diff options
| -rw-r--r-- | fpm/src/fpm_backend.f90 | 34 |
1 files changed, 33 insertions, 1 deletions
diff --git a/fpm/src/fpm_backend.f90 b/fpm/src/fpm_backend.f90 index 6b56799..ab8d9c5 100644 --- a/fpm/src/fpm_backend.f90 +++ b/fpm/src/fpm_backend.f90 @@ -1,4 +1,30 @@ -!> Implements the native fpm build backend +!># Build backend +!> Uses a valid `[[fpm_model]]` instance to schedule and execute the +!> compilation and linking of package targets. +!> +!> The package build process (`[[build_package]]`) comprises three steps: +!> +!> 1. __Target sorting:__ topological sort of the target dependency graph (`[[sort_target]]`) +!> 2. __Target scheduling:__ group targets into schedule regions based on the sorting (`[[schedule_targets]]`) +!> 3. __Target building:__ generate targets by compilation or linking +!> +!> @note If compiled with OpenMP, targets will be build in parallel where possible. +!> +!>### Incremental compilation +!> The backend process supports *incremental* compilation whereby targets are not +!> re-compiled if their corresponding dependencies have not been modified. +!> +!> - Source-based targets (*i.e.* objects) are not re-compiled if the corresponding source +!> file is unmodified AND all of the target dependencies are not marked for re-compilation +!> +!> - Link targets (*i.e.* executables and libraries) are not re-compiled if the +!> target output file already exists AND all of the target dependencies are not marked for +!> re-compilation +!> +!> Source file modification is determined by a file digest (hash) which is calculated during +!> the source parsing phase ([[fpm_source_parsing]]) and cached to disk after a target is +!> successfully generated. +!> module fpm_backend use fpm_environment, only: run @@ -60,6 +86,12 @@ end subroutine build_package !> Checks disk-cached source hashes to determine if objects are !> up-to-date. Up-to-date sources are tagged as skipped. !> +!> On completion, `target` should either be marked as +!> sorted (`target%sorted=.true.`) or skipped (`target%skip=.true.`) +!> +!> If `target` is marked as sorted, `target%schedule` should be an +!> integer greater than zero indicating the region for scheduling +!> recursive subroutine sort_target(target) type(build_target_t), intent(inout), target :: target |