On Mon, Jan 12, 2026 at 03:19:22PM +0100, Herve Codina wrote:
> The parser needs to get header flags value in different places.
>
> It relies on the fact that the rule used to parse the dts file is always
> headers memreserves devicetree
>
> With that only rule to parse the file, it uses '$<flags>-1' construct to
> get the flags value.
>
> With the future introduction of import symbols parsing, this rule will
> change and the parser couldn't rely anymore on '$<flags>-1' to get flags
> value. Indeed, import symbols parsing will add a new optional symbol in
> this rule leading to two possible rules (with and without the new
> symbol) to parse the source file.
>
> Introduce the last_header_flags variable to explicitly keep track of
> flags while also being agnostic of the rule structure and use this new
> variable instead of '$<flags>-1'.
I'm not sure this approach is safe: I'm not sure bison guarantees that
semantic rules will always be executed in the same order, so using
global variables is risky.
>
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> ---
> dtc-parser.y | 28 +++++++++-------------------
> 1 file changed, 9 insertions(+), 19 deletions(-)
>
> diff --git a/dtc-parser.y b/dtc-parser.y
> index 4e46e9d..48c40e8 100644
> --- a/dtc-parser.y
> +++ b/dtc-parser.y
> @@ -24,6 +24,8 @@ extern void yyerror(char const *s);
> extern struct dt_info *parser_output;
> extern bool treesource_error;
>
> +unsigned int last_header_flags;
> +
> static bool is_ref_relative(const char *ref)
> {
> return ref[0] != '/' && strchr(&ref[1], '/');
> @@ -122,14 +124,17 @@ header:
> DT_V1 ';'
> {
> $$ = DTSF_V1;
> + last_header_flags = $$;
> }
> | DT_V1 ';' DT_PLUGIN ';'
> {
> $$ = DTSF_V1 | DTSF_PLUGIN;
> + last_header_flags = $$;
> }
> | DT_V1 ';' DT_ADDON ';'
> {
> $$ = DTSF_V1 | DTSF_ADDON;
> + last_header_flags = $$;
> }
> ;
>
> @@ -179,12 +184,7 @@ devicetree:
> }
> | dt_ref nodedef
> {
> - /*
> - * We rely on the rule being always:
> - * versioninfo plugindecl memreserves devicetree
> - * so $-1 is what we want (plugindecl)
> - */
> - if (!($<flags>-1 & DTSF_PLUGIN))
> + if (!(last_header_flags & DTSF_PLUGIN))
> ERROR(&@2, "Label or path %s not found", $1);
> else if (is_ref_relative($1))
> ERROR(&@2, "Label-relative reference %s not supported in plugin", $1);
> @@ -197,7 +197,7 @@ devicetree:
> {
> struct node *target = get_node_by_ref($1, $3);
>
> - if (($<flags>-1 & DTSF_PLUGIN) && is_ref_relative($3))
> + if ((last_header_flags & DTSF_PLUGIN) && is_ref_relative($3))
> ERROR(&@2, "Label-relative reference %s not supported in plugin", $3);
>
> if (target) {
> @@ -209,12 +209,7 @@ devicetree:
> }
> | devicetree DT_PATH_REF nodedef
> {
> - /*
> - * We rely on the rule being always:
> - * versioninfo plugindecl memreserves devicetree
> - * so $-1 is what we want (plugindecl)
> - */
> - if ($<flags>-1 & DTSF_PLUGIN) {
> + if (last_header_flags & DTSF_PLUGIN) {
> if (is_ref_relative($2))
> ERROR(&@2, "Label-relative reference %s not supported in plugin", $2);
> add_orphan_node($1, $3, $2);
> @@ -235,12 +230,7 @@ devicetree:
> if (target) {
> merge_nodes(target, $3);
> } else {
> - /*
> - * We rely on the rule being always:
> - * versioninfo plugindecl memreserves devicetree
> - * so $-1 is what we want (plugindecl)
> - */
> - if ($<flags>-1 & DTSF_PLUGIN)
> + if (last_header_flags & DTSF_PLUGIN)
> add_orphan_node($1, $3, $2);
> else
> ERROR(&@2, "Label or path %s not found", $2);
> --
> 2.52.0
>
>
--
David Gibson (he or they) | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you, not the other way
| around.
http://www.ozlabs.org/~dgibson