We have included x64 optimized asm of FillChar() and Move() for Win64 - for corresponding compiler targets, i.e. Delphi XE2 and XE3.
It will handle properly cache prefetch and appropriate SSE2 move instructions

The System.pas unit of Delphi RTL will be patched at startup, unless the NOX64PATCHRTL conditional is defined.
Therefore, whole application may benefit for this optimized version.

Performance improvement is noticeable, when compared with the original pascal-based version included in System.pas.

By the way, the Delphi x64 built-in assembler does not recognize the movnti opcode... so we had to inline it as plain db hexadecimal values.
A bit disappointing. Until now, we did not suffer from anything in regard to the x64 compatibility at Delphi level.

No stand-alone unit available yet, since it is included in our SynCommons.pas shared unit, starting with the 1.18 revision of mORMot.

Feedback is welcome, as usual!