		{
+			if(type1==Assignment::Target::SWIZZLE && type2==Assignment::Target::SWIZZLE)
+				overlap = index1&index2;
+			else if(type1==Assignment::Target::ARRAY && index1<4)
+				overlap = index2&(1<<index1);
+			else if(type2==Assignment::Target::ARRAY && index2<4)
+				overlap = index1&(1<<index2);
+			// Treat other combinations as overlapping (shouldn't happen)
+		}
+		else
+			overlap = (type1==type2 && (index1==index2 || index1==0x3F || index2==0x3F));
+	}
+
+	return overlap;
+}
+
 } // namespace SL
 } // namespace GL
 } // namespace Msp
diff --git a/source/glsl/syntax.h b/source/glsl/syntax.h
index 8567555a..95c15ac0 100644
--- a/source/glsl/syntax.h
+++ b/source/glsl/syntax.h
@@ -555,6 +555,7 @@ std::string get_unused_variable_name(const Block &, const std::string &);
 
 int get_layout_value(const Layout &, const std::string &, int = -1);
 void add_to_chain(Assignment::Target &, Assignment::Target::ChainType, unsigned);
+bool targets_overlap(const Assignment::Target &, const Assignment::Target &);
 
 } // namespace SL
 } // namespace GL
-- 
2.43.0