From 3fb05c382a386ee9ba98bc165732c62bb02167c9 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <admin@akyoto.dev>
Date: Wed, 12 Feb 2025 17:02:51 +0100
Subject: [PATCH] Reduced number of register moves

---
 src/core/CompileReturn.go |  8 +++++++-
 src/core/UsesRegister.go  | 13 ++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/core/CompileReturn.go b/src/core/CompileReturn.go
index 752669f..fb93354 100644
--- a/src/core/CompileReturn.go
+++ b/src/core/CompileReturn.go
@@ -18,7 +18,13 @@ func (f *Function) CompileReturn(node *ast.Return) error {
 	}
 
 	for i := len(node.Values) - 1; i >= 0; i-- {
-		f.SaveRegister(f.CPU.Output[i])
+		for j := range i {
+			if f.UsesRegister(node.Values[j], f.CPU.Output[i]) {
+				f.SaveRegister(f.CPU.Output[i])
+				break
+			}
+		}
+
 		typ, err := f.ExpressionToRegister(node.Values[i], f.CPU.Output[i])
 
 		if err != nil {
diff --git a/src/core/UsesRegister.go b/src/core/UsesRegister.go
index 0ad2d90..74519bd 100644
--- a/src/core/UsesRegister.go
+++ b/src/core/UsesRegister.go
@@ -4,12 +4,23 @@ import (
 	"git.akyoto.dev/cli/q/src/ast"
 	"git.akyoto.dev/cli/q/src/cpu"
 	"git.akyoto.dev/cli/q/src/expression"
+	"git.akyoto.dev/cli/q/src/token"
 )
 
 // UsesRegister returns true if evaluating the expression would write or read the given register.
 func (f *Function) UsesRegister(expr *expression.Expression, register cpu.Register) bool {
 	if expr.IsLeaf() {
-		return false
+		if expr.Token.Kind != token.Identifier {
+			return false
+		}
+
+		variable := f.VariableByName(expr.Token.Text(f.File.Bytes))
+
+		if variable == nil || variable.Register != register {
+			return false
+		}
+
+		return true
 	}
 
 	if ast.IsFunctionCall(expr) {