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(gcc-300.info)Vector Operations

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Vector Operations
=================

   All normal RTL expressions can be used with vector modes; they are
interpreted as operating on each part of the vector independently.
Additionally, there are a few new expressions to describe specific
vector operations.

`(vec_merge:M VEC1 VEC2 ITEMS)'
     This describes a merge operation between two vectors.  The result
     is a vector of mode M; its elements are selected from either VEC1
     or VEC2.  Which elements are selected is described by ITEMS, which
     is a bit mask represented by a `const_int'; a zero bit indicates
     the corresponding element in the result vector is taken from VEC2
     while a set bit indicates it is taken from VEC1.

`(vec_select:M VEC1 SELECTION)'
     This describes an operation that selects parts of a vector.  VEC1
     is the source vector, SELECTION is a `parallel' that contains a
     `const_int' for each of the subparts of the result vector, giving
     the number of the source subpart that should be stored into it.

`(vec_concat:M VEC1 VEC2)'
     Describes a vector concat operation.  The result is a
     concatenation of the vectors VEC1 and VEC2; its length is the sum
     of the lengths of the two inputs.

`(vec_const:M SUBPARTS)'
     This describes a constant vector.  SUBPARTS is a `parallel' that
     contains a constant for each of the subparts of the vector.

`(vec_duplicate:M VEC)'
     This operation converts a small vector into a larger one by
     duplicating the input values.  The output vector mode must have
     the same submodes as the input vector mode, and the number of
     output parts must be an integer multiple of the number of input
     parts.