You may have heard about Rational Developer for Power Systems Software , which now has support for development of COBOL on AIX, C/C++ on AIX and Power Linux as well as IBM i application development.  It is easy to kick the tires by downloading the trial from here . But if you only have 5 minutes just check out the YouTube video below and be amazed at the C/C++ functionality now available for AIX and Linux developers. For more information go to the product web site at http://www-01.ibm.com/software/rational/products/rdp/ .

Tags:  rational rdpower linux debugger aix

  The following PTFs are now available: October 2010 PTF for XL C for AIX, V10.1 October 2010 PTF for XL C/C++ for AIX, V10.1 October 2010 PTF for XL C/C++ for AIX, V10.1 Runtime In addition to defect fixes, these PTFs also added support for AIX7.1 and the URT functionality! Click on the links to find out more details and download them!

Tags:  c/c++ ptf v10.1 updates

If you’ve been waiting for a formal evaluation of the IBM Power8 architecture on common financial workloads, then you need to read this!   The certified STAC report, which was published in March, marked the first time the IBM Power8 architecture has gone through STAC-A2 testing. The STAC Pack used IBM XL , a suite for C/C++ developers that includes the C++ Compiler and the Mathematical Acceleration Subsystem libraries (MASS), as well as the Engineering and Scientific Subroutine Library (ESSL). Please click here to get... [More]

z/OS XL C/C++ compiler supports the "__ptr32" type qualifier to facilitate porting structures with pointer members from 32-bit mode to 64-bit mode. However, if you fail to use it in the right way, it cause unexpected results at run time that are hard to debug.   Let's take the following code as an example, and think about why we can't get the expected result.   > cat test.C #define PTR_TYPE char * __ptr32 int main(){ PTR_TYPE p = (PTR_TYPE)(~0); PTR_TYPE * __ptr32 addr = &p; if((((unsigned int)(*addr)) &... [More]

Tags:  __ptr32 z/os

Now there’s an even easier way to get you started with your evaluation of the latest XL C/C++ (V13.1.1) and XL Fortran (V15.1.1) for Linux compilers for the little endian Linux distributions on Power Systems (Ubuntu 14.04, Ubuntu 14.10, and SLES 12). We are now hosting the latest evaluation versions on public apt-get and zypper repositories. You can find everything that you need to get started at http://public.dhe.ibm.com/software/server/POWER/Linux/xl-compiler/eval/ppc64le/

The Variadic Template Function The latest language standard has further complicated C++ by adding variadic templates. One problem I had in my attempt to understand this new feature was the lack of simple examples showing how it worked. Here's my attempt to show some of the basics of a variadic template function. template <class ...A> int func(A... arg) { return sizeof...(arg); } int main(void) { return func(1,2,3,4,5,6); } First the basic vocabulary: A template parameter can now be a template parameter pack... [More]

  I got curious about what the real speedup is from using -O2, so I did a few runs on an old machine we have sitting around in our shop.  I used  XLC V11.1 and XLF V13.1 to measure the old SPEC CPU2000 benchmark suite.  I did two measurements: one with -O2 and one without optimization.  The results are presented below in a table and they confirm what I suspected –  Code compiled with -O2 consistently performs 2-3 times faster than the same code compiled without optimization!   ... [More]

Tags:  optimization cppcafe

In this meeting, Bjarne Stroustrup opined that "The Atomics have become unstable at Fermilab".. Of course, Fermilab is a wonderful place, where one of the first sub-atomic particle, the top-quark was discovered. The architecture of this facility stands out uniquely with pi-shaped main building, telephone poles, and Archimedean spiral pumping stations. Much of the facility is opened to public visit. The main mission of the Lab is one of keen interest to our future and that is the search for Dark matter, Dark Energy which of course can... [More]

Tags:  c++0x fermilab c++ standard

The AIX tprof utility is a valuable tool for optimization which provides features to identify performance bottlenecks within programs and to aid in analysis of performance-critical code. The IBM XL C/C++ Compiler provides features to aid in the use of tprof for performance analysis of programs. This document provides a brief introduction to select features of the tprof utility, with focus on features which interact with XL compiler listing files to allow performance analysis at the source-line or instruction level.   In its most simple usage,... [More]

Tags:  tools optimization profiling performance

The variable template, which comes from N3651, is one of the major proposals in Standard C++14. The main purpose of the variable template is to simplify definitions and uses of parameterized constants. [1][2] Rules before C++14 do not allow declaring a variable using a template declaration. There are workarounds for this problem before C++14, but they are either redundant or complicated. The first workaround is constexpr static data members of class templates as shown in Code 1. However, duplicate declarations are required: one inside the class... [More]

  OpenMP is a widely used parallel programming method for shared memory multi-processing. As previous blog( OpenMP support in XL C/C++ and XL Fortran compilers for Linux on Power little endian ) said, on little endian Linux on Power, you could start to use OpenMP with IBM XLC/C++ 13.1.2 to boost application performance.   For the OpenMP specification, you can get it from the OpenMP website: http://openmp.org/wp/openmp-specifications/   ,For more information about the OpenMP features in the XL compilers, you could also reference... [More]

What XL compiler options should I use to optimize C++ code? IBM recently released Version 13.1.2 of the XL C/C++ compiler on Linux, with improved performance for POWER8. With the new focus on POWER Linux, IBM has embraced Clang technology, beginning with XL C/C++ V13.1.1. This strategy of embracing open source technology gives you a seamless migration path to POWER Linux systems. However, one challenge is that the XL C/C++ compiler comes with a wide range of optimization options. Should you use the default optimization options? Under what... [More]

OpenPOWER ABI will bring you more performance gains on function calls, you need to see this article. Improve the performance of function calls with OpenPOWER ABI Anatomy of function calls with OpenPOWER ABI supplement This article is to explain what OpenPOWER application binary interface (ABI) introduces to improve performance of function call. Different from the 64-bit IBM PowerPC® ELF ABI Supplement 1.9 (ELF ABI v1), OpenPOWER ABI gets rid of function descriptor and doesn't require callers to initialize environment any more. Aligned... [More]

IBM's new XL C/C++ compiler for Linux on z Systems Version 1.1, released in 2015, enables support for incorporating user's assembler codes directly into C/C++ programs (inline assembly). Besides the ability to generate highly optimized codes, maximizing hardware utilization, the new compiler provides advanced users with greater flexibility to access instructions at chip level. With inline assembly, software engineers are able to handcraft assembler codes for the most performance-sensitive parts of C/C++ programs. This will further... [More]

Tags:  zsystems assembly z13 inlineasm xlc++ asm acceleration xlc z performance

When migrating your application from big endian to little endian on the IBM POWER8 platform, there are a number of differences that need to be considered.  This can range from vectors, storage association between items of different sizes, long doubles, complex numbers, and serialization.  The IBM XL C/C++ for little endian Linux on Power Systems contains new options and built-in functions to help with your migration.  Here's a link to an article that will help you understand what to look out for and provide suggestions on... [More]

Tags:  xlc power8 migration linux power compilers

Today, IBM announced a brand new C/C++ compiler for Linux on z Systems. Built on top of the advanced optimization technology already in use by the Java and Enterprise COBOL compilers, the XL C/C++ for Linux on z Systems compiler generate highly optimized code to significantly improve runtime performance of applications. It leverages the Clang open source infrastructure for a portion of the compiler front end resulting in a high level of source compatibility with GCC and includes partial support of the latest C11 and C++11 language standards. In... [More]

Tags:  z13 c/c++ zlinux

In June 2014, documentation for XL C/C++ for AIX and Linux, V13.1 was published successfully on IBM Knowledge Center, instead of information center.   Prior to IBM Knowledge Center, IBM product documentation was hosted on various information center servers and maintained separately by various product teams. IBM Knowledge Center provides a central repository for all IBM product documentation. With IBM Knowledge Center, you can easily perform the following tasks with product documentation: 1. Read and search documentation by IBM product... [More]

The XL C and XL C/C++ compilers support the following compiler options and function attributes that control function inlining. The noinline function attribute (IBM extension): prevents the function to which it is applied from being inlined. The always_inline function attribute (IBM extension): instructs the compiler to inline a function. The -qinline compiler option: attempts to inline functions instead of generating calls to those functions, for improved performance. The -qinline+< function_name > option: specifies that the named... [More]

Tags:  inlining

The SuperComputing Conference has served as the crossroads for the entire HPC/Technical Computing community for 25 years. The conference connects with the latest developments through the diverse programs: technical programs, exhibit hall, and HPC Interconnections . During the SC13 silver anniversary celebration this year, IBM was honored to present computer artifacts and a graphical timeline spanning over 67 years of HPC innovation.    The IBM Compiler Team had two of its members in attendance: Yaoqing Gao, Rational STSM in... [More]

I attended Supercomputing in my third year as OpenMP CEO to both represent IBM and OpenMP. This was a big year for us as we closed with many milestones in what I call a Significant Paradigm shift in Parallelism. The most significant milestone was that t he OpenMP Consortium has released OpenMP 4.0 in 2013 with new parallelism features that are productive, portable, and performant across C, C++, and Fortran. OpenMP 4.0 contains significant additions for accelerators, standardized for a broad set of architectures, and an industry-first support... [More]

The usage and advantage of the decltype specifier are introduced in Part I. For details, see https://www.ibm.com/developerworks/community/blogs/5894415f-be62-4bc0-81c5-3956e82276f3/entry/c_11_the_decltype_specifier_part_i?lang=en   The deduction rules of decltype are introduced in Part II. For details, see https://www.ibm.com/developerworks/community/blogs/5894415f-be62-4bc0-81c5-3956e82276f3/entry/c_11_the_decltype_specifier_part_ii?lang=en   In this section, I will state the inheritance of cv-qualifiers and the disposal of redundant... [More]

In Part 1 of this C++ Standard September, 2013 meeting trip report, I wanted to mostly go over the core, library issues that affects C++14 and are urgent for the new Standard to emerge. What some people forget is that while this drive for C++14 is happening, there are still some parts of the Committee working on large and small features beyond C++14. This part will describe the many future feature proposals. Many of these proposals may only get full air time during the plenary session and these plenary sessions are getting longer and... [More]

Tags:  c++ sg standard c++14

We are pleased to announce the Managed Beta Program for IBM®XL C/C++ for Linux on System z. This Beta Program is separated into two stages, namely, features and compatibility, and, quality and performance.   Clients participating in the Managed Beta program will join developers and product management for education and discussions.  Participants will evaluate code and have access to a private website. The beta website will include a tool for reporting problems and feature requests. There will also be a forum for questions and... [More]

Tags:  mainframe systemz zlinux

Having trouble identifying the correct compiler version installed on your AIX machine? There are a couple of ways such as using the -qversion compiler option or lslpp for the correct compiler filesets. Feel free to checkout the technote below for more information. How to determine the installed XL C/C++ for AIX compiler version? Please let me know if you find this useful.

The IBM XL C and XL C/C++ compilers support the -qalias option. This option indicates whether a program contains certain categories of aliasing or does not conform to C/C++ standard aliasing rules. The -qalias option takes several suboptions, including ansi and typeptr .   When ansi is in effect, type-based aliasing is used during optimization; that is, pointers can only point to an object of the same type. The only exception is that a char* dereference can alias any other types.   typeptr complies to more restrictive aliasing rules... [More]

Have you ever wondered why your child threads in a multi-threaded application on AIX fail to acquire a large amount of memory from the stack (even though your ulimits are set to unlimited) ?   The reason is simple. For a 32-bit compiled application on AIX, the default pthread stacksize is 96 KB; and for a 64-bit compiled application on AIX,  the default stacksize is 192 KB. Both of these default values are defined in the pthread.h header file.    Let's use the following test case as an example.  $ cat test.c  ... [More]

As C++ templates and generic programming become popular, programmers find it sometimes difficult to express the type for a variable or function. People are in urgent need of a mechanism to automatically deduce types for expressions. This new programming mechanism didn't appear until the appearance of decltype. Decltype solves the problem through getting the type or derived type of an expression and acting as the type specifier of another expression whose type needs to be deduced. Here is an example:       int i;... [More]

  In the C++11 standard, the auto keyword is no longer a storage class specifier, but acts as a type specifier that directs the compiler to deduce the type of a declared variable from its initialization expression.   With the auto type deduction feature enabled, you no longer need to specify a type while declaring a variable. Instead, the compiler deduces the type of an auto variable from the type of its initializer expression. For example: auto i = 1.1;    // i : double   You can also qualify the auto keyword with... [More]

Tags:  c++11 auto

 Check out updated exercises in the Power sandbox. You can find them here   You can learn about tracking compiler use, performance, auto-vectorization, optimization,  interoperability, debugging and reporting.    

Tags:  exercises compilers try sandbox