[Bug tree-optimization/93843] [10 Regression] wrong code at -O3 on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93843

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Sandiford <rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:b6268016bf46dd63227dcbb73d13c30a3b4b9d2a

commit r10-6863-gb6268016bf46dd63227dcbb73d13c30a3b4b9d2a
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Tue Feb 25 19:20:58 2020 +0000

    optabs: Don't use scalar conversions for vectors [PR93843]

    In this PR we had a conversion between two integer vectors that
    both had scalar integer modes.  We then tried to implement the
    conversion using the scalar optab for those modes, instead of
    doing the conversion elementwise.

    I wondered about letting through scalar modes for single-element
    vectors, but I don't have any evidence that that's useful/necessary,
    so it seemed better to keep things simple.

    2020-02-26  Richard Sandiford  <richard.sandiford@arm.com>

    gcc/
        PR middle-end/93843
        * optabs-tree.c (supportable_convert_operation): Reject types with
        scalar modes.

    gcc/testsuite/
        PR middle-end/93843
        * gcc.dg/vect/pr93843-1.c: New test.
        * gcc.dg/vect/pr93843-2.c: Likewise.