From: johnrreagan@earthlink.net   
      
   On 2/24/2025 4:43 PM, Arne Vajhøj wrote:   
   > On 2/24/2025 4:22 PM, Michael S wrote:   
   >> On Mon, 24 Feb 2025 15:08:57 -0500   
   >> Arne Vajhøj  wrote:   
   >>> On 2/24/2025 12:42 PM, Michael S wrote:   
   >   
   >>> C++ VMS x86-64 is clang which in the (older) clang version used   
   >>> should mean C++14 while C++ VMS Itanium is very very old (like   
   >>> C++ 98 old).   
   >>>   
   >>>> According to the benchmarks that you posted here several months (a   
   >>>> year?) ago, VMS x86-64 compilers are quite awful comparatively to   
   >>>> x86-64 compilers available on Windows/Linux/BSD.   
   >>>> Do you want to say that VMS Itanium compilers are worse?   
   >>>   
   >>> I believe the conclusion was that the VMS x86-64 compilers except C++   
   >>> was slower than C/C++ on other OS and C++ on VMS.   
   >>   
   >> Somehow I got an impression that C++ compilers were also significantly   
   >> slower than C++ compilers on other platforms.   
   >> Do I misremember?   
   >   
   > I don't even remember that I posted non-VMS numbers here. Age! :-)   
   >   
   > But I just checked VMS C++ latest (CXX/OPT=LEVEL:5 and clang -O3) vs a   
   > random Windows GCC 14.1 (g++ -O3):   
   >   
   > VMS is a little faster for integer   
   > they are about the same for floating point   
   > Windows is a lot faster for string   
   >   
   > And given that this is a micro-benchmark with in reality just an inner   
   > loop evaluating a single expression, which means huge uncertainty, then   
   > I don't see this as proof of a significant difference.   
   >   
   > Arne   
   >   
   We are aware of the string/char performance issues.   
      
   On Alpha and Itanium, the lowlevel routines inside of LIBOTS for things   
   like OTS$MOVE, string compare, memmove, etc. are all written in   
   hand-crafted assembly.  For x86, we are still using a set of BLISS   
   reference code that is simple.  Plus the LIBOTS we all have on our   
   systems was compiled with a non-optimizing BLISS cross-compiler.   
      
   We are currently playing with native compiled LIBOTS code and doing some   
   benchmarks.  Besides the brain-dead BLISS code, we have versions that   
   loop with larger chunks of data which are even faster.  The fastest   
   we've seen so far is a native assembly version that uses the REP   
   instruction prefix on the MOVSB.  That version didn't check for   
   overlapping source/dest however so any real version gets a little   
   slower.  I'm not sure when we can incorporate these, but I'm trying to   
   push them as soon as possible.   
      
   A fun reference to read is   
      
   https://cdrdv2-public.intel.com/814198/248966-Optimization-Refer   
   nce-Manual-V1-050.pdf   
      
   --- SoupGate-DOS v1.05   
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