Hi Milton.
On Wed, Jul 05, 2006 at 02:01:26AM -0500, Milton Miller wrote:
> Al wanted to see why Kbuild wanted to build files, to help debug
> Makefiles or dependency chains.
>
> Here is my second draft, with with whitespace handled by strip. It
> also now considers cmd_$@ before the targets variable because its
> both what the rules do and because the toplevel doesn't use targets.
> It still always prints the non-existing $^ stuff that only
> if_changed_dep uses.
I like the idea and I have played around with it a bit before.
To keep noise level down the "why got it rebuild" info should be on same
line as the CC command and to trigger it increasing verbose level to 2
seems more natural.
Following patch does this.
The patch contains a few clean-ups to make the "why" part slimmer.
Comments?
Sam
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 2180c88..4e5f0aa 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -113,30 +113,33 @@ # See Documentation/kbuild/makefiles.txt
ifneq ($(KBUILD_NOCMDDEP),1)
# Check if both arguments has same arguments. Result in empty string if equal
# User may override this check using make KBUILD_NOCMDDEP=1
-arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) )
+arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
+ $(filter-out $(cmd_$@), $(cmd_$(1))) )
endif
# echo command. Short version is $(quiet) equals quiet, otherwise full command
echo-cmd = $(if $($(quiet)cmd_$(1)), \
- echo ' $(call escsq,$($(quiet)cmd_$(1)))';)
+ echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))
+# Any prerequisites that require target to be built - phony prereq's skipped
+get-prereq = $(filter-out $(PHONY),$?)
+
# function to only execute the passed command if necessary
# >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file
# note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars
#
-if_changed = $(if $(strip $(filter-out $(PHONY),$?) \
- $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \
+if_changed = $(if $(strip $(get-prereq) $(arg-check) ), \
@set -e; \
$(echo-cmd) $(cmd_$(1)); \
echo 'cmd_$@ := $(make-cmd)' > $(@D)/.$(@F).cmd)
# execute the command and also postprocess generated .d dependencies
# file
-if_changed_dep = $(if $(strip $(filter-out $(PHONY),$?) \
+if_changed_dep = $(if $(strip $(get-prereq) \
$(filter-out FORCE $(wildcard $^),$^) \
- $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \
+ $(arg-check) ), \
@set -e; \
$(echo-cmd) $(cmd_$(1)); \
scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(@D)/.$(@F).tmp; \
@@ -146,7 +149,41 @@ if_changed_dep = $(if $(strip $(filter-o
# Usage: $(call if_changed_rule,foo)
# will check if $(cmd_foo) changed, or any of the prequisites changed,
# and if so will execute $(rule_foo)
-if_changed_rule = $(if $(strip $(filter-out $(PHONY),$?) \
- $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),\
- @set -e; \
+if_changed_rule = $(if $(strip $(filter-out $(PHONY),$?) \
+ $(arg-check) ), @set -e; \
$(rule_$(1)))
+
+###
+# why - tell why a a target got build
+# enabled by make V=2
+# Output:
+# (1) due to: command line change
+# (2) due to: file1.h file2.h
+# (3) due to: no .cmd file
+# (4) due to: target not in $(targets)
+# (5) due to: target missing
+# (1) The command line stored in the file named dir/.target.cmd
+# differed from actual command line. This happens when compiler
+# options changes
+# (2) Prerequisite is newer than target
+# (3) No dir/.target.cmd file (used to store command line)
+# (4) No dir/.target.cmd file and target not listed in $(targets)
+# This is a good hint that there is a bug in the kbuild file
+# (5) No target, so we better build it
+ifeq ($(KBUILD_VERBOSE),2)
+why = \
+ $(if $(wildcard $@), \
+ $(if $(strip $(get-prereq)),- due to: $(get-prereq), \
+ $(if $(arg-check), \
+ $(if $(cmd_$@),- due to: command line change, \
+ $(if $(filter $@, $(targets)), \
+ - due to: no .cmd file, \
+ -due to: $(notdir $@) not in $$(targets) \
+ ) \
+ ) \
+ ) \
+ ), \
+ - due to: target missing \
+ )
+echo-why = $(call escsq, $(strip $(why)))
+endif
-
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