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Generating NEON instructions from C or C++ code

You must use RVCT 3.1 or later, or ARM Compiler 4.1 or later, with a valid NEON compiler license.

To generate NEON instructions from C or C++ code, you must specify the following compiler options:

  • a target --cpu that has NEON capability, for example Cortex-A7, Cortex-A8, Cortex-A9, or Cortex-A15

  • --vectorize to enable NEON vectorization

  • -O2 (default) or -O3 optimization level

  • -Otime to optimize for performance instead of code size.

You can also use --diag_warning=optimizations to obtain useful diagnostics from the compiler on what it can and cannot optimize or vectorize. For example:

armcc --cpu Cortex-A8 --vectorize -O3 -Otime --diag_warning=optimizations source.c

See also

Other information

Introducing the ARM Compiler toolchain: