video_core/{ast, expr}: Use std::move where applicable

Avoids unnecessary atomic reference count increments and decrements.

src/video_core/shader/expr.cpp

@@ -2,14 +2,21 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
-#pragma once
-
 #include <memory>
 #include <variant>
 
 #include "video_core/shader/expr.h"
 
 namespace VideoCommon::Shader {
+namespace {
+bool ExprIsBoolean(const Expr& expr) {
+    return std::holds_alternative<ExprBoolean>(*expr);
+}
+
+bool ExprBooleanGet(const Expr& expr) {
+    return std::get_if<ExprBoolean>(expr.get())->value;
+}
+} // Anonymous namespace
 
 bool ExprAnd::operator==(const ExprAnd& b) const {
     return (*operand1 == *b.operand1) && (*operand2 == *b.operand2);
@@ -23,19 +30,11 @@ bool ExprNot::operator==(const ExprNot& b) const {
     return (*operand1 == *b.operand1);
 }
 
-bool ExprIsBoolean(Expr expr) {
-    return std::holds_alternative<ExprBoolean>(*expr);
-}
-
-bool ExprBooleanGet(Expr expr) {
-    return std::get_if<ExprBoolean>(expr.get())->value;
-}
-
 Expr MakeExprNot(Expr first) {
     if (std::holds_alternative<ExprNot>(*first)) {
         return std::get_if<ExprNot>(first.get())->operand1;
     }
-    return MakeExpr<ExprNot>(first);
+    return MakeExpr<ExprNot>(std::move(first));
 }
 
 Expr MakeExprAnd(Expr first, Expr second) {
@@ -45,7 +44,7 @@ Expr MakeExprAnd(Expr first, Expr second) {
     if (ExprIsBoolean(second)) {
         return ExprBooleanGet(second) ? first : second;
     }
-    return MakeExpr<ExprAnd>(first, second);
+    return MakeExpr<ExprAnd>(std::move(first), std::move(second));
 }
 
 Expr MakeExprOr(Expr first, Expr second) {
@@ -55,14 +54,14 @@ Expr MakeExprOr(Expr first, Expr second) {
     if (ExprIsBoolean(second)) {
         return ExprBooleanGet(second) ? second : first;
     }
-    return MakeExpr<ExprOr>(first, second);
+    return MakeExpr<ExprOr>(std::move(first), std::move(second));
 }
 
-bool ExprAreEqual(Expr first, Expr second) {
+bool ExprAreEqual(const Expr& first, const Expr& second) {
     return (*first) == (*second);
 }
 
-bool ExprAreOpposite(Expr first, Expr second) {
+bool ExprAreOpposite(const Expr& first, const Expr& second) {
     if (std::holds_alternative<ExprNot>(*first)) {
         return ExprAreEqual(std::get_if<ExprNot>(first.get())->operand1, second);
     }
@@ -72,7 +71,7 @@ bool ExprAreOpposite(Expr first, Expr second) {
     return false;
 }
 
-bool ExprIsTrue(Expr first) {
+bool ExprIsTrue(const Expr& first) {
     if (ExprIsBoolean(first)) {
         return ExprBooleanGet(first);
     }