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

[Uros Bizjak <ubizjak@gmail.com>]

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.

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.