PR middle-end/52979
* stor-layout.c (get_best_mode): Don't return mode with bitsize
larger than maxbits. Don't compute maxbits modulo align.
Also check that unit bytes long store at bitpos / unit * unit
doesn't affect bits beyond bitregion_end.
* expmed.c (store_bit_field_1): Avoid trying insv if OP_MODE MEM
would not fit into bitregion_start ... bitregion_end + 1 bit
region.
(store_split_bit_field): Decrease unit close to end of bitregion_end
if access is restricted in order to avoid mutual recursion.
* gcc.c-torture/compile/pr52979-1.c: New test.
* gcc.c-torture/execute/pr52979-1.c: New test.
* gcc.c-torture/execute/pr52979-2.c: New test.
From-SVN: r186819
