[Bug tree-optimization/118487] [15 Regression] ICE tree check: expected vector_cst, have ssa_name in vector_cst_encoded_nelts, at tree.h:4683 since r15-5563-g1c4d39ada33d36

[cmuellner at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118487

--- Comment #3 from Christoph Müllner <cmuellner at gcc dot gnu.org> ---
My initial comment about the need to sanitize the mask elements of
VEC_PERM_EXPR was correct, but there is nothing to be done for that, because
this is handled by ccp1.

The ICE reported here comes from the issue of not checking the TREE_CODE of the
mask tree.
I've sent a fix for that to the list:
  https://gcc.gnu.org/pipermail/gcc-patches/2025-January/673703.html

While analysing this, I noticed that we make redundant calls to to_constant(),
which is addressed here:
  https://gcc.gnu.org/pipermail/gcc-patches/2025-January/673702.html