> On 16 Mar 2025, at 3:02 pm, David Cole <dbc...@colesoft.com> wrote: > > I think the more interesting question is not, whether the compiler is slower. > It's whether the compiled code is slower. > > Is it? >
That’s an interesting question because the legacy XL C/C++ compiler has been functionally stabilized. There is significant concern that Metal/C has not been updated to support the z16 architecture. In our experiments, the Open XL C/C++ Clang compiler is 26 times slower at compiling the same code compared to Clang running on a zCX container on the same LPAR. The binary is also 236M compared to 123K on Linux. This is very much a work in progress. The most concerning issue I have encountered is the limited runtime. For example, features like extended stdio for VSAM and SVC 99 are not enabled. We do not consider this compiler ready for product development. However, it is excellent for porting Linux applications to z/OS. > > > Dave Cole, Developer > dbc...@gmail.com <mailto:dbc...@gmail.com> (personal) > dbc...@colesoft.com <mailto:dbc...@colesoft.com> (business) > 540-456-6518 (cell) > > > > > At 3/16/2025 01:33 AM, Allan Staller wrote: >> Classification: Confidential >> >> Region. The Optimizer takes a whole lot of virtual storage >> >> -----Original Message----- >> From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU >> <mailto:IBM-MAIN@LISTSERV.UA.EDU>> On Behalf Of Charles Mills >> Sent: Friday, March 14, 2025 1:39 PM >> To: IBM-MAIN@LISTSERV.UA.EDU <mailto:IBM-MAIN@LISTSERV.UA.EDU> >> Subject: Open XL C dramaticallly slower thant z/OS XL C compiler - expected? >> >> [CAUTION: This Email is from outside the Organization. Unless you trust the >> sender, Donâ?Tt click links or open attachments as it may be a Phishing >> email, which can steal your Information and compromise your Computer.] >> >> I am trying to get started with the new, "open," Clang-based XLC compiler. I >> am stunned at how noticeably slower it is than the legacy C compiler. I >> wasn't looking to benchmark -- the slow compile times just jumped out at me. >> >> Is this to be expected? I wish I had numbers for exactly the same source >> code but there are different userids involved and it's a little complicated. >> Different options for the two compiles because the option specifications are >> incompatible. Both modules are fairly vanilla source code written by the >> same author. >> >> Both of the following are on the same machine, the same virtual machine at >> IBM Dallas. It's a z16 A01. >> >> Compile under the legacy XL C compiler, a C++ compile of a 1886-line source >> module: 4 seconds elapsed, .36 CPU seconds. >> >> Compile under Open XL C compiler, a C++ compile of a 415-line source module: >> 26 seconds elapsed, 1.32 CPU seconds. >> >> Is this what others are seeing? Is this to be expected? IS anyone using the >> new compiler? >> >> Charles >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, send email >> to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >> ::DISCLAIMER:: >> ________________________________ >> The contents of this e-mail and any attachment(s) are confidential and >> intended for the named recipient(s) only. E-mail transmission is not >> guaranteed to be secure or error-free as information could be intercepted, >> corrupted, lost, destroyed, arrive late or incomplete, or may contain >> viruses in transmission. The e mail and its contents (with or without >> referred errors) shall therefore not attach any liability on the originator >> or HCL or its affiliates. Views or opinions, if any, presented in this email >> are solely those of the author and may not necessarily reflect the views or >> opinions of HCL or its affiliates. Any form of reproduction, dissemination, >> copying, disclosure, modification, distribution and / or publication of this >> message without the prior written consent of authorized representative of >> HCL is strictly prohibited. If you have received this email in error please >> delete it and notify the sender immediately. Before opening any email and/or >> attachments, please check them for viruses and other defects. >> ________________________________ >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, >> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu <mailto:lists...@listserv.ua.edu> with > the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
