static inline bool
set_copy_of_val (tree dest, tree first)
{
unsigned int dest_ver = SSA_NAME_VERSION (dest);
tree old_first, old_last, new_last;
/* Set FIRST to be the first link in COPY_OF[DEST]. If that
changed, return true. */
old_first = copy_of[dest_ver].value;
copy_of[dest_ver].value = first;
if (old_first != first)
return true;
/* If FIRST and OLD_FIRST are the same, we need to check whether the
copy-of chain starting at FIRST ends in a different variable. If
the copy-of chain starting at FIRST ends up in a different
variable than the last cached value we had for DEST, then return
true because DEST is now a copy of a different variable.
This test is necessary because even though the first link in the
copy-of chain may not have changed, if any of the variables in
the copy-of chain changed its final value, DEST will now be the
copy of a different variable, so we have to do another round of
propagation for everything that depends on DEST. */
old_last = cached_last_copy_of[dest_ver];
new_last = get_last_copy_of (dest);
cached_last_copy_of[dest_ver] = new_last;
return (old_last != new_last);
}
static enum ssa_prop_result
copy_prop_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
{
enum ssa_prop_result retval = SSA_PROP_VARYING;
location_t loc = gimple_location (stmt);
tree op0 = gimple_cond_lhs (stmt);
tree op1 = gimple_cond_rhs (stmt);
/* The only conditionals that we may be able to compute statically
are predicates involving two SSA_NAMEs. */
if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
{
op0 = get_last_copy_of (op0);
op1 = get_last_copy_of (op1);
/* See if we can determine the predicate's value. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Trying to determine truth value of ");
fprintf (dump_file, "predicate ");
print_gimple_stmt (dump_file, stmt, 0, 0);
}
/* We can fold COND and get a useful result only when we have
the same SSA_NAME on both sides of a comparison operator. */
if (op0 == op1)
{
tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
boolean_type_node, op0, op1);
if (folded_cond)
{
basic_block bb = gimple_bb (stmt);
*taken_edge_p = find_taken_edge (bb, folded_cond);
if (*taken_edge_p)
retval = SSA_PROP_INTERESTING;
}
}
}
if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p)
fprintf (dump_file, "\nConditional will always take edge %d->%d\n",
(*taken_edge_p)->src->index, (*taken_edge_p)->dest->index);
return retval;
}
static void
fini_copy_prop (void)
{
size_t i;
prop_value_t *tmp;
/* Set the final copy-of value for each variable by traversing the
copy-of chains. */
tmp = XCNEWVEC (prop_value_t, num_ssa_names);
for (i = 1; i < num_ssa_names; i++)
{
tree var = ssa_name (i);
if (var && copy_of[i].value && copy_of[i].value != var)
tmp[i].value = get_last_copy_of (var);
}
substitute_and_fold (tmp, false);
free (cached_last_copy_of);
free (copy_of);
free (tmp);
}
static void
fini_copy_prop (void)
{
size_t i;
prop_value_t *tmp;
/* Set the final copy-of value for each variable by traversing the
copy-of chains. */
tmp = XCNEWVEC (prop_value_t, num_ssa_names);
for (i = 1; i < num_ssa_names; i++)
{
tree var = ssa_name (i);
if (!var
|| !copy_of[i].value
|| copy_of[i].value == var)
continue;
tmp[i].value = get_last_copy_of (var);
/* In theory the points-to solution of all members of the
copy chain is their intersection. For now we do not bother
to compute this but only make sure we do not lose points-to
information completely by setting the points-to solution
of the representative to the first solution we find if
it doesn't have one already. */
if (tmp[i].value != var
&& POINTER_TYPE_P (TREE_TYPE (var))
&& SSA_NAME_PTR_INFO (var)
&& !SSA_NAME_PTR_INFO (tmp[i].value))
duplicate_ssa_name_ptr_info (tmp[i].value, SSA_NAME_PTR_INFO (var));
}
substitute_and_fold (tmp, false);
free (cached_last_copy_of);
free (copy_of);
free (tmp);
}
static enum ssa_prop_result
copy_prop_visit_phi_node (gimple phi)
{
enum ssa_prop_result retval;
unsigned i;
prop_value_t phi_val = { 0, NULL_TREE };
tree lhs = gimple_phi_result (phi);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nVisiting PHI node: ");
print_gimple_stmt (dump_file, phi, 0, dump_flags);
fprintf (dump_file, "\n\n");
}
for (i = 0; i < gimple_phi_num_args (phi); i++)
{
prop_value_t *arg_val;
tree arg = gimple_phi_arg_def (phi, i);
edge e = gimple_phi_arg_edge (phi, i);
/* We don't care about values flowing through non-executable
edges. */
if (!(e->flags & EDGE_EXECUTABLE))
continue;
/* Constants in the argument list never generate a useful copy.
Similarly, names that flow through abnormal edges cannot be
used to derive copies. */
if (TREE_CODE (arg) != SSA_NAME || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg))
{
phi_val.value = lhs;
break;
}
/* Avoid copy propagation from an inner into an outer loop.
Otherwise, this may move loop variant variables outside of
their loops and prevent coalescing opportunities. If the
value was loop invariant, it will be hoisted by LICM and
exposed for copy propagation. Not a problem for virtual
operands though. */
if (is_gimple_reg (lhs)
&& loop_depth_of_name (arg) > loop_depth_of_name (lhs))
{
phi_val.value = lhs;
break;
}
/* If the LHS appears in the argument list, ignore it. It is
irrelevant as a copy. */
if (arg == lhs || get_last_copy_of (arg) == lhs)
continue;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\tArgument #%d: ", i);
dump_copy_of (dump_file, arg);
fprintf (dump_file, "\n");
}
arg_val = get_copy_of_val (arg);
/* If the LHS didn't have a value yet, make it a copy of the
first argument we find. Notice that while we make the LHS be
a copy of the argument itself, we take the memory reference
from the argument's value so that we can compare it to the
memory reference of all the other arguments. */
if (phi_val.value == NULL_TREE)
{
phi_val.value = arg_val->value ? arg_val->value : arg;
continue;
}
/* If PHI_VAL and ARG don't have a common copy-of chain, then
this PHI node cannot be a copy operation. Also, if we are
copy propagating stores and these two arguments came from
different memory references, they cannot be considered
copies. */
if (get_last_copy_of (phi_val.value) != get_last_copy_of (arg))
{
phi_val.value = lhs;
break;
}
}
if (phi_val.value && may_propagate_copy (lhs, phi_val.value)
&& set_copy_of_val (lhs, phi_val.value))
retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
else
retval = SSA_PROP_NOT_INTERESTING;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nPHI node ");
dump_copy_of (dump_file, lhs);
fprintf (dump_file, "\nTelling the propagator to ");
if (retval == SSA_PROP_INTERESTING)
fprintf (dump_file, "add SSA edges out of this PHI and continue.");
else if (retval == SSA_PROP_VARYING)
fprintf (dump_file, "add SSA edges out of this PHI and never visit again.");
else
fprintf (dump_file, "do nothing with SSA edges and keep iterating.");
fprintf (dump_file, "\n\n");
}
return retval;
}
