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Subject[PATCH 5/8] kbuild: change if_changed_rule to accept multi-line recipe
Date
GNU Make supports 'define' ... 'endef' directive, which can describe
a recipe that consists of multiple lines.

For example,

all:
@echo hello
@echo world

... can be written as:

define greeting
@echo hello
@echo world
endif

all:
$(greeting)

This is useful to confine a series of shell commands into a single
macro, keeping readability.

However, if_changed_rule cannot accept multi-line recipe. As you see
rule_cc_o_c and rule_as_o_S in scripts/Makefile.build, it must be
written like this:

define rule_cc_o_c
@[action1] ; \
[action2] ; \
[action3]
endef

This does not actually exploit the benefits of 'define' ... 'endef'
form. All shell commands must be concatenated with '; \' so that it
looks like a single command from the Makefile point of view. '@' can
only appear before the first action.

The root cause of this misfortune is the '@set -e;' in if_changed_rule.
It is easily solvable by moving '@set -e' to the 'cmd' macro.

The combo of $(call echo-cmd,*) $(cmd_*) in rule_cc_o_c and rule_as_o_S
were replaced with $(call cmd,*). The tailing back-slashes went away.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

scripts/Kbuild.include | 6 ++----
scripts/Makefile.build | 22 +++++++++++-----------
2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 1eafc85..5e47bf6 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -215,7 +215,7 @@ echo-cmd = $(if $($(quiet)cmd_$(1)),\
echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)

# printing commands
-cmd = @$(echo-cmd) $(cmd_$(1))
+cmd = @set -e; $(echo-cmd) $(cmd_$(1))

# Add $(obj)/ for paths that are not absolute
objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
@@ -269,9 +269,7 @@ cmd_and_fixdep = \
# Usage: $(call if_changed_rule,foo)
# Will check if $(cmd_foo) or any of the prerequisites changed,
# and if so will execute $(rule_foo).
-if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \
- @set -e; \
- $(rule_$(1)), @:)
+if_changed_rule = $(if $(strip $(any-prereq) $(arg-check)), $(rule_$(1)), @:)

###
# why - tell why a target got built
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index e5ba9b1..5528a6a 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -263,20 +263,20 @@ cmd_gen_ksymdeps = \
endif

define rule_cc_o_c
- $(call echo-cmd,checksrc) $(cmd_checksrc) \
- $(call cmd_and_fixdep,cc_o_c) \
- $(cmd_gen_ksymdeps) \
- $(cmd_checkdoc) \
- $(call echo-cmd,objtool) $(cmd_objtool) \
- $(cmd_modversions_c) \
- $(call echo-cmd,record_mcount) $(cmd_record_mcount)
+ $(call cmd,checksrc)
+ @$(call cmd_and_fixdep,cc_o_c)
+ $(call cmd,gen_ksymdeps)
+ $(call cmd,checkdoc)
+ $(call cmd,objtool)
+ $(call cmd,modversions_c)
+ $(call cmd,record_mcount)
endef

define rule_as_o_S
- $(call cmd_and_fixdep,as_o_S) \
- $(cmd_gen_ksymdeps) \
- $(call echo-cmd,objtool) $(cmd_objtool) \
- $(cmd_modversions_S)
+ @$(call cmd_and_fixdep,as_o_S)
+ $(call cmd,gen_ksymdeps)
+ $(call cmd,objtool)
+ $(call cmd,modversions_S)
endef

# List module undefined symbols (or empty line if not enabled)
--
2.7.4
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