Re: [edk2-devel] [PATCH v1 1/1] CryptoPkg/IntrinsicLib: Fix CLANG38 IA32 build problem

["Xiaoyu Lu" <xiaoyux.lu@intel.com>]

Hi Liming,

> -----Original Message-----
> From: Gao, Liming
> Sent: Wednesday, June 5, 2019 1:57 PM
> To: devel@edk2.groups.io; Lu, XiaoyuX <xiaoyux.lu@intel.com>
> Cc: Bi, Dandan <dandan.bi@intel.com>; Wang, Jian J <jian.j.wang@intel.com>
> Subject: RE: [edk2-devel] [PATCH v1 1/1] CryptoPkg/IntrinsicLib: Fix
> CLANG38 IA32 build problem
> 
> Xiaoyu:
> 
> >-----Original Message-----
> >From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> >Xiaoyu Lu
> >Sent: Wednesday, June 05, 2019 1:25 PM
> >To: devel@edk2.groups.io
> >Cc: Lu, XiaoyuX <xiaoyux.lu@intel.com>; Bi, Dandan
> <dandan.bi@intel.com>;
> >Wang, Jian J <jian.j.wang@intel.com>
> >Subject: [edk2-devel] [PATCH v1 1/1] CryptoPkg/IntrinsicLib: Fix CLANG38
> >IA32 build problem
> >
> >When use clang-3.8 to build the NetworkPkg, compiler optimization
> >may use memcpy for memory copy. For example:
> >
> > CryptoPkg/Library/OpensslLib/openssl/ssl/ssl_rsa.c:918: undefined
> > reference to `memcpy'`
> >
> >Compiler optimization is sophisticated, but we can work around it
> >use __attribute__((__used__)) to informs the compiler that symbol
> >should be retained in the object file, even if it may be
> >unreferenced.
> >
> >Cc: Jian J Wang <jian.j.wang@intel.com>
> >Cc: Dandan Bi <dandan.bi@intel.com>
> >Signed-off-by: Xiaoyu Lu <xiaoyux.lu@intel.com>
> >---
> > CryptoPkg/Library/IntrinsicLib/CopyMem.c | 13 +++++++++++++
> > 1 file changed, 13 insertions(+)
> >
> >diff --git a/CryptoPkg/Library/IntrinsicLib/CopyMem.c
> >b/CryptoPkg/Library/IntrinsicLib/CopyMem.c
> >index e29b4918d200..7faf5a34d8c1 100644
> >--- a/CryptoPkg/Library/IntrinsicLib/CopyMem.c
> >+++ b/CryptoPkg/Library/IntrinsicLib/CopyMem.c
> >@@ -10,8 +10,21 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
> > #include <Base.h>
> > #include <Library/BaseMemoryLib.h>
> >
> >+#if defined(__clang__) && !defined(__APPLE__)
> 
> So, this change is only for CLANG tool chain.
> 
> >+
> >+/* Copies bytes between buffers */
> >+static __attribute__((__used__))
> 
> What purpose for static?
> 

Because I want __memcpy only use in this file scope.

> >+void * __memcpy (void *dest, const void *src, unsigned int count)
> >+{
> >+  return CopyMem (dest, src, (UINTN)count);
> >+}
> >+__attribute__((__alias__("__memcpy")))
> >+void * memcpy (void *dest, const void *src, unsigned int count);
> 
> __memcpy is IA32 Intrinsic API, memcpy is X64 Intrinsic API, right?
> 

__memcpy isn't IA32 Intrinsic API, only memcpy is intrinsic API for both IA32 and X64.

The reason I alias memcpy and use __attribute__((__used__)) is let compiler retain symbol in object file,
So it can link correct.

Is this correct?

> Thanks
> Liming

> >+
> >+#else
> > /* Copies bytes between buffers */
> > void * memcpy (void *dest, const void *src, unsigned int count)
> > {
> >   return CopyMem (dest, src, (UINTN)count);
> > }
> >+#endif
> >--
> >2.7.4
> >
> >
> >