Re: [PATCH] PR target/93319: x32: Add x32 support to -mtls-dialect=gnu2

[Uros Bizjak <ubizjak at gmail dot com>]

On Sun, Jan 19, 2020 at 7:07 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sun, Jan 19, 2020 at 9:48 AM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > On Sun, Jan 19, 2020 at 6:43 PM Uros Bizjak <ubizjak@gmail.com> wrote:
> > >
> > > On Sun, Jan 19, 2020 at 2:58 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > >
> > > > To add x32 support to -mtls-dialect=gnu2, we need to replace DI with
> > > > P in GNU2 TLS patterns.  Since thread pointer is in ptr_mode, PLUS in
> > > > GNU2 TLS address computation must be done in ptr_mode to support
> > > > -maddress-mode=long.  Also drop the "q" suffix from lea to support
> > > > both "lea foo@TLSDESC(%rip), %eax" and "foo@TLSDESC(%rip), %rax".
> > >
> > > Please use "lea%z0" instead.
> > >
> > > > Tested on Linux/x86-64.  OK for master?
> > > >
> > > > Thanks.
> > > >
> > > > H.J.
> > > > ---
> > > > gcc/
> > > >
> > > >         PR target/93319
> > > >         * config/i386/i386.c (legitimize_tls_address): Pass Pmode to
> > > >         gen_tls_dynamic_gnu2_64.  Compute GNU2 TLS address in ptr_mode.
> > > >         * config/i386/i386.md (tls_dynamic_gnu2_64): Renamed to ...
> > > >         (@tls_dynamic_gnu2_64_<mode>): This.  Replace DI with P.
> > > >         (*tls_dynamic_gnu2_lea_64): Renamed to ...
> > > >         (*tls_dynamic_gnu2_lea_64_<mode>): This.  Replace DI with P.
> > > >         Remove the {q} suffix from lea.
> > > >         (*tls_dynamic_gnu2_call_64): Renamed to ...
> > > >         (*tls_dynamic_gnu2_call_64_<mode>): This.  Replace DI with P.
> > > >         (*tls_dynamic_gnu2_combine_64): Renamed to ...
> > > >         (*tls_dynamic_gnu2_combine_64_<mode>): This.  Replace DI with P.
> > > >         Pass Pmode to gen_tls_dynamic_gnu2_64.
> > > >
> > > > gcc/testsuite/
> > > >
> > > >         PR target/93319
> > > >         * gcc.target/i386/pr93319-1a.c: New test.
> > > >         * gcc.target/i386/pr93319-1b.c: Likewise.
> > > >         * gcc.target/i386/pr93319-1c.c: Likewise.
> > > >         * gcc.target/i386/pr93319-1d.c: Likewise.
> > > > ---
> > > >  gcc/config/i386/i386.c                     | 31 +++++++++++--
> > > >  gcc/config/i386/i386.md                    | 54 +++++++++++-----------
> > > >  gcc/testsuite/gcc.target/i386/pr93319-1a.c | 24 ++++++++++
> > > >  gcc/testsuite/gcc.target/i386/pr93319-1b.c |  7 +++
> > > >  gcc/testsuite/gcc.target/i386/pr93319-1c.c |  7 +++
> > > >  gcc/testsuite/gcc.target/i386/pr93319-1d.c |  7 +++
> > > >  6 files changed, 99 insertions(+), 31 deletions(-)
> > > >  create mode 100644 gcc/testsuite/gcc.target/i386/pr93319-1a.c
> > > >  create mode 100644 gcc/testsuite/gcc.target/i386/pr93319-1b.c
> > > >  create mode 100644 gcc/testsuite/gcc.target/i386/pr93319-1c.c
> > > >  create mode 100644 gcc/testsuite/gcc.target/i386/pr93319-1d.c
> > > >
> > > > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > > > index 2c087a4a3e0..8c437dbe1f3 100644
> > > > --- a/gcc/config/i386/i386.c
> > > > +++ b/gcc/config/i386/i386.c
> > > > @@ -10764,12 +10764,24 @@ legitimize_tls_address (rtx x, enum tls_model model, bool for_mov)
> > > >        if (TARGET_GNU2_TLS)
> > > >         {
> > > >           if (TARGET_64BIT)
> > > > -           emit_insn (gen_tls_dynamic_gnu2_64 (dest, x));
> > > > +           emit_insn (gen_tls_dynamic_gnu2_64 (Pmode, dest, x));
> > > >           else
> > > >             emit_insn (gen_tls_dynamic_gnu2_32 (dest, x, pic));
> > > >
> > > >           tp = get_thread_pointer (Pmode, true);
> > > > -         dest = force_reg (Pmode, gen_rtx_PLUS (Pmode, tp, dest));
> > > > +
> > > > +         /* NB: Since thread pointer is in ptr_mode, make sure that
> > > > +            PLUS is done in ptr_mode.  */
> >
> > Actually, thread_pointer is in Pmode, see the line just above your
> > change. Also, dest is in Pmode, so why do we need all this subreg
> > dance?
>
> dest set from  gen_tls_dynamic_gnu2_64 is in ptr_mode by
>
> call *foo@TLSCALL(%rax)

It looks to me that we have Pmode/ptr_mode mixup in
legitimize_tls_address & friends for TARGET_GNU2_TLS. I think that we
need to perform all calculations in ptr_mode, since get_thread_pointer
in effect always returns ptr_mode (SImode) value, and also the above
call always returns ptr_mode (SImode) value. In case of
-maddress-mode=long, the value would be zero-extended to Pmode.

Uros.