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

["Liming Gao" <liming.gao@intel.com>]

Xiaoyu:

> -----Original Message-----
> From: Lu, XiaoyuX
> Sent: Wednesday, June 5, 2019 2:34 PM
> To: Gao, Liming <liming.gao@intel.com>; devel@edk2.groups.io
> 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
> 
> 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?
> 

Make sense. What test have been done by you? Build pass and Boot pass?

> > 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
> > >
> > >
> > >