Intel® Fortran Compiler Professional Edition offers the best support for creating multi-threaded applications. Only the Professional Edition offers the breadth of advanced optimization, multi-threading, and processor support that includes automatic processor dispatch, vectorization, auto-parallelization, OpenMP*, data prefetching, loop unrolling, substantial Fortran 2003 support, and an optimized math processing library.


The Professional Edition combines a high performance compiler with Intel® Math Kernel Library (Intel® MKL). While this library is available separately, the Professional Edition creates a strong foundation for building robust, high performance parallel code at significant price savings.

The Standard Edition compiler has the same performance and features as the Professional Edition compiler, but does not include Intel MKL.

Cluster OpenMP* for Intel Fortran Compiler for Linux is also available to provide all the functionality of the Intel Fortran Compiler for Linux, plus a simple means of extending OpenMP parallelism to 64-bit Intel® architecture-based clusters.

Product Brief [PDF 696KB]

The Intel Fortran Compiler for Linux delivers rapid development and winning performance for the full range of Intel® processor-based platforms. It is a full-language Fortran 95 compiler with many features from the Fortran 2003 standard, plus a wide range of popular extensions. Automatically optimize and parallelize software to take best advantage of multi-core Intel processors, including dual-core mobile, desktop, and enterprise platforms.

Performance

Intel Fortran Compiler Professional Edition lets you choose the tools that get most out of multi-core processors by combining the Fortran compiler and its built-in optimization, threading, and security capabilities with a highly optimized math library that simplifies the introduction of robust, scalable, multi-threaded math functions.


Advanced Optimization Features

Software compiled using the Intel Fortran Compiler for Linux benefits from advanced optimization features, a few of which are explained briefly here, with links to more complete descriptions:

• Multithreaded Application Support, including OpenMP and auto-parallelization for simple and efficient software threading.
• Auto-vectorization parallelizes code to utilize the Streaming SIMD Extensions (SSE) instruction set architectures (SSE, SSE2, SSE3, SSSE3, and SSE4) of our latest processors.
• High-Performance Parallel Optimizer (HPO) restructures and optimizes loops to ensure that auto-vectorization, OpenMP, or auto-parallelization best utilizes the processor’s capabilities for cache and memory accesses, SIMD instruction sets, and for multiple cores. This revolutionary capability, new for 10.0, combines vectorization, parallelization and loop transformations into a single pass which is faster, more effective and more reliable than prior discrete phases.
• Interprocedural Optimization (IPO) dramatically improves performance of small- or medium-sized functions that are used frequently, especially programs that contain calls within loops. The analysis capabilities of this optimizer can also give feedback on vulnerabilities and coding errors, such as uninitialized variables or OpenMP API issues, which cannot be detected as well by compilers which rely strictly on analysis by a compiler front-end.
• Profile-Guided Optimization (PGO) improves application performance by reducing instruction-cache thrashing, reorganizing code layout, shrinking code size, and reducing branch mispredictions.
• Optimized Code Debugging with the Intel® Debugger improves the efficiency of the debugging process on code that has been optimized for Intel architecture.

The Intel Fortran Compiler for Linux builds on a winning foundation. Position yourself to create next-generation software, for next-generation hardware.

What’s new	Benefit to you
More Fortran 2003 features	C Interoperability features make it easier to develop mixed-language applications. Asynchronous I/O enhances performance of applications which read and write large files. See the compiler Release Notes for a full list of supported Fortran 2003 features.
Improved Performance and Threading New Parallel/Loop Optimizer (HPO)	Better application performance for computationally intensive applications such as graphics/digital media, financial modeling, and high-performance computing for threaded and non-threaded applications. Our new High Performance Parallel Optimizer, HPO, offers an improved ability to analyze, optimize, and parallelize more loop nests.
Security Checking and Diagnostics GNU Mudflap Static Verifier for buffer overflow OpenMP* API verification.	Ability to create code that is less susceptible to security vulnerabilities, such as buffer overflow. The diagnostics are very helpful for novice and expert users for catching common coding errors, from uninitialized variables to mismatched dummy and actual arguments to OpenMP API coding issues.
Optimization Reports	More detailed optimization diagnostics for users who want to use our advanced optimizations to help the compiler do a better job at tuning their applications. The new VTune™ Analyzer 9.0 can filter optimization reports to help guide optimization efforts.
Support for the Latest Multi-Core Processors The Intel Fortran Compiler provides optimization support for the very latest multi-core Intel processors, including: Intel® Core™2 Duo processor Intel® Core™2 Quad processor Quad-Core Intel® Xeon® processor 5300 series Dual-Core Intel® Xeon® processor 3000 series Dual-Core Intel® Xeon® processor 5000 series Dual-Core Intel® Xeon® processor 7000 series Dual-Core Intel® Itanium® 2 processor	Intel® compilers future-proof your investment with assurances that they rapidly provide world-class support for each successive generation of processors. That's a key advantage in a world where new hardware platforms come to market with awesome speed. Support for auto-parallelization and OpenMP enable you to create optimized, multithreaded applications that take full advantage of multi-core processing features to deliver outstanding performance.
Professional Edition	Includes not only the advanced capabilities of the compiler, but also the Intel Math Kernel Library (Intel MKL) with highly optimized functions for math processing.

This section gives detailed descriptions of the compiler’s advanced optimization features.

Multithreaded Application Support

OpenMP and auto-parallelization help convert serial applications into parallel applications, allowing you to take full advantage of multi-core technology like the Intel® Core™ Duo processor and Dual-Core Intel Itanium 2 processor, as well as symmetric multiprocessing systems:

• OpenMP is the industry standard for portable multithreaded application development. It is effective at fine-grain (loop-level) and large-grain (function-level) threading.
  
  OpenMP directives are an easy and powerful way to convert serial applications into parallel applications, enabling potentially big performance gains from parallel execution on multi-core and symmetric multiprocessor systems.
• Auto Parallelization improves application performance on multiprocessor systems by means of automatic threading of loops. This option detects parallel loops capable of being executed safely in parallel and automatically generates multithreaded code.
  
  Automatic parallelization relieves the user from having to deal with the low-level details of iteration partitioning, data sharing, thread scheduling, and synchronizations. It also provides the performance benefits available from multiprocessor systems and systems that support Hyper-Threading Technology.

For more information on multithreaded application support, visit Intel's Threading Developer Center.


High Performance, Parallel Optimizer (HPO)

This revolutionary capability, new for 10.0, combines automatic vectorization, automatic parallelization and loop transformations into a single pass which is faster, more effective and more reliable than prior discrete phases.

HPO optimizes and restructures program loops to ensure that auto-parallelization, OpenMP and auto-vectorization occur smoothly in conjunction with each other. HPO’s optimization technology utilizes a unique cost-benefit analysis to make the right optimization decisions for the given program and loop structure. It will perform many transformations such as loop unrolling, peeling, interchange, splitting, etc., as well as other optimizations to ensure the processor’s cache architecture, SIMD instruction set, and multiple cores are well utilized. These loop transformation are done automatically so that manual code changes are not required.

Automatic Vectorizer

Vectorization automatically parallelizes code to maximize underlying processor capabilities. This advanced optimization analyzes loops and determines when it is safe and effective to execute several iterations of the loop in parallel by utilizing MMX™, SSE, SSE2, and SSE3 instructions. Figure 1. is a graphical representation of a vectorized loop that shows four iterations computed with one SSE2 operation.

Use vectorization to optimize your application code and take advantage of these new extensions when running on Intel processors. Features include support for advanced, dynamic data alignment strategies, including loop peeling to generate aligned loads and loop unrolling to match the prefetch of a full cache line.



Interprocedural Optimization (IPO)

Interprocedural optimization (IPO) can dramatically improve application performance in programs that contain many small- or medium-sized functions that are frequently used, especially for programs that contain calls within loops. This set of techniques, which can be enabled for automatic operation in the Intel compilers, uses multiple files or whole programs to detect and perform optimizations, rather than focusing within individual functions.



The IPO process, shown in Figure 2, first requires that source files are compiled with the IPO option, creating object (.o) files that contain the intermediate language (IL) used by the compiler. Upon linking, the compiler combines all of the IL information and analyzes it for optimization opportunities. Typical optimizations made as part of the IPO process include procedure inlining and re-ordering, eliminating dead (unreachable) code, and constant propagation, or the substitution of known values for constants. IPO enables more aggressive optimization than what is available at the intra-procedural level, since the added context of multiple procedures makes those more-aggressive optimizations safe.

The analysis capabilities of IPO can also give feedback on vulnerabilities and coding errors, such as uninitialized variables, which cannot be detected as well by compilers which rely strictly on analysis by a compiler front-end.

Profile-Guided Optimization (PGO)

The Profile-guided optimization (PGO) compilation process enables the Intel C++ compiler to take better advantage of the processor microarchitecture, more effectively use instruction paging and cache memory, and make better branch predictions. It improves application performance by reorganizing code layout to reduce instruction-cache thrashing, shrinking code size and reducing branch mispredictions.

PGO is a three-stage process, as shown in Figure 3. Those steps include 1) a compile of the application with instrumentation added, 2) a profile-generation phase, where the application is executed and monitored, and 3) a recompile where the data collected during the first run aids optimization. A description of several code size influencing profile-guided optimizations follows:

• Basic block and function ordering — Place frequently-executed blocks and functions together to take advantage of instruction-cache locality.
• Aid inlining decisions — Inline frequently-executed functions so the increase in code size is paid in areas of highest performance impact.
• Aid vectorization decisions — Vectorize high trip count and frequently-executed loops so the increase in code size is mitigated by the increase in performance.

Optimized Code Debugging with the Intel Debugger

The Intel Debugger enables optimized code debugging (i.e., debugging code that has been significantly transformed for optimal execution on specific hardware architecture). Intel compilers produce standards-compliant debug information for optimized code debugging that is available to all debuggers that support Intel compilers. The Intel Debugger supports multi-core architectures by enabling debugging of multithreaded applications, providing the following related capabilities:

• An all-stop/all-go execution model (i.e., all threads are stopped when one is stopped, and all threads are resumed when one is resumed)
• List all created threads
• Switch focus between threads
• Examine detailed thread state
• Set breakpoints (including all stop, trace and watch variations) and display a back-trace of the stack for all threads or for a subset of threads
• The built-in GUI provides a thread panel (on the Current Source pane) that activates when a thread is created, and that allows an operator to select thread focus and display related details

The recently enhanced GNU Project Debugger (GDB debugger) can also be used for parallel applications. For additional information, please refer to the Intel Debugger Technical White Paper.

Standards Compliance and Broad Compatibility

The Intel Fortran Compiler 10.0 for Linux fully supports the Fortran 95 language standard, as well as the previous standards Fortran 90, Fortran 77 and Fortran IV. It also includes many features from the Fortran 2003 language standard, as well as numerous popular language extensions. Significant supported language extensions include:

• Quadruple precision REAL data type REAL(16)
• STRUCTURE, RECORD, UNION, MAP syntax for user-defined types
• Directives and functions to enhance mixed-language application development
• Binary stream I/O

For a complete list of language features, see the product documentation.

The Intel Fortran Compiler 10.0 for Linux also enhances programmer productivity with features such as:

• Run-time array and string bounds checking
• Cross-file procedure interface checking
• Run-time uninitialized variable detection
• Error traceback with file name and line number

Winning Performance across Application Domains

The Intel Fortran Compiler for Linux delivers exceptional performance, usability, and business advantages to a wide variety of software markets.



Next-generation data-intensive application developers benefit from dramatic performance optimizations using the Intel compilers to decrease latency and processing times, while also allowing software architects to add additional features without unacceptable impacts to performance.


Scientific, research, and related applications benefit from fast compile times, high-performance execution, and solid technical support. Numerically intensive software can make excellent use of the parallelism in Intel processor-based platforms.

With the purchase of an Intel Fortran Compiler, you will receive one year of technical support and product updates from Intel® Premier Support, our interactive issue management and communication web site. This premium support service allows you to submit questions, download product updates, and access technical notes, application notes, and other documentation. For more information, visit the Intel® Registration Center.

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This section provides system requirements to develop applications for three different hardware platforms, which are described below.

Processor Terminology

Intel compilers support three platforms: general combinations of processor and operating system type. This section explains the terms that Intel uses to describe the platforms in its documentation, installation procedures and support site.

IA-32 architecture - IA-32 (Intel Architecture, 32-bit) architecture refers to systems based on 32-bit processors supporting at least the Pentium® II instruction set, (for example, Intel® Core™ architecture-based processor or Intel® Xeon® processor), or processors from other manufacturers supporting the same instruction set, running a 32-bit operating system ("Linux x86").

Intel® 64 architecture - Intel 64 architecture (formerly Intel® EM64T) refers to systems based on IA-32 architecture-based processors which have 64-bit architectural extensions, (for example, Intel® Core™2 processor family or Intel Xeon processor), running a 64-bit operating system ("Linux x86_64"). If the system is running a 32-bit version of the Linux operating system, then IA-32 architecture applies instead. Systems based on the AMD* Athlon64* and Opteron* processors running a 64-bit operating system are also supported by Intel compilers for Intel 64 architecture-based applications.

IA-64 architecture - Refers to systems based on the Intel Itanium 2 processor running a 64-bit operating system.

Native and Cross-Platform Development
The term "native" refers to building an application that will run on the same platform that it was built on, for example, building on IA-32 architecture to run on IA-32 architecture. The term "cross-platform" or "cross-compilation" refers to building an application on a platform type different from the one on which it will be run, for example, building on IA-32 architecture to run on IA-64 architecture. Not all combinations of cross-platform development are supported, and some combinations may require installation of optional tools and libraries.

The following list describes the supported combinations of compilation host (system on which you build the application) and application target (system on which the application runs).

• IA-32 architecture host - Supported target: IA-32 architecture
• Intel 64 architecture host - Supported targets: IA-32 and Intel 64 architectures
• IA-64 architecture host - Supported target: IA-64 architecture

Note: Development for a target different from the host may require optional library components to be installed from your Linux Distribution.

Note: Cluster OpenMP for Intel Compilers for Linux is a separately licensed feature and has different system requirements from that of the compilers. Please refer to the product website for further details.

• Requirements to develop IA-32 architecture-based applications
• Requirements to develop applications for processors that support Intel 64 Architecture or for AMD Opteron processors
• Requirements to develop IA-64 architecture-based applications

Component	Minimum	Recommended
Processor	A system based on an IA-32 architecture-based processor (minimum 450 MHz), Intel 64 architecture-based processor, or a system based on an AMD Athlon or AMD Opteron processor.	Intel Core Duo processor Intel® Pentium® 4 processor Intel® Pentium® D processor Intel Xeon processor
RAM	256MB	512MB
Disk Space	100 MB of disk space, plus an additional 200 MB during installation for the download and temporary files	NA
Operating System	Linux system with glibc 2.2.4, 2.2.5, 2.2.93, 2.3.2 , 2.3.3, 2.3.4, or 2.3.5 and the 2.4.X or 2.6.X Linux kernel as represented by the following distributions. Note: Not all distributions listed are validated and not all distributions are listed. Fedora* Core 6 Mandriva* Linux 2007 Red Flag* DC Server 5.0 Red Hat Enterprise Linux* 3, 4, 5 SUSE LINUX Enterprise Server* 9, 10 TurboLinux* 10	NA
Other Software	Linux Developer tools component installed, including gcc 3.2 or later, g++ and related tools. Linux component compat-libstdc++ providing libstdc++.so.5	NA

Component	Minimum	Recommended
Processor	Intel processor with Intel 64 architecture	Intel Core 2 processor family Intel Xeon processor
RAM	256MB	512MB
Disk Space	300 MB free hard disk space, plus an additional 300 MB during installation for download and temporary files. 100 MB of hard disk space for the virtual memory paging file. Be sure to use at least the minimum amount of virtual memory recommended for the installed distribution of Linux.	NA
Operating System	Linux system with glibc 2.2.93, 2.3.2, 2.3.3, 2.3.4 or 2.3.5 and the 2.4.X or 2.6.X Linux kernel as represented by the following Linux distributions, running in 64-bit mode. Note: Not all distributions listed are validated and not all distributions are listed. Fedora Core 6 Mandriva Linux 2007 Red Flag DC Server 5.0 Red Hat Enterprise Linux 3, 4, 5 SGI ProPack 4, 5 SUSE LINUX Enterprise Server 9, 10 TurboLinux 10	NA
Other Software	Linux Developer tools component installed, including gcc 3.2 or later, g++ and related tools. Linux component compat-libstdc++ providing libstdc++.so.5	NA

Component	Minimum	Recommended
Processor	Itanium 2 processor	NA
RAM	512MB	1GB
Disk Space	150 MB of disk space, plus an additional 200 MB during installation for the download and temporary files.	NA
Operating System	Linux system with glibc 2.2.4, 2.2.93, 2.3.2, 2.3.3 or 2.3.4 and the 2.4.X or 2.6.X Linux kernel as represented by the following distributions. Note: Not all distributions listed are validated and not all distributions are listed. Red Flag DC Server 5.0 Red Hat Enterprise Linux 3, 4, 5 SGI ProPack 5 SUSE LINUX Enterprise Server 9, 10 TurboLinux 10	NA
Other Software	Linux Developer tools component installed, including gcc 3.2 or later, g++ and related tools. Linux component compat-libstdc++ providing libstdc++.so.5	We recommend using binutils 2.14 or later, especially if using shared libraries as there are known issues with binutils 2.11

Notes:

The above lists of processor model names are not exhaustive - other processor models correctly supporting the same instruction set as those listed are expected to work. Please contact Intel® Premier Support if you have questions regarding a specific processor model.

Compiling very large source files (several thousands of lines) using advanced optimizations such as -O3, -ipo and -openmp, may require substantially larger amounts of RAM.

Some optimization options have restrictions regarding the processor type on which the application is run. Please see the documentation of these options for more information.