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Commit fa8cedae authored by Ulf Magnusson's avatar Ulf Magnusson Committed by Masahiro Yamada
Browse files

kconfig: Clarify expression rewriting 



menu_finalize() is one of the more opaque parts of Kconfig, and I need
to make some changes to it to fix an issue related to modules. Add some
comments related to expression rewriting and dependency propagation as a
review aid. They will also help other people trying to understand the
code.

Signed-off-by: default avatarUlf Magnusson <ulfalizer@gmail.com>
Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
parent 9a826842

scripts/kconfig/menu.c

+52 −0
Original line number Diff line number Diff line
@@ -306,6 +306,11 @@ void menu_finalize(struct menu *parent) 


	sym = parent->sym;

	if (parent->list) {

		/*

		 * This menu node has children. We (recursively) process them

		 * and propagate parent dependencies before moving on.

		 */



		if (sym && sym_is_choice(sym)) {

			if (sym->type == S_UNKNOWN) {

				/* find the first choice value to find out choice type */
@@ -329,24 +334,66 @@ void menu_finalize(struct menu *parent) 
		else

			parentdep = parent->dep;



		/* For each child menu node... */

		for (menu = parent->list; menu; menu = menu->next) {

			/*

			 * Propagate parent dependencies to the child menu

			 * node, also rewriting and simplifying expressions

			 */

			basedep = expr_transform(menu->dep);

			basedep = expr_alloc_and(expr_copy(parentdep), basedep);

			basedep = expr_eliminate_dups(basedep);

			menu->dep = basedep;



			if (menu->sym)

				/*

				 * Note: For symbols, all prompts are included

				 * too in the symbol's own property list

				 */

				prop = menu->sym->prop;

			else

				/*

				 * For non-symbol menu nodes, we just need to

				 * handle the prompt

				 */

				prop = menu->prompt;



			/* For each property... */

			for (; prop; prop = prop->next) {

				if (prop->menu != menu)

					/*

					 * Two possibilities:

					 *

					 * 1. The property lacks dependencies

					 *    and so isn't location-specific,

					 *    e.g. an 'option'

					 *

					 * 2. The property belongs to a symbol

					 *    defined in multiple locations and

					 *    is from some other location. It

					 *    will be handled there in that

					 *    case.

					 *

					 * Skip the property.

					 */

					continue;



				/*

				 * Propagate parent dependencies to the

				 * property's condition, rewriting and

				 * simplifying expressions at the same time

				 */

				dep = expr_transform(prop->visible.expr);

				dep = expr_alloc_and(expr_copy(basedep), dep);

				dep = expr_eliminate_dups(dep);

				if (menu->sym && menu->sym->type != S_TRISTATE)

					dep = expr_trans_bool(dep);

				prop->visible.expr = dep;



				/*

				 * Handle selects and implies, which modify the

				 * dependencies of the selected/implied symbol

				 */

				if (prop->type == P_SELECT) {

					struct symbol *es = prop_get_symbol(prop);

					es->rev_dep.expr = expr_alloc_or(es->rev_dep.expr,
@@ -358,6 +405,11 @@ void menu_finalize(struct menu *parent) 
				}

			}

		}



		/*

		 * Recursively process children in the same fashion before

		 * moving on

		 */

		for (menu = parent->list; menu; menu = menu->next)

			menu_finalize(menu);

	} else if (sym) {