[Bug rtl-optimization/51374] [avr] insn combine reorders volatile memory accesses

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51374

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.7.0                       |
      Known to fail|                            |4.7.0

--- Comment #5 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-12-08 
16:40:28 UTC ---
This bug also affects 4.7.0 but up to now, the problem for 4.7 is hidden behind
PR51425 because avr-gcc 4.7 fails to produce SBIS/SBIC instructions altogether.

Smaller test case:


void __vector_18 (void)
{
    extern char slot;
    unsigned char status = (*(volatile unsigned char*) 0x2B);
    unsigned char data   = (*(volatile unsigned char*) 0x2C);

    if (status & 0x10)
        slot = 0;
}