Feature-test Macros

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Feature-test Macros#

Description#

oneTBB defines a set of preprocessor macros corresponding to the features provided by the library. They are intended for detecting the presence of these features.

Each of these macros is defined in the header <oneapi/tbb/version.h> and in the feature headers specified in the table below.

For preview features, the feature test macro is only defined if the feature is enabled by defining its preview macro. You cannot use a feature test macro to guard setting of the feature preview macro. For example:

// Wrong
#include <oneapi/tbb/version.h>
#if TBB_HAS_FEATURE_X
#define TBB_PREVIEW_FEATURE_X 1 // Never reached
#include <oneapi/tbb/feature_header.h>
#endif
// Correct
#define TBB_PREVIEW_FEATURE_X 1
#include <oneapi/tbb/version.h>
#if TBB_HAS_FEATURE_X
#include <oneapi/tbb/feature_header.h>
#endif

Each macro value follows the pattern YYYYMM, where YYYY is a year, and MM is a month when the corresponding feature was introduced or updated. These values can be increased if the capabilities of given features are extended. The table below contains only the most recent values.

Feature

Macro Name

Value

Header(s)

Resource Limiting in the Flow Graph

TBB_HAS_FLOW_GRAPH_RESOURCE_LIMITING

202603

<oneapi/tbb/flow_graph.h>

parallel_phase Interface for Task Arena

TBB_HAS_PARALLEL_PHASE

202603

<oneapi/tbb/task_arena.h>

Core Type Selector for Task Arena Constraints

TBB_HAS_TASK_ARENA_CORE_TYPE_SELECTOR

202603
<oneapi/tbb/task_arena.h>
<oneapi/tbb/info.h>

task_group Dynamic Dependencies

TBB_HAS_TASK_GROUP_DEPENDENCIES

202603
<oneapi/tbb/task_group.h>
<oneapi/tbb/task_arena.h>

Waiting for Individual Tasks in task_group

TBB_HAS_TASK_GROUP_WAIT_FOR_SINGLE_TASK

202603
<oneapi/tbb/task_group.h>
<oneapi/tbb/task_arena.h>

Example#

The following example uses a feature-test macro to conditionally enable parallel_phase hints when supported by the library:

#define TBB_PREVIEW_PARALLEL_PHASE 1

#include <oneapi/tbb/version.h>
#include <oneapi/tbb/parallel_for.h>

#if TBB_HAS_PARALLEL_PHASE
#include <oneapi/tbb/task_arena.h>
#endif

int main() {
#if TBB_HAS_PARALLEL_PHASE
    tbb::this_task_arena::start_parallel_phase();
#endif

    tbb::parallel_for(parallel_loop1_begin, parallel_loop1_end,
                      parallel_loop1_body{});

    tbb::parallel_for(parallel_loop2_begin, parallel_loop2_end,
                      parallel_loop2_body{});

#if TBB_HAS_PARALLEL_PHASE
    tbb::this_task_arena::end_parallel_phase(/*with_fast_leave=*/true);
#endif
}
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