On Sun, Sep 20, 2026 at 12:25 AM Stefan Schulze Frielinghaus
<[email protected]> wrote:
>
> On Sat, Sep 19, 2026 at 05:49:50AM -0700, Andrea Pinski wrote:
> > On Fri, Sep 18, 2026 at 11:50 PM Stefan Schulze Frielinghaus
> > <[email protected]> wrote:
> > >
> > > From: Stefan Schulze Frielinghaus <[email protected]>
> > >
> > > When expand_mult handles a constant vector multiplier where the scalar
> > > operand is a CONST_WIDE_INT, then also look through the vector mode
> > > while determining the shift amount since here we need the scalar mode.
> > > Note, when we call later on into expand_shift we need the vector mode,
> > > i.e., only for the shift amount we need the scalar mode.
> > >
> > > I guess it would have been sound to call unconditionally into
> > > GET_MODE_INNER, i.e., even for scalars (kinda similar as for
> > > GET_MODE_UNIT_BITSIZE from above), however, I think checking for
> > > VECTOR_MODE_P here makes the intend explicit.
> > >
> > > PR middle-end/127474
> > >
> > > gcc/ChangeLog:
> > >
> > > * expmed.cc (expand_mult): Look through vector mode.
> > Ok except for a minor change to the testcase listed below.
> >
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > * gcc.target/s390/pr127474.c: New test.
> > > ---
> > > Bootstrapped and regtested for
> > > - aarch64-unknown-linux-gnu
> > > - powerpc64le-unknown-linux-gnu
> > > - s390x-ibm-linux-gnu
> > > - x86_64-pc-linux-gnu
> > > Ok for mainline?
> > >
> > > gcc/expmed.cc | 4 +++-
> > > gcc/testsuite/gcc.target/s390/pr127474.c | 11 +++++++++++
> > > 2 files changed, 14 insertions(+), 1 deletion(-)
> > > create mode 100644 gcc/testsuite/gcc.target/s390/pr127474.c
> > >
> > > diff --git a/gcc/expmed.cc b/gcc/expmed.cc
> > > index c6494484251..b82c0bb10db 100644
> > > --- a/gcc/expmed.cc
> > > +++ b/gcc/expmed.cc
> > > @@ -3633,7 +3633,9 @@ expand_mult (machine_mode mode, rtx op0, rtx op1,
> > > rtx target,
> > > else if (CONST_DOUBLE_AS_INT_P (scalar_op1))
> > > #endif
> > > {
> > > - int shift = wi::exact_log2 (rtx_mode_t (scalar_op1, mode));
> > > + machine_mode scalar_mode = VECTOR_MODE_P (mode)
> > > + ? GET_MODE_INNER (mode) : mode;
> > > + int shift = wi::exact_log2 (rtx_mode_t (scalar_op1,
> > > scalar_mode));
> > > /* Perfect power of 2 (other than 1, which is handled above).
> > > */
> > > if (shift > 0)
> > > return expand_shift (LSHIFT_EXPR, mode, op0,
> > > diff --git a/gcc/testsuite/gcc.target/s390/pr127474.c
> > > b/gcc/testsuite/gcc.target/s390/pr127474.c
> > > new file mode 100644
> > > index 00000000000..a5580ee3b6a
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.target/s390/pr127474.c
> > > @@ -0,0 +1,11 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-options "-O2 -march=z17" } */
> >
> > Can you place this in gcc.dg/torture/
> > and change dg-options to dg-additional-options and make that s390x and
> > remove -O2?
>
> I also added dg-require-effective-target int128 and ran the new test for
Thanks for adding `dg-require-effective-target int128` here. I forgot
about that when requesting to move the testcase.
Thanks,
Andrea
> - aarch64-unknown-linux-gnu
> - powerpc64le-unknown-linux-gnu
> - s390x-ibm-linux-gnu
> - x86_64-pc-linux-gnu
> Pushed as r17-4477-g5dc4ab23e0d.
>
> Cheers,
> Stefan
>
> >
> > Thanks,
> > Andrea
> >
> > > +
> > > +/* Previously we ICE'd in expand_mult when dealing with a
> > > CONST_WIDE_INT. */
> > > +
> > > +typedef __int128 v1ti __attribute__ ((vector_size (16)));
> > > +
> > > +v1ti foo (v1ti x)
> > > +{
> > > + return x * (v1ti){(__int128)123456789 << 64 | (__int128)123456789};
> > > +}
> > > --
> > > 2.55.0
> > >
