diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-11-02 16:10:23 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-12-22 16:00:23 +0100 |
| commit | 5ffb3505412b08fb6398748de7eb0fb2cfbfe4e7 (patch) | |
| tree | ecf33b4bbb55afcca9aa988675f9dedfd7dce97a /rules.mak | |
| parent | eb7a20a3616085d46aa6b4b4224e15587ec67e6e (diff) | |
| download | qemu-5ffb3505412b08fb6398748de7eb0fb2cfbfe4e7.tar.gz | |
rules.mak: speedup save-vars load-vars
Unnesting variables spends a lot of time parsing and executing foreach
and if functions. Because actually very few variables have to be
saved and restored, a good strategy is to remember what has to be done
in load-vars, and only iterate the right variables in load-vars.
For save-vars, unroll the foreach loop to provide another small
improvement.
This speeds up a "noop" build from around 15.5 seconds on my laptop
to 11.7 (25% roughly).
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'rules.mak')
| -rw-r--r-- | rules.mak | 22 |
1 files changed, 10 insertions, 12 deletions
@@ -192,15 +192,15 @@ clean: clean-timestamp # save-vars # Usage: $(call save-vars, vars) # Save each variable $v in $vars as save-vars-$v, save their object's -# variables, then clear $v. +# variables, then clear $v. saved-vars-$v contains the variables that +# where saved for the objects, in order to speedup load-vars. define save-vars $(foreach v,$1, $(eval save-vars-$v := $(value $v)) - $(foreach o,$($v), - $(foreach k,cflags libs objs, - $(if $($o-$k), - $(eval save-vars-$o-$k := $($o-$k)) - $(eval $o-$k := )))) + $(eval saved-vars-$v := $(foreach o,$($v), \ + $(if $($o-cflags), $o-cflags $(eval save-vars-$o-cflags := $($o-cflags))$(eval $o-cflags := )) \ + $(if $($o-libs), $o-libs $(eval save-vars-$o-libs := $($o-libs))$(eval $o-libs := )) \ + $(if $($o-objs), $o-objs $(eval save-vars-$o-objs := $($o-objs))$(eval $o-objs := )))) $(eval $v := )) endef @@ -213,12 +213,10 @@ define load-vars $(eval $2-new-value := $(value $2)) $(foreach v,$1, $(eval $v := $(value save-vars-$v)) - $(foreach o,$($v), - $(foreach k,cflags libs objs, - $(if $(save-vars-$o-$k), - $(eval $o-$k := $(save-vars-$o-$k)) - $(eval save-vars-$o-$k := )))) - $(eval save-vars-$v := )) + $(foreach o,$(saved-vars-$v), + $(eval $o := $(save-vars-$o)) $(eval save-vars-$o := )) + $(eval save-vars-$v := ) + $(eval saved-vars-$v := )) $(eval $2 := $(value $2) $($2-new-value)) endef |