middle-end/111975 - dump -> GIMPLE FE roundtrip improvements
The following improves the manual work needed to make a -gimple dump
valid input to the GIMPLE FE. First of all it recognizes the 'sizetype'
tree and dumps it as __SIZETYPE__, then it changes dumping vector types
without name from 'vector(n) T' to 'T [[gnu::vector_size(n')]]' which
we can parse in most relevant contexts (and that's shorter than
using __attribute__). Third it avoids a NULL_TREE TMR_STEP when
it would be one, an optimization that's re-done when generating RTL.
PR middle-end/111975
* tree-pretty-print.cc (dump_generic_node): Dump
sizetype as __SIZETYPE__ with TDF_GIMPLE.
Dump unnamed vector types as T [[gnu::vector_size(n)]] with
TDF_GIMPLE.
* tree-ssa-address.cc (create_mem_ref_raw): Never generate
a NULL STEP when INDEX is specified.