kbuild: Fix clang detection

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>

diff --git a/Makefile b/Makefile
index 13270c0a93363f079ccc3a112bfa7d7d80c7f429..5ccbb58553aba71aa128576ae21d22117596574d 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -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)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 05f464eb69527e1d59dff1a13fdd449d6b7aa25f..dfe88896b06c0904535ba88f0cacc35b0c34043d 100644 (file)
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -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 ' ; \

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index d3437b82ac256cb7bca2527f0cfe43e07f66a1cb..3523df613391057aab24f63c978facef08e60a2c 100644 (file)
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -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))
 

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index f734033af219d267fd67428432feb9bacee0baae..4efedcbe4165f48ac1afbca50f3612bd312e9b70 100644 (file)
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -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)