diff options
| -rw-r--r-- | scripts/kconfig/expr.c | 43 |
1 files changed, 37 insertions, 6 deletions
diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c index d5dc682f7dc6..e83fe0c3d62f 100644 --- a/scripts/kconfig/expr.c +++ b/scripts/kconfig/expr.c @@ -442,6 +442,7 @@ static struct expr *expr_join_or(struct expr *e1, struct expr *e2) } } if (sym1->type == S_BOOLEAN) { + // a || !a -> y if ((e1->type == E_NOT && e1->left.expr->type == E_SYMBOL && e2->type == E_SYMBOL) || (e2->type == E_NOT && e2->left.expr->type == E_SYMBOL && e1->type == E_SYMBOL)) return expr_alloc_symbol(&symbol_yes); @@ -647,6 +648,30 @@ struct expr *expr_eliminate_dups(struct expr *e) * Performs various simplifications involving logical operators and * comparisons. * + * For bool type: + * A=n -> !A + * A=m -> n + * A=y -> A + * A!=n -> A + * A!=m -> y + * A!=y -> !A + * + * For any type: + * !!A -> A + * !(A=B) -> A!=B + * !(A!=B) -> A=B + * !(A<=B) -> A>B + * !(A>=B) -> A<B + * !(A<B) -> A>=B + * !(A>B) -> A<=B + * !(A || B) -> !A && !B + * !(A && B) -> !A || !B + * + * For constant: + * !y -> n + * !m -> m + * !n -> y + * * Allocates and returns a new expression. */ struct expr *expr_transform(struct expr *e) @@ -674,12 +699,14 @@ struct expr *expr_transform(struct expr *e) if (e->left.sym->type != S_BOOLEAN) break; if (e->right.sym == &symbol_no) { + // A=n -> !A e->type = E_NOT; e->left.expr = expr_alloc_symbol(e->left.sym); e->right.sym = NULL; break; } if (e->right.sym == &symbol_mod) { + // A=m -> n printf("boolean symbol %s tested for 'm'? test forced to 'n'\n", e->left.sym->name); e->type = E_SYMBOL; e->left.sym = &symbol_no; @@ -687,6 +714,7 @@ struct expr *expr_transform(struct expr *e) break; } if (e->right.sym == &symbol_yes) { + // A=y -> A e->type = E_SYMBOL; e->right.sym = NULL; break; @@ -696,11 +724,13 @@ struct expr *expr_transform(struct expr *e) if (e->left.sym->type != S_BOOLEAN) break; if (e->right.sym == &symbol_no) { + // A!=n -> A e->type = E_SYMBOL; e->right.sym = NULL; break; } if (e->right.sym == &symbol_mod) { + // A!=m -> y printf("boolean symbol %s tested for 'm'? test forced to 'y'\n", e->left.sym->name); e->type = E_SYMBOL; e->left.sym = &symbol_yes; @@ -708,6 +738,7 @@ struct expr *expr_transform(struct expr *e) break; } if (e->right.sym == &symbol_yes) { + // A!=y -> !A e->type = E_NOT; e->left.expr = expr_alloc_symbol(e->left.sym); e->right.sym = NULL; @@ -717,7 +748,7 @@ struct expr *expr_transform(struct expr *e) case E_NOT: switch (e->left.expr->type) { case E_NOT: - // !!a -> a + // !!A -> A tmp = e->left.expr->left.expr; free(e->left.expr); free(e); @@ -726,7 +757,7 @@ struct expr *expr_transform(struct expr *e) break; case E_EQUAL: case E_UNEQUAL: - // !a='x' -> a!='x' + // !(A=B) -> A!=B tmp = e->left.expr; free(e); e = tmp; @@ -734,7 +765,7 @@ struct expr *expr_transform(struct expr *e) break; case E_LEQ: case E_GEQ: - // !a<='x' -> a>'x' + // !(A<=B) -> A>B tmp = e->left.expr; free(e); e = tmp; @@ -742,14 +773,14 @@ struct expr *expr_transform(struct expr *e) break; case E_LTH: case E_GTH: - // !a<'x' -> a>='x' + // !(A<B) -> A>=B tmp = e->left.expr; free(e); e = tmp; e->type = e->type == E_LTH ? E_GEQ : E_LEQ; break; case E_OR: - // !(a || b) -> !a && !b + // !(A || B) -> !A && !B tmp = e->left.expr; e->type = E_AND; e->right.expr = expr_alloc_one(E_NOT, tmp->right.expr); @@ -758,7 +789,7 @@ struct expr *expr_transform(struct expr *e) e = expr_transform(e); break; case E_AND: - // !(a && b) -> !a || !b + // !(A && B) -> !A || !B tmp = e->left.expr; e->type = E_OR; e->right.expr = expr_alloc_one(E_NOT, tmp->right.expr); |