Re: PING^1 [PATCH] i386: Disallow sibcall when calling ifunc functions with PIC register

["H.J. Lu" <hjl.tools@gmail.com>]

On Mon, Jun 20, 2022 at 7:51 AM Uros Bizjak <ubizjak@gmail.com> wrote:
>
> On Mon, Jun 20, 2022 at 4:03 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Tue, Jun 14, 2022 at 12:25 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > Disallow siball when calling ifunc functions with PIC register so that
> > > PIC register can be restored.
> > >
> > > gcc/
> > >
> > >         PR target/105960
> > >         * config/i386/i386.cc (ix86_function_ok_for_sibcall): Return
> > >         false if PIC register is used when calling ifunc functions.
> > >
> > > gcc/testsuite/
> > >
> > >         PR target/105960
> > >         * gcc.target/i386/pr105960.c: New test.
>
> LGTM.

OK to backport to GCC 12 branch?

Thanks.

> Thanks,
> Uros.
>
> > > ---
> > >  gcc/config/i386/i386.cc                  |  9 +++++++++
> > >  gcc/testsuite/gcc.target/i386/pr105960.c | 19 +++++++++++++++++++
> > >  2 files changed, 28 insertions(+)
> > >  create mode 100644 gcc/testsuite/gcc.target/i386/pr105960.c
> > >
> > > diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> > > index 3d189e124e4..1ca7836e11e 100644
> > > --- a/gcc/config/i386/i386.cc
> > > +++ b/gcc/config/i386/i386.cc
> > > @@ -1015,6 +1015,15 @@ ix86_function_ok_for_sibcall (tree decl, tree exp)
> > >         }
> > >      }
> > >
> > > +  if (decl && ix86_use_pseudo_pic_reg ())
> > > +    {
> > > +      /* When PIC register is used, it must be restored after ifunc
> > > +        function returns.  */
> > > +       cgraph_node *node = cgraph_node::get (decl);
> > > +       if (node && node->ifunc_resolver)
> > > +        return false;
> > > +    }
> > > +
> > >    /* Otherwise okay.  That also includes certain types of indirect calls.  */
> > >    return true;
> > >  }
> > > diff --git a/gcc/testsuite/gcc.target/i386/pr105960.c b/gcc/testsuite/gcc.target/i386/pr105960.c
> > > new file mode 100644
> > > index 00000000000..db137a1642d
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.target/i386/pr105960.c
> > > @@ -0,0 +1,19 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-require-ifunc "" } */
> > > +/* { dg-options "-O2 -fpic" } */
> > > +
> > > +__attribute__((target_clones("default","fma")))
> > > +static inline double
> > > +expfull_ref(double x)
> > > +{
> > > +  return __builtin_pow(x, 0.1234);
> > > +}
> > > +
> > > +double
> > > +exp_ref(double x)
> > > +{
> > > +  return expfull_ref(x);
> > > +}
> > > +
> > > +/* { dg-final { scan-assembler "jmp\[ \t\]*expfull_ref@PLT" { target { ! ia32 } } } } */
> > > +/* { dg-final { scan-assembler "call\[ \t\]*expfull_ref@PLT" { target ia32 } } } */
> > > --
> > > 2.36.1
> > >
> >
> > PING.
> >
> > --
> > H.J.



-- 
H.J.