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

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

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.

> >
> > 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.