From: Trent Piepho Date: Mon, 25 Feb 2019 23:55:14 +0000 (+0000) Subject: package/pkg-generic: speed up RECURSIVE_FINAL_DEPENDENCIES X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a21212fb7cf;p=buildroot.git package/pkg-generic: speed up RECURSIVE_FINAL_DEPENDENCIES Evaluating all the _RECURSIVE_FINAL_DEPENDENCIES variables (abbreviated RFD hereafter) ends up being quite slow. Enough, on a reasonable modern workstation, to increase the time it takes to run "make printvars" from 13 seconds in 2018.02 to 371 seconds in 2019.02. This patch improves this by using dynamic programming to speed the evaluation of RFD, reducing the before mentioned printvars time to about 14.6 seconds. The evaluation of PKG1_RFD requires recursively evaluating each of PKG1's dependencies' RFDs, then their dependencies' RFDs, and so on. The same is done for PKG2_RFD. But it's likely that many of the dependencies of PKG2 are the same as PKG1. And when we consider all packages, the dependencies are re-computed many thousands of times. To avoid this re-computation we memoize, or save, the computed value of each RFD variable when it found the first time. Subsequent evaluations re-use the memoized value. Surprisingly, this ends up being not all the hard to implement in make. The basic construct is this: VAR = $(if !defined(VAR__X),$(eval VAR__X := value))$(VAR__X) The first time VAR is evaluated VAR__X will not be defined, and code to set VAR__X to the computed value is eval'd. Then the now defined value of VAR__X is returned. Subsequent evaluations can just return VAR__X. It is important to note that VAR is defined with '=', as not enough information (namely, all packages' dependencies) is know when it is parsed to find the correct value. VAR will be evaluated each time it is used. But VAR__X is defined with ":=", so that it is evaluated once when defined, and not each time it is used. Signed-off-by: Trent Piepho Tested-by: "Yann E. MORIN" Acked-by: "Yann E. MORIN" Signed-off-by: Peter Korsgaard --- diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk index 6168b40e89..4353bd3868 100644 --- a/package/pkg-generic.mk +++ b/package/pkg-generic.mk @@ -637,14 +637,17 @@ $(2)_FINAL_ALL_DEPENDENCIES = \ $$($(2)_FINAL_DOWNLOAD_DEPENDENCIES) \ $$($(2)_FINAL_EXTRACT_DEPENDENCIES) \ $$($(2)_FINAL_PATCH_DEPENDENCIES)) -$(2)_FINAL_RECURSIVE_DEPENDENCIES = \ - $$(sort \ - $$(foreach p,\ - $$($(2)_FINAL_ALL_DEPENDENCIES),\ - $$(p)\ - $$($$(call UPPERCASE,$$(p))_FINAL_RECURSIVE_DEPENDENCIES)\ - )\ - ) +$(2)_FINAL_RECURSIVE_DEPENDENCIES = $$(sort \ + $$(if $$(filter undefined,$$(origin $(2)_FINAL_RECURSIVE_DEPENDENCIES__X)), \ + $$(eval $(2)_FINAL_RECURSIVE_DEPENDENCIES__X := \ + $$(foreach p, \ + $$($(2)_FINAL_ALL_DEPENDENCIES), \ + $$(p) \ + $$($$(call UPPERCASE,$$(p))_FINAL_RECURSIVE_DEPENDENCIES) \ + ) \ + ) \ + ) \ + $$($(2)_FINAL_RECURSIVE_DEPENDENCIES__X)) $(2)_INSTALL_STAGING ?= NO $(2)_INSTALL_IMAGES ?= NO