VAX: Accept ASHIFT in address expressions

VAX: Accept ASHIFT in address expressions

Fix regressions:

FAIL: gcc.c-torture/execute/20090113-2.c   -O1  (internal compiler error)
FAIL: gcc.c-torture/execute/20090113-2.c   -O1  (test for excess errors)
FAIL: gcc.c-torture/execute/20090113-3.c   -O1  (internal compiler error)
FAIL: gcc.c-torture/execute/20090113-3.c   -O1  (test for excess errors)

triggering if LRA is used rather than old reload and caused by:

(plus:SI (plus:SI (mult:SI (reg:SI 30 [ _10 ])
            (const_int 4 [0x4]))
        (reg/f:SI 26 [ _6 ]))
    (const_int 12 [0xc]))

coming from:

(insn 58 57 59 10 (set (reg:SI 33 [ _13 ])
        (zero_extract:SI (mem:SI (plus:SI (plus:SI (mult:SI (reg:SI 30 [ _10 ])
                            (const_int 4 [0x4]))
                        (reg/f:SI 26 [ _6 ]))
                    (const_int 12 [0xc])) [4 _6->bits[_10]+0 S4 A32])
            (reg:QI 56)
            (reg:SI 53)))
".../gcc/testsuite/gcc.c-torture/execute/20090113-2.c":64:12 490 {*extzv_non_const}
     (expr_list:REG_DEAD (reg:QI 56)
        (expr_list:REG_DEAD (reg:SI 53)
            (expr_list:REG_DEAD (reg:SI 30 [ _10 ])
                (expr_list:REG_DEAD (reg/f:SI 26 [ _6 ])
                    (nil))))))

being converted into:

(plus:SI (plus:SI (ashift:SI (reg:SI 30 [ _10 ])
            (const_int 2 [0x2]))
        (reg/f:SI 26 [ _6 ]))
    (const_int 12 [0xc]))

which is an rtx the VAX backend currently does not recognize as a valid
machine address, although apparently it is only inside MEM rtx's that
indexed addressing is supposed to be canonicalized to a MULT rather than
ASHIFT form.  Handle the ASHIFT form too throughout the backend then.

The change appears to also improve code generation with old reload and
code size stats are as follows, collected from 18153 executables built
in `check-c' GCC testing:

              samples average  median
--------------------------------------
regressions        47  0.702%  0.521%
unchanged       17503  0.000%  0.000%
progressions      603 -0.920% -0.403%
--------------------------------------
total           18153 -0.029%  0.000%

with a small number of outliers (over 5% size change):

old     new     change  %change filename
----------------------------------------------------
1885    1645    -240   -12.7320 pr53505.exe
1331    1221    -110    -8.2644 pr89634.exe
1553    1473    -80     -5.1513 stdatomic-vm.exe
1413    1341    -72     -5.0955 pr45830.exe
1415    1343    -72     -5.0883 stdatomic-vm.exe
25765   24463   -1302   -5.0533 strlen-5.exe
25765   24463   -1302   -5.0533 strlen-5.exe
25765   24463   -1302   -5.0533 strlen-5.exe
1191    1131    -60     -5.0377 20050527-1.exe

(all changes on the expansion side are below 5%).

	gcc/
	* config/vax/vax.c (print_operand_address, vax_address_cost_1)
	(index_term_p): Handle ASHIFT too.