> 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.
There is a report on glibc issue here
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97264
it turned out to be a latent glibc bug type punning const char * and
const unsigned char *.
I wonder if it is same as problem you are seeing?
Honza
>
>
> > > On 27/09/2020, 22:46, "Gcc-patches on behalf of Jan Hubicka"
> > > <[email protected] on behalf of [email protected]> 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 <[email protected]>
> > >
> > > * 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. */
> > >
