*** empty log message ***

[libfirm] / ir / be / belower.c

diff --git a/ir/be/belower.c b/ir/be/belower.c
index ed533bd..9e39567 100644 (file)
--- a/ir/be/belower.c
+++ b/ir/be/belower.c
@@ -350,8 +350,8 @@ static void lower_perm_node(ir_node *irn, void *walk_env) {
 //TODO: - iff PERM_CYCLE && do_copy -> determine free temp reg and insert copy to/from it before/after
 //        the copy cascade (this reduces the cycle into a chain)
 
-               /* build copy/swap nodes */
-               for (i = 0; i < cycle->n_elems - 1; i++) {
+               /* build copy/swap nodes from back to front */
+               for (i = cycle->n_elems - 2; i >= 0; i--) {
                        arg1 = get_node_for_register(pairs, n, cycle->elems[i], 0);
                        arg2 = get_node_for_register(pairs, n, cycle->elems[i + 1], 0);
 
@@ -370,6 +370,33 @@ static void lower_perm_node(ir_node *irn, void *walk_env) {
                                in[0] = arg1;
                                in[1] = arg2;
 
+                               /* At this point we have to handle the following problem:     */
+                               /*                                                            */
+                               /* If we have a cycle with more than two elements, then       */
+                               /* this could correspond to the following Perm node:          */
+                               /*                                                            */
+                               /*   +----+   +----+   +----+                                 */
+                               /*   | r1 |   | r2 |   | r3 |                                 */
+                               /*   +-+--+   +-+--+   +--+-+                                 */
+                               /*     |        |         |                                   */
+                               /*     |        |         |                                   */
+                               /*   +-+--------+---------+-+                                 */
+                               /*   |         Perm         |                                 */
+                               /*   +-+--------+---------+-+                                 */
+                               /*     |        |         |                                   */
+                               /*     |        |         |                                   */
+                               /*   +-+--+   +-+--+   +--+-+                                 */
+                               /*   |Proj|   |Proj|   |Proj|                                 */
+                               /*   | r2 |   | r3 |   | r1 |                                 */
+                               /*   +----+   +----+   +----+                                 */
+                               /*                                                            */
+                               /* This node is about to be split up into two 2x Perm's       */
+                               /* for which we need 4 Proj's and the one additional Proj     */
+                               /* of the first Perm has to be one IN of the second. So in    */
+                               /* general we need to create one additional Proj for each     */
+                               /* "middle" Perm and set this to one in node of the successor */
+                               /* Perm.                                                      */
+
                                DBG((mod, LEVEL_1, "%+F creating exchange node (%+F, %s) and (%+F, %s) with\n",
                                        irn, arg1, cycle->elems[i]->name, arg2, cycle->elems[i + 1]->name));
                                DBG((mod, LEVEL_1, "%+F                        (%+F, %s) and (%+F, %s)\n",
@@ -377,8 +404,21 @@ static void lower_perm_node(ir_node *irn, void *walk_env) {
 
                                cpyxchg = be_new_Perm(reg_class, env->chord_env->irg, block, 2, in);
 
+                               if (i > 0) {
+                                       /* cycle is not done yet */
+                                       int pidx = get_pairidx_for_regidx(pairs, n, cycle->elems[i]->index, 0);
+
+                                       /* create intermediate proj */
+                                       res2 = new_r_Proj(get_irn_irg(irn), block, cpyxchg, get_irn_mode(res1), 0);
+
+                                       /* set as in for next Perm */
+                                       pairs[pidx].in_node = res2;
+                               }
+                               else {
+                                       sched_remove(res2);
+                               }
+
                                sched_remove(res1);
-                               sched_remove(res2);
 
                                set_Proj_pred(res2, cpyxchg);
                                set_Proj_proj(res2, 0);
@@ -407,11 +447,13 @@ static void lower_perm_node(ir_node *irn, void *walk_env) {
 
                        /* insert the copy/exchange node in schedule after the magic schedule node (see above) */
                        sched_add_after(sched_point, cpyxchg);
+                       /* set the new scheduling point */
+                       sched_point = cpyxchg;
 
                        DBG((mod, LEVEL_1, "replacing %+F with %+F, placed new node after %+F\n", irn, cpyxchg, sched_point));
                }
 
-               free(cycle->elems);
+               free((void *) cycle->elems);
                free(cycle);
        }
 
@@ -487,7 +529,7 @@ static void lower_call_node(ir_node *call, const void *walk_env) {
                        reg = arch_register_for_index(reg_class, j);
 
                        /* only check caller save registers */
-                       if (arch_register_type_is(reg, caller_saved)) {
+                       if (arch_register_type_is(reg, caller_save)) {
 
                                /* Only create new proj, iff not already present */
                                if (!bitset_is_set(proj_set, bitset_idx)) {