43 lines
1.2 KiB
ReStructuredText
43 lines
1.2 KiB
ReStructuredText
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.. _omp150:
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Parallel region merged with parallel region at <location>. [OMP150]
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===================================================================
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This optimization remark indicates that a parallel region was merged with others
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into a single parallel region. Parallel region merging fuses consecutive
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parallel regions to reduce the team activation overhead of forking and increases
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the scope of possible OpenMP-specific optimizations within merged parallel
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regions. This optimization can also guard sequential code between two parallel
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regions if applicable.
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Example
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-------
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This optimization should apply to any compatible and consecutive parallel
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regions. In this case the sequential region between the parallel regions will be
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guarded so it is only executed by a single thread in the new merged region.
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.. code-block:: c++
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void foo() {
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#pragma omp parallel
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parallel_work();
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sequential_work();
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#pragma omp parallel
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parallel_work();
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}
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.. code-block:: console
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$ clang++ -fopenmp -O2 -Rpass=openmp-opt -mllvm -openmp-opt-enable-merging omp150.cpp
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omp150.cpp:2:1: remark: Parallel region merged with parallel region at merge.cpp:7:1. [OMP150]
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#pragma omp parallel
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^
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Diagnostic Scope
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----------------
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OpenMP optimization remark.
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