| TODO_verify_ssa, /* todo_flags_finish */
0 /* letter */
};
+
+
+/* Structure to keep track of the value of a dereferenced PHI result
+ and the set of virtual operands used for that dereference. */
+
+struct phiprop_d
+{
+ tree value;
+ tree vop_stmt;
+};
+
+/* Verify if the value recorded for NAME in PHIVN is still valid at
+ the start of basic block BB. */
+
+static bool
+phivn_valid_p (struct phiprop_d *phivn, tree name, basic_block bb)
+{
+ tree vop_stmt = phivn[SSA_NAME_VERSION (name)].vop_stmt;
+ ssa_op_iter ui;
+ tree vuse;
+
+ /* The def stmts of all virtual uses need to be post-dominated
+ by bb. */
+ FOR_EACH_SSA_TREE_OPERAND (vuse, vop_stmt, ui, SSA_OP_VUSE)
+ {
+ tree use_stmt;
+ imm_use_iterator ui2;
+ bool ok = true;
+
+ FOR_EACH_IMM_USE_STMT (use_stmt, ui2, vuse)
+ {
+ /* If BB does not dominate a VDEF, the value is invalid. */
+ if (((TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
+ && !ZERO_SSA_OPERANDS (use_stmt, SSA_OP_VDEF))
+ || TREE_CODE (use_stmt) == PHI_NODE)
+ && !dominated_by_p (CDI_DOMINATORS, bb_for_stmt (use_stmt), bb))
+ {
+ ok = false;
+ BREAK_FROM_IMM_USE_STMT (ui2);
+ }
+ }
+ if (!ok)
+ return false;
+ }
+
+ return true;
+}
+
+/* Insert a new phi node for the dereference of PHI at basic_block
+ BB with the virtual operands from USE_STMT. */
+
+static tree
+phiprop_insert_phi (basic_block bb, tree phi, tree use_stmt,
+ struct phiprop_d *phivn, size_t n)
+{
+ tree res, new_phi;
+ edge_iterator ei;
+ edge e;
+
+ /* Build a new PHI node to replace the definition of
+ the indirect reference lhs. */
+ res = GIMPLE_STMT_OPERAND (use_stmt, 0);
+ SSA_NAME_DEF_STMT (res) = new_phi = create_phi_node (res, bb);
+
+ /* Add PHI arguments for each edge inserting loads of the
+ addressable operands. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ tree old_arg, new_var, tmp;
+
+ old_arg = PHI_ARG_DEF_FROM_EDGE (phi, e);
+ while (TREE_CODE (old_arg) == SSA_NAME
+ && (SSA_NAME_VERSION (old_arg) >= n
+ || phivn[SSA_NAME_VERSION (old_arg)].value == NULL_TREE))
+ {
+ tree def_stmt = SSA_NAME_DEF_STMT (old_arg);
+ old_arg = GIMPLE_STMT_OPERAND (def_stmt, 1);
+ }
+
+ if (TREE_CODE (old_arg) == SSA_NAME)
+ /* Reuse a formely created dereference. */
+ new_var = phivn[SSA_NAME_VERSION (old_arg)].value;
+ else
+ {
+ old_arg = TREE_OPERAND (old_arg, 0);
+ new_var = create_tmp_var (TREE_TYPE (old_arg), NULL);
+ tmp = build2 (GIMPLE_MODIFY_STMT, void_type_node,
+ NULL_TREE, unshare_expr (old_arg));
+ if (TREE_CODE (TREE_TYPE (old_arg)) == COMPLEX_TYPE
+ || TREE_CODE (TREE_TYPE (old_arg)) == VECTOR_TYPE)
+ DECL_GIMPLE_REG_P (new_var) = 1;
+ add_referenced_var (new_var);
+ new_var = make_ssa_name (new_var, tmp);
+ GIMPLE_STMT_OPERAND (tmp, 0) = new_var;
+
+ bsi_insert_on_edge (e, tmp);
+
+ update_stmt (tmp);
+ mark_symbols_for_renaming (tmp);
+ }
+
+ add_phi_arg (new_phi, new_var, e);
+ }
+
+ update_stmt (new_phi);
+
+ return res;
+}
+
+/* Propagate between the phi node arguments of PHI in BB and phi result
+ users. For now this matches
+ # p_2 = PHI <&x, &y>
+ <Lx>:;
+ p_3 = p_2;
+ z_2 = *p_3;
+ and converts it to
+ # z_2 = PHI <x, y>
+ <Lx>:;
+ Returns true if a transformation was done and edge insertions
+ need to be committed. Global data PHIVN and N is used to track
+ past transformation results. We need to be especially careful here
+ with aliasing issues as we are moving memory reads. */
+
+static bool
+propagate_with_phi (basic_block bb, tree phi, struct phiprop_d *phivn, size_t n)
+{
+ tree ptr = PHI_RESULT (phi);
+ tree use_stmt, res = NULL_TREE;
+ block_stmt_iterator bsi;
+ imm_use_iterator ui;
+ use_operand_p arg_p, use;
+ ssa_op_iter i;
+ bool phi_inserted;
+
+ if (MTAG_P (SSA_NAME_VAR (ptr))
+ || !POINTER_TYPE_P (TREE_TYPE (ptr))
+ || !is_gimple_reg_type (TREE_TYPE (TREE_TYPE (ptr))))
+ return false;
+
+ /* Check if we can "cheaply" dereference all phi arguments. */
+ FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
+ {
+ tree arg = USE_FROM_PTR (arg_p);
+ /* Walk the ssa chain until we reach a ssa name we already
+ created a value for or we reach a definition of the form
+ ssa_name_n = &var; */
+ while (TREE_CODE (arg) == SSA_NAME
+ && !SSA_NAME_IS_DEFAULT_DEF (arg)
+ && (SSA_NAME_VERSION (arg) >= n
+ || phivn[SSA_NAME_VERSION (arg)].value == NULL_TREE))
+ {
+ tree def_stmt = SSA_NAME_DEF_STMT (arg);
+ if (TREE_CODE (def_stmt) != GIMPLE_MODIFY_STMT)
+ return false;
+ arg = GIMPLE_STMT_OPERAND (def_stmt, 1);
+ }
+ if ((TREE_CODE (arg) != ADDR_EXPR
+ /* Avoid to have to decay *&a to a[0] later. */
+ || !is_gimple_reg_type (TREE_TYPE (TREE_OPERAND (arg, 0))))
+ && !(TREE_CODE (arg) == SSA_NAME
+ && phivn[SSA_NAME_VERSION (arg)].value != NULL_TREE
+ && phivn_valid_p (phivn, arg, bb)))
+ return false;
+ }
+
+ /* Find a dereferencing use. First follow (single use) ssa
+ copy chains for ptr. */
+ while (single_imm_use (ptr, &use, &use_stmt)
+ && TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
+ && GIMPLE_STMT_OPERAND (use_stmt, 1) == ptr
+ && TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 0)) == SSA_NAME)
+ ptr = GIMPLE_STMT_OPERAND (use_stmt, 0);
+
+ /* Replace the first dereference of *ptr if there is one and if we
+ can move the loads to the place of the ptr phi node. */
+ phi_inserted = false;
+ FOR_EACH_IMM_USE_STMT (use_stmt, ui, ptr)
+ {
+ ssa_op_iter ui2;
+ tree vuse;
+
+ /* Check whether this is a load of *ptr. */
+ if (!(TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 0)) == SSA_NAME
+ && TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == INDIRECT_REF
+ && TREE_OPERAND (GIMPLE_STMT_OPERAND (use_stmt, 1), 0) == ptr
+ /* We cannot replace a load that may throw or is volatile. */
+ && !tree_can_throw_internal (use_stmt)))
+ continue;
+
+ /* Check if we can move the loads. The def stmts of all virtual uses
+ need to be post-dominated by bb. */
+ FOR_EACH_SSA_TREE_OPERAND (vuse, use_stmt, ui2, SSA_OP_VUSE)
+ {
+ tree def_stmt = SSA_NAME_DEF_STMT (vuse);
+ if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
+ && (bb_for_stmt (def_stmt) == bb
+ || !dominated_by_p (CDI_DOMINATORS,
+ bb, bb_for_stmt (def_stmt))))
+ goto next;
+ }
+
+ /* Found a proper dereference. Insert a phi node if this
+ is the first load transformation. */
+ if (!phi_inserted)
+ {
+ res = phiprop_insert_phi (bb, phi, use_stmt, phivn, n);
+
+ /* Remember the value we created for *ptr. */
+ phivn[SSA_NAME_VERSION (ptr)].value = res;
+ phivn[SSA_NAME_VERSION (ptr)].vop_stmt = use_stmt;
+
+ /* Remove old stmt. The phi is taken care of by DCE, if we
+ want to delete it here we also have to delete all intermediate
+ copies. */
+ bsi = bsi_for_stmt (use_stmt);
+ bsi_remove (&bsi, 0);
+
+ phi_inserted = true;
+ }
+ else
+ {
+ /* Further replacements are easy, just make a copy out of the
+ load. */
+ GIMPLE_STMT_OPERAND (use_stmt, 1) = res;
+ update_stmt (use_stmt);
+ }
+
+next:;
+ /* Continue searching for a proper dereference. */
+ }
+
+ return phi_inserted;
+}
+
+/* Helper walking the dominator tree starting from BB and processing
+ phi nodes with global data PHIVN and N. */
+
+static bool
+tree_ssa_phiprop_1 (basic_block bb, struct phiprop_d *phivn, size_t n)
+{
+ bool did_something = false;
+ basic_block son;
+ tree phi;
+
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ did_something |= propagate_with_phi (bb, phi, phivn, n);
+
+ for (son = first_dom_son (CDI_DOMINATORS, bb);
+ son;
+ son = next_dom_son (CDI_DOMINATORS, son))
+ did_something |= tree_ssa_phiprop_1 (son, phivn, n);
+
+ return did_something;
+}
+
+/* Main entry for phiprop pass. */
+
+static unsigned int
+tree_ssa_phiprop (void)
+{
+ struct phiprop_d *phivn;
+
+ calculate_dominance_info (CDI_DOMINATORS);
+
+ phivn = XCNEWVEC (struct phiprop_d, num_ssa_names);
+
+ if (tree_ssa_phiprop_1 (ENTRY_BLOCK_PTR, phivn, num_ssa_names))
+ bsi_commit_edge_inserts ();
+
+ free (phivn);
+
+ return 0;
+}
+
+static bool
+gate_phiprop (void)
+{
+ return 1;
+}
+
+struct tree_opt_pass pass_phiprop = {
+ "phiprop", /* name */
+ gate_phiprop, /* gate */
+ tree_ssa_phiprop, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_TREE_FORWPROP, /* tv_id */
+ PROP_cfg | PROP_ssa, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func
+ | TODO_ggc_collect
+ | TODO_update_ssa
+ | TODO_verify_ssa, /* todo_flags_finish */
+ 0 /* letter */
+};
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