Hi Matthias, Sorry for my late reply. 2017-08-03 1:46 GMT+09:00 Matthias Kaehlcke <mka@xxxxxxxxxxxx>: > El Fri, Jul 21, 2017 at 02:56:56PM -0700 Matthias Kaehlcke ha dit: > >> The macro cc-option receives two parameters (the second may be empty). It >> returns the first parameter if it is a valid compiler option, otherwise >> the second one. It is not evaluated if the second parameter is a valid >> compiler option. This seems to be fine in virtually all cases, however >> there are scenarios where the second paramater needs to be evaluated too, >> and an empty value (or a third option) should be returned if it is not >> valid. >> >> The macro cc-option-3 receives three parameters and returns parameter 1 >> or 2 (in this order) if one of them is found to be a valid compiler >> option, and otherwise paramater 3. The macro __cc-option-3 works >> analogously. > > Any comment on this? > > Thanks > > Matthias > >> Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> >> --- >> scripts/Kbuild.include | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include >> index dd8e2dde0b34..dc83635f2317 100644 >> --- a/scripts/Kbuild.include >> +++ b/scripts/Kbuild.include >> @@ -113,6 +113,11 @@ as-instr = $(call try-run,\ >> __cc-option = $(call try-run,\ >> $(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4)) >> >> +# __cc-option-3 >> +# Usage: MY_CFLAGS += $(call __cc-option-3,$(CC),$(MY_CFLAGS),\ >> +# -mpreferred-stack-boundary=2,-mstack-alignment=4,) >> +__cc-option-3 = $(call __cc-option,$(1),$(2),$(3),$(call __cc-option,$(1),$(2),$(4),$(5))) >> + >> # Do not attempt to build with gcc plugins during cc-option tests. >> # (And this uses delayed resolution so the flags will be up to date.) >> CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) >> @@ -123,6 +128,10 @@ CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) >> cc-option = $(call __cc-option, $(CC),\ >> $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2)) >> >> +# cc-option-3 >> +# Usage: cflags-y += $(call cc-option-3,-mpreferred-stack-boundary=3,-mstack-alignment=8,) >> +cc-option-3 = $(call cc-option,$(1),$(call cc-option,$(2),$(3))) I do not like this macro much for the following reasons: [1] I guess your motivation is to evaluate the second option, not receive the third option. If this is the demand, I thought it might be nicer to change cc-option to always evaluate the second option. (I do no have a good idea for the implementation.) [2] cc-option-3 = $(call cc-option,$(1),$(call cc-option,$(2),$(3))) evaluates the inner $(call cc-option,) first. This works a bit differently from our expectation. For example, let's consider the following case. $(call cc-option-3,-Oz,-Os,-O2) I think we generally expect -Oz, -Os are tested in this order. (If -Oz is supported by the compiler, the test for -Os will be skipped.) In fact, cc-option-3 tests -Os, -Oz in this order because inner cc-option is evaluated before the outer one. The test for -Os may or may not be necessary. I do not have a good idea to improve this... -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
