* Global CSE and constant/copy propagation.

* Global CSE and constant/copy propagation.

        * Makefile.in (OBJS): Add gcse.o
        (STAGESTUFF): Add *.gcse.
        (gcse.o): Add dependencies.
        (mostlyclean): Remove *.gcse and */*.gcse.
        * gcse.c: New file.
        * loop.c (loop_optimize): Move call to init_alias_analysis.
        * recog.c (validate_replace_src): New function.
        * toplev.c (gcse_dump): New global variable.
        (flag_gcse, gcse_time): Likewise.
        (compile_file): Initialize gcse_time and clean out the gcse dump
        file if necessary.
        (rest_of_compilation): Call gcse_main as requested.  Dump RTL
        after gcse if requested.
        (main): Enable gcse for -O2 and above.  Handle -dG.  Enable gcse
        dumps for -da.
        * gcc.texi: Add gcse related internal documentation.
        * invoke.texi: Note new command line options for gcse.
        * tm.texi: Document AVOID_CCMODE_COPIES.
        * mips.h (AVOID_CCMODE_COPIES): Define.

Co-Authored-By: Jeffrey A Law <law@cygnus.com>
From-SVN: r19901