[avr-gcc-list] Posible bug in avr-gcc-4.0.2 (inline asm)

[Anatoly Sokolov]

Hello.

Studying avr-libc bug #14486 I have written the following test case.

#define SFR (*(unsigned char *)(0x80))

#define foo()                                   \
({                                              \
   __asm__ __volatile__                        \
   (                                           \
       "sts %0, 0x00\n\t"                      \
       : "=m" (SFR)                              \
   );                                          \
})

int main (void)
{
   foo ();
   foo ();
}

The avr-gcc version 4.0.2 with optimisation  (-O3 or -Os ) generates a
following code:
...
.LM2:
ldi r30,lo8(128)
ldi r31,hi8(128)
/* #APP */
sts Z, 0x00

.LM3:
sts Z, 0x00

/* #NOAPP */
....
It is not true, pointer register cannot be the first operand of sts
instruction, only constant.
If to leave only one foo in main:

int main (void)
{
   foo ();
   //foo ();
}
The correct code is generated;
...
.LM2:
/* #APP */
sts 128, 0x00

/* #NOAPP */
...

If to compile without optimization, again a mistake:

int main (void)
{
   foo ();
   //foo ();
}
...
.LM2:
ldi r30,lo8(128)
ldi r31,hi8(128)
/* #APP */
sts Z, 0x00

/* #NOAPP */
...

The avr-gcc version 3.4.4 with and without optimisation generates a correct
code:
...
.LBB2:
.LM2:
/* #APP */
sts 128, 0x00

/* #NOAPP */
.LBE2:
.LBB3:
.LM3:
/* #APP */

sts 128, 0x00

/* #NOAPP */
...

It is a bug in the avr-gcc or it is erroneous to use "m" parameter with the
sts instruction?

Anatoly.