* config/i386/i386-features.h
(general_scalar_chain::~general_scalar_chain): Add.
(general_scalar_chain::insns_conv): New bitmap.
(general_scalar_chain::n_sse_to_integer): New.
(general_scalar_chain::n_integer_to_sse): Likewise.
(general_scalar_chain::make_vector_copies): Adjust signature.
* config/i386/i386-features.c
(general_scalar_chain::general_scalar_chain): Outline,
initialize new members.
(general_scalar_chain::~general_scalar_chain): New.
(general_scalar_chain::mark_dual_mode_def): Record insns
we need to insert conversions at and count them.
(general_scalar_chain::compute_convert_gain): Account
for conversion instructions at chain boundary.
(general_scalar_chain::make_vector_copies): Generate a single
copy for a def by a specific insn.
(general_scalar_chain::convert_registers): First populate
defs_map, then make copies at out-of chain insns.