bitint: Handle complex types in build_bitint_stmt_ssa_conflicts [PR114425]

bitint: Handle complex types in build_bitint_stmt_ssa_conflicts [PR114425]

The task of the build_bitint_stmt_ssa_conflicts hook for
tree-ssa-coalesce.cc next to special casing the
multiplication/division/modulo is to ignore statements with
large/huge _BitInt lhs which isn't in names bitmap and on the
other side pretend all uses of the stmt are used in a later stmt
(single user of that SSA_NAME or perhaps single user of lhs of
the single user etc.) where the lowering will actually emit the
code.

Unfortunately the function wasn't handling COMPLEX_TYPE of the large/huge
BITINT_TYPE, while the FE doesn't really support such types, they are
used under the hood for __builtin_{add,sub,mul}_overflow{,_p}, they are
also present or absent from the names bitmap and should be treated the same.

Without this patch, the operands of .ADD_OVERFLOW were incorrectly pretended
to be used right in that call statement rather than on the cast stmt from
IMAGPART_EXPR of .ADD_OVERFLOW return value to some integral type.

2024-03-23  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/114425
	* gimple-lower-bitint.cc (build_bitint_stmt_ssa_conflicts): Handle
	_Complex large/huge _BitInt types like the large/huge _BitInt types.

	* gcc.dg/torture/bitint-67.c: New test.