build: introduce cpp_flags macro

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/Makefile

@@ -410,7 +410,7 @@ include/xen/compile.h: include/xen/compile.h.in .banner
 	@mv -f $@.new $@
 
 asm-offsets.s: arch/$(TARGET_ARCH)/$(TARGET_SUBARCH)/asm-offsets.c
-	$(CC) $(filter-out -Wa$(comma)% -flto,$(c_flags)) -S -g0 -o $@.new -MQ $@ $<
+	$(CC) $(call cpp_flags,$(c_flags)) -S -g0 -o $@.new -MQ $@ $<
 	$(call move-if-changed,$@.new,$@)
 
 include/asm-$(TARGET_ARCH)/asm-offsets.h: asm-offsets.s

xen/Rules.mk

@@ -133,6 +133,9 @@ endif
 # Always build obj-bin files as binary even if they come from C source. 
 $(obj-bin-y): XEN_CFLAGS := $(filter-out -flto,$(XEN_CFLAGS))
 
+# To be use with e.g. $(a_flags) or $(c_flags) to produce CPP flags
+cpp_flags = $(filter-out -Wa$(comma)% -flto,$(1))
+
 # Calculation of flags, first the generic flags, then the arch specific flags,
 # and last the flags modified for a target or a directory.
 
@@ -222,13 +225,13 @@ $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): %.init.o: %.o FORCE
 	$(call if_changed,obj_init_o)
 
 quiet_cmd_cpp_i_c = CPP     $@
-cmd_cpp_i_c = $(CPP) $(filter-out -Wa$(comma)%,$(c_flags)) -MQ $@ -o $@ $<
+cmd_cpp_i_c = $(CPP) $(call cpp_flags,$(c_flags)) -MQ $@ -o $@ $<
 
 quiet_cmd_cc_s_c = CC      $@
 cmd_cc_s_c = $(CC) $(filter-out -Wa$(comma)%,$(c_flags)) -S $< -o $@
 
 quiet_cmd_cpp_s_S = CPP     $@
-cmd_cpp_s_S = $(CPP) $(filter-out -Wa$(comma)%,$(a_flags)) -MQ $@ -o $@ $<
+cmd_cpp_s_S = $(CPP) $(call cpp_flags,$(a_flags)) -MQ $@ -o $@ $<
 
 %.i: %.c FORCE
 	$(call if_changed,cpp_i_c)

xen/arch/x86/Makefile

@@ -292,7 +292,7 @@ $(BASEDIR)/include/asm-x86/asm-macros.h: asm-macros.i Makefile
 
 efi.lds: AFLAGS-y += -DEFI
 xen.lds efi.lds: xen.lds.S
-	$(CPP) -P $(filter-out -Wa$(comma)%,$(a_flags)) -MQ $@ -o $@ $<
+	$(CPP) -P $(call cpp_flags,$(a_flags)) -MQ $@ -o $@ $<
 
 boot/mkelf32: boot/mkelf32.c
 	$(HOSTCC) $(HOSTCFLAGS) -o $@ $<

xen/arch/x86/mm/Makefile

@@ -15,7 +15,7 @@ guest_walk_%.o: guest_walk.c Makefile
 	$(CC) $(c_flags) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
 
 guest_walk_%.i: guest_walk.c Makefile
-	$(CPP) $(filter-out -Wa$(comma)%,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
+	$(CPP) $(call cpp_flags,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
 
 guest_walk_%.s: guest_walk.c Makefile
 	$(CC) $(filter-out -Wa$(comma)%,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -S $< -o $@

xen/arch/x86/mm/hap/Makefile

@@ -9,7 +9,7 @@ guest_walk_%level.o: guest_walk.c Makefile
 	$(CC) $(c_flags) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
 
 guest_walk_%level.i: guest_walk.c Makefile
-	$(CPP) $(filter-out -Wa$(comma)%,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
+	$(CPP) $(call cpp_flags,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
 
 guest_walk_%level.s: guest_walk.c Makefile
 	$(CC) $(filter-out -Wa$(comma)%,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -S $< -o $@

xen/arch/x86/mm/shadow/Makefile

@@ -10,7 +10,7 @@ guest_%.o: multi.c Makefile
 	$(CC) $(c_flags) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
 
 guest_%.i: multi.c Makefile
-	$(CPP) $(filter-out -Wa$(comma)%,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
+	$(CPP) $(call cpp_flags,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -c $< -o $@
 
 guest_%.s: multi.c Makefile
 	$(CC) $(filter-out -Wa$(comma)%,$(c_flags)) -DGUEST_PAGING_LEVELS=$* -S $< -o $@