[autovect] [patch] misc minor cleanups

[Dorit Naishlos <DORIT at il dot ibm dot com>]

Mostly minor technical cleanups I ran across - missing new lines, 80 column
overflow, outdated documentation, etc. The only two bits of new
functionality in this patch are:
1) don't fail vectorization in the presence of a computation that is used
out of the loop, if this computation is loop invariant. In this special
case we can leave the scalar computation in place even if the loop gets
vectorized. This is handled by a new function -
vectorizable_live_operation. Currently this function handles only
invariants (cause these can be trivially handled, by simply doing nothing).
In the future it will also handle other cases, like inducion variables (for
which we'd want to compute the last value of the induction at the loop
exit).
2) don't vectorize the loop if there's no operation that actually needs to
be transformed. This happens for example in cases that a loop computes an
invariant value and can be removed (such loops may exist after PRE, see
vect-62.c - the second loop in this testcase is left unvectorized).

Bootstrapped and tested on powerpc-apple-darwin, committed to
autovect-branch.

dorit

Changelog:

        * tree-vect-analyze.c (vect_determine_vectorization_factor): Fix 80
        columns overflow.
        (vect_analyze_operations): Check RELEVANT_P stmts and LIVE_P stmts
        separately. Call vectorizable_live_operation. Check if
vectorization
        is needed.
        (vect_enhance_data_refs_alignment): New line after declarations.
        (vect_stmt_relevant_p): Remove redundant comment.
        (vect_mark_stmts_to_be_vectorized): Add comments. Move invariant
        computation out of the loop.
        (vect_can_advance_ivs_p): Fix print format.
        (vect_analyze_loop): Fix comment.
        * tree-vect-transform (vectorizable_assignment): Remove handling of
        LIVE_P case (factored out to vectorizable_live_operation).
        (vectorizable_live_operation): New.
        (vect_transform_stmt): Handle RELEVANT_P stmts and LIVE_P stmts
        separately. Call vectorizable_live_operation.
        * tree-vectorizer.h (vectorizable_live_operation): New declaration.

testsuite/Changelog:

        * gcc.dg/vect/no_version/vect-62.c: Update comment. Check that we
don't
        vectorize the second loop cause we chose not to.
        * gcc.dg/vect/no_version/vect-91.c: Duplicate of vect-71.c. Changed
to
        check a different functionality.
        * gcc.dg/vect/vect-reduc-1.c: Remove include of stdio.h.
        * gcc.dg/vect/vect-reduc-2.c: Likewise.
        * gcc.dg/vect/vect-reduc-3.c: Likewise.
        * gcc.dg/vect/vect-reduc-4.c: Likewise. Remove option
        -fno-tree-vect-loop-version.
        * gcc.dg/vect/vect-reduc-5.c: Likewise.
        * gcc.dg/vect/vect-reduc-6.c: Remove include of stdio.h. Change
        effective_target to vect_float.

Patch:

(See attached file: autovect.cleanups)

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