[patch]Add option ftree-vect-loop-version

[Keith Besaw <kbesaw at us dot ibm dot com>]

This patch adds the option ftree-vect-loop-version.  It is the
first of several patches to move Loop Versioning for Alignment
(Stage 2.1 of the GCC 4.1 Projects) from the autovect branch to
mainline.

Loop versioning causes code bloat because two versions of a loop
are generated; one is vectorized and one is not.  There is a
runtime data alignment check to determine which loop is executed.
This option allows loop versioning to be turned off when code
bloat is unacceptable.  Loop versioning is also be turned off
by the Os option (optimize for size).

This option is being added as the first step so that updates
can be made in the current vector test set to use the
fno-tree-vect-loop-version before loop versioning is added.

tested on ppc

OK for mainline?

Keith

Changelog:

      2005-04-20  Keith Besaw  <kbesaw@us.ibm.com>

      * common.opt: add the ftree-vect-loop-version option
      and the flag flag_tree_vect_loop_version initialized to 1.
      * doc/invoke.texi: Add documentation for
      ftree-vect-loop-version.

Attachment: vect.4-20m.diff
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