grafts: Improve performance for derivations with many inputs.

Partly fixes <https://bugs.gnu.org/41702>.
Reported by Lars-Dominik Braun <ldb@leibniz-psychology.org>.

Previously we'd potentially traverse the same sub-graph of DEPS several
times.

With this patch, command:

  guix environment --ad-hoc r-learnr --search-paths

goes from 11.3s to 4.6s.

* guix/grafts.scm (reference-origin): Rename to...
(reference-origins): ... this.  Change 'item' parameter to 'items'.
[lookup-derivers]: New procedure.
(cumulative-grafts)[dependency-grafts]: Change 'item' to 'items' and use
'reference-origins'.
Remove 'mapm' around 'dependency-grafts' call.

0 files changed, 0 insertions, 0 deletions