kconfig: cache expression values

Cache expression values to avoid recalculating them repeatedly.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

1 files changed, 30 insertions, 4 deletions

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index 476dcaa9078e..78738ef412de 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -887,7 +887,7 @@ static enum string_value_kind expr_parse_string(const char *str,
 	       ? kind : k_string;
 }
 
-tristate expr_calc_value(struct expr *e)
+static tristate __expr_calc_value(struct expr *e)
 {
 	tristate val1, val2;
 	const char *str1, *str2;
@@ -895,9 +895,6 @@ tristate expr_calc_value(struct expr *e)
 	union string_value lval = {}, rval = {};
 	int res;
 
-	if (!e)
-		return yes;
-
 	switch (e->type) {
 	case E_SYMBOL:
 		sym_calc_value(e->left.sym);
@@ -961,6 +958,35 @@ tristate expr_calc_value(struct expr *e)
 	}
 }
 
+/**
+ * expr_calc_value - return the tristate value of the given expression
+ * @e: expression
+ * return: tristate value of the expression
+ */
+tristate expr_calc_value(struct expr *e)
+{
+	if (!e)
+		return yes;
+
+	if (!e->val_is_valid) {
+		e->val = __expr_calc_value(e);
+		e->val_is_valid = true;
+	}
+
+	return e->val;
+}
+
+/**
+ * expr_invalidate_all - invalidate all cached expression values
+ */
+void expr_invalidate_all(void)
+{
+	struct expr *e;
+
+	hash_for_each(expr_hashtable, e, node)
+		e->val_is_valid = false;
+}
+
 static int expr_compare_type(enum expr_type t1, enum expr_type t2)
 {
 	if (t1 == t2)