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Subject: [Bug c/55882] unaligned load/store : incorrect struct offset
Date: Tue, 08 Jan 2013 15:26:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55882

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-08 15:25:46 UTC ---
GCC clealy thinks that

(insn 21 20 0 2 (set (mem/j:SI (plus:SI (reg/f:SI 195)
                (const_int 10 [0xa])) [0+-2 S4 A32])
        (reg:SI 201)) t.i:85 -1

is 4-byte aligned (but it _does_ have this strange MEM_OFFSET setting ...
which should be useless without a MEM_EXPR).

Does

unsigned short
testfunction(void)
{
    mystruct dmfe[8];
    unsigned i = 0;
    dmfe[0].use_alt_rd_dqs = 1;
    dmfe[i].use_alt_rd_dqs = 0;
    return dmfe[0].use_alt_rd_dqs;
}

extern void abort (void);
int main () { if (testfunction() != 0) abort (); }

abort for you?