Re: [edk2-devel] [Patch 09/12] CryptoPkg IntrinsicLib: Make _fltused always be used

["Yao, Jiewen" <jiewen.yao@intel.com>]

Hi

+int  GLOBAL_USED _fltused = 1;

May I know what is the use of GLOBAL_USED? Only for compiler stub symbol?

If so, why we add __GNUC__ here? Any other usage?

+#if defined(__GNUC__) || defined(__clang__)
+  #define GLOBAL_USED __attribute__((used))
+#else
+  #define GLOBAL_USED
+#endif

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Liming Gao
> Sent: Friday, September 27, 2019 3:47 PM
> To: devel@edk2.groups.io
> Subject: [edk2-devel] [Patch 09/12] CryptoPkg IntrinsicLib: Make _fltused always
> be used
> 
> With this change, global variable _fltused will not be removed by LTO
> 
> Signed-off-by: Liming Gao <liming.gao@intel.com>
> ---
>  CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
> b/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
> index 6e4d4a68cc..94fe341bec 100644
> --- a/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
> +++ b/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
> @@ -2,7 +2,7 @@
>    Intrinsic Memory Routines Wrapper Implementation for OpenSSL-based
>    Cryptographic Library.
> 
> -Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
>  SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -13,9 +13,15 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  typedef UINTN  size_t;
> 
> +#if defined(__GNUC__) || defined(__clang__)
> +  #define GLOBAL_USED __attribute__((used))
> +#else
> +  #define GLOBAL_USED
> +#endif
> +
>  /* OpenSSL will use floating point support, and C compiler produces the _fltused
>     symbol by default. Simply define this symbol here to satisfy the linker. */
> -int _fltused = 1;
> +int  GLOBAL_USED _fltused = 1;
> 
>  /* Sets buffers to a specified character */
>  void * memset (void *dest, int ch, size_t count)
> --
> 2.13.0.windows.1
> 
> 
>