[Bug tree-optimization/92645] Hand written vector code is 450 times slower when compiled with GCC compared to Clang

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92645

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Nov 28 12:22:04 2019
New Revision: 278806

URL: https://gcc.gnu.org/viewcvs?rev=278806&root=gcc&view=rev
Log:
2019-11-28  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/92645
        * tree-ssa-forwprop.c (get_bit_field_ref_def): Also handle
        conversions inside a mode class.  Remove restriction on
        preserving the element size.
        (simplify_vector_constructor): Deal with the above and for
        identity permutes also try using VEC_UNPACK_[FLOAT_]LO_EXPR
        and VEC_PACK_TRUNC_EXPR.

        * gcc.target/i386/pr92645-4.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.target/i386/pr92645-4.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-forwprop.c