On November 19, 2004 10:55 am, you wrote:
> The answer is: it's a gcc bug. The attached program should print
> x = 12.3
> y = 12.3
>
> but if compiled with -O or -O2 on Stefan's machine, I get garbage:
>
> $ gcc -O ftest.c
> $ ./a.out
> x = 12.3
> y = 1.47203e-39
> $ gcc -v
> Reading specs from /usr/lib/gcc-lib/sparc64-unknown-openbsd3.6/3.3.2/specs
> Configured with:
> Thread model: single
> gcc version 3.3.2 (propolice)
> $
I can confirm this behavior on Solaris 8/sparc 64 as well.
bash-2.03$ gcc -O -m64 test.c
bash-2.03$ ./a.out
x = 12.3
y = 2.51673e-42
bash-2.03$ file a.out
a.out: ELF 64-bit MSB executable SPARCV9 Version 1, dynamically
linked, not stripped
bash-2.03$ gcc -v
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-solaris2.8/3.3.2/specs
Configured with: ../configure --with-as=/usr/ccs/bin/as
--with-ld=/usr/ccs/bin/ld --disable-nls
Thread model: posix
gcc version 3.3.2
bash-2.03$ gcc -m64 test.c
bash-2.03$ ./a.out
x = 12.3
y = 12.3
bash-2.03$ gcc -m64 -02 test.c
gcc: unrecognized option `-02'
bash-2.03$ gcc -m64 -O2 test.c
bash-2.03$ ./a.out
x = 12.3
y = 2.51673e-42
bash-2.03$ gcc -m64 -O3 test.c
bash-2.03$ ./a.out
x = 12.3
y = 12.3
bash-2.03$
>
> regards, tom lane
>
>
> #include <stdio.h>
>
> float
> returnfloat(float *x)
> {
> return *x;
> }
>
> int
> main()
> {
> float x = 12.3;
> union {
> float f;
> char *t;
> } y;
>
> y.f = returnfloat(&x);
>
> printf("x = %g\n", x);
> printf("y = %g\n", y.f);
>
> return 0;
> }
>
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--
Darcy Buskermolen
Wavefire Technologies Corp.
ph: 250.717.0200
fx: 250.763.1759
http://www.wavefire.com
