Re: [PATCH] [x86] Fix unrecognizable insn due to illegal immediate_operand (const_int 255) of QImode.

[Hongtao Liu <crazylht@gmail.com>]

On Wed, Nov 30, 2022 at 3:12 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Mon, Nov 28, 2022 at 11:04 PM Hongtao Liu <crazylht@gmail.com> wrote:
> >
> > On Mon, Nov 28, 2022 at 9:06 PM liuhongt <hongtao.liu@intel.com> wrote:
> > >
> > > For __builtin_ia32_vec_set_v16qi (a, -1, 2) with
> > > !flag_signed_char. it's transformed to
> > > __builtin_ia32_vec_set_v16qi (_4, 255, 2) in the gimple,
> > > and expanded to (const_int 255) in the rtl. But for immediate_operand,
> > > it expects (const_int 255) to be signed extended to
> > > (const_int -1). The mismatch caused an unrecognizable insn error.
> > >
> > > expand_expr_real_1 generates (const_int 255) without considering the target mode.
> > > I guess it's on purpose, so I'll leave that alone and only change the expander
> > > in the backend. After applying convert_modes to (const_int 255),
> > > it's transformed to (const_int -1) which fix the issue.
> > >
> > > Bootstrapped and regtested x86_64-pc-linux-gnu{-m32,}.
> > > Ok for trunk(and backport to GCC-10/11/12 release branches)?
> > Drop this patch since it's not a complete solution, there're also
> > other QI builtins which is not handled.
>
> I checked the x86 backend.  __builtin_ia32_vec_set_v16qi is the
> only intrinsic with this issue.
Ok, I'll commit the patch.
>
> > >
> > > gcc/ChangeLog:
> > >
> > >         PR target/107863
> > >         * config/i386/i386-expand.cc (ix86_expand_vec_set_builtin):
> > >         Convert op1 to target mode whenever mode mismatch.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > >         * gcc.target/i386/pr107863.c: New test.
> > > ---
> > >  gcc/config/i386/i386-expand.cc           | 2 +-
> > >  gcc/testsuite/gcc.target/i386/pr107863.c | 8 ++++++++
> > >  2 files changed, 9 insertions(+), 1 deletion(-)
> > >  create mode 100644 gcc/testsuite/gcc.target/i386/pr107863.c
> > >
> > > diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> > > index 0373c3614a4..c639ee3a9f7 100644
> > > --- a/gcc/config/i386/i386-expand.cc
> > > +++ b/gcc/config/i386/i386-expand.cc
> > > @@ -12475,7 +12475,7 @@ ix86_expand_vec_set_builtin (tree exp)
> > >    op1 = expand_expr (arg1, NULL_RTX, mode1, EXPAND_NORMAL);
> > >    elt = get_element_number (TREE_TYPE (arg0), arg2);
> > >
> > > -  if (GET_MODE (op1) != mode1 && GET_MODE (op1) != VOIDmode)
> > > +  if (GET_MODE (op1) != mode1)
> > >      op1 = convert_modes (mode1, GET_MODE (op1), op1, true);
> > >
> > >    op0 = force_reg (tmode, op0);
> > > diff --git a/gcc/testsuite/gcc.target/i386/pr107863.c b/gcc/testsuite/gcc.target/i386/pr107863.c
> > > new file mode 100644
> > > index 00000000000..99fd85d9765
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.target/i386/pr107863.c
> > > @@ -0,0 +1,8 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-options "-mavx2 -O" } */
> > > +
> > > +typedef char v16qi __attribute__((vector_size(16)));
> > > +
> > > +v16qi foo(v16qi a){
> > > +  return __builtin_ia32_vec_set_v16qi (a, -1, 2);
> > > +}
> > > --
> > > 2.27.0
> > >
> >
> >
> > --
> > BR,
> > Hongtao
>
>
>
> --
> H.J.



-- 
BR,
Hongtao