static gimple
get_prop_dest_stmt (tree name, tree *final_name_p)
{
use_operand_p use;
gimple use_stmt;
do {
/* If name has multiple uses, bail out. */
if (!single_imm_use (name, &use, &use_stmt))
return NULL;
/* If this is not a trivial copy, we found it. */
if (!gimple_assign_copy_p (use_stmt)
|| TREE_CODE (gimple_assign_lhs (use_stmt)) != SSA_NAME
|| gimple_assign_rhs1 (use_stmt) != name)
break;
/* Continue searching uses of the copy destination. */
name = gimple_assign_lhs (use_stmt);
} while (1);
if (final_name_p)
*final_name_p = name;
return use_stmt;
}
static gimple
get_prop_source_stmt (tree name, bool single_use_only, bool *single_use_p)
{
bool single_use = true;
do {
gimple def_stmt = SSA_NAME_DEF_STMT (name);
if (!has_single_use (name))
{
single_use = false;
if (single_use_only)
return NULL;
}
/* If name is defined by a PHI node or is the default def, bail out. */
if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
return NULL;
/* If name is not a simple copy destination, we found it. */
if (!gimple_assign_copy_p (def_stmt)
|| TREE_CODE (gimple_assign_rhs1 (def_stmt)) != SSA_NAME)
{
tree rhs;
if (!single_use_only && single_use_p)
*single_use_p = single_use;
/* We can look through pointer conversions in the search
for a useful stmt for the comparison folding. */
rhs = gimple_assign_rhs1 (def_stmt);
if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))
&& TREE_CODE (rhs) == SSA_NAME
&& POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (def_stmt)))
&& POINTER_TYPE_P (TREE_TYPE (rhs)))
name = rhs;
else
return def_stmt;
}
else
{
/* Continue searching the def of the copy source name. */
name = gimple_assign_rhs1 (def_stmt);
}
} while (1);
}
static bool
remove_prop_source_from_use (tree name, gimple up_to_stmt)
{
gimple_stmt_iterator gsi;
gimple stmt;
do {
if (!has_zero_uses (name))
return false;
stmt = SSA_NAME_DEF_STMT (name);
if (stmt == up_to_stmt)
return true;
gsi = gsi_for_stmt (stmt);
release_defs (stmt);
gsi_remove (&gsi, true);
name = (gimple_assign_copy_p (stmt)) ? gimple_assign_rhs1 (stmt) : NULL;
} while (name && TREE_CODE (name) == SSA_NAME);
return false;
}
static unsigned int
tree_nrv (void)
{
tree result = DECL_RESULT (current_function_decl);
tree result_type = TREE_TYPE (result);
tree found = NULL;
basic_block bb;
gimple_stmt_iterator gsi;
struct nrv_data data;
/* If this function does not return an aggregate type in memory, then
there is nothing to do. */
if (!aggregate_value_p (result, current_function_decl))
return 0;
/* If a GIMPLE type is returned in memory, finalize_nrv_r might create
non-GIMPLE. */
if (is_gimple_reg_type (result_type))
return 0;
/* Look through each block for assignments to the RESULT_DECL. */
FOR_EACH_BB (bb)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple stmt = gsi_stmt (gsi);
tree ret_val;
if (gimple_code (stmt) == GIMPLE_RETURN)
{
/* In a function with an aggregate return value, the
gimplifier has changed all non-empty RETURN_EXPRs to
return the RESULT_DECL. */
ret_val = gimple_return_retval (stmt);
if (ret_val)
gcc_assert (ret_val == result);
}
else if (is_gimple_assign (stmt)
&& gimple_assign_lhs (stmt) == result)
{
tree rhs;
if (!gimple_assign_copy_p (stmt))
return 0;
rhs = gimple_assign_rhs1 (stmt);
/* Now verify that this return statement uses the same value
as any previously encountered return statement. */
if (found != NULL)
{
/* If we found a return statement using a different variable
than previous return statements, then we can not perform
NRV optimizations. */
if (found != rhs)
return 0;
}
else
found = rhs;
/* The returned value must be a local automatic variable of the
same type and alignment as the function's result. */
if (TREE_CODE (found) != VAR_DECL
|| TREE_THIS_VOLATILE (found)
|| DECL_CONTEXT (found) != current_function_decl
|| TREE_STATIC (found)
|| TREE_ADDRESSABLE (found)
|| DECL_ALIGN (found) > DECL_ALIGN (result)
|| !useless_type_conversion_p (result_type,
TREE_TYPE (found)))
return 0;
}
else if (is_gimple_assign (stmt))
{
tree addr = get_base_address (gimple_assign_lhs (stmt));
/* If there's any MODIFY of component of RESULT,
then bail out. */
if (addr && addr == result)
return 0;
}
}
}
if (!found)
return 0;
/* If dumping details, then note once and only the NRV replacement. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "NRV Replaced: ");
print_generic_expr (dump_file, found, dump_flags);
fprintf (dump_file, " with: ");
print_generic_expr (dump_file, result, dump_flags);
fprintf (dump_file, "\n");
}
/* At this point we know that all the return statements return the
same local which has suitable attributes for NRV. Copy debugging
information from FOUND to RESULT. */
DECL_NAME (result) = DECL_NAME (found);
DECL_SOURCE_LOCATION (result) = DECL_SOURCE_LOCATION (found);
DECL_ABSTRACT_ORIGIN (result) = DECL_ABSTRACT_ORIGIN (found);
TREE_ADDRESSABLE (result) = TREE_ADDRESSABLE (found);
/* Now walk through the function changing all references to VAR to be
RESULT. */
data.var = found;
data.result = result;
FOR_EACH_BB (bb)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
{
gimple stmt = gsi_stmt (gsi);
/* If this is a copy from VAR to RESULT, remove it. */
if (gimple_assign_copy_p (stmt)
&& gimple_assign_lhs (stmt) == result
&& gimple_assign_rhs1 (stmt) == found)
gsi_remove (&gsi, true);
else
{
struct walk_stmt_info wi;
memset (&wi, 0, sizeof (wi));
wi.info = &data;
walk_gimple_op (stmt, finalize_nrv_r, &wi);
gsi_next (&gsi);
}
}
}
/* FOUND is no longer used. Ensure it gets removed. */
var_ann (found)->used = 0;
return 0;
}
