Experimental Physics and
Industrial Control System

Marty Kraimer <[email protected]> · Fri, 25 Sep 1998 10:09:23 -0500

GPIB device support which is implemented by starting the John Winan's
template
has the statements:

static struct devGpibParmBlock devSupParams;

...

static struct devGpibParmBlock devSupParams = {
...
};

Note that this is legal ISO C but is not legal C++

Josh Stein (APS/ASD) could not make GPIB work with beta12.
We discovered that the above does not work on beta12 but does work on
beta11.

Below is  proof that it is a compiler bug.

Question: Has anyone else seen this bug?
If so do you know a solution?
Will a later version of GNU C fix the problem?

Comment:

If devSupParams is made external it works.

Proof of compiler bug.

The following test was run.

#include <stdio.h>
struct test {
    int x;
    int y;
};
static struct test mystruct;
static struct test mystruct = {1,2};

int myTest()
{
printf("mystruct %d %d\n",mystruct.x,mystruct.y);
return(0);
}

On VxWorks version 5.3.1 the result is:

mystruct 0 0

On VxWorks version 5.2 the result is

mystruct 1 2

On VxWorks version 5.3.1 the compiler output is:

#NO_APP
gcc2_compiled.:
___gnu_compiled_c:
        .long 1
        .long 2
.text
LC0:
        .ascii "mystruct %d %d\12\0"
        .even
.globl _myTest
_myTest:
        pea a6@
        movel sp,a6
        lea _statics+4,a0
        movel a0@,sp@-
        movel a0@(-4),sp@-
        pea LC0
        jbsr _printf
        clrl d0
        unlk a6
        rts
.data
        .even
_statics:
        .skip 8

VxWorks version 5.2 generated.

#NO_APP
gcc2_compiled.:
.data
        .even
_mystruct:
        .long 1
        .long 2
.text
LC0:
        .ascii "mystruct %d %d\12\0"
        .even
.globl _myTest
_myTest:
        link a6,#0
        movel _mystruct+4,sp@-
        movel _mystruct,sp@-
        pea LC0
        jbsr _printf
        clrl d0
        unlk a6
        rts

Marty Kraimer

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System