forked from OSchip/llvm-project
118 lines
3.8 KiB
ReStructuredText
118 lines
3.8 KiB
ReStructuredText
OpenMP Optimization Remarks
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===========================
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The :doc:`OpenMP-Aware optimization pass </optimizations/OpenMPOpt>` is able to
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generate compiler remarks for performed and missed optimisations. To emit them,
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pass these options to the Clang invocation: ``-Rpass=openmp-opt
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-Rpass-analysis=openmp-opt -Rpass-missed=openmp-opt``. For more information and
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features of the remark system, consult the clang documentation:
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+ `Clang options to emit optimization reports <https://clang.llvm.org/docs/UsersManual.html#options-to-emit-optimization-reports>`_
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+ `Clang diagnostic and remark flags <https://clang.llvm.org/docs/ClangCommandLineReference.html#diagnostic-flags>`_
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+ The `-foptimization-record-file flag
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<https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-foptimization-record-file>`_
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and the `-fsave-optimization-record flag
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<https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang1-fsave-optimization-record>`_
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OpenMP Remarks
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--------------
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.. toctree::
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:hidden:
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:maxdepth: 1
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OMP100
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OMP101
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OMP102
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OMP110
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OMP111
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OMP112
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OMP113
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OMP120
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OMP121
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OMP130
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OMP131
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OMP132
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OMP133
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OMP140
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OMP150
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OMP160
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OMP170
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OMP180
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OMP190
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.. list-table::
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:widths: 15 15 70
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:header-rows: 1
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* - Diagnostics Number
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- Diagnostics Kind
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- Diagnostics Description
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* - :ref:`OMP100 <omp100>`
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- Analysis
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- Potentially unknown OpenMP target region caller.
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* - :ref:`OMP101 <omp101>`
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- Analysis
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- Parallel region is used in unknown / unexpected ways. Will not attempt to
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rewrite the state machine.
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* - :ref:`OMP102 <omp102>`
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- Analysis
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- Parallel region is not called from a unique kernel. Will not attempt to
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rewrite the state machine.
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* - :ref:`OMP110 <omp110>`
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- Optimization
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- Moving globalized variable to the stack.
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* - :ref:`OMP111 <omp111>`
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- Optimization
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- Replaced globalized variable with X bytes of shared memory.
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* - :ref:`OMP112 <omp112>`
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- Missed
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- Found thread data sharing on the GPU. Expect degraded performance due to
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data globalization.
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* - :ref:`OMP113 <omp113>`
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- Missed
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- Could not move globalized variable to the stack. Variable is potentially
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captured in call. Mark parameter as `__attribute__((noescape))` to
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override.
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* - :ref:`OMP120 <omp120>`
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- Optimization
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- Transformed generic-mode kernel to SPMD-mode.
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* - :ref:`OMP121 <omp121>`
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- Analysis
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- Value has potential side effects preventing SPMD-mode execution. Add
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`__attribute__((assume(\"ompx_spmd_amenable\")))` to the called function
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to override.
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* - :ref:`OMP130 <omp130>`
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- Optimization
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- Removing unused state machine from generic-mode kernel.
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* - :ref:`OMP131 <omp131>`
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- Optimization
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- Rewriting generic-mode kernel with a customized state machine.
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* - :ref:`OMP132 <omp132>`
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- Analysis
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- Generic-mode kernel is executed with a customized state machine that
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requires a fallback.
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* - :ref:`OMP133 <omp133>`
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- Analysis
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- Call may contain unknown parallel regions. Use
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`__attribute__((assume("omp_no_parallelism")))` to override.
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* - :ref:`OMP140 <omp140>`
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- Analysis
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- Could not internalize function. Some optimizations may not be possible.
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* - :ref:`OMP150 <omp150>`
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- Optimization
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- Parallel region merged with parallel region at <location>.
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* - :ref:`OMP160 <omp160>`
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- Optimization
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- Removing parallel region with no side-effects.
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* - :ref:`OMP170 <omp170>`
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- Optimization
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- OpenMP runtime call <call> deduplicated.
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* - :ref:`OMP180 <omp180>`
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- Optimization
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- Replacing OpenMP runtime call <call> with <value>.
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* - :ref:`OMP190 <omp190>`
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- Optimization
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- Redundant barrier eliminated. (device only)
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