* local-alloc.c (requires_inout): Don't use reserved range for
        EXTRA_CONSTRAINTS; use anything not matched by REG_CLASS_FROM_LETTER.
        * recog.c (asm_operand_ok): Likewise.
        (preprocess_constraints, constrain_operands): Likewise.
        * regclass.c (record_reg_classes): Likewise.
        * reload.c (find_reloads): Likewise.
        * reload1.c (maybe_fix_stack_asms): Likewise.
        (reload_cse_simplify_operands): Likewise.
        * stmt.c (expand_asm_operands): Likewise.

        * md.texi: Update constraints documentation.
        * tm.texi (EXTRA_CONSTRAINT): Update.

From-SVN: r36023