meyering@cs.utexas.edu (Jim Meyering) (02/22/89)
In these 3 cases, if -O is used, we get the right answer.
Similarly, if statements like "foo = n*n;" or "printf("%d\n",n);"
are placed between the definition and the use of n, the
problem does not arise.
% gcc -DARGV gcc-bug.c; a.out 1
n=1, n*n=-134219372
% gcc -DLITERAL gcc-bug.c; a.out 1
n=1, n*n=124
% gcc -DCONSTANT gcc-bug.c; a.out 1
n=1, n*n=1
% gcc -v -DARGV gcc-bug.c
gcc version 1.33
/p/lib/gcc-1.33/gcc-cpp -v -DARGV -undef -D__GNUC__ -Dsparc -Dsun -Dunix -D__sparc__ -D__sun__ -D__unix__ gcc-bug.c /tmp/cca25288.cpp
GNU CPP version 1.33
/p/lib/gcc-1.33/gcc-cc1 /tmp/cca25288.cpp -quiet -dumpbase gcc-bug.c -version -o /tmp/cca25288.s
GNU C version 1.33 (sparc) compiled by GNU C version 1.33.
as /tmp/cca25288.s -o gcc-bug.o
ld -e start -dc -dp /lib/crt0.o gcc-bug.o /p/lib/gcc-1.33/gcc-gnulib -lc
0.2u 1.0s 0:06 17% 0+272k 86+32io 157pf+0w
%
------------------------------------
void
main(argc,argv)
int argc;
char **argv;
{
int n, atoi();
#if defined(ARGV)
if (argc < 2) {
printf("usage: %s n\n",argv[0]);
exit(1);
}
n = atoi(argv[1]);
#elif defined(LITERAL)
n = atoi("1");
#elif defined(CONSTANT)
n = 1;
#else
# error "must use -D(ARGV|LITERAL|CONSTANT)"
#endif
printf("n=%d, n*n=%d\n", n, n*n);
exit(0);
}
--
---
Jim Meyering meyering@cs.utexas.edu