🚀 go-pugleaf

I have an IBM SP/2 running aix-4.1.[34]. I have discovered a
compatibility problem between gcc-2.7.2 and the IBM xlc compiler.
This problem also exists with earlier versions of gcc (2.6.3 and
2.7.0).

The IBM xlc compiler aligns 'long long' objects to a 8 byte boundary,
and aligns doubles to a 4 byte boundary.  Gcc aligns both 'long long'
objects and doubles to a 4 byte boundary.   I discovered this when I
noticed structure mismatches between gcc and the native compiler.

I've appended a trivial example which illustrates the problem.

Does anyone have a suggestion of how to fix this bug?  Increasing
alignment restrictions to 64 bits won't work, as doubles will have
their alignment broken.

Thanks for any help, suggestions, or whatever!
bolo/Josef Burger
---------------------- example follows ------------------------

sp2(bolo) cat trouble.c
struct trouble {
        int     a;
#ifdef USE_DOUBLE
        double b;
#else
        long long b;
#endif
};

main()
{
        printf("sizeof(struct trouble) == %d\n", sizeof(struct trouble));

        return 0;
}

Here's what the native compiler does ...

sp2(bolo) cc -o ccl c.c
sp2(bolo) cc -o ccd -DUSE_DOUBLE c.c
sp2(bolo) ./ccl
sizeof(struct trouble) == 16
sp2(bolo) ./ccd
sizeof(struct trouble) == 12

And here's what gcc does  ...

sp2(bolo) which gcc
/s/gcc-2.7.2/bin/gcc
sp2(bolo) gcc -v
Reading specs from /s/gcc-2.7.2/rs_aix41/lib/gcc-lib/rs6000-ibm-aix4.1.3.0/2.7.s
gcc version 2.7.2
sp2(bolo) gcc -o gcl c.c
sp2(bolo) gcc -o gcd -DUSE_DOUBLE c.c
sp2(bolo) ./gcl
sizeof(struct trouble) == 12
sp2(bolo) ./gcd
sizeof(struct trouble) == 12

-- 
| Joe Burger	U of WI-Madison Computer Sciences | "No matter where you go,
| "bolo"	bolo@cs.wisc.edu   uwvax!bolo     |  There you are"
|               http://www.cs.wisc.edu/~bolo/     |     -- Buckaroo Banzai