[PATCH 0/5][tree-sra.c] PR/63679 Make SRA replace constant pool loads

[Alan Lawrence <alan dot lawrence at arm dot com>]

ssa-dom-cse-2.c fails on a number of platforms because the input array is pushed
out to the constant pool, preventing later stages from folding away the entire
computation. This patch series fixes the failure by extending SRA to pull the
constants back in.

This is my first patch(set) to SRA and as such I'd appreciate suggestions about
the approach. I think the first two patches, which essentially just extend SRA
to deal with ARRAY_TYPE as well as RECORD_TYPE, are fairly straightforward and
may stand alone. Later patches, in particular, may be better done in a different
way and I'd welcome feedback as to what a patch (series) should look like.

Also the heuristic for controlling SRA, when dealing with constant-pool loads,
may want something better/other than the default
--param sra-max-scalarization-size-O{speed,size}, or else platforms where the
initializer is forced to memory, will still suffer in terms of constant
propagation.