Add new optabs for reducing vectors to scalars
PR tree-optimization/61114
* doc/md.texi (Standard Names): Add reduc_(plus,[us](min|max))|scal
optabs, and note in reduc_[us](plus|min|max) to prefer the former.
* expr.c (expand_expr_real_2): Use reduc_..._scal if available, fall
back to old reduc_... + BIT_FIELD_REF only if not.
* optabs.c (optab_for_tree_code): for REDUC_(MAX,MIN,PLUS)_EXPR,
return the reduce-to-scalar (reduc_..._scal) optab.
(scalar_reduc_to_vector): New.
* optabs.def (reduc_smax_scal_optab, reduc_smin_scal_optab,
reduc_plus_scal_optab, reduc_umax_scal_optab, reduc_umin_scal_optab):
New.
* optabs.h (scalar_reduc_to_vector): Declare.
* tree-vect-loop.c (vectorizable_reduction): Look for optabs reducing
to either scalar or vector.
From-SVN: r216737