Intel® Fortran Compiler Classic and Intel® Fortran Compiler Developer Guide and Reference

ID 767251
Date 11/07/2023
Public

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Document Table of Contents

New Features for ifx Only

ifx is now fully compliant with Fortran 2018, and it has feature parity with ifort.

New Features

  • Option -fopenmp-device-code-split (Linux) and /Qopenmp-device-code-split (Windows), which enable parallel compilation of SPIR-V* kernels for OpenMP offload Ahead-Of-Time compilation. For more information, see fopenmp-device-code-split, Qopenmp-device-code-split.

  • Option -fopenmp-max-parallel-link-jobs (Linux) and /Qopenmp-max-parallel-link-jobs (Windows), which determine the maximum number of parallel actions to be performed during device linking steps, where applicable.. For more information, see fopenmp-max-parallel-link-jobs, Qopenmp-max-parallel-link-jobs.

  • Option fsanitize, which enables the specified code sanitizer to detect certain issues at runtime. For more information, see fsanitize.

  • Option fprofile-ml-use, which enables the use of a pre-trained machine learning model to predict branch execution probabilities driving profile-guided optimizations. For more information, see fprofile-ml-use.

  • Options -mno-gather (Linux) and /Qgather- (Windows), which disable the generation of gather instructions in auto-vectorization. For more information, see mno-gather, Qgather-.

  • Options -mno-scatter (Linux) and /Qscatter- (Windows), which disable the generation of scatter instructions in auto-vectorization. For more information, see mno-scatter, Qscatter-.

  • Options -mauto-arch (Linux) and /Qauto-arch (Windows), which tell the compiler to generate multiple, feature-specific auto-dispatch code paths for x86 architecture processors if there is a performance benefit. For more information, see mauto-arch, Qauto-arch.

  • Option -flink-huge-device-code, which tells the compiler to place device code later in the linked binary. This is to prevent 32-bit PC-relative relocations between surrounding Executable and Linkable Format (ELF) sections when the device code is larger than 2GB. For more information, see flink-huge-device-code. Previous option -fsycl-link-huge-device-code is now deprecated and will be removed in a future release.

New OpenMP* Features

  • You can now specify contexts and context selectors. For more information, see OpenMP* Contexts. Context selectors are permitted in the MATCH clause in the DECLARE VARIANT directive. For more information, see DECLARE VARIANT.

  • For DEPOBJ directives, the previous syntax for clause DESTROY has been deprecated. The new syntax is DESTROY (destroy-var). For more information, see DEPOBJ.

  • In a TASKLOOP directive, you can now specify modifier STRICT for clauses GRAINSIZE and NUM_TASKS. For more information, see TASKLOOP.

  • The ORDER clause replaces the ORDER (CONCURRENT) clause. For more information, see ORDER Clause.

  • You can now specify an ORDER clause in the DISTRIBUTE directive. For more information, see DISTRIBUTE Clause.

  • GROUPPRIVATE directive

    Specifies that a variable is replicated once per group of threads participating in a parallel region. For more information, see GROUPPRIVATE.

  • DEVICE_TYPE clause

    Specifies whether a version of a procedure or a copy of a data entity is to be available on a HOST device, a non-HOST device, or both. For more information, see DEVICE_TYPE.

Previous Features Added to ifx

  • Option fopenmp-default-allocator (and Qopenmp-default-allocator), which tells the compiler that all Fortran ALLOCATE statements should be treated as though there was an explicit OpenMP ALLOCATE directive that preceded them. For more information, see fopenmp-default-allocator, Qopenmp-default-allocator.

  • Enhancement to option -check uninit for Linux. For more information, see option check.

  • ALLOCATORS directive

    Specifies memory allocators to be used to allocate variables in the associated Fortran ALLOCATE statement and to use in their deallocation. For more information, see ALLOCATORS.

  • TILE directive

    Tiles (or blocks) one or more loops of a loop-nest. For more information, see TILE.

  • Iterators are now supported in the DEPEND clause.

  • Optional END construct directives are now supported with strictly structured block construct bodies.

  • ASSUMES directive

    Provides hints to the optimizer about the current compilation unit and all the code it can reach through procedure calls. For more information, see ASSUMES.

  • ERROR directive

    Causes the compiler or runtime system to process an error condition. For more information, see ERROR.

  • NOTHING directive

    Provides documentary clarity in conditionally compiled code or conditional OpenMP code. It has no effect on the semantics or execution of the program. For more information, see NOTHING .

  • new clauses LINK and INDIRECT for directive DECLARE TARGET

    The LINK clause maps the list items for specific device executions, supporting functions called in a TARGET region that refer to the list items. The INDIRECT clause determines whether procedures specified in an ENTER clause can be called by an indirect device invocation. For more information, see DECLARE TARGET.

  • PREFETCH directive for OpenMP

    This is an Intel® language extension. For more information, see PREFETCH.

  • DEPOBJ construct

    Initializes, updates, or uninitializes an OpenMP depend object. For more information, see DEPOBJ.

  • INTEROP clause for DISPATCH

    For more information, see DISPATCH.

  • DEPEND types MUTEXINOUTSET, INOUTSET, and DEPOBJ

    For more information, see DEPEND.

  • DECLARE MAPPER with variable length arrays

    For more information, see DECLARE MAPPER.

  • PREFER_TYPE in the APPEND_ARGS clause of DECLARE VARIANT

    For more information, see DECLARE VARIANT.

  • SCOPE construct

    For more information, see SCOPE.

  • Compiler option flto

    Enables whole program link time optimization (LTO). For more information, see flto.

    Note that this option is equivalent to option [Q]ipo on ifort.

  • OpenMP 5.1 feature: UNROLL construct

    Partially or fully unrolls a DO loop. For more information, see UNROLL.

  • OpenMP 5.1 feature: You can now specify PRESENT as a map-type-modifier in a MAP clause. For more information, see MAP .

  • OpenMP 5.1 feature: SCAN directive (previously in ifort)

    Specifies a scan computation that updates each list item in each iteration of the loop. For more information, see SCAN .

  • Compiler option fopenmp-target-do-concurrent and Qopenmp-target-do-concurrent

    This option determines whether a DO CONCURRENT construct is automatically converted into an OpenMP* TARGET region. For more information, see fopenmp-target-do-concurrent, Qopenmp-target-do-concurrent.

  • Support for ATTRIBUTES directives DLLIMPORT and DLLEXPORT

    These directives enable you to create and use dynamic libraries in the Windows environment.

  • Fortran 2018 coarray features and coarrays with allocatable fields

    Coarrays, including Fortran 2018 teams and events, are now fully supported.

  • Support for Fortran 2018 C interoperability

    All C interoperability features, including assumed rank arrays and C array descriptors are now supported.

  • Support for compiler option check bounds

    Array bounds checking is now supported

  • Support for general directive !DIR$ ASSUME

    The !DIR$ ASSUME directive is now supported for the check and assume options that ifx supports.

  • Support for compiler option [Q]init

    This option allows classes of variables to be initialized to zero or IEEE exceptional values.

  • Support for dynamic COMMON

    Compiler option [Q]dyncom allows COMMON blocks to be allocated dynamically instead of statically.

  • F2008 Parameterized derived types (PDTs).

  • IEEE compares (-assume ieee_compares).

  • The DIM argument of many array intrinsics can now be a present optional argument.

  • VAX union and structures (Intel language extension).

  • The argument to the C_LOC function in the intrinsic module ISO_C_BINDING now conforms to the Fortran standard definition.

  • DECLARE MAPPER directive

    Declares a user-defined mapper for the specified type, and optionally declares a map-identifier which can be used in a MAP clause on other directives or in a motion-clause of a TARGET UPDATE directive. For more information, see DECLARE MAPPER.

  • FIRSTPRIVATE and PRIVATE clauses have been added to the TARGET directive, and implicit-behaviors ALLOC, TO, TOFROM, FROM, FIRSTPRIVATE, NONE and default have been added to the DEFAULTMAP clause of the TARGET directive. For more information, see TARGET.

  • You can now specify implicit-behavior in the DEFAULTMAP clause for the TARGET directive. For more information, see TARGET.

  • You can now specify the TO clause for the DECLARE TARGET directive. For more information, see DECLARE TARGET.

  • ifx provides improved debugging of CPU and offloaded code.

  • Variable expressions are supported in FORMAT specifiers. See Variable Format Expressions.

  • Option [q or Q]opt-for-throughput

    Determines how the compiler optimizes for throughput depending on whether the program is to run in single-job or multi-job mode. For more information see qopt-for-throughput, Qopt-for-throughput.

  • You can now specify the DEPEND clause and the NOWAIT clause in an OpenMP* TASKWAIT directive.

  • You can now specify PRIMARY as a PROC_BIND specifier in an OpenMP* PARALLEL directive.

  • Option -fopenmp-target-buffers=default|4G and /Qopenmp-target-buffers:default|4G

    Specifying 4G enables a way to overcome the problem where some offload SPIR_V devices produce incorrect code when a target object is greater than 4GB. For more information see fopenmp-target-buffers, Qopenmp-target-buffers.

  • Option -fopenmp has been deprecated, use option -qopenmp or option -fiopenmp.

  • You can now specify BLOCK constructs.

  • You can now specify intrinsic routine EXECUTE_COMMAND_LINE.

  • You can now specify intrinsic routine FINDLOC.

  • You can now specify the BACK argument in MAXLOC and MINLOC intrinsic routines.

  • You can now specify the IN_REDUCTION clause and the HAS_DEVICE_ADDR clause in the TARGET directive.

  • You can now specify the ALIGN clause in an ALLOCATE directive.

  • You can now specify the ALIGN modifier in an ALLOCATE clause.

  • You can now specify the MASKED construct (without the FILTER clause) as an alternate to MASTER, which has been deprecated.

  • You can now specify OpenMP* combined constructs with MASKED or MASTER in them.

  • Preprocessor cmake macro __INTEL_LLVM_COMPILER

    Is replaced by the version of the compiler in format VVVVMMUU. For more information on the macro and format, see Using Predefined Preprocessor Symbols.

  • Enhancement to the DECLARE VARIANT directive

    You can now specify clauses ADJUST_ARGS and APPEND_ARGS and you can specify one or more architectures in the MATCH (context-selector-specification) for the directive. For more information, including what architecture values you can specify, see DECLARE VARIANT.

  • Intel-specific OpenMP* memory allocators

    You can now specify additional predefined memory spaces that are Intel extensions to the OpenMP* standard. For more information, see OpenMP* Memory Spaces and Allocators.

  • TASK and DEFAULT OpenMP* reduction modifiers

    You can now specify TASK and DEFAULT in REDUCTION clauses. For more information, see REDUCTION.

  • USE_DEVICE_ADDR clause

    Indicates that list iems in the structured block of the construct are references to the device address of the item if the item has corresponding storage in the device data environment. For more information, see TARGET DATA.

  • Compiler option fopenmp-targets and Qopenmp-targets

    Enables offloading to a specified GPU target if OpenMP* features have been enabled. For more information, see fopenmp-targets, Qopenmp-targets.

  • ALLOCATE clause

    Specifies the memory allocator to be used for one or more private variables or common blocks of a construct. For more information, see ALLOCATE Clause.

  • ALLOCATE directive

    Specifies memory allocators to use for object allocation and deallocation. For more information, see ALLOCATE Directive.

  • DECLARE VARIANT directive

    Identifies a variant of a base procedure and specifies the context in which this variant is used. For more information, see DECLARE VARIANT.

  • DISPATCH directive

    Determines if a variant of a procedure is called for a given function or subroutine call. For more information, see DISPATCH.

  • INTEROP directive

    Identifies a foreign runtime context and identifies runtime characteristics of that context, enabling interoperability with it. For more information, see INTEROP.

  • LOOP construct

    Specifies that the iterations of the associated loops can execute concurrently. For more information, see LOOP.

  • ORDER (CONCURRENT) clause

    Indicates that the iterations of the loop may execute in any order or simultaneously. For more information, see LOOP and DO Directive.

  • PARALLEL LOOP directive

    Specifies a shortcut for indicating that a loop or loop nest can execute concurrently across multiple threads. For more information, see PARALLEL LOOP.

  • REQUIRES directive

    Lists the features that an implementation must support so that the program compiles and runs correctly. For more information, see REQUIRES.

  • TARGET PARALLEL LOOP directive

    Specifies a shortcut for specifying a parallel loop inside a TARGET construct that contains no other statements than the parallel loop. For more information, see TARGET PARALLEL LOOP.

  • TARGET TEAMS LOOP construct

    Specifies a shortcut for specifying a TEAMS LOOP construct inside a TEAMS construct that contains no other statements. For more information, see TARGET TEAMS LOOP.

  • TARGET VARIANT DISPATCH directive

    Conditionally calls a procedure offload variant if the device is free; otherwise, executes the procedure on the host. For more information, see TARGET VARIANT DISPATCH.

  • TEAMS construct

    You can now specify a TEAMS construct outside of a TARGET region. For more information about about the construct, see TEAMS.

  • TEAMS LOOP construct

    Specifies a shortcut for specifying a LOOP construct inside a TEAMS construct. For more information, see TEAMS LOOP.