kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj)

Kbuild provides per-file compiler flag addition/removal:

  CFLAGS_<basetarget>.o
  CFLAGS_REMOVE_<basetarget>.o
  AFLAGS_<basetarget>.o
  AFLAGS_REMOVE_<basetarget>.o
  CPPFLAGS_<basetarget>.lds
  HOSTCFLAGS_<basetarget>.o
  HOSTCXXFLAGS_<basetarget>.o

The <basetarget> is the filename of the target with its directory and
suffix stripped.

This syntax comes into a trouble when two files with the same basename
appear in one Makefile, for example:

  obj-y += foo.o
  obj-y += dir/foo.o
  CFLAGS_foo.o := <some-flags>

Here, the <some-flags> applies to both foo.o and dir/foo.o

The real world problem is:

  scripts/kconfig/util.c
  scripts/kconfig/lxdialog/util.c

Both files are compiled into scripts/kconfig/mconf, but only the
latter should be given with the ncurses flags.

It is more sensible to use the relative path to the Makefile, like this:

  obj-y += foo.o
  CFLAGS_foo.o := <some-flags>
  obj-y += dir/foo.o
  CFLAGS_dir/foo.o := <other-flags>

At first, I attempted to replace $(basetarget) with $*. The $* variable
is replaced with the stem ('%') part in a pattern rule. This works with
most of cases, but does not for explicit rules.

For example, arch/ia64/lib/Makefile reuses rule_as_o_S in its own
explicit rules, so $* will be empty, resulting in ignoring the per-file
AFLAGS.

I introduced a new variable, target-stem, which can be used also from
explicit rules.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Marc Zyngier <maz@kernel.org>

1 files changed, 11 insertions, 11 deletions

diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index b402c619147d..4c51c95d40f4 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -80,9 +80,9 @@ host-cxxshobjs	:= $(addprefix $(obj)/,$(host-cxxshobjs))
 # Handle options to gcc. Support building with separate output directory
 
 _hostc_flags   = $(KBUILD_HOSTCFLAGS)   $(HOST_EXTRACFLAGS)   \
-                 $(HOSTCFLAGS_$(basetarget).o)
+                 $(HOSTCFLAGS_$(target-stem).o)
 _hostcxx_flags = $(KBUILD_HOSTCXXFLAGS) $(HOST_EXTRACXXFLAGS) \
-                 $(HOSTCXXFLAGS_$(basetarget).o)
+                 $(HOSTCXXFLAGS_$(target-stem).o)
 
 # $(objtree)/$(obj) for including generated headers from checkin source files
 ifeq ($(KBUILD_EXTMOD),)
@@ -102,7 +102,7 @@ hostcxx_flags  = -Wp,-MD,$(depfile) $(_hostcxx_flags)
 # host-csingle -> Executable
 quiet_cmd_host-csingle 	= HOSTCC  $@
       cmd_host-csingle	= $(HOSTCC) $(hostc_flags) $(KBUILD_HOSTLDFLAGS) -o $@ $< \
-		$(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
+		$(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem))
 $(host-csingle): $(obj)/%: $(src)/%.c FORCE
 	$(call if_changed_dep,host-csingle)
 
@@ -110,8 +110,8 @@ $(host-csingle): $(obj)/%: $(src)/%.c FORCE
 # host-cmulti -> executable
 quiet_cmd_host-cmulti	= HOSTLD  $@
       cmd_host-cmulti	= $(HOSTCC) $(KBUILD_HOSTLDFLAGS) -o $@ \
-			  $(addprefix $(obj)/,$($(@F)-objs)) \
-			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
+			  $(addprefix $(obj)/, $($(target-stem)-objs)) \
+			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem))
 $(host-cmulti): FORCE
 	$(call if_changed,host-cmulti)
 $(call multi_depend, $(host-cmulti), , -objs)
@@ -128,8 +128,8 @@ $(host-cobjs): $(obj)/%.o: $(src)/%.c FORCE
 quiet_cmd_host-cxxmulti	= HOSTLD  $@
       cmd_host-cxxmulti	= $(HOSTCXX) $(KBUILD_HOSTLDFLAGS) -o $@ \
 			  $(foreach o,objs cxxobjs,\
-			  $(addprefix $(obj)/,$($(@F)-$(o)))) \
-			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
+			  $(addprefix $(obj)/, $($(target-stem)-$(o)))) \
+			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem))
 $(host-cxxmulti): FORCE
 	$(call if_changed,host-cxxmulti)
 $(call multi_depend, $(host-cxxmulti), , -objs -cxxobjs)
@@ -161,8 +161,8 @@ $(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
 # *.o -> .so shared library (host-cshlib)
 quiet_cmd_host-cshlib	= HOSTLLD -shared $@
       cmd_host-cshlib	= $(HOSTCC) $(KBUILD_HOSTLDFLAGS) -shared -o $@ \
-			  $(addprefix $(obj)/,$($(@F:.so=-objs))) \
-			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
+			  $(addprefix $(obj)/, $($(target-stem)-objs)) \
+			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem).so)
 $(host-cshlib): FORCE
 	$(call if_changed,host-cshlib)
 $(call multi_depend, $(host-cshlib), .so, -objs)
@@ -171,8 +171,8 @@ $(call multi_depend, $(host-cshlib), .so, -objs)
 # *.o -> .so shared library (host-cxxshlib)
 quiet_cmd_host-cxxshlib	= HOSTLLD -shared $@
       cmd_host-cxxshlib	= $(HOSTCXX) $(KBUILD_HOSTLDFLAGS) -shared -o $@ \
-			  $(addprefix $(obj)/,$($(@F:.so=-objs))) \
-			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
+			  $(addprefix $(obj)/, $($(target-stem)-objs)) \
+			  $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem).so)
 $(host-cxxshlib): FORCE
 	$(call if_changed,host-cxxshlib)
 $(call multi_depend, $(host-cxxshlib), .so, -objs)