[Bug middle-end/45722] [4.6 Regression] FAIL: gcc.c-torture/execute/20040709-2.c execution at -O1 and -Os

["dave at hiauly1 dot hia.nrc.ca" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45722

--- Comment #7 from dave at hiauly1 dot hia.nrc.ca 2010-10-09 20:46:50 UTC ---
Took another at this bug.  At least at -O1 with r165177, the nature
of the FAIL seems to have changed.  The testcase now fails in testB
with a segmentation fault caused by a misaligned load.

Program received signal SIGBUS, Bus error.
0x00002d90 in testB () at pr45722.c:48
48      x = sB;
(gdb) disass 0x00002d80,0x00002da0
Dump of assembler code from 0x2d80 to 0x2da0:
   0x00002d80 <testB+152>:    ldb,ma 1(r31),r21
   0x00002d84 <testB+156>:    stb,ma r20,1(r22)
   0x00002d88 <testB+160>:    addib,>= -2,r19,0x2d7c <testB+148>
   0x00002d8c <testB+164>:    stb,ma r21,1(r22)
=> 0x00002d90 <testB+168>:    ldw 2(r4),r4
   0x00002d94 <testB+172>:    b,l 0x2c80 <fn3B>,rp
   0x00002d98 <testB+176>:    copy r5,r26
   0x00002d9c <testB+180>:    ldb 50(r3),r20
(gdb) p &sB
$1 = (struct B *) 0x40001a50
(gdb) p/x $r4
$2 = 0x40001a50

It appears the load for sB.l is not expanded correctly given that the
struct is packed:

;; x$l_3 = MEM[(struct B *)&sB + 2B];

(insn 106 105 107 (set (reg/f:SI 205)
        (high:SI (symbol_ref:SI ("sB") [flags 0x200]  <var_decl 7afa7f00 sB>)))
pr45722.c:48 -1
     (nil))

(insn 107 106 108 (set (reg/f:SI 204)
    (lo_sum:SI (reg/f:SI 205)
        (symbol_ref:SI ("sB") [flags 0x200]  <var_decl 7afa7f00 sB>)))
pr45722.c:48 -1
     (expr_list:REG_EQUAL (symbol_ref:SI ("sB") [flags 0x200]  <var_decl
7afa7f00 sB>)
    (nil)))

(insn 108 107 109 (set (reg/f:SI 206)
    (plus:SI (reg/f:SI 204)
        (const_int 0 [0]))) pr45722.c:48 -1
    (nil))

(insn 109 108 0 (set (reg:SI 142 [ x$l ])
    (mem/c:SI (plus:SI (reg/f:SI 206)
        (const_int 2 [0x2])) [0 MEM[(struct B *)&sB + 2B]+0 S4 A8]))
pr5722.c:48 -1
    (nil))

;; r_16 = fn3B (a_13);
--
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)