Re: [PATCH] x86: Disable -mforce-indirect-call for PIC in 32-bit mode

[Uros Bizjak <ubizjak@gmail.com>]

On Mon, Jan 16, 2023 at 7:56 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> -mforce-indirect-call generates invalid instruction in 32-bit MI thunk
> since there are no available scratch registers in 32-bit PIC mode.
> Disable -mforce-indirect-call for PIC in 32-bit mode when generating
> MI thunk.
>
> gcc/
>
>         PR target/105980
>         * config/i386/i386.cc (x86_output_mi_thunk): Disable
>         -mforce-indirect-call for PIC in 32-bit mode.
>
> gcc/testsuite/
>
>         PR target/105980
>         * g++.target/i386/pr105980.C: New test.

OK.

Thanks,
Uros.

> ---
>  gcc/config/i386/i386.cc                  | 6 ++++++
>  gcc/testsuite/g++.target/i386/pr105980.C | 8 ++++++++
>  2 files changed, 14 insertions(+)
>  create mode 100644 gcc/testsuite/g++.target/i386/pr105980.C
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 19fb03cfd44..3cacf738c4a 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -21480,6 +21480,7 @@ x86_output_mi_thunk (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
>    rtx this_reg, tmp, fnaddr;
>    unsigned int tmp_regno;
>    rtx_insn *insn;
> +  int saved_flag_force_indirect_call = flag_force_indirect_call;
>
>    if (TARGET_64BIT)
>      tmp_regno = R10_REG;
> @@ -21492,6 +21493,9 @@ x86_output_mi_thunk (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
>         tmp_regno = DX_REG;
>        else
>         tmp_regno = CX_REG;
> +
> +      if (flag_pic)
> +  flag_force_indirect_call = 0;
>      }
>
>    emit_note (NOTE_INSN_PROLOGUE_END);
> @@ -21659,6 +21663,8 @@ x86_output_mi_thunk (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
>    final (insn, file, 1);
>    final_end_function ();
>    assemble_end_function (thunk_fndecl, fnname);
> +
> +  flag_force_indirect_call = saved_flag_force_indirect_call;
>  }
>
>  static void
> diff --git a/gcc/testsuite/g++.target/i386/pr105980.C b/gcc/testsuite/g++.target/i386/pr105980.C
> new file mode 100644
> index 00000000000..d8dbc332ea2
> --- /dev/null
> +++ b/gcc/testsuite/g++.target/i386/pr105980.C
> @@ -0,0 +1,8 @@
> +// { dg-do assemble { target { fpic } } }
> +// { dg-options "-O0 -fpic -mforce-indirect-call" }
> +
> +struct A {
> +  virtual ~A();
> +};
> +struct B : virtual A {};
> +void bar() { B(); }
> --
> 2.39.0
>