kbuild: print short log in addition to the whole command with V=1

"make V=1" prints the whole command instead of the short log, but I
think it is nicer to print both so that you can easily spot the build
rule of your interest.

This commit changes V=1 to print the short log (the line starts with
'#'), followed by the full log.

In parallel builds, the short/full logs from the same build rule may
be interspersed. If you want to avoid it, please add -Otarget option.
Kbuild will never set it by default because Make would buffer the logs
and lose the escape sequences. (Modern compilers print warnings and
errors in color, but only when they write to a terminal.)

This is also a preparation for supporting V=12 because V=2 appends the
reason for rebuilding to the short log.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Makefile

@@ -56,22 +56,18 @@ unexport GREP_OPTIONS
 # Beautify output
 # ---------------------------------------------------------------------------
 #
-# Normally, we echo the whole command before executing it. By making
-# that echo $($(quiet)$(cmd)), we now have the possibility to set
-# $(quiet) to choose other forms of output instead, e.g.
+# Most of build commands in Kbuild start with "cmd_". You can optionally define
+# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from
+# that command is printed by default.
 #
-#         quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
-#         cmd_cc_o_c       = $(CC) $(c_flags) -c -o $@ $<
-#
-# If $(quiet) is empty, the whole command will be printed.
-# If it is set to "quiet_", only the short version will be printed.
-# If it is set to "silent_", nothing will be printed at all, since
-# the variable $(silent_cmd_cc_o_c) doesn't exist.
+# e.g.)
+#    quiet_cmd_depmod = DEPMOD  $(MODLIB)
+#          cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
 #
 # A simple variant is to prefix commands with $(Q) - that's useful
 # for commands that shall be hidden in non-verbose mode.
 #
-#	$(Q)ln $@ :<
+#    $(Q)$(MAKE) $(build)=scripts/basic
 #
 # If KBUILD_VERBOSE equals 0 then the above command will be hidden.
 # If KBUILD_VERBOSE equals 1 then the above command is displayed.

scripts/Kbuild.include

@@ -125,15 +125,15 @@ dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj
 # $(Q)$(MAKE) $(clean)=dir
 clean := -f $(srctree)/scripts/Makefile.clean obj
 
-# echo command.
-# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
-echo-cmd = $(if $($(quiet)cmd_$(1)),\
-	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
-
-# sink stdout for 'make -s'
-       redirect :=
- quiet_redirect :=
-silent_redirect := exec >/dev/null;
+# pring log
+#
+# If quiet is "silent_", print nothing and sink stdout
+# If quiet is "quiet_", print short log
+# If quiet is empty, print short log and whole command
+silent_log_print = exec >/dev/null;
+ quiet_log_print = $(if $(quiet_cmd_$1), echo '  $(call escsq,$(quiet_cmd_$1)$(why))';)
+       log_print = echo '$(pound) $(call escsq,$(or $(quiet_cmd_$1),cmd_$1 $@))'; \
+                   echo '  $(call escsq,$(cmd_$1))';
 
 # Delete the target on interruption
 #
@@ -156,8 +156,8 @@ delete-on-interrupt = \
 		$(foreach sig, HUP INT QUIT TERM PIPE, \
 			trap 'rm -f $@; trap - $(sig); kill -s $(sig) $$$$' $(sig);))
 
-# printing commands
-cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(delete-on-interrupt) $(cmd_$(1))
+# print and execute commands
+cmd = @$(if $(cmd_$(1)),set -e; $($(quiet)log_print) $(delete-on-interrupt) $(cmd_$(1)),:)
 
 ###
 # if_changed      - execute command if any prerequisite is newer than
@@ -234,7 +234,7 @@ if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:)
 # (6) No dir/.target.cmd file and target not listed in $(targets)
 #     This is a good hint that there is a bug in the kbuild file
 ifeq ($(KBUILD_VERBOSE),2)
-why =                                                                        \
+_why =                                                                        \
     $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
         $(if $(wildcard $@),                                                 \
             $(if $(newer-prereqs),- due to: $(newer-prereqs),                \
@@ -251,7 +251,7 @@ why =                                                                        \
          )                                                                   \
      )
 
-echo-why = $(call escsq, $(strip $(why)))
+why = $(space)$(strip $(_why))
 endif
 
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