static void
execute_return_slot_opt (void)
{
basic_block bb;
FOR_EACH_BB (bb)
{
block_stmt_iterator i;
for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
{
tree stmt = bsi_stmt (i);
tree call;
if (TREE_CODE (stmt) == MODIFY_EXPR
&& (call = TREE_OPERAND (stmt, 1),
TREE_CODE (call) == CALL_EXPR)
&& !CALL_EXPR_RETURN_SLOT_OPT (call)
&& aggregate_value_p (call, call))
{
def_operand_p def_p;
ssa_op_iter op_iter;
/* We determine whether or not the LHS address escapes by
asking whether it is call clobbered. When the LHS isn't a
simple decl, we need to check the VDEFs, so it's simplest
to just loop through all the DEFs. */
FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, op_iter, SSA_OP_ALL_DEFS)
{
tree def = DEF_FROM_PTR (def_p);
if (TREE_CODE (def) == SSA_NAME)
def = SSA_NAME_VAR (def);
if (is_call_clobbered (def))
goto unsafe;
}
/* No defs are call clobbered, so the optimization is safe. */
CALL_EXPR_RETURN_SLOT_OPT (call) = 1;
/* This is too late to mark the target addressable like we do
in gimplify_modify_expr_rhs, but that's OK; anything that
wasn't already addressable was handled there. */
unsafe:;
}
}
static bool
all_immediate_uses_same_place (def_operand_p def_p)
{
tree var = DEF_FROM_PTR (def_p);
imm_use_iterator imm_iter;
use_operand_p use_p;
gimple *firstuse = NULL;
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
{
if (is_gimple_debug (USE_STMT (use_p)))
continue;
if (firstuse == NULL)
firstuse = USE_STMT (use_p);
else
if (firstuse != USE_STMT (use_p))
return false;
}
return true;
}
static basic_block
nearest_common_dominator_of_uses (def_operand_p def_p, bool *debug_stmts)
{
tree var = DEF_FROM_PTR (def_p);
bitmap blocks = BITMAP_ALLOC (NULL);
basic_block commondom;
unsigned int j;
bitmap_iterator bi;
imm_use_iterator imm_iter;
use_operand_p use_p;
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
{
gimple *usestmt = USE_STMT (use_p);
basic_block useblock;
if (gphi *phi = dyn_cast <gphi *> (usestmt))
{
int idx = PHI_ARG_INDEX_FROM_USE (use_p);
useblock = gimple_phi_arg_edge (phi, idx)->src;
}
else if (is_gimple_debug (usestmt))
{
*debug_stmts = true;
continue;
}
else
{
useblock = gimple_bb (usestmt);
}
/* Short circuit. Nothing dominates the entry block. */
if (useblock == ENTRY_BLOCK_PTR_FOR_FN (cfun))
{
BITMAP_FREE (blocks);
return NULL;
}
bitmap_set_bit (blocks, useblock->index);
}
