"Why write in assembler?" is a strange question to ask on an assembler list! <grin>
We don't have the C compiler. We only have Enterprise COBOL. Have you every looked at the assembler output from it?? <shudder> The company does agree that writing is assembler is not cost effective, for us. So we are trying to retire all assembler code and replace what is absolutely required with COBOL. -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * (817)-691-6183 cell [email protected] * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM > -----Original Message----- > From: IBM Mainframe Assembler List > [mailto:[email protected]] On Behalf Of Kirk Wolf > Sent: Monday, August 23, 2010 10:47 AM > To: [email protected] > Subject: Re: Selecting which instruction(s) to use. Thoughts > for discussioni > > If you want to find out how to best optimize for Intel chips, you > would get the Intel compilers and see what they do. The same thing is > useful for z. > > One suggestion would be to code a algorithms similar to what you want > to code in assembler and run it through the IBM xlC/C++ compiler (or > Metal C) with the highest optimization level and look at the generated > psuedo-assembler listing. Make sure to compile with "ARCH" at the > level of the target machine instruction set. > > You'll find that everything runs "baseless", and that memcpy() (where > the length is not known by the compiler) generates code that doesn't > use MVCL. The loop unwinding stuff that it does is also fascinating, > as well as storage access/use decoupling stuff that it does to take > advantage of pipe-lining. > > Given that IBM is really the only one who knows completely how to > optimize for z, at some point you have to ask "why write in assembler" > for z? For Linux on z, the answer, is that most people shouldn't > unless you write device drivers. On z/OS, the system API is still > largely assembler (for customers; IBM uses PL/X), and Metal-C doesn't > really offer a practical alternative. Dignus' approach for > imbedding assembler in C/C++ seems much cleaner to me, but aren't we > at the mercy of IBM to do really good optimizing compilers? > > Kirk Wolf > Dovetailed Technologies > http://dovetail.com > >
