Prefetch bytes into the global cache.
void prefetch(const __global gentype *p, size_t num_gentypes);
Prefetch num_gentypes * sizeof(gentype) bytes into the global cache. The prefetch instruction is applied to a work-item in a work-group and does not affect the functional behavior of the kernel.
The generic type name gentype indicates the built-in data types char, char{2|3|4|8|16}, uchar, uchar{2|3|4|8|16}, short, short{2|3|4|8|16}, ushort, ushort{2|3|4|8|16}, int, int{2|3|4|8|16}, uint, uint{2|3|4|8|16}, long, long{2|3|4|8|16}, ulong, ulong{2|3|4|8|16}, float, float{2|3|4|8|16}, or double, double{2|3|4|8|16} as the type for the arguments unless otherwise stated.
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asyncCopyFunctions(3clc)
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OpenCL Specification
page 276, section 6.12.10 - Async Copies from Global to Local Memory...