re PR tree-optimization/78436 (incorrect write to larger-than-type bitfield (signed...

re PR tree-optimization/78436 (incorrect write to larger-than-type bitfield (signed char x:9))

	PR tree-optimization/78436
	* gimple-ssa-store-merging.c (zero_char_buf): Removed.
	(shift_bytes_in_array, shift_bytes_in_array_right,
	merged_store_group::apply_stores): Formatting fixes.
	(clear_bit_region): Likewise.  Use memset.
	(encode_tree_to_bitpos): Formatting fixes.  Fix comment typos - EPXR
	instead of EXPR and inerted instead of inserted.  Use memset instead
	of zero_char_buf.  For !BYTES_BIG_ENDIAN decrease byte_size by 1
	if shift_amnt is 0.

	* gcc.c-torture/execute/pr78436.c: New test.

From-SVN: r242691