processor_costs has costs of RTL expressions and costs of moves:

1. Costs of RTL expressions is computed as COSTS_N_INSNS which are used
to generate RTL expressions with the lowest costs.  Costs of RTL memory
operation can be very close to costs of fast instructions to indicate
fast memory operations.

2. After RTL expressions have been generated, costs of moves are used by
TARGET_REGISTER_MOVE_COST and TARGET_MEMORY_MOVE_COST to compute move
costs for register allocator.  Costs of load and store are higher than
costs of register moves to reduce stack usages by register allocator.

We should separate costs of RTL expressions from costs of moves so that
they can be adjusted independently.  This patch moves costs of moves to
the new used_by_ra field and duplicates costs of moves which are also
used for costs of RTL expressions.

All cost models have been checked with

static void
check_one (const struct processor_costs *p)
{
  if (p->used_by_ra.int_load[2] != p->int_load)
    abort ();
  if (p->used_by_ra.int_store[2] != p->int_store)
    abort ();
  if (p->used_by_ra.xmm_move != p->xmm_move)
    abort ();
  if (p->used_by_ra.sse_to_integer != p->sse_to_integer)
    abort ();
  if (p->used_by_ra.integer_to_sse != p->integer_to_sse)
    abort ();
  if (memcmp (p->used_by_ra.sse_load, p->sse_load, sizeof (p->sse_load)))
    abort ();
  if (memcmp (p->used_by_ra.sse_store, p->sse_store, sizeof (p->sse_store)))
    abort ();
}

static void
check_cost ()
{
 check_one (&ix86_size_cost);
  for (unsigned int i = 0; i < ARRAY_SIZE (processor_cost_table); i++)
    check_one (processor_cost_table[i]);
}

by calling check_cost from ix86_option_override_internal.

PR target/90878
* config/i386/i386-features.c
(dimode_scalar_chain::compute_convert_gain): Replace int_store[2]
and int_load[2] with int_store and int_load.
* config/i386/i386.c (inline_memory_move_cost): Use used_by_ra
for costs of moves.
(ix86_register_move_cost): Likewise.
(ix86_builtin_vectorization_cost): Replace int_store[2] and
int_load[2] with int_store and int_load.
* config/i386/i386.h (processor_costs): Move costs of moves to
used_by_ra.  Add int_load, int_store, xmm_move, sse_to_integer,
integer_to_sse, sse_load, sse_store, sse_unaligned_load and
sse_unaligned_store for costs of RTL expressions.
* config/i386/x86-tune-costs.h: Duplicate int_load, int_store,
xmm_move, sse_to_integer, integer_to_sse, sse_load, sse_store
for costs of RTL expressions.  Use sse_unaligned_load and
sse_unaligned_store only for costs of RTL expressions.

-- 
H.J.