IBM XL C/C++ for Linux, V16.1.1

What's New for XL C/C++Version 16.1.1

GC27-8041-01

IBM

IBM XL C/C++ for Linux, V16.1.1

What's New for XL C/C++Version 16.1.1

GC27-8041-01

IBM

NoteBefore using this information and the product it supports, read the information in “Notices” on page 11.

First edition

This edition applies to IBM XL C/C++ for Linux, V16.1.1 (Program 5765-J13, 5725-C73) and to all subsequentreleases and modifications until otherwise indicated in new editions. Make sure you are using the correct editionfor the level of the product.

© Copyright IBM Corporation 2017, 2018.US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contractwith IBM Corp.

Contents

About this document . . . . . . . . . vWho should read this document . . . . . . . . vHow to send your comments . . . . . . . . . v

Chapter 1. OpenMP support . . . . . . 1

Chapter 2. New IBM Support website . . 3

Chapter 3. Other compiler behaviorchanges. . . . . . . . . . . . . . . 5

Chapter 4. Available help information . . 7

Appendix. Accessibility features for IBMXL C/C++ for Linux . . . . . . . . . . 9

Notices . . . . . . . . . . . . . . 11Trademarks . . . . . . . . . . . . . . 13

Index . . . . . . . . . . . . . . . 15

© Copyright IBM Corp. 2017, 2018 iii

iv XL C/C++: What's New for XL C/C++

About this document

This information provides an executive overview of new functions in the IBM® XLC/C++ for Linux, V16.1.1 compiler. The topics in this information provide aframework for describing new functions in the IBM XL C/C++ for Linux, V16.1.1compiler. New functions are categorized according to user benefits.

Who should read this documentThis information is written primarily for people who are evaluating and planningfor IBM XL C/C++ for Linux, V16.1.1.

How to send your commentsYour feedback is important in helping us to provide accurate and high-qualityinformation. If you have any comments or questions about this information or anyother XL C/C++ information, send compinfo@cn.ibm.com an email.

Be sure to include the name of the manual, the part number of the manual, theversion of XL C/C++, and, if applicable, the specific location of the text you arecommenting on (for example, a page number or table number).

© Copyright IBM Corp. 2017, 2018 v

vi XL C/C++: What's New for XL C/C++

Chapter 1. OpenMP support

IBM XL C/C++ for Linux, V16.1.1 now fully supports the OpenMP API V4.5specification.

The new OpenMP support falls into the following categories:v “New directives”v “Updated clauses”v “New environment variables”v “Updated environment variables” on page 2

For more information, see the XL C/C++ Compiler Reference.

New directives

In addition to the existing OpenMP directives, IBM XL C/C++ for Linux, V16.1.1adds support for the following directives and their clauses.

omp declare reductionYou can use the omp declare reduction directive to define customreductions. This directive declares a reduction-identifier that you can use in areduction clause.

Updated clauses

The following clauses are updated in IBM XL C/C++ for Linux, V16.1.1.

reduction_clauseYou can now specify array and array section list items in the reductionclause. To learn more about the array section, see "2.4 Array Sections" inthe OpenMP 4.5 specifications.

The clause is supported on the following directives:v omp for

v omp for simd

v omp distribute parallel for

v omp distribute parallel for simd

v omp distribute simd

v omp parallel

v omp section, omp sections

v omp simd

v omp teams

New environment variables

IBM XL C/C++ for Linux, V16.1.1 adds support for the following newenvironment variables for OpenMP.

OMP_DEV_HEAPSIZEYou can use the OMP_DEV_HEAPSIZE environment variable to controlthe size of the heap used by malloc() and free() device system calls forprocesses created by the OpenMP implementation to run on the device.

© Copyright IBM Corp. 2017, 2018 1

OMP_DEV_STACKSIZEYou can use the OMP_DEV_STACKSIZE environment variable to controlthe size of the stack for threads created by the OpenMP implementation torun on the device.

OMP_NUM_TEAMSYou can use the OMP_NUM_TEAMS environment variable to set thenumber of teams to use for the omp teams constructs on the device.

Updated environment variables

The following environment variable for OpenMP is updated in IBM XL C/C++ forLinux, V16.1.1.

OMP_DISPLAY_ENVThe new DEBUG value for OMP_DISPLAY_ENV displays the stack sizeand heap size that are in effect for a device. WithOMP_DISPLAY_ENV=true, the values you specify for theOMP_DEV_HEAPSIZE and OMP_DEV_STACKSIZE environmentvariables are displayed in kilobytes. With OMP_DISPLAY_ENV=verbose,help information about the OMP_DEV_HEAPSIZE andOMP_DEV_STACKSIZE environment variables is displayed in addition tothe information displayed in OMP_DISPLAY_ENV=true.

2 XL C/C++: What's New for XL C/C++

Chapter 2. New IBM Support website

IBM has introduced a new IBM Support website to replace the IBM ServiceRequest Tool.

Now, if you have an issue for IBM XL C/C++ for Linux, open a Case at the newIBM Support website at https://www.ibm.com/mysupport/s.

To learn more about this support website change, see IBM Z is moving to the newIBM Support site to replace the IBM Service Request Tool.

© Copyright IBM Corp. 2017, 2018 3

4 XL C/C++: What's New for XL C/C++

Chapter 3. Other compiler behavior changes

This section describes other compiler behavior changes in IBM XL C/C++ forLinux, V16.1.1.

The __llvm__ macro is no longer predefined

In IBM XL C/C++ for Linux, V16.1.1, the __llvm__ macro is not predefined.However, in releases earlier than V16.1.1, the __llvm__ macro was predefined as 1.

Use NVIDIA CUDA Toolkit 10.1 starting from V16.1.1.3

NVIDIA CUDA Toolkit with support for IBM Power® Little Endian (POWER9™),which are available from NVIDIA, are required for the compilation and linkingprocess for programs that use OpenMP 4.5 to offload computation to the NVIDIAGPUs.

Install NVIDIA CUDA Toolkit 10.1 if your compiler is IBM XL C/C++ for LinuxV16.1.1.3 or up. Install NVIDIA CUDA Toolkit 9.2 if your compiler is IBM XLC/C++ for Linux V16.1.1.0, V16.1.1.1, or V16.1.1.2.

Support for RHEL 7.6 and 8.0 starting from V16.1.1.3 and RHEL8.1 starting from V16.1.1.6

IBM XL C/C++ for Linux adds support for RHEL 7.6 and 8.0 starting fromV16.1.1.3 and adds support for RHEL 8.1 starting from V16.1.1.6. For a list ofoperating systems supported in IBM XL C/C++ for Linux, see Operating systemand hardware support.

© Copyright IBM Corp. 2017, 2018 5

6 XL C/C++: What's New for XL C/C++

Chapter 4. Available help information

IBM XL C/C++ information

XL C/C++ provides product information in the following formats:v Quick Start Guide

The Quick Start Guide (quickstart.pdf) is intended to get you started with IBMXL C/C++ for Linux, V16.1.1. It is located by default in the XL C/C++ directoryand in the \quickstart directory of the installation DVD.

v README filesREADME files contain late-breaking information, including changes andcorrections to the product information. README files are located by default inthe XL C/C++ directory, and in the root directory and subdirectories of theinstallation DVD.

v Installable man pagesMan pages are provided for the compiler invocations and all command-lineutilities provided with the product. Instructions for installing and accessing theman pages are provided in the IBM XL C/C++ for Linux, V16.1.1 InstallationGuide.

v Online product documentationThe fully searchable HTML-based documentation is viewable in IBM KnowledgeCenter at http://www.ibm.com/support/knowledgecenter/SSXVZZ_16.1.1/com.ibm.compilers.linux.doc/welcome.html.

v PDF documentsPDF documents are available on the web at https://www.ibm.com/support/knowledgecenter/SSXVZZ_16.1.1/com.ibm.compilers.linux.doc/download_pdf.html.The following files comprise the full set of XL C/C++ product information.

Note: To ensure that you can access cross-reference links to other XL C/C++PDF documents, download and unzip the .zip file that contains all the productdocumentation files, or you can download each document into the samedirectory on your local machine.

Table 1. XL C/C++ PDF files

Document title PDF file name Description

What's New for IBM XLC/C++ for Linux,V16.1.1, GC27-8041-01

whats_new.pdf Provides an executive overview of newfunctions in the IBM XL C/C++ forLinux, V16.1.1 compiler, with newfunctions categorized according to userbenefits.

Getting Started withIBM XL C/C++ forLinux, V16.1.1,GI13-3564-01

getstart.pdf Contains an introduction to XL C/C++,with information about setting up andconfiguring your environment,compiling and linking programs, andtroubleshooting compilation errors.

IBM XL C/C++ forLinux, V16.1.1Installation Guide,GC27-8039-01

install.pdf Contains information for installing XLC/C++ and configuring yourenvironment for basic compilation andprogram execution.

© Copyright IBM Corp. 2017, 2018 7

Table 1. XL C/C++ PDF files (continued)

Document title PDF file name Description

IBM XL C/C++ forLinux, V16.1.1 MigrationGuide, GC27-8042-01

migrate.pdf Contains migration considerations forusing XL C/C++ to compile programsthat were previously compiled ondifferent platforms, by previous releasesof XL C/C++, or by other compilers.

IBM XL C/C++ forLinux, V16.1.1 CompilerReference, SC27-8047-01

compiler.pdf Contains information about the variouscompiler options, pragmas, macros,environment variables, and built-infunctions.

IBM XL C/C++ forLinux, V16.1.1 LanguageReference, SC27-8045-01

langref.pdf Contains information about languageextensions for portability andconformance to nonproprietarystandards.

IBM XL C/C++ forLinux, V16.1.1Optimization andProgramming Guide,SC27-8046-01

proguide.pdf Contains information about advancedprogramming topics, such asapplication porting, interlanguage callswith Fortran code, library development,application optimization, and the XLC/C++ high-performance libraries.

To read a PDF file, use Adobe Reader. If you do not have Adobe Reader, youcan download it (subject to license terms) from the Adobe website athttp://www.adobe.com.

More information related to XL C/C++, including IBM Redbooks® publications,white papers, and other articles, is available on the web at http://www.ibm.com/support/docview.wss?uid=swg27036675.

For more information about the compiler, see the XL compiler on Powercommunity at http://ibm.biz/xl-power-compilers.

Other IBM informationv ESSL product documentation available at http://www.ibm.com/support/

knowledgecenter/SSFHY8/essl_welcome.html?lang=en.

Other informationv Using the GNU Compiler Collection available at http://gcc.gnu.org/onlinedocs.

8 XL C/C++: What's New for XL C/C++

Appendix. Accessibility features for IBM XL C/C++ for Linux

Accessibility features assist users who have a disability, such as restricted mobilityor limited vision, to use information technology content successfully.

Accessibility features

IBM XL C/C++ for Linux uses the latest W3C Standard, WAI-ARIA 1.0(http://www.w3.org/TR/wai-aria/), to ensure compliance to US Section 508(http://www.access-board.gov/guidelines-and-standards/communications-and-it/about-the-section-508-standards/section-508-standards) and Web ContentAccessibility Guidelines (WCAG) 2.0 (http://www.w3.org/TR/WCAG20/). To takeadvantage of accessibility features, use the latest release of your screen reader incombination with the latest web browser that is supported by this product.

The IBM XL C/C++ for Linux online product documentation in IBM KnowledgeCenter is enabled for accessibility. The accessibility features of IBM KnowledgeCenter are described at IBM Knowledge Center help.

Keyboard navigation

This product uses standard navigation keys.

Interface information

You can use speech recognition software like a Text-to-speech (TTS) tool to viewthe output generated by the compiler.

The IBM XL C/C++ for Linux online product documentation is available in IBMKnowledge Center, which is viewable from a standard web browser.

PDF files have limited accessibility support. With PDF documentation, you can useoptional font enlargement, high-contrast display settings, and can navigate bykeyboard alone.

To enable your screen reader to accurately read syntax diagrams, source codeexamples, and text that contains the period or comma PICTURE symbols, youmust set the screen reader to speak all punctuation.

Related accessibility information

To learn the accessibility features of the operation systems that are supported byIBM XL C/C++ for Linux, see the following information:v Ubuntu (https://help.ubuntu.com/community/Accessibility)v SUSE Linux Enterprise Server (https://www.suse.com)v Red Hat Enterprise Linux (http://www.redhat.com)v Community Enterprise Operating System (https://www.centos.org/)

In addition to standard IBM help desk and support websites, IBM has establisheda TTY telephone service for use by deaf or hard of hearing customers to accesssales and support services:

© Copyright IBM Corp. 2017, 2018 9

TTY service 800-IBM-3383 (800-426-3383) (within North America)

IBM and accessibility

For more information about the commitment that IBM has to accessibility, see IBMAccessibility (www.ibm.com/able).

10 XL C/C++: What's New for XL C/C++

Notices

Programming interfaces: Intended programming interfaces allow the customer towrite programs to obtain the services of IBM XL C/C++ for Linux.

This information was developed for products and services offered in the U.S.A.IBM may not offer the products, services, or features discussed in this document inother countries. Consult your local IBM representative for information on theproducts and services currently available in your area. Any reference to an IBMproduct, program, or service is not intended to state or imply that only that IBMproduct, program, or service may be used. Any functionally equivalent product,program, or service that does not infringe any IBM intellectual property right maybe used instead. However, it is the user's responsibility to evaluate and verify theoperation of any non-IBM product, program, or service.

IBM may have patents or pending patent applications covering subject matterdescribed in this document. The furnishing of this document does not give youany license to these patents. You can send license inquiries, in writing, to:

IBM Director of LicensingIBM CorporationNorth Castle Drive, MD-NC119Armonk, NY 10504-1785U.S.A.

For license inquiries regarding double-byte (DBCS) information, contact the IBMIntellectual Property Department in your country or send inquiries, in writing, to:

Intellectual Property LicensingLegal and Intellectual Property LawIBM Japan, Ltd.19-21, Nihonbashi-Hakozakicho, Chuo-kuTokyo 103-8510, Japan

The following paragraph does not apply to the United Kingdom or any othercountry where such provisions are inconsistent with local law:INTERNATIONAL BUSINESS MACHINES CORPORATION PROVIDES THISPUBLICATION "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHEREXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIEDWARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY OR FITNESSFOR A PARTICULAR PURPOSE. Some states do not allow disclaimer of express orimplied warranties in certain transactions, therefore, this statement may not applyto you.

This information could include technical inaccuracies or typographical errors.Changes are periodically made to the information herein; these changes will beincorporated in new editions of the publication. IBM may make improvementsand/or changes in the product(s) and/or the program(s) described in thispublication at any time without notice.

Any references in this information to non-IBM websites are provided forconvenience only and do not in any manner serve as an endorsement of those

© Copyright IBM Corp. 2017, 2018 11

websites. The materials at those websites are not part of the materials for this IBMproduct and use of those websites is at your own risk.

IBM may use or distribute any of the information you supply in any way itbelieves appropriate without incurring any obligation to you.

Licensees of this program who want to have information about it for the purposeof enabling: (i) the exchange of information between independently createdprograms and other programs (including this one) and (ii) the mutual use of theinformation which has been exchanged, should contact:

Intellectual Property Dept. for Rational SoftwareIBM Corporation5 Technology Park DriveWestford, MA 01886U.S.A.

Such information may be available, subject to appropriate terms and conditions,including in some cases, payment of a fee.

The licensed program described in this document and all licensed materialavailable for it are provided by IBM under terms of the IBM Customer Agreement,IBM International Program License Agreement or any equivalent agreementbetween us.

Any performance data contained herein was determined in a controlledenvironment. Therefore, the results obtained in other operating environments mayvary significantly. Some measurements may have been made on development-levelsystems and there is no guarantee that these measurements will be the same ongenerally available systems. Furthermore, some measurements may have beenestimated through extrapolation. Actual results may vary. Users of this documentshould verify the applicable data for their specific environment.

Information concerning non-IBM products was obtained from the suppliers ofthose products, their published announcements or other publicly available sources.IBM has not tested those products and cannot confirm the accuracy ofperformance, compatibility or any other claims related to non-IBM products.Questions on the capabilities of non-IBM products should be addressed to thesuppliers of those products.

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COPYRIGHT LICENSE:

This information contains sample application programs in source language, whichillustrates programming techniques on various operating platforms. You may copy,modify, and distribute these sample programs in any form without payment toIBM, for the purposes of developing, using, marketing or distributing applicationprograms conforming to the application programming interface for the operating

12 XL C/C++: What's New for XL C/C++

platform for which the sample programs are written. These examples have notbeen thoroughly tested under all conditions. IBM, therefore, cannot guarantee orimply reliability, serviceability, or function of these programs. The sampleprograms are provided “AS IS”, without warranty of any kind. IBM shall not beliable for any damages arising out of your use of the sample programs.

Each copy or any portion of these sample programs or any derivative work, mustinclude a copyright notice as follows:

© (your company name) (year). Portions of this code are derived from IBM Corp.Sample Programs. © Copyright IBM Corp. 1998, 2018.

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For more information about the use of various technologies, including cookies, forthese purposes, see IBM's Privacy Policy at http://www.ibm.com/privacy andIBM's Online Privacy Statement at http://www.ibm.com/privacy/details in thesection entitled “Cookies, Web Beacons and Other Technologies,” and the “IBMSoftware Products and Software-as-a-Service Privacy Statement” athttp://www.ibm.com/software/info/product-privacy.

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Adobe and the Adobe logo are either registered trademarks or trademarks ofAdobe Systems Incorporated in the United States, other countries, or both.

Linux is a registered trademark of Linus Torvalds in the United States, othercountries, or both.

NVIDIA is either registered trademark or trademark of NVIDIA Corporation in theUnited States, other countries, or both.

Notices 13

14 XL C/C++: What's New for XL C/C++

Index

Aaccessibility

interfaces 9keyboard navigation 9

Mmore enhancements

new featuresV16.1.1 5

© Copyright IBM Corp. 2017, 2018 15

16 XL C/C++: What's New for XL C/C++

IBM®

Product Number: 5765-J13, 5725-C73

Printed in USA

GC27-8041-01