[Bug target/114107] poor vectorization at -O3 when dealing with arrays of different multiplicity, good with -O2

[liuhongt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114107

Hongtao Liu <liuhongt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |liuhongt at gcc dot gnu.org

--- Comment #7 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
perm_cost is very low in x86 backend, and it maybe ok for 128-bit vectors,
pshufb/shufps are avaible for most cases.
But for 256/512-bit vectors, when the permuation is cross-lane, the cost could
be higher. One solution is increase perm_cost when vector size is more than 128
since vperm is most likely used instead of vblend/vpblend/vpshuf/vshuf.