Preventing gcc from aligning stack???

[Johan Kullstam]

Horst von Brand <vonbrand en sleipnir.valparaiso.cl> writes:

> My question in this vein would be the -fno-strength-reduce. The gcc bug
> that placed this in the kernel was in gcc-2.7.2, and was worked around in
> 2.7.2.3 by just making this option unconditional. Both 2.2.15pre4 and
> 2.3.41pre2 at least demand gcc-2.7.2.3 as minimal version.

just when you thought it was safe to go into the water...

strength-reduction is broken again in gcc-2.95.2 (aka the current
release).  i'm not sure about what versions actually do work.

for fun, try this one out.  cut and paste the program bug.c.

$ gcc -O2 bug.c -o b0
$ gcc -O2 -fno-strength-reduce bug.c -o b1

run b1.  notice it finish immediately.
now run b0.  notice how b0 never terminates (until you ^C it).

-- bug.c -----------------------------------------
static void bug(int size, int tries)
{
  int i;
  int num = 0;

  while (num < size)
  {
    for (i = 1; i < tries; i++) num++;
  }
}

int main()
{
  bug(5, 10);
  return 0;
}
-- bug.c -----------------------------------------

-- 
J o h a n  K u l l s t a m
[kullstam en ne.mediaone.net]
Don't Fear the Penguin!

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