The 10/05/2020 17:28, Szabolcs Nagy via Gcc-patches wrote:
> The 10/05/2020 12:52, Vaseeharan Vinayagamoorthy wrote:
> > Hi,
> >
> > After this patch, I am noticing that some glibc crypto tests get stuck in
> > scanf which goes into busy loop.
> >
> > My build/host/target setup is:
> > Build: aarch64-none-linux-gnu
> > Host: aarch64-none-linux-gnu
> > Target: aarch64-none-linux-gnu
>
> i can reproduce this on aarch64, i'm looking at it:
>
> if i compile glibc with gcc trunk after this commit i see
>
> $ ./testrun.sh crypt/cert < $glibcsrc/crypt/cert.input
> K: 0000000000000000 P: 0000000000000000 C: 0000000000000000 Encrypt FAIL
> K: 0000000000000000 P: 0000000000000000 C: 0000000000000000 Encrypt FAIL
> K: 0000000000000000 P: 0000000000000000 C: 0000000000000000 Encrypt FAIL
> K: 0000000000000000 P: 0000000000000000 C: 0000000000000000 Encrypt FAIL
> K: 0000000000000000 P: 0000000000000000 C: 0000000000000000 Encrypt FAIL
> K: 0000000000000000 P: 0000000000000000 C: 0000000000000000 Encrypt FAIL
> ...
>
> it just keeps printing this.
>
> same test binary with glibc code compiled with an
> older gcc works, so something in glibc gets miscompiled.
>
> i will have to do more digging to figure out what.
minimal reproducer:
#include <stdio.h>
int main()
{
int r,t;
r = sscanf("01", "%2x", &t);
printf("scanf: %d %02x\n", r, t);
return 0;
}
should print
scanf: 1 01
but when glibc is compiled with gcc trunk on aarch64 it prints
scanf: 0 00
i will continute the debugging from here tomorrow.
> > On 27/09/2020, 22:46, "Gcc-patches on behalf of Jan Hubicka"
> > <gcc-patches-boun...@gcc.gnu.org on behalf of hubi...@ucw.cz> wrote:
> >
> > Hi,
> > this patch fixes a pasto in modref_summary::useful_p that made
> > ipa-modref to give up on tracking stores when all load info got lost.
> >
> > Bootstrapped/regtested x86_64-linux, comitted.
> >
> > gcc/ChangeLog:
> >
> > 2020-09-27 Jan Hubicka <hubi...@ucw.cz>
> >
> > * ipa-modref.c (modref_summary::useful_p): Fix testing of stores.
> >
> > diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
> > index 728c6c1523d..6225552e41a 100644
> > --- a/gcc/ipa-modref.c
> > +++ b/gcc/ipa-modref.c
> > @@ -135,7 +135,7 @@ modref_summary::useful_p (int ecf_flags)
> > return true;
> > if (ecf_flags & ECF_PURE)
> > return false;
> > - return stores && !loads->every_base;
> > + return stores && !stores->every_base;
> > }
> >
> > /* Dump A to OUT. */
> >
