[v2,1/2] eal/arm: fix gcc build for optimization level 0

  Gcc build with '-O0' on platforms with RTE_ARM_FEATURE_ATOMICS set
failed for:
 ../lib/librte_efd/rte_efd.c
 Assembler messages:
3866: Error: selected processor does not support `crc32cb w0,w0,w1'
3890: Error: selected processor does not support `crc32ch w0,w0,w1'
3914: Error: selected processor does not support `crc32cw w0,w0,w1'
3938: Error: selected processor does not support `crc32cx w0,w0,x1'

This was caused by an architecture specifier added for Clang.
Unlike Clang, Gcc considers each inline assembly block to be dependent
and therefore, the architecture specifier impacts assemble of some
blocks require certain extension support.

Used arch_extension instead to not override architecture.
Referred for [1] to fix the issue.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dd1f6308b28edf0452dd5dc7877992903ec61e69

Fixes: 8fce34cd0a6a ("eal/arm: fix clang build of native target")

Reported-by: Feifei Wang <feifei.wang2@arm.com>
Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
v2:
New approach to use arch_extension instead.

 lib/librte_eal/arm/include/rte_atomic_64.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
  

> -----Original Message-----
> From: Ruifeng Wang <ruifeng.wang@arm.com>
> Sent: Friday, November 27, 2020 6:15 PM
> To: jerinj@marvell.com; Ruifeng Wang <Ruifeng.Wang@arm.com>;
> Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> Cc: dev@dpdk.org; nd <nd@arm.com>; Feifei Wang
> <Feifei.Wang2@arm.com>
> Subject: [PATCH v2 1/2] eal/arm: fix gcc build for optimization level 0
> 
> Gcc build with '-O0' on platforms with RTE_ARM_FEATURE_ATOMICS set
> failed for:
>  ../lib/librte_efd/rte_efd.c
>  Assembler messages:
> 3866: Error: selected processor does not support `crc32cb w0,w0,w1'
> 3890: Error: selected processor does not support `crc32ch w0,w0,w1'
> 3914: Error: selected processor does not support `crc32cw w0,w0,w1'
> 3938: Error: selected processor does not support `crc32cx w0,w0,x1'
> 
> This was caused by an architecture specifier added for Clang.
> Unlike Clang, Gcc considers each inline assembly block to be dependent and
> therefore, the architecture specifier impacts assemble of some blocks
> require certain extension support.
> 
> Used arch_extension instead to not override architecture.
> Referred for [1] to fix the issue.
> 
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i
> d=dd1f6308b28edf0452dd5dc7877992903ec61e69
> 
> Fixes: 8fce34cd0a6a ("eal/arm: fix clang build of native target")
> 
> Reported-by: Feifei Wang <feifei.wang2@arm.com>
> Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
> v2:
> New approach to use arch_extension instead.
> 
>  lib/librte_eal/arm/include/rte_atomic_64.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_eal/arm/include/rte_atomic_64.h
> b/lib/librte_eal/arm/include/rte_atomic_64.h
> index 7fcd17466..6584bc38c 100644
> --- a/lib/librte_eal/arm/include/rte_atomic_64.h
> +++ b/lib/librte_eal/arm/include/rte_atomic_64.h
> @@ -46,7 +46,7 @@ rte_atomic_thread_fence(int memorder)
>  /*------------------------ 128 bit atomic operations -------------------------*/
> 
>  #if defined(__ARM_FEATURE_ATOMICS) ||
> defined(RTE_ARM_FEATURE_ATOMICS)
> -#define __LSE_PREAMBLE	".arch armv8-a+lse\n"
> +#define __LSE_PREAMBLE	".arch_extension lse\n"

This approach has issue on earlier version Clang (eg. clang-6).
I think it is better to take approach in v1.
> 
>  #define __ATOMIC128_CAS_OP(cas_op_name, op_string)                          \
>  static __rte_noinline rte_int128_t                                          \
> --
> 2.20.1