[Xen-devel] [PATCH v5 2/5] build: filter out command line assembler arguments

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

If the assembler is not used. This happens when using cc -E or cc -S
for example. GCC will just ignore the -Wa,... when the assembler is
not called, but clang will complain loudly and fail.

Also enable passing -Wa,-I$(BASEDIR)/include to clang now that it's
safe to do so.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Changes since v4:
 - Also add the filter to the tree rules near the end of xen/Rules.mk.

Changes since v3:
 - Filter using '-Wa,%' instead of '-Wa%' so that -Wall is not
   matched.
 - Pass -Wa,-I$(BASEDIR)/include to clang also.
---
 xen/Rules.mk          | 6 +++---
 xen/arch/x86/Makefile | 6 +++---
 xen/arch/x86/Rules.mk | 5 +----
 xen/include/Makefile  | 2 +-
 4 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/xen/Rules.mk b/xen/Rules.mk
index da3c35ba36..2918019b92 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -208,13 +208,13 @@ $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): 
%.init.o: %.o Makefile
        $(OBJCOPY) $(foreach s,$(SPECIAL_DATA_SECTIONS),--rename-section 
.$(s)=.init.$(s)) $< $@
 
 %.i: %.c Makefile
-       $(CPP) $(CFLAGS) $< -o $@
+       $(CPP) $(filter-out -Wa$(comma)%,$(CFLAGS)) $< -o $@
 
 %.s: %.c Makefile
-       $(CC) $(CFLAGS) -S $< -o $@
+       $(CC) $(filter-out -Wa$(comma)%,$(CFLAGS)) -S $< -o $@
 
 # -std=gnu{89,99} gets confused by # as an end-of-line comment marker
 %.s: %.S Makefile
-       $(CPP) $(AFLAGS) $< -o $@
+       $(CPP) $(filter-out -Wa$(comma)%,$(AFLAGS)) $< -o $@
 
 -include $(DEPS_INCLUDE)
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index d903b7abb9..389096139c 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -215,15 +215,15 @@ efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o: 
$(BASEDIR)/arch/x86/ef
 efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o: ;
 
 asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c
-       $(CC) $(filter-out -flto,$(CFLAGS)) -S -o $@ $<
+       $(CC) $(filter-out -Wa$(comma)% -flto,$(CFLAGS)) -S -o $@ $<
 
 xen.lds: xen.lds.S
-       $(CC) -P -E -Ui386 $(AFLAGS) -o $@ $<
+       $(CC) -P -E -Ui386 $(filter-out -Wa$(comma)%,$(AFLAGS)) -o $@ $<
        sed -e 's/xen\.lds\.o:/xen\.lds:/g' <.xen.lds.d >.xen.lds.d.new
        mv -f .xen.lds.d.new .xen.lds.d
 
 efi.lds: xen.lds.S
-       $(CC) -P -E -Ui386 -DEFI $(AFLAGS) -o $@ $<
+       $(CC) -P -E -Ui386 -DEFI $(filter-out -Wa$(comma)%,$(AFLAGS)) -o $@ $<
        sed -e 's/efi\.lds\.o:/efi\.lds:/g' <.$(@F).d >.$(@F).d.new
        mv -f .$(@F).d.new .$(@F).d
 
diff --git a/xen/arch/x86/Rules.mk b/xen/arch/x86/Rules.mk
index 56b2ea8356..1dc5c3785a 100644
--- a/xen/arch/x86/Rules.mk
+++ b/xen/arch/x86/Rules.mk
@@ -42,8 +42,5 @@ CFLAGS += -DCONFIG_INDIRECT_THUNK
 export CONFIG_INDIRECT_THUNK=y
 endif
 
-# Set up the assembler include path properly for older GCC toolchains.  Clang
-# objects to the agument being passed however.
-ifneq ($(clang),y)
+# Set up the assembler include path properly for older toolchains.
 CFLAGS += -Wa,-I$(BASEDIR)/include
-endif
diff --git a/xen/include/Makefile b/xen/include/Makefile
index 19066a33a0..69052ade24 100644
--- a/xen/include/Makefile
+++ b/xen/include/Makefile
@@ -65,7 +65,7 @@ compat/%.h: compat/%.i Makefile 
$(BASEDIR)/tools/compat-build-header.py
        mv -f $@.new $@
 
 compat/%.i: compat/%.c Makefile
-       $(CPP) $(filter-out -M% %.d -include %/include/xen/config.h,$(CFLAGS)) 
$(cppflags-y) -o $@ $<
+       $(CPP) $(filter-out -Wa$(comma)% -M% %.d -include 
%/include/xen/config.h,$(CFLAGS)) $(cppflags-y) -o $@ $<
 
 compat/%.c: public/%.h xlat.lst Makefile 
$(BASEDIR)/tools/compat-build-source.py
        mkdir -p $(@D)
-- 
2.16.1


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