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kbuild: Fix clang detection

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We cannot detect clang before including the arch Makefile, because that
can set the default cross compiler. We also cannot detect clang after
including the arch Makefile, because powerpc wants to know about clang.
Solve this by using an deferred variable. This costs us a few shell
invocations, but this is only a constant number.

Reported-by: Behan Webster <behanw@converseincode.com>
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
This commit is contained in:
Michal Marek 2015-08-19 17:36:41 +02:00
parent d179e22762
commit 5631d9c429
4 changed files with 10 additions and 13 deletions
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9
Makefile
View file

@ -661,14 +661,7 @@ endif
endif
KBUILD_CFLAGS += $(stackp-flag)
ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)
COMPILER := clang
else
COMPILER := gcc
endif
export COMPILER
ifeq ($(COMPILER),clang)
ifeq ($(cc-name),clang)
KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)

8
arch/powerpc/Makefile
View file

@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
override CC += -mlittle-endian
ifneq ($(COMPILER),clang)
ifneq ($(cc-name),clang)
override CC += -mno-strict-align
endif
override AS += -mlittle-endian
@ -333,7 +333,7 @@ TOUT := .tmp_gas_check
# - Require gcc 4.0 or above on 64-bit
# - gcc-4.2.0 has issues compiling modules on 64-bit
checkbin:
@if test "${COMPILER}" != "clang" \
@if test "$(cc-name)" != "clang" \
&& test "$(cc-version)" = "0304" ; then \
if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) >/dev/null 2>&1 ; then \
echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer build '; \
@ -342,14 +342,14 @@ checkbin:
false; \
fi ; \
fi
@if test "${COMPILER}" != "clang" \
@if test "$(cc-name)" != "clang" \
&& test "$(cc-version)" -lt "0400" \
&& test "x${CONFIG_PPC64}" = "xy" ; then \
echo -n "Sorry, GCC v4.0 or above is required to build " ; \
echo "the 64-bit powerpc kernel." ; \
false ; \
fi
@if test "${COMPILER}" != "clang" \
@if test "$(cc-name)" != "clang" \
&& test "$(cc-fullversion)" = "040200" \
&& test "x${CONFIG_MODULES}${CONFIG_PPC64}" = "xyy" ; then \
echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \

4
scripts/Kbuild.include
View file

@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
cc-disable-warning = $(call try-run,\
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
# cc-name
# Expands to either gcc or clang
cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
# cc-version
cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))

2
scripts/Makefile.extrawarn
View file

@ -56,7 +56,7 @@ endif
KBUILD_CFLAGS += $(warning)
else
ifeq ($(COMPILER),clang)
ifeq ($(cc-name),clang)
KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
KBUILD_CFLAGS += $(call cc-disable-warning, format)