renamed symconst_size to symconst_type_size
[libfirm] / ir / opt / ifconv.c
index ce27609..9d9fab3 100644 (file)
 
 #if 1
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+#ifdef HAVE_MALLOC_H
+#include <malloc.h>
+#endif
+#ifdef HAVE_ALLOCA_H
+#include <alloca.h>
+#endif
+
 #include <assert.h>
-#include <stdlib.h>
+
+#include "obst.h"
+#include "irnode_t.h"
 #include "cdep.h"
 #include "ircons.h"
 #include "ifconv.h"
 #include "irgwalk.h"
 #include "irtools.h"
 #include "return.h"
-#include "xmalloc.h"
+#include "array.h"
 
 // debug
 #include "irdump.h"
-#include "irprintf.h"
-
+#include "debug.h"
 
-static ir_node* walk_to_projx(ir_node* start)
-{
-       ir_node* pred;
-       ir_node* cdep;
-
-       pred = get_nodes_block(start);
-       cdep = get_unique_cdep(pred);
-       if (cdep == NULL) return NULL;
-
-       assert(get_irn_arity(pred) == 1);
-       pred = get_irn_n(pred, 0);
-       if (get_irn_op(pred) == op_Proj) {
-               assert(get_irn_mode(pred) == mode_X);
-               return pred;
-       } else {
-               return NULL;
-       }
-}
+DEBUG_ONLY(firm_dbg_module_t *dbg);
 
 
+/**
+ * Additional block info.
+ */
 typedef struct block_info {
-       ir_node* phi;
-       int evil;
+       ir_node *phi;   /**< head of the Phi list */
+       int has_pinned; /**< set if the block contains instructions that cannot be moved */
 } block_info;
 
-#define get_block_blockinfo(block) ((block_info*)get_irn_link(block))
+#define get_block_blockinfo(block) ((block_info *)get_irn_link(block))
+
+/**
+ * Returns non-zero if a Block can be emptied.
+ */
+static int can_empty_block(ir_node *block)
+{
+       return !get_block_blockinfo(block)->has_pinned;
+}
+
 
-static int can_empty_block(ir_node* block)
+static ir_node* walk_to_projx(ir_node* start, const ir_node* dependency)
 {
-       return !get_block_blockinfo(block)->evil;
+       int arity;
+       int i;
+
+       /* No need to find the conditional block if this block cannot be emptied and
+        * therefore not moved
+        */
+       if (!can_empty_block(start)) return NULL;
+
+       arity = get_irn_arity(start);
+       for (i = 0; i < arity; ++i) {
+               ir_node* pred = get_irn_n(start, i);
+               ir_node* pred_block = get_nodes_block(pred);
+
+               if (pred_block == dependency) {
+                       assert(is_Proj(pred));
+                       assert(get_irn_mode(pred) == mode_X);
+                       return pred;
+               }
+
+               if (is_Proj(pred)) {
+                       assert(get_irn_mode(pred) == mode_X);
+                       return NULL;
+               }
+
+               if (is_cdep_on(pred_block, dependency)) {
+                       return walk_to_projx(pred_block, dependency);
+               }
+       }
+       return NULL;
 }
 
 
@@ -79,263 +113,281 @@ static ir_node* copy_to(ir_node* node, ir_node* src_block, int i)
        if (get_nodes_block(node) != src_block) return node;
        if (get_irn_op(node) == op_Phi) return get_irn_n(node, i);
 
-       copy_irn_to_irg(node, current_ir_graph);
-       copy = get_irn_link(node);
+       copy = exact_copy(node);
        dst_block = get_nodes_block(get_irn_n(src_block, i));
        set_nodes_block(copy, dst_block);
 
-       ir_fprintf(stderr, "Copying node %+F to block %+F, copy is %+F\n",
-               node, dst_block, copy
-       );
+       DB((dbg, LEVEL_1, "Copying node %+F to block %+F, copy is %+F\n",
+               node, dst_block, copy));
 
        arity = get_irn_arity(node);
        for (j = 0; j < arity; ++j) {
                set_irn_n(copy, j, copy_to(get_irn_n(node, j), src_block, i));
-               ir_fprintf(stderr, "-- pred %d is %+F\n", j, get_irn_n(copy, j));
+               DB((dbg, LEVEL_2, "-- pred %d is %+F\n", j, get_irn_n(copy, j)));
        }
        return copy;
 }
 
 
 /**
- * Duplicate and move the contents of ith block predecessor into its
- * predecessors if the block has multiple control dependencies and only one
- * successor.
- * Also bail out if the block contains non-movable nodes, because later
- * if-conversion would be pointless.
+ * Remove predecessors i and j from node and add predecessor new_pred
+ */
+static void rewire(ir_node* node, int i, int j, ir_node* new_pred)
+{
+       int arity = get_irn_arity(node);
+       ir_node **ins;
+       int k;
+       int l;
+
+       NEW_ARR_A(ir_node *, ins, arity - 1);
+
+       l = 0;
+       for (k = 0; k < i; ++k) ins[l++] = get_irn_n(node, k);
+       for (++k; k < j; ++k) ins[l++] = get_irn_n(node, k);
+       for (++k; k < arity; ++k) ins[l++] = get_irn_n(node, k);
+       ins[l++] = new_pred;
+       assert(l == arity - 1);
+       set_irn_in(node, l, ins);
+}
+
+
+/**
+ * Remove the jth predecessors from the ith predecessor of block and add it to block
  */
-static int fission_block(ir_node* block, int i)
+static void split_block(ir_node* block, int i, int j)
 {
-       ir_node* pred = get_irn_n(block, i);
-       ir_node* pred_block;
-       block_info* info;
+       ir_node* pred_block = get_nodes_block(get_irn_n(block, i));
+       int arity = get_irn_arity(block);
+       int new_pred_arity;
        ir_node* phi;
-       int pred_arity;
-       int arity;
-       ir_node** ins;
-       int j;
+       ir_node **ins;
+       ir_node **pred_ins;
+       int k;
 
-       if (get_irn_op(pred) != op_Jmp) return 0;
-       pred_block = get_nodes_block(pred);
+       DB((dbg, LEVEL_1, "Splitting predecessor %d of predecessor %d of %+F\n", j, i, block));
 
-       if (!has_multiple_cdep(pred_block)) return 0;
-       if (!can_empty_block(pred_block)) return 0;
+       NEW_ARR_A(ir_node*, ins, arity + 1);
 
-       ir_fprintf(stderr, "Fissioning block %+F\n", pred_block);
+       for (phi = get_block_blockinfo(block)->phi; phi != NULL; phi = get_irn_link(phi)) {
+               ir_node* copy = copy_to(get_irn_n(phi, i), pred_block, j);
 
-       pred_arity = get_irn_arity(pred_block);
-       arity = get_irn_arity(block);
-       info = get_irn_link(block);
-       ins = xmalloc(sizeof(*ins) * (arity + pred_arity - 1));
-       for (phi = info->phi; phi != NULL; phi = get_irn_link(phi)) {
-               for (j = 0; j < i; ++j) ins[j] = get_irn_n(phi, j);
-               for (j = 0; j < pred_arity; ++j) {
-                       ins[i + j] = copy_to(get_irn_n(phi, i), pred_block, j);
-               }
-               for (j = i + 1; j < arity; ++j) {
-                       ins[pred_arity - 1 + j] = get_irn_n(phi, j);
+               for (k = 0; k < i; ++k) ins[k] = get_irn_n(phi, k);
+               ins[k++] = copy;
+               for (; k < arity; ++k) ins[k] = get_irn_n(phi, k);
+               ins[k] = get_irn_n(phi, i);
+               assert(k == arity);
+               set_irn_in(phi, arity + 1, ins);
+       }
+
+       for (k = 0; k < i; ++k) ins[k] = get_irn_n(block, k);
+       ins[k++] = get_irn_n(pred_block, j);
+       for (; k < arity; ++k) ins[k] = get_irn_n(block, k);
+       ins[k] = get_irn_n(block, i);
+       assert(k == arity);
+       set_irn_in(block, arity + 1, ins);
+
+       new_pred_arity = get_irn_arity(pred_block) - 1;
+       NEW_ARR_A(ir_node*, pred_ins, new_pred_arity);
+
+       for (phi = get_block_blockinfo(pred_block)->phi; phi != NULL; phi = get_irn_link(phi)) {
+               for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(phi, k);
+               for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(phi, k + 1);
+               assert(k == new_pred_arity);
+               if (new_pred_arity > 1) {
+                       set_irn_in(phi, new_pred_arity, pred_ins);
+               } else {
+                       exchange(phi, pred_ins[0]);
                }
-               set_irn_in(phi, arity + pred_arity - 1, ins);
        }
-       for (j = 0; j < i; ++j) ins[j] = get_irn_n(block, j);
-       for (j = 0; j < pred_arity; ++j) ins[i + j] = get_irn_n(pred_block, j);
-       for (j = i + 1; j < arity; ++j) ins[pred_arity - 1 + j] = get_irn_n(block, j);
-       set_irn_in(block, arity + pred_arity - 1, ins);
-       xfree(ins);
-
-       /* Kill all Phis in the fissioned block
-        * This is to make sure they're not kept alive
-        */
-       info = get_irn_link(pred_block);
-       phi = info->phi;
-       while (phi != NULL) {
-               ir_node* next = get_irn_link(phi);
-               exchange(phi, new_Bad());
-               phi = next;
+
+       for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(pred_block, k);
+       for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(pred_block, k + 1);
+       assert(k == new_pred_arity);
+       if (new_pred_arity > 1) {
+               set_irn_in(pred_block, new_pred_arity, pred_ins);
+       } else {
+               exchange(pred_block, get_nodes_block(pred_ins[0]));
+       }
+}
+
+
+static void prepare_path(ir_node* block, int i, const ir_node* dependency)
+{
+       ir_node* pred = get_nodes_block(get_irn_n(block, i));
+       int pred_arity;
+       int j;
+
+       DB((dbg, LEVEL_1, "Preparing predecessor %d of %+F\n", i, block));
+
+       pred_arity = get_irn_arity(pred);
+       for (j = 0; j < pred_arity; ++j) {
+               ir_node* pred_pred = get_nodes_block(get_irn_n(pred, j));
+
+               if (is_cdep_on(pred_pred, dependency)) {
+                       prepare_path(pred, j, dependency);
+                       split_block(block, i, j);
+                       break;
+               }
        }
-       return 1;
 }
 
 
 static void if_conv_walker(ir_node* block, void* env)
 {
-       ir_node* phi;
        int arity;
        int i;
 
-       // Bail out, if there are no Phis at all
+       /* Bail out, if there are no Phis at all */
        if (get_block_blockinfo(block)->phi == NULL) return;
 
 restart:
-       arity = get_irn_arity(block);
-       for (i = 0; i < arity; ++i) {
-               if (fission_block(block, i)) goto restart;
-       }
-       //return;
-
        arity = get_irn_arity(block);
        for (i = 0; i < arity; ++i) {
                ir_node* pred;
-               ir_node* cond;
-               ir_node* projx0;
-               int j;
-
-               projx0 = walk_to_projx(get_irn_n(block, i));
-               if (projx0 == NULL) return;
-               pred = get_Proj_pred(projx0);
-               if (get_irn_op(pred) != op_Cond || get_irn_mode(get_Cond_selector(pred)) != mode_b) continue;
-               cond = pred;
-
-               if (!can_empty_block(get_nodes_block(get_irn_n(block, i)))) {
-                       ir_fprintf(stderr, "Cannot empty block %+F\n",
-                               get_nodes_block(get_irn_n(block, i))
-                       );
-                       continue;
-               }
+               cdep* cdep;
 
-               for (j = i + 1; j < arity; ++j) {
-                       ir_node* projx1;
-                       ir_node* psi_block;
-                       ir_node* conds[1];
-                       ir_node* vals[2];
-                       ir_node* psi;
-
-                       projx1 = walk_to_projx(get_irn_n(block, j));
-                       if (projx1 == NULL) continue;
-                       pred = get_Proj_pred(projx1);
-                       if (get_irn_op(pred) != op_Cond || get_irn_mode(get_Cond_selector(pred)) != mode_b) continue;
-                       if (pred != cond) continue;
-                       ir_fprintf(stderr, "Found Cond %+F with proj %+F and %+F\n", cond, projx0, projx1);
-
-                       if (!can_empty_block(get_nodes_block(get_irn_n(block, j)))) {
-                               ir_fprintf(stderr, "Cannot empty block %+F\n",
-                                       get_nodes_block(get_irn_n(block, j))
-                               );
-                               continue;
-                       }
+               pred = get_nodes_block(get_irn_n(block, i));
+               for (cdep = find_cdep(pred); cdep != NULL; cdep = cdep->next) {
+                       const ir_node* dependency = cdep->node;
+                       ir_node* projx0 = walk_to_projx(pred, dependency);
+                       ir_node* cond;
+                       int j;
 
-                       conds[0] = get_Cond_selector(cond);
-
-                       psi_block = get_nodes_block(cond);
-                       phi = get_block_blockinfo(block)->phi;
-                       do {
-                               // Don't generate PsiMs
-                               if (get_irn_mode(phi) == mode_M) {
-                                       /* Something is very fishy if to predecessors of a PhiM point into the
-                                        * block but not at the same memory node
-                                        */
-                                       assert(get_irn_n(phi, i) == get_irn_n(phi, j));
-                                       // fake memory Psi
-                                       psi = get_irn_n(phi, i);
-                                       ir_fprintf(stderr, "Handling memory Phi %+F\n", phi);
-                               } else {
-                                       if (get_Proj_proj(projx0) == pn_Cond_true) {
-                                               vals[0] = get_irn_n(phi, i);
-                                               vals[1] = get_irn_n(phi, j);
+                       if (projx0 == NULL) continue;
+
+                       cond = get_Proj_pred(projx0);
+                       if (get_irn_op(cond) != op_Cond) continue;
+                       /* We only handle boolean decisions, no switches */
+                       if (get_irn_mode(get_Cond_selector(cond)) != mode_b) continue;
+
+                       for (j = i + 1; j < arity; ++j) {
+                               ir_node* projx1;
+                               ir_node* conds[1];
+                               ir_node* vals[2];
+                               ir_node* psi;
+                               ir_node* psi_block;
+                               ir_node* phi;
+
+                               pred = get_nodes_block(get_irn_n(block, j));
+
+                               if (!is_cdep_on(pred, dependency)) continue;
+
+                               projx1 = walk_to_projx(pred, dependency);
+
+                               if (projx1 == NULL) continue;
+
+                               DB((dbg, LEVEL_1, "Found Cond %+F with proj %+F and %+F\n",
+                                       cond, projx0, projx1
+                               ));
+
+                               prepare_path(block, i, dependency);
+                               prepare_path(block, j, dependency);
+                               arity = get_irn_arity(block);
+
+                               conds[0] = get_Cond_selector(cond);
+
+                               psi_block = get_nodes_block(cond);
+                               phi = get_block_blockinfo(block)->phi;
+                               do {
+                                       ir_node* val_i = get_irn_n(phi, i);
+                                       ir_node* val_j = get_irn_n(phi, j);
+
+                                       if (val_i == val_j) {
+                                               psi = val_i;
+                                               DB((dbg, LEVEL_2,  "Generating no psi, because both values are equal\n"));
                                        } else {
-                                               vals[0] = get_irn_n(phi, j);
-                                               vals[1] = get_irn_n(phi, i);
+                                               /* Something is very fishy if two predecessors of a PhiM point into
+                                                * one block, but not at the same memory node
+                                                */
+                                               assert(get_irn_mode(phi) != mode_M);
+                                               if (get_Proj_proj(projx0) == pn_Cond_true) {
+                                                       vals[0] = val_i;
+                                                       vals[1] = val_j;
+                                               } else {
+                                                       vals[0] = val_j;
+                                                       vals[1] = val_i;
+                                               }
+                                               psi = new_r_Psi(
+                                                       current_ir_graph, psi_block, 1, conds, vals, get_irn_mode(phi)
+                                               );
+                                               DB((dbg, LEVEL_2, "Generating %+F for %+F\n", psi, phi));
+                                       }
+
+                                       if (arity == 2) {
+                                               exchange(phi, psi);
+                                       } else {
+                                               rewire(phi, i, j, psi);
                                        }
-                                       psi = new_r_Psi(
-                                               current_ir_graph, psi_block, 1, conds, vals, get_irn_mode(phi)
-                                       );
-                                       ir_fprintf(stderr, "Generating %+F for %+F\n", psi, phi);
-                               }
+
+                                       phi = get_irn_link(phi);
+                               } while (phi != NULL);
+
+                               exchange(get_nodes_block(get_irn_n(block, i)), psi_block);
+                               exchange(get_nodes_block(get_irn_n(block, j)), psi_block);
 
                                if (arity == 2) {
-                                       exchange(phi, psi);
+#if 1
+                                       DB((dbg, LEVEL_1,  "Welding block %+F and %+F\n", block, psi_block));
+                                       get_block_blockinfo(block)->has_pinned |=       get_block_blockinfo(psi_block)->has_pinned;
+                                       set_irn_in(block, get_irn_arity(psi_block), get_irn_in(psi_block) + 1);
+                                       exchange_cdep(psi_block, block);
+                                       exchange(psi_block, block);
+#else
+                                       DB((dbg, LEVEL_1,  "Welding block %+F to %+F\n", block, psi_block));
+                                       get_block_blockinfo(psi_block)->has_pinned |=   get_block_blockinfo(block)->has_pinned;
+                                       exchange(block, psi_block);
+#endif
+                                       return;
                                } else {
-                                       ir_node** ins = xmalloc(sizeof(*ins) * (arity - 1));
-                                       int k;
-                                       int l;
-
-                                       l = 0;
-                                       for (k = 0; k < i; ++k) ins[l++] = get_irn_n(phi, k);
-                                       for (++k; k < j; ++k) ins[l++] = get_irn_n(phi, k);
-                                       for (++k; k < arity; ++k) ins[l++] = get_irn_n(phi, k);
-                                       ins[l++] = psi;
-                                       assert(l == arity - 1);
-                                       set_irn_in(phi, l, ins);
-
-                                       xfree(ins);
+                                       rewire(block, i, j, new_r_Jmp(current_ir_graph, psi_block));
+                                       goto restart;
                                }
-
-                               phi = get_irn_link(phi);
-                       } while (phi != NULL && get_irn_op(phi) == op_Phi);
-
-                       exchange(get_nodes_block(get_irn_n(block, i)), psi_block);
-                       exchange(get_nodes_block(get_irn_n(block, j)), psi_block);
-
-                       if (arity == 2) {
-                               ir_fprintf(stderr, "Welding block %+F to %+F\n", block, psi_block);
-                               get_block_blockinfo(psi_block)->evil |= get_block_blockinfo(block)->evil;
-                               exchange(block, psi_block);
-                               return;
-                       } else {
-                               ir_node** ins = xmalloc(sizeof(*ins) * (arity - 1));
-                               int k;
-                               int l;
-
-                               l = 0;
-                               for (k = 0; k < i; ++k) ins[l++] = get_irn_n(block, k);
-                               for (++k; k < j; ++k) ins[l++] = get_irn_n(block, k);
-                               for (++k; k < arity; ++k) ins[l++] = get_irn_n(block, k);
-                               ins[l++] = new_r_Jmp(current_ir_graph, psi_block);
-                               assert(l == arity - 1);
-                               set_irn_in(block, l, ins);
-
-                               xfree(ins);
-                               goto restart;
                        }
                }
        }
 }
 
-
-static void init_block_link(ir_node* block, void* env)
+/**
+ * Block walker: add additional data
+ */
+static void init_block_link(ir_node *block, void *env)
 {
-       block_info* bi = xmalloc(sizeof(*bi));
+       struct obstack *obst = env;
+       block_info *bi = obstack_alloc(obst, sizeof(*bi));
 
        bi->phi = NULL;
-       bi->evil = 0;
+       bi->has_pinned = 0;
        set_irn_link(block, bi);
 }
 
 
-/* Daisy-chain all phis in a block
- * If a non-movable node is encountered set the evil flag
+/**
+ * Daisy-chain all phis in a block
+ * If a non-movable node is encountered set the has_pinned flag
  */
-static void collect_phis(ir_node* node, void* env)
+static void collect_phis(ir_node *node, void *env)
 {
-       ir_node* block;
-       block_info* bi;
-
-       if (get_irn_op(node) == op_Block) return;
+       if (is_Phi(node)) {
+               ir_node *block = get_nodes_block(node);
+               block_info *bi = get_block_blockinfo(block);
 
-       block = get_nodes_block(node);
-       bi = get_irn_link(block);
-
-       if (get_irn_op(node) == op_Phi) {
                set_irn_link(node, bi->phi);
                bi->phi = node;
-       } else {
-#if 1
-               if (get_irn_op(node) == op_Call ||
-                               get_irn_op(node) == op_Store ||
-                               get_irn_op(node) == op_Load) {
-                       ir_fprintf(stderr, "Node %+F in block %+F is unmovable\n", node, block);
-                       bi->evil = 1;
-               }
-#else
-               if (get_irn_op(node) != op_Jmp &&
-                               get_irn_op(node) != op_Proj &&
-                               get_irn_op(node) != op_Cond &&
-                               get_irn_op(node) != op_Cmp &&
-                   !mode_is_datab(get_irn_mode(node))) {
-       ir_fprintf(stderr, "Node %+F in block %+F is unmovable\n", node, block);
-                       bi->evil = 1;
+       }
+       else {
+               if (is_no_Block(node) && get_irn_pinned(node) == op_pin_state_pinned) {
+                       /*
+                        * Ignore control flow nodes, these will be removed.
+                        * This ignores Raise. That is surely bad. FIXME.
+                        */
+                       if (! is_cfop(node)) {
+                               ir_node *block = get_nodes_block(node);
+                               block_info *bi = get_block_blockinfo(block);
+
+                               DB((dbg, LEVEL_2, "Node %+F in block %+F is unmovable\n", node, block));
+                               bi->has_pinned = 1;
+                       }
                }
-#endif
        }
 }
 
@@ -370,10 +422,10 @@ static ir_node* fold_psi(ir_node* psi)
        }
 
        if (arity == new_arity) return psi; // no attached Psis found
-       ir_fprintf(stderr, "Folding %+F from %d to %d conds\n", psi, arity, new_arity);
+       DB((dbg, LEVEL_1, "Folding %+F from %d to %d conds\n", psi, arity, new_arity));
 
-       conds = xmalloc(new_arity * sizeof(*conds));
-       vals = xmalloc((new_arity + 1) * sizeof(*vals));
+       NEW_ARR_A(ir_node *, conds, new_arity);
+       NEW_ARR_A(ir_node *, vals, new_arity + 1);
        j = 0;
        for (i = 0; i < arity; ++i) {
                ir_node* c = get_Psi_cond(psi, i);
@@ -414,10 +466,8 @@ static ir_node* fold_psi(ir_node* psi)
                current_ir_graph, get_nodes_block(psi),
                new_arity, conds, vals, get_irn_mode(psi)
        );
-       ir_fprintf(stderr, "Folded %+F into new %+F\n", psi, new_psi);
+       DB((dbg, LEVEL_1, "Folded %+F into new %+F\n", psi, new_psi));
        exchange(psi, new_psi);
-       xfree(vals);
-       xfree(conds);
        return new_psi;
 }
 
@@ -425,7 +475,7 @@ static ir_node* fold_psi(ir_node* psi)
 /*
  * Merge consecutive psi inputs if the data inputs are the same
  */
-static void meld_psi(ir_node* psi)
+static ir_node* meld_psi(ir_node* psi)
 {
        int arity = get_Psi_n_conds(psi);
        int new_arity;
@@ -439,32 +489,30 @@ static void meld_psi(ir_node* psi)
 
        new_arity = 1;
        val = get_Psi_val(psi, 0);
-       ir_fprintf(stderr, "Pred  0 of %+F is %+F\n", psi, val);
+       DB((dbg, LEVEL_1, "Pred  0 of %+F is %+F\n", psi, val));
        for (i = 1; i < arity; ++i) {
                ir_node* v = get_Psi_val(psi, i);
-               ir_fprintf(stderr, "Pred %2d of %+F is %+F\n", i, psi, v);
+               DB((dbg, LEVEL_1, "Pred %2d of %+F is %+F\n", i, psi, v));
                if (val != v) {
                        val = v;
                        ++new_arity;
                }
        }
-       ir_fprintf(stderr, "Default of %+F is %+F\n", psi, get_Psi_default(psi));
+       DB((dbg, LEVEL_1, "Default of %+F is %+F\n", psi, get_Psi_default(psi)));
        if (val == get_Psi_default(psi)) --new_arity;
 
-       ir_fprintf(stderr, "Melding Psi %+F from %d conds to %d\n",
-               psi, arity, new_arity
-       );
+       DB((dbg, LEVEL_1, "Melding Psi %+F from %d conds to %d\n", psi, arity, new_arity));
 
-       if (new_arity == arity) return;
+       if (new_arity == arity) return psi;
 
-       // If all data inputs of the Psi are equal, exchange the Psi with that value
+       /* If all data inputs of the Psi are equal, exchange the Psi with that value */
        if (new_arity == 0) {
                exchange(psi, val);
-               return;
+               return val;
        }
 
-       conds = xmalloc(sizeof(*conds) * new_arity);
-       vals = xmalloc(sizeof(*vals) * (new_arity + 1));
+       NEW_ARR_A(ir_node *, conds, new_arity);
+       NEW_ARR_A(ir_node *, vals, new_arity + 1);
        cond = get_Psi_cond(psi, 0);
        val = get_Psi_val(psi, 0);
        j = 0;
@@ -494,8 +542,42 @@ static void meld_psi(ir_node* psi)
                current_ir_graph, get_nodes_block(psi),
                new_arity, conds, vals, get_irn_mode(psi)
        );
-       ir_fprintf(stderr, "Molded %+F into %+F\n", psi, new_psi);
+       DB((dbg, LEVEL_1, "Molded %+F into %+F\n", psi, new_psi));
        exchange(psi, new_psi);
+       return new_psi;
+}
+
+
+/**
+ * Split a Psi with multiple conditions into multiple Psis with one condtition
+ * each
+ */
+static ir_node* split_psi(ir_node* psi)
+{
+       int arity = get_Psi_n_conds(psi);
+       ir_mode* mode;
+       ir_node* block;
+       ir_node* rval;
+       int i;
+
+       if (arity == 1) return psi;
+
+       mode = get_irn_mode(psi);
+       block = get_nodes_block(psi);
+       rval = get_Psi_default(psi);
+       for (i = arity - 1; i >= 0; --i) {
+               ir_node* conds[1];
+               ir_node* vals[2];
+
+               conds[0] = get_Psi_cond(psi, i);
+               vals[0] = get_Psi_val(psi, i);
+               vals[1] = rval;
+               rval = new_r_Psi(
+                       current_ir_graph, block, 1, conds, vals, mode
+               );
+       }
+       exchange(psi, rval);
+       return rval;
 }
 
 
@@ -506,14 +588,24 @@ static void optimise_psis(ir_node* node, void* env)
        node = fold_psi(node);
 #endif
 #if 1
-       meld_psi(node);
+       node = meld_psi(node);
+#endif
+#if 1
+       node = split_psi(node);
 #endif
 }
 
 
 void opt_if_conv(ir_graph *irg, const opt_if_conv_info_t *params)
 {
-       ir_fprintf(stderr, "Running if-conversion on %+F\n", irg);
+       struct obstack obst;
+
+       if (!get_opt_if_conversion())
+               return;
+
+       FIRM_DBG_REGISTER(dbg, "firm.opt.ifconv");
+
+       DB((dbg, LEVEL_1, "Running if-conversion on %+F\n", irg));
 
        dump_ir_block_graph(irg, "_00_pre");
 
@@ -523,18 +615,22 @@ void opt_if_conv(ir_graph *irg, const opt_if_conv_info_t *params)
        dump_ir_block_graph(irg, "_01_normal");
 
        compute_cdep(irg);
-       compute_doms(irg);
+       assure_doms(irg);
 
-       irg_block_walk_graph(irg, init_block_link, NULL, NULL);
+       obstack_init(&obst);
+       irg_block_walk_graph(irg, init_block_link, NULL, &obst);
        irg_walk_graph(irg, collect_phis, NULL, NULL);
        irg_block_walk_graph(irg, NULL, if_conv_walker, NULL);
 
        dump_ir_block_graph(irg, "_02_ifconv");
-
        local_optimize_graph(irg);
+       dump_ir_block_graph(irg, "_03_postopt");
+
        irg_walk_graph(irg, NULL, optimise_psis, NULL);
 
-       dump_ir_block_graph(irg, "_03_postifconv");
+       dump_ir_block_graph(irg, "_04_postifconv");
+
+       obstack_free(&obst, NULL);
 
        free_dom(irg);
        free_cdep(irg);
@@ -562,9 +658,6 @@ void opt_if_conv(ir_graph *irg, const opt_if_conv_info_t *params)
 #ifdef HAVE_ALLOCA_H
 #include <alloca.h>
 #endif
-#ifdef HAVE_xmalloc_H
-#include <xmalloc.h>
-#endif
 
 #include "irgraph_t.h"
 #include "irnode_t.h"