> -----Original Message----- > From: IBM Mainframe Assembler List [mailto:ASSEMBLER- > [email protected]] On Behalf Of Paul Gilmartin > Sent: Tuesday, January 17, 2012 10:32 AM > To: [email protected] > Subject: Re: How bad is the EX instruction? > > On Jan 16, 2012, at 08:21, Kerry wrote: > > > > Performance is one of the strongest reasons for coding in assembler and > > this discussion characterizes some of the low hanging fruit available > > for the attainment thereof. > > > Others have said here that performance is a strong reason > for _not_ coding in assembler: > > o Compiler developers have done the research on instruction > timings and know better than most end users what sequences > fit the pipelines optimally.
Notoriously NOT for the IBM COBOL compilers. I plead ignorance for the PL/1 and Fortran compilers, but the C/C++ compiler is the only current compiler in my personal experience that actually exhibits a knowledge of instruction timings and latency and AGI interrupts, etc., for current and recent pipelined "z" processors. IMHO, COBOL generated code is so bad that if I was on the COBOL code-generation development team I would be embarrassed to admit it. > o Compiled code can be re-optimized for a new generation of > hardware simply by recompiling. > > o Interpreters can dynamically recompile based on statistical > profiles evaluated at the actual time of execution. > -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system.
