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From
Subjectgcc 2.95.2 is buggy
Yesterday night I wrote

> Note: this is not yet a confirmed compiler bug

but in the meantime there is good confirmation.
This really is a bug in gcc 2.95.2.

From bernds@redhat.com Thu Nov 23 10:45:07 2000
> Please, could you send me ...

From torvalds@transmeta.com Thu Nov 23 18:00:48 2000
> Can we get a show of hands?

Below a demo program.

Andries

-------------------- bug.c -----------------------------
/*
* bug.c - aeb, 001124
*
* This program shows a bug in gcc 2.95.2.
* It should print 0x0 and exit.
* For me it prints 0x84800000.
*
* Compile with:
* gcc -Wall -O2 -o bug bug.c
*/
#include <stdio.h>

struct inode {
long long i_size;
struct super_block *i_sb;
};

struct file {
long long f_pos;
};

struct super_block {
int s_blocksize;
unsigned char s_blocksize_bits;
int s_hs;
};

static char *
isofs_bread(unsigned int block)
{
printf("0x%x\n", block);
exit(0);
}

static int
do_isofs_readdir(struct inode *inode, struct file *filp)
{
int bufsize = inode->i_sb->s_blocksize;
unsigned char bufbits = inode->i_sb->s_blocksize_bits;
unsigned int block, offset;
char *bh = NULL;
int hs;

if (filp->f_pos >= inode->i_size)
return 0;

offset = filp->f_pos & (bufsize - 1);
block = filp->f_pos >> bufbits;
hs = inode->i_sb->s_hs;

while (filp->f_pos < inode->i_size) {
if (!bh)
bh = isofs_bread(block);

hs += block << bufbits;

if (hs == 0)
filp->f_pos++;

if (offset >= bufsize)
offset &= bufsize - 1;

if (*bh)
filp->f_pos++;

filp->f_pos++;
}
return 0;
}

struct super_block s;
struct inode i;
struct file f;

int
main(int argc, char **argv){
s.s_blocksize = 512;
s.s_blocksize_bits = 9;
i.i_size = 2048;
i.i_sb = &s;
f.f_pos = 0;

do_isofs_readdir(&i,&f);
return 0;
}
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