tree-vectorizer.c: New File: loop vectorization on SSAed GIMPLE trees.

tree-vectorizer.c: New File: loop vectorization on SSAed GIMPLE trees.

        * tree-vectorizer.c: New File: loop vectorization on SSAed GIMPLE trees.
        * tree-vectorizer.h: New File: Same.
        * Makefile.in (tree-vectorizer.c, tree-vectorizer.h): Add new files.
        * common.opt (ftree-vectorize): New flag to enable vectorization.
        * timevar.def (TV_TREE_VECTORIZATION): New dump file for vectorization
        pass.
        * tree-data-ref.h (init_data_ref): Additional argument.
        (array_base_name_differ_p): Moved to tree-data-ref.c.
        * tree-data-ref.c (array_base_name_differ_p): Revised.
        (initialize_data_dependence_relation): Call array_base_name_differ_p
        with an extra argument.
        (analyze_all_data_dependences): Same.
        (init_data_ref): Additional argument is_read to set DR_IS_READ.
        * tree-ssa-phiopt.c (empty_block_p): Expose for usage out of this file.
        * tree-flow.h (vectorize_loops, empty_block_p): Add declaration.
        * tree-optimize.c (pass_vectorize): Schedule the vectorization pass.
        * tree-pass.h (tree_opt_pass pass_vectorize): Declare the new
        vectorization pass.
        * tree-ssa-loop.c (tree_ssa_loop_init): Call scev_initialize.
        (tree_ssa_loop_done): Call scev_finalize.
        (tree_vectorize): Define the new vectorization pass.
        * defaults.h (UNITS_PER_SIMD_WORD): Allow targets to specify the size of
        the vector they support (until support for multiple vector sizes is
        added to the vectorizer).
        * config/i386/i386.h (UNITS_PER_SIMD_WORD): Define.
        * config/rs6000/rs6000.h (UNITS_PER_SIMD_WORD): Define.
        * invoke.texi (fdump-tree-vect, ftree-vectorize): Add
        documentation.

From-SVN: r86131