Hi Robert,
I'm having trouble with mspgcc version 3.2.3 accessing a variable
that's been declared as volatile twice, when my code refers to it
only once. This is a problem because that variable happens to be
I2CIV, the value of which changes upon access.
... Snip
Is this a known problem? Is there a fix in a later version of gcc?
I have not seen this issue before, although I had noticed some thing
like it with switching in the timer interrupt vectors and had not
tracked it down.
I did some testing and gcc-3.2 on i386 generates the same code sequence,
and gcc-4.1.0 (i386) is ok.
mspgcc-3.2.3 is really the only working option, Ill have a look at
gcc-3.3.4 (really the only other option for a working version of gcc,
gcc 4.xx is not working due to problems in the machine description file).
Interestingly this generates the correct code:
volatile int test;
int main( void )
{
int i;
switch( test )
{
case 0: i = 1; break;
case 1: i = 2; break;
case 2: i = 3; break;
case 3: i = 4; break;
case 4: i = 5; break;
case 5: i = 6; break;
case 6: i = 7; break;
case 700: i = 8; break;
}
}
as does
volatile int test;
int main( void )
{
int i;
switch( test )
{
case 0: i = 1; break;
case 1: i = 2; break;
case 2: i = 3; break;
case 3: i = 4; break;
case 4: i = 5; break;
case 5: i = 6; break;
case 6: i = 7; break;
case 7: i = 8; break;
default: i = 0; break;
}
}
as does
volatile int test;
int main( void )
{
int i;
int j;
j = test;
switch( j )
{
case 0: i = 1; break;
case 1: i = 2; break;
case 2: i = 3; break;
case 3: i = 4; break;
case 4: i = 5; break;
case 5: i = 6; break;
case 6: i = 7; break;
case 7: i = 8; break;
}
}
So yes gcc-3.2.3 generates broken code in some case, there are many
options to make it generate the correct code, I suspect the problem is
somewhere in the gcc-3.2 language processing part, not in the msp430
backend.
Regards,
--
Peter Jansen
STS
Antarctic Division
203 Channel Highway
Kingston
TAS 7050
AUSTRALIA
Phone +61 3 6232 3533
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