[PATCH 1/2] alpha: enable building with clang

[Matt Turner <mattst88@gmail.com>]

Register the clang target triple for alpha, and pass -Wa,-mev6 only when
building with gcc.  That flag exists to stop gas emulating instructions
the assembler thinks the target lacks; it is a gas-only option, and
clang's integrated assembler does not emulate instructions in the first
place, so nothing is needed there.

With this, LLVM=1 (and LLVM_IAS=1) builds work.  Note that the alpha
backend is not in upstream LLVM yet; it lives in

  https://github.com/alphalinux-org/llvm-project

and is a work in progress.

Signed-off-by: Matt Turner <mattst88@gmail.com>
---
 arch/alpha/Makefile    | 8 +++++++-
 scripts/Makefile.clang | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/Makefile b/arch/alpha/Makefile
index 35445ff2e489..54283705911f 100644
--- a/arch/alpha/Makefile
+++ b/arch/alpha/Makefile
@@ -27,10 +27,16 @@ cpuflags-$(CONFIG_ALPHA_GENERIC)	:= -mcpu=ev56 -mtune=ev6
 cflags-y				+= $(cpuflags-y)
 
 
+KBUILD_CFLAGS += $(cflags-y)
+
 # For TSUNAMI, we must have the assembler not emulate our instructions.
 # The same is true for IRONGATE, POLARIS, PYXIS.
 # BWX is most important, but we don't really want any emulation ever.
-KBUILD_CFLAGS += $(cflags-y) -Wa,-mev6
+# Only gas emulates instructions the target does not implement, and only gas
+# understands -mev6; clang's integrated assembler never emulates.
+ifdef CONFIG_CC_IS_GCC
+KBUILD_CFLAGS += -Wa,-mev6
+endif
 
 libs-y				+= arch/alpha/lib/
 
diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
index b67636b28c35..2434cf90ad7e 100644
--- a/scripts/Makefile.clang
+++ b/scripts/Makefile.clang
@@ -1,6 +1,7 @@
 # Individual arch/{arch}/Makefiles should use -EL/-EB to set intended
 # endianness and -m32/-m64 to set word size based on Kconfigs instead of
 # relying on the target triple.
+CLANG_TARGET_FLAGS_alpha	:= alpha-linux-gnu
 CLANG_TARGET_FLAGS_arm		:= arm-linux-gnueabi
 CLANG_TARGET_FLAGS_arm64	:= aarch64-linux-gnu
 CLANG_TARGET_FLAGS_hexagon	:= hexagon-linux-musl

-- 
2.54.0