1 files changed, 48 insertions, 11 deletions

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index 330e7c0048a8..d6626521f9b9 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -7,15 +7,13 @@
 #include <stdlib.h>
 #include <string.h>
 
-#define LKC_DIRECT_LINK
 #include "lkc.h"
 
 #define DEBUG_EXPR	0
 
 struct expr *expr_alloc_symbol(struct symbol *sym)
 {
-	struct expr *e = malloc(sizeof(*e));
-	memset(e, 0, sizeof(*e));
+	struct expr *e = xcalloc(1, sizeof(*e));
 	e->type = E_SYMBOL;
 	e->left.sym = sym;
 	return e;
@@ -23,8 +21,7 @@ struct expr *expr_alloc_symbol(struct symbol *sym)
 
 struct expr *expr_alloc_one(enum expr_type type, struct expr *ce)
 {
-	struct expr *e = malloc(sizeof(*e));
-	memset(e, 0, sizeof(*e));
+	struct expr *e = xcalloc(1, sizeof(*e));
 	e->type = type;
 	e->left.expr = ce;
 	return e;
@@ -32,8 +29,7 @@ struct expr *expr_alloc_one(enum expr_type type, struct expr *ce)
 
 struct expr *expr_alloc_two(enum expr_type type, struct expr *e1, struct expr *e2)
 {
-	struct expr *e = malloc(sizeof(*e));
-	memset(e, 0, sizeof(*e));
+	struct expr *e = xcalloc(1, sizeof(*e));
 	e->type = type;
 	e->left.expr = e1;
 	e->right.expr = e2;
@@ -42,8 +38,7 @@ struct expr *expr_alloc_two(enum expr_type type, struct expr *e1, struct expr *e
 
 struct expr *expr_alloc_comp(enum expr_type type, struct symbol *s1, struct symbol *s2)
 {
-	struct expr *e = malloc(sizeof(*e));
-	memset(e, 0, sizeof(*e));
+	struct expr *e = xcalloc(1, sizeof(*e));
 	e->type = type;
 	e->left.sym = s1;
 	e->right.sym = s2;
@@ -64,14 +59,14 @@ struct expr *expr_alloc_or(struct expr *e1, struct expr *e2)
 	return e2 ? expr_alloc_two(E_OR, e1, e2) : e1;
 }
 
-struct expr *expr_copy(struct expr *org)
+struct expr *expr_copy(const struct expr *org)
 {
 	struct expr *e;
 
 	if (!org)
 		return NULL;
 
-	e = malloc(sizeof(*org));
+	e = xmalloc(sizeof(*org));
 	memcpy(e, org, sizeof(*org));
 	switch (org->type) {
 	case E_SYMBOL:
@@ -1013,6 +1008,48 @@ int expr_compare_type(enum expr_type t1, enum expr_type t2)
 #endif
 }
 
+static inline struct expr *
+expr_get_leftmost_symbol(const struct expr *e)
+{
+
+	if (e == NULL)
+		return NULL;
+
+	while (e->type != E_SYMBOL)
+		e = e->left.expr;
+
+	return expr_copy(e);
+}
+
+/*
+ * Given expression `e1' and `e2', returns the leaf of the longest
+ * sub-expression of `e1' not containing 'e2.
+ */
+struct expr *expr_simplify_unmet_dep(struct expr *e1, struct expr *e2)
+{
+	struct expr *ret;
+
+	switch (e1->type) {
+	case E_OR:
+		return expr_alloc_and(
+		    expr_simplify_unmet_dep(e1->left.expr, e2),
+		    expr_simplify_unmet_dep(e1->right.expr, e2));
+	case E_AND: {
+		struct expr *e;
+		e = expr_alloc_and(expr_copy(e1), expr_copy(e2));
+		e = expr_eliminate_dups(e);
+		ret = (!expr_eq(e, e1)) ? e1 : NULL;
+		expr_free(e);
+		break;
+		}
+	default:
+		ret = e1;
+		break;
+	}
+
+	return expr_get_leftmost_symbol(ret);
+}
+
 void expr_print(struct expr *e, void (*fn)(void *, struct symbol *, const char *), void *data, int prevtoken)
 {
 	if (!e) {