This series of patches converts CONST_VECTOR to use the same encoding scheme as VECTOR_CST. I'd originally being holding it back until the vec_perm series had been processed, but that was probably a mistake.
The main difference from VECTOR_CST is that we still include all the elements for fixed-length vectors, to help with code that operates directly on XVEC and XVECEXP. See the covering note of patch 2 for more details. Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64el-linux-gnu. Also tested by comparing the before-and-after assembly output for at least one target per CPU directory. OK to install? Thanks, Richard [FWIW, the vec_perm patches are the only ones holding up the rest of the poly_int ones.]