I think the more interesting question is not, whether the compiler is slower.
It's whether the compiled code is slower.
Is it?
Dave Cole, Developer
dbc...@gmail.com (personal)
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> On Behalf Of Charles Mills
Sent: Friday, March 14, 2025 1:39 PM
To: 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 with the message: INFO IBM-MAIN
