diff mbox series

[XEN,for-4.17,v6,2/5] libs/light: Rework targets prerequisites

Message ID 20230120194431.55922-3-anthony.perard@citrix.com (mailing list archive)
State New, archived
Headers show
Series Toolstack build system improvement, toward non-recursive makefiles | expand

Commit Message

Anthony PERARD Jan. 20, 2023, 7:44 p.m. UTC
No need for $(AUTOSRCS), GNU make can generate them as needed when
trying to build them as needed when trying to build the object. Also,
those two AUTOSRCS don't need to be a prerequisite of "all". As for
the "clean" target, those two files are already removed via "_*.c".

We don't need $(AUTOINCS) either:
- As for both _libxl_save_msgs*.h headers, we are adding more
  selective dependencies so the headers will still be generated as
  needed.
- "clean" rule already delete the _*.h files, so AUTOINCS aren't needed
  there.

"libxl_internal_json.h" doesn't seems to have ever existed, so the
dependency is removed.

Rework objects prerequisites, to have them dependents on either
"libxl.h" or "libxl_internal.h". "libxl.h" is not normally included
directly in the source code as "libxl_internal.h" is used instead, but
we have "libxl.h" as prerequisite of "libxl_internal.h", so generated
headers will still be generated as needed.

Make doesn't need "libxl.h" to generate "testidl.c", "libxl.h" is only
needed later when building "testidl.o". This avoid the need to
regenerate "testidl.c" when only "libxl.h" changed. Also use automatic
variables $< and $@.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---

Notes:
    v6:
    - rebased, part of the patch commited as 4ff0811
    - reword commit message
    
    v4:
    - new patch

 tools/libs/light/Makefile | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

Comments

Andrew Cooper Feb. 6, 2023, 6:02 p.m. UTC | #1
On 20/01/2023 7:44 pm, Anthony PERARD wrote:
> No need for $(AUTOSRCS), GNU make can generate them as needed when
> trying to build them as needed when trying to build the object. Also,
> those two AUTOSRCS don't need to be a prerequisite of "all". As for
> the "clean" target, those two files are already removed via "_*.c".
>
> We don't need $(AUTOINCS) either:
> - As for both _libxl_save_msgs*.h headers, we are adding more
>   selective dependencies so the headers will still be generated as
>   needed.
> - "clean" rule already delete the _*.h files, so AUTOINCS aren't needed
>   there.
>
> "libxl_internal_json.h" doesn't seems to have ever existed, so the
> dependency is removed.
>
> Rework objects prerequisites, to have them dependents on either
> "libxl.h" or "libxl_internal.h". "libxl.h" is not normally included
> directly in the source code as "libxl_internal.h" is used instead, but
> we have "libxl.h" as prerequisite of "libxl_internal.h", so generated
> headers will still be generated as needed.
>
> Make doesn't need "libxl.h" to generate "testidl.c", "libxl.h" is only
> needed later when building "testidl.o". This avoid the need to
> regenerate "testidl.c" when only "libxl.h" changed. Also use automatic
> variables $< and $@.
>
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>
> Notes:
>     v6:
>     - rebased, part of the patch commited as 4ff0811
>     - reword commit message
>     
>     v4:
>     - new patch
>
>  tools/libs/light/Makefile | 28 ++++++++++++++++------------
>  1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/tools/libs/light/Makefile b/tools/libs/light/Makefile
> index cd3fa855e1..b28447a2ae 100644
> --- a/tools/libs/light/Makefile
> +++ b/tools/libs/light/Makefile
> @@ -148,9 +148,6 @@ LIBXL_TEST_OBJS += $(foreach t, $(LIBXL_TESTS_INSIDE),libxl_test_$t.opic)
>  TEST_PROG_OBJS += $(foreach t, $(LIBXL_TESTS_PROGS),test_$t.o) test_common.o
>  TEST_PROGS += $(foreach t, $(LIBXL_TESTS_PROGS),test_$t)
>  
> -AUTOINCS = _libxl_save_msgs_callout.h _libxl_save_msgs_helper.h
> -AUTOSRCS = _libxl_save_msgs_callout.c _libxl_save_msgs_helper.c
> -
>  CLIENTS = testidl libxl-save-helper
>  
>  SAVE_HELPER_OBJS = libxl_save_helper.o _libxl_save_msgs_helper.o
> @@ -178,13 +175,13 @@ libxl_x86_acpi.o libxl_x86_acpi.opic: CFLAGS += -I$(XEN_ROOT)/tools
>  $(SAVE_HELPER_OBJS): CFLAGS += $(CFLAGS_libxenctrl) $(CFLAGS_libxenevtchn) $(CFLAGS_libxenguest)
>  
>  testidl.o: CFLAGS += $(CFLAGS_libxenctrl) $(CFLAGS_libxenlight)
> -testidl.c: libxl_types.idl gentest.py $(XEN_INCLUDE)/libxl.h $(AUTOINCS)
> -	$(PYTHON) gentest.py libxl_types.idl testidl.c.new
> -	mv testidl.c.new testidl.c
> +testidl.c: libxl_types.idl gentest.py
> +	$(PYTHON) gentest.py $< $@.new
> +	mv -f $@.new $@

Doesn't this want to be a mov-if-changed?

We don't need to force a rebuild if testidl.c hasn't changed, I don't think.

>  
> -all: $(CLIENTS) $(TEST_PROGS) $(AUTOSRCS) $(AUTOINCS)
> +all: $(CLIENTS) $(TEST_PROGS)
>  
> -$(OBJS-y) $(PIC_OBJS) $(SAVE_HELPER_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS): $(AUTOINCS) libxl.api-ok
> +$(OBJS-y) $(PIC_OBJS) $(SAVE_HELPER_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS): libxl.api-ok
>  
>  $(DSDT_FILES-y): acpi
>  
> @@ -196,7 +193,7 @@ libxl.api-ok: check-libxl-api-rules _libxl.api-for-check
>  	$(PERL) $^
>  	touch $@
>  
> -_libxl.api-for-check: $(XEN_INCLUDE)/libxl.h $(AUTOINCS)
> +_libxl.api-for-check: $(XEN_INCLUDE)/libxl.h
>  	$(CC) $(CPPFLAGS) $(CFLAGS) -c -E $< $(APPEND_CFLAGS) \
>  		-DLIBXL_EXTERNAL_CALLERS_ONLY=LIBXL_EXTERNAL_CALLERS_ONLY \
>  		>$@.new
> @@ -208,14 +205,22 @@ _libxl_save_msgs_helper.h _libxl_save_msgs_callout.h: \
>  	$(PERL) -w $< $@ >$@.new
>  	$(call move-if-changed,$@.new,$@)
>  
> +#
> +# headers dependencies on generated headers
> +#
>  $(XEN_INCLUDE)/libxl.h: $(XEN_INCLUDE)/_libxl_types.h
>  $(XEN_INCLUDE)/libxl_json.h: $(XEN_INCLUDE)/_libxl_types_json.h
>  libxl_internal.h: $(XEN_INCLUDE)/libxl.h $(XEN_INCLUDE)/libxl_json.h
>  libxl_internal.h: _libxl_types_internal.h _libxl_types_private.h _libxl_types_internal_private.h
> -libxl_internal_json.h: _libxl_types_internal_json.h
> +libxl_internal.h: _libxl_save_msgs_callout.h
>  
> -$(OBJS-y) $(PIC_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS) $(SAVE_HELPER_OBJS): $(XEN_INCLUDE)/libxl.h
> +#
> +# objects dependencies on headers that depends on generated headers
> +#
> +$(TEST_PROG_OBJS): $(XEN_INCLUDE)/libxl.h
>  $(OBJS-y) $(PIC_OBJS) $(LIBXL_TEST_OBJS): libxl_internal.h
> +$(SAVE_HELPER_OBJS): $(XEN_INCLUDE)/libxl.h _libxl_save_msgs_helper.h
> +testidl.o: $(XEN_INCLUDE)/libxl.h

I know you're just rearranging existing the existing logic, but why
doesn't `#include <libxl.h>` not generate suitable dependences ?

~Andrew
Anthony PERARD Feb. 7, 2023, 11:37 a.m. UTC | #2
On Mon, Feb 06, 2023 at 06:02:51PM +0000, Andrew Cooper wrote:
> On 20/01/2023 7:44 pm, Anthony PERARD wrote:
> > diff --git a/tools/libs/light/Makefile b/tools/libs/light/Makefile
> > index cd3fa855e1..b28447a2ae 100644
> > --- a/tools/libs/light/Makefile
> > +++ b/tools/libs/light/Makefile
> > @@ -178,13 +175,13 @@ libxl_x86_acpi.o libxl_x86_acpi.opic: CFLAGS += -I$(XEN_ROOT)/tools
> >  $(SAVE_HELPER_OBJS): CFLAGS += $(CFLAGS_libxenctrl) $(CFLAGS_libxenevtchn) $(CFLAGS_libxenguest)
> >  
> >  testidl.o: CFLAGS += $(CFLAGS_libxenctrl) $(CFLAGS_libxenlight)
> > -testidl.c: libxl_types.idl gentest.py $(XEN_INCLUDE)/libxl.h $(AUTOINCS)
> > -	$(PYTHON) gentest.py libxl_types.idl testidl.c.new
> > -	mv testidl.c.new testidl.c
> > +testidl.c: libxl_types.idl gentest.py
> > +	$(PYTHON) gentest.py $< $@.new
> > +	mv -f $@.new $@
> 
> Doesn't this want to be a mov-if-changed?
> 
> We don't need to force a rebuild if testidl.c hasn't changed, I don't think.

I don't like move-if-changed, as when the prerequisites happens to be
newer than the target, the rules keeps been executed on incremental
builds.

Also in this case, only two targets depends on this one, "testidl.o" and
"testidl", so move-if-changed would not be very useful.

> > @@ -208,14 +205,22 @@ _libxl_save_msgs_helper.h _libxl_save_msgs_callout.h: \
> >  	$(PERL) -w $< $@ >$@.new
> >  	$(call move-if-changed,$@.new,$@)
> >  
> > +#
> > +# headers dependencies on generated headers
> > +#
> >  $(XEN_INCLUDE)/libxl.h: $(XEN_INCLUDE)/_libxl_types.h
> >  $(XEN_INCLUDE)/libxl_json.h: $(XEN_INCLUDE)/_libxl_types_json.h
> >  libxl_internal.h: $(XEN_INCLUDE)/libxl.h $(XEN_INCLUDE)/libxl_json.h
> >  libxl_internal.h: _libxl_types_internal.h _libxl_types_private.h _libxl_types_internal_private.h
> > -libxl_internal_json.h: _libxl_types_internal_json.h
> > +libxl_internal.h: _libxl_save_msgs_callout.h
> >  
> > -$(OBJS-y) $(PIC_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS) $(SAVE_HELPER_OBJS): $(XEN_INCLUDE)/libxl.h
> > +#
> > +# objects dependencies on headers that depends on generated headers
> > +#
> > +$(TEST_PROG_OBJS): $(XEN_INCLUDE)/libxl.h
> >  $(OBJS-y) $(PIC_OBJS) $(LIBXL_TEST_OBJS): libxl_internal.h
> > +$(SAVE_HELPER_OBJS): $(XEN_INCLUDE)/libxl.h _libxl_save_msgs_helper.h
> > +testidl.o: $(XEN_INCLUDE)/libxl.h
> 
> I know you're just rearranging existing the existing logic, but why
> doesn't `#include <libxl.h>` not generate suitable dependences ?

Make doesn't know how to read *.c files ;-). But more importantly, we
don't have any logic to generate dependencies ahead of building the
object, so make doesn't know about it.

Thanks,
Jürgen Groß Feb. 8, 2023, 7:35 a.m. UTC | #3
On 20.01.23 20:44, Anthony PERARD wrote:
> No need for $(AUTOSRCS), GNU make can generate them as needed when
> trying to build them as needed when trying to build the object. Also,
> those two AUTOSRCS don't need to be a prerequisite of "all". As for
> the "clean" target, those two files are already removed via "_*.c".
> 
> We don't need $(AUTOINCS) either:
> - As for both _libxl_save_msgs*.h headers, we are adding more
>    selective dependencies so the headers will still be generated as
>    needed.
> - "clean" rule already delete the _*.h files, so AUTOINCS aren't needed
>    there.
> 
> "libxl_internal_json.h" doesn't seems to have ever existed, so the
> dependency is removed.
> 
> Rework objects prerequisites, to have them dependents on either
> "libxl.h" or "libxl_internal.h". "libxl.h" is not normally included
> directly in the source code as "libxl_internal.h" is used instead, but
> we have "libxl.h" as prerequisite of "libxl_internal.h", so generated
> headers will still be generated as needed.
> 
> Make doesn't need "libxl.h" to generate "testidl.c", "libxl.h" is only
> needed later when building "testidl.o". This avoid the need to
> regenerate "testidl.c" when only "libxl.h" changed. Also use automatic
> variables $< and $@.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen
diff mbox series

Patch

diff --git a/tools/libs/light/Makefile b/tools/libs/light/Makefile
index cd3fa855e1..b28447a2ae 100644
--- a/tools/libs/light/Makefile
+++ b/tools/libs/light/Makefile
@@ -148,9 +148,6 @@  LIBXL_TEST_OBJS += $(foreach t, $(LIBXL_TESTS_INSIDE),libxl_test_$t.opic)
 TEST_PROG_OBJS += $(foreach t, $(LIBXL_TESTS_PROGS),test_$t.o) test_common.o
 TEST_PROGS += $(foreach t, $(LIBXL_TESTS_PROGS),test_$t)
 
-AUTOINCS = _libxl_save_msgs_callout.h _libxl_save_msgs_helper.h
-AUTOSRCS = _libxl_save_msgs_callout.c _libxl_save_msgs_helper.c
-
 CLIENTS = testidl libxl-save-helper
 
 SAVE_HELPER_OBJS = libxl_save_helper.o _libxl_save_msgs_helper.o
@@ -178,13 +175,13 @@  libxl_x86_acpi.o libxl_x86_acpi.opic: CFLAGS += -I$(XEN_ROOT)/tools
 $(SAVE_HELPER_OBJS): CFLAGS += $(CFLAGS_libxenctrl) $(CFLAGS_libxenevtchn) $(CFLAGS_libxenguest)
 
 testidl.o: CFLAGS += $(CFLAGS_libxenctrl) $(CFLAGS_libxenlight)
-testidl.c: libxl_types.idl gentest.py $(XEN_INCLUDE)/libxl.h $(AUTOINCS)
-	$(PYTHON) gentest.py libxl_types.idl testidl.c.new
-	mv testidl.c.new testidl.c
+testidl.c: libxl_types.idl gentest.py
+	$(PYTHON) gentest.py $< $@.new
+	mv -f $@.new $@
 
-all: $(CLIENTS) $(TEST_PROGS) $(AUTOSRCS) $(AUTOINCS)
+all: $(CLIENTS) $(TEST_PROGS)
 
-$(OBJS-y) $(PIC_OBJS) $(SAVE_HELPER_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS): $(AUTOINCS) libxl.api-ok
+$(OBJS-y) $(PIC_OBJS) $(SAVE_HELPER_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS): libxl.api-ok
 
 $(DSDT_FILES-y): acpi
 
@@ -196,7 +193,7 @@  libxl.api-ok: check-libxl-api-rules _libxl.api-for-check
 	$(PERL) $^
 	touch $@
 
-_libxl.api-for-check: $(XEN_INCLUDE)/libxl.h $(AUTOINCS)
+_libxl.api-for-check: $(XEN_INCLUDE)/libxl.h
 	$(CC) $(CPPFLAGS) $(CFLAGS) -c -E $< $(APPEND_CFLAGS) \
 		-DLIBXL_EXTERNAL_CALLERS_ONLY=LIBXL_EXTERNAL_CALLERS_ONLY \
 		>$@.new
@@ -208,14 +205,22 @@  _libxl_save_msgs_helper.h _libxl_save_msgs_callout.h: \
 	$(PERL) -w $< $@ >$@.new
 	$(call move-if-changed,$@.new,$@)
 
+#
+# headers dependencies on generated headers
+#
 $(XEN_INCLUDE)/libxl.h: $(XEN_INCLUDE)/_libxl_types.h
 $(XEN_INCLUDE)/libxl_json.h: $(XEN_INCLUDE)/_libxl_types_json.h
 libxl_internal.h: $(XEN_INCLUDE)/libxl.h $(XEN_INCLUDE)/libxl_json.h
 libxl_internal.h: _libxl_types_internal.h _libxl_types_private.h _libxl_types_internal_private.h
-libxl_internal_json.h: _libxl_types_internal_json.h
+libxl_internal.h: _libxl_save_msgs_callout.h
 
-$(OBJS-y) $(PIC_OBJS) $(LIBXL_TEST_OBJS) $(TEST_PROG_OBJS) $(SAVE_HELPER_OBJS): $(XEN_INCLUDE)/libxl.h
+#
+# objects dependencies on headers that depends on generated headers
+#
+$(TEST_PROG_OBJS): $(XEN_INCLUDE)/libxl.h
 $(OBJS-y) $(PIC_OBJS) $(LIBXL_TEST_OBJS): libxl_internal.h
+$(SAVE_HELPER_OBJS): $(XEN_INCLUDE)/libxl.h _libxl_save_msgs_helper.h
+testidl.o: $(XEN_INCLUDE)/libxl.h
 
 # This exploits the 'multi-target pattern rule' trick.
 # gentypes.py should be executed only once to make all the targets.
@@ -262,5 +267,4 @@  clean::
 	$(RM) testidl.c.new testidl.c *.api-ok
 	$(RM) $(TEST_PROGS) libxenlight_test.so libxl_test_*.opic
 	$(RM) -r __pycache__
-	$(RM) $(AUTOSRCS) $(AUTOINCS)
 	$(MAKE) -C $(ACPI_PATH) ACPI_BUILD_DIR=$(CURDIR) clean