X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fana%2Firscc.c;h=fab28267f6db8c58036e46275da2690ae29f0556;hb=4b13e0fa13fd6021973a7b09e6b3e9279dd1869e;hp=ed19bac6dd82b235237b85e9f3911179f2fccc57;hpb=56a871bc4bfe49ae51c8d16fea662a3b1ab1836e;p=libfirm

diff --git a/ir/ana/irscc.c b/ir/ana/irscc.c
index ed19bac6d..fab28267f 100644
--- a/ir/ana/irscc.c
+++ b/ir/ana/irscc.c
@@ -3,6 +3,8 @@
  * File name:   ir/ana/irscc.c
  * Purpose:     Compute the strongly connected regions and build
  *              backedge/loop datastructures.
+ *              A variation on the Tarjan algorithm. See also [Trapp:99],
+ *              Chapter 5.2.1.2.
  * Author:      Goetz Lindenmaier
  * Modified by:
  * Created:     7.2002
@@ -18,21 +20,30 @@
 #include <string.h>
 
 #include "irloop_t.h"
-#include "irnode.h"
+#include "irnode_t.h"
 #include "irgraph_t.h"
 #include "array.h"
+#include "pmap.h"
 #include "irgwalk.h"
-#include "irprog.h"
+#include "irprog_t.h"
+#include "irdump.h"
 
 ir_graph *outermost_ir_graph;      /* The outermost graph the scc is computed
-				      for */
+                      for */
 static ir_loop *current_loop;      /* Current loop construction is working
-				      on. */
+                      on. */
 static int loop_node_cnt = 0;      /* Counts the number of allocated loop nodes.
-				      Each loop node gets a unique number.
-				      What for? ev. remove. @@@ */
+                      Each loop node gets a unique number.
+                      What for? ev. remove. @@@ */
 static int current_dfn = 1;        /* Counter to generate depth first numbering
-				      of visited nodes.  */
+                      of visited nodes.  */
+
+/**********************************************************************/
+/* Node attributes                                                   **/
+/**********************************************************************/
+
+/* A map to get from irnodes to loop nodes. */
+static pmap *node_loop_map = NULL;
 
 /**********************************************************************/
 /* Node attributes needed for the construction.                      **/
@@ -42,7 +53,7 @@ typedef struct scc_info {
   bool in_stack;         /* Marks whether node is on the stack. */
   int dfn;               /* Depth first search number. */
   int uplink;            /* dfn number of ancestor. */
-  ir_loop *loop;         /* Refers to the containing loop. */
+  //  ir_loop *loop;         /* Refers to the containing loop. */
   /*
       struct section *section;
       xset def;
@@ -59,62 +70,95 @@ static INLINE scc_info* new_scc_info(void) {
 static INLINE void
 mark_irn_in_stack (ir_node *n) {
   assert(get_irn_link(n));
-  ((scc_info *)get_irn_link(n))->in_stack = true;
+  // to slow
+  //((scc_info *)get_irn_link(n))->in_stack = true;
+  ((scc_info *)n->link)->in_stack = true;
 }
 
 static INLINE void
 mark_irn_not_in_stack (ir_node *n) {
   assert(get_irn_link(n));
-  ((scc_info *)get_irn_link(n))->in_stack = false;
+  // to slow
+  //((scc_info *)get_irn_link(n))->in_stack = false;
+  ((scc_info *)n->link)->in_stack = false;
 }
 
 static INLINE bool
 irn_is_in_stack (ir_node *n) {
   assert(get_irn_link(n));
-  return ((scc_info *)get_irn_link(n))->in_stack;
+  // to slow
+  //return ((scc_info *)get_irn_link(n))->in_stack;
+  return ((scc_info *)n->link)->in_stack;
 }
 
 static INLINE void
 set_irn_uplink (ir_node *n, int uplink) {
   assert(get_irn_link(n));
-  ((scc_info *)get_irn_link(n))->uplink = uplink;
+  // to slow
+  //((scc_info *)get_irn_link(n))->uplink = uplink;
+  ((scc_info *)n->link)->uplink = uplink;
 }
 
 static INLINE int
 get_irn_uplink (ir_node *n) {
   assert(get_irn_link(n));
-  return ((scc_info *)get_irn_link(n))->uplink;
+  // to slow
+  //return ((scc_info *)get_irn_link(n))->uplink;
+  return ((scc_info *)n->link)->uplink;
 }
 
 static INLINE void
 set_irn_dfn (ir_node *n, int dfn) {
-  if (! get_irn_link(n)) { DDMN(n); DDME(get_irg_ent(current_ir_graph));}
   assert(get_irn_link(n));
-  ((scc_info *)get_irn_link(n))->dfn = dfn;
+  // to slow
+  //((scc_info *)get_irn_link(n))->dfn = dfn;
+  ((scc_info *)n->link)->dfn = dfn;
 }
 
 static INLINE int
 get_irn_dfn (ir_node *n) {
   assert(get_irn_link(n));
-  return ((scc_info *)get_irn_link(n))->dfn;
+  // to slow
+  //return ((scc_info *)get_irn_link(n))->dfn;
+  return ((scc_info *)n->link)->dfn;
 }
 
+#if 0
+/* Replaced node loop map by real field as hash access dominates runtime
+ * of the algorithm. ! */
 /* Uses temporary information to set the loop */
 static INLINE void
-set_irn_loop_tmp (ir_node *n, ir_loop* loop) {
-  assert(get_irn_link(n));
-  ((scc_info *)get_irn_link(n))->loop = loop;
+set_irn_loop (ir_node *n, ir_loop* loop) {
+  assert(node_loop_map && "not initialized!");
+  pmap_insert(node_loop_map, (void *)n, (void *)loop);
 }
 
-#if 0
 /* Uses temporary information to get the loop */
-static INLINE ir_loop *
-get_irn_loop_tmp (ir_node *n) {
-  assert(get_irn_link(n));
-  return ((scc_info *)get_irn_link(n))->loop;
+INLINE ir_loop *
+get_irn_loop (ir_node *n) {
+  ir_loop *res = NULL;
+  if (!node_loop_map) return NULL;
+
+  if (pmap_contains(node_loop_map, (void *)n))
+    res = (ir_loop *) pmap_get(node_loop_map, (void *)n);
+
+  return res;
+}
+#else
+static INLINE void
+set_irn_loop (ir_node *n, ir_loop* loop) {
+  n->loop = loop;
+}
+
+/* Uses temporary information to get the loop */
+INLINE ir_loop *
+get_irn_loop (ir_node *n) {
+  return n->loop;
 }
 #endif
 
+
+#if 0
 static ir_loop *find_nodes_loop (ir_node *n, ir_loop *l) {
   int i;
   ir_loop *res = NULL;
@@ -140,6 +184,7 @@ ir_loop * get_irn_loop(ir_node *n) {
   l = find_nodes_loop(n, l);
   return l;
 }
+#endif
 
 /**********************************************************************/
 /* A stack.                                                          **/
@@ -192,6 +237,7 @@ static INLINE void
 pop_scc_to_loop (ir_node *n)
 {
   ir_node *m;
+  int i = 0;
 
   /*for (;;) {*/
   do
@@ -200,9 +246,13 @@ pop_scc_to_loop (ir_node *n)
     loop_node_cnt++;
     set_irn_dfn(m, loop_node_cnt);
     add_loop_node(current_loop, m);
-    set_irn_loop_tmp(m, current_loop);
+    set_irn_loop(m, current_loop);
+    i++;
     /*    if (m==n) break;*/
     } while(m != n);
+
+  if(i > 1)
+    printf("Mehr als eine Iteration!!!!!!!!!!!!!!!!!!!!!!!!!!!!11111\n");
 }
 
 /* GL ??? my last son is my grandson???  Removes loops with no
@@ -217,15 +267,18 @@ void close_loop (ir_loop *l)
   if (get_kind(last_son) == k_ir_loop &&
       get_loop_n_elements(last_son) == 1)
     {
+      ir_loop *gson;
+
       lelement = get_loop_element(last_son, 0);
-      ir_loop *gson = lelement.son;
+      gson = lelement.son;
       if(get_kind(gson) == k_ir_loop)
-	{
-	  gson -> outer_loop = l;
+    {
           loop_element new_last_son;
+
+      gson -> outer_loop = l;
           new_last_son.son = gson;
-	  l -> children[last] = new_last_son;
-	}
+      l -> children[last] = new_last_son;
+    }
     }
 
   current_loop = l;
@@ -270,6 +323,11 @@ static ir_loop *new_loop (void) {
     son->depth = 0;
   }
 
+#ifdef DEBUG_libfirm
+  son->loop_nr = get_irp_new_node_nr();
+  son->link = NULL;
+#endif
+
   current_loop = son;
   return father;
 }
@@ -369,7 +427,7 @@ ir_node *get_loop_node (ir_loop *loop, int pos) {
 static INLINE void
 add_loop_node(ir_loop *loop, ir_node *n) {
   loop_element ln;
-  ln.node=n;
+  ln.node = n;
   assert(loop && loop->kind == k_ir_loop);
   assert(get_kind(n) == k_ir_node);
   ARR_APP1 (loop_element, loop->children, ln);
@@ -395,6 +453,42 @@ loop_element get_loop_element (ir_loop *loop, int pos) {
   return(loop -> children[pos]);
 }
 
+int get_loop_element_pos(ir_loop *loop, void *le) {
+  int i;
+  assert(loop && loop->kind == k_ir_loop);
+
+  for (i = 0; i < get_loop_n_elements(loop); i++)
+    if (get_loop_element(loop, i).node == le) return i;
+  return -1;
+}
+
+int get_loop_loop_nr(ir_loop *loop) {
+  assert(loop && loop->kind == k_ir_loop);
+#ifdef DEBUG_libfirm
+  return loop->loop_nr;
+#else
+  return (int)loop;
+#endif
+}
+
+
+/** A field to connect additional information to a loop.  Only valid
+    if libfirm_debug is set. */
+void  set_loop_link (ir_loop *loop, void *link) {
+  assert(loop && loop->kind == k_ir_loop);
+#ifdef DEBUG_libfirm
+  loop->link = link;
+#endif
+}
+void *get_loop_link (const ir_loop *loop) {
+  assert(loop && loop->kind == k_ir_loop);
+#ifdef DEBUG_libfirm
+  return loop->link;
+#else
+  return NULL;
+#endif
+}
+
 /* The outermost loop is remarked in the surrounding graph. */
 void     set_irg_loop(ir_graph *irg, ir_loop *loop) {
   assert(irg);
@@ -420,34 +514,41 @@ init_node (ir_node *n, void *env) {
   /* Also init nodes not visible in intraproc_view. */
     /* @@@ init_node is called for too many nodes -- this wastes memory!.
        The mem is not lost as its on the obstack. */
-  if (get_irn_op(n) == op_Filter) {
+  if (intern_get_irn_op(n) == op_Filter) {
     for (i = 0; i < get_Filter_n_cg_preds(n); i++)
       init_node(get_Filter_cg_pred(n, i), NULL);
   }
-  if (get_irn_op(n) == op_Block) {
+  if (intern_get_irn_op(n) == op_Block) {
     for (i = 0; i < get_Block_cg_n_cfgpreds(n); i++) {
       init_node(get_Block_cg_cfgpred(n, i), NULL);
     }
   }
   /* The following pattern matches only after a call from above pattern. */
-  if ((get_irn_op(n) == op_Proj) /*&& (get_Proj_proj(n) == 0)*/) {
+  if ((intern_get_irn_op(n) == op_Proj) /*&& (get_Proj_proj(n) == 0)*/) {
     /* @@@ init_node is called for every proj -- this wastes memory!.
        The mem is not lost as its on the obstack. */
     ir_node *cb = get_Proj_pred(n);
-    if ((get_irn_op(cb) == op_CallBegin) ||
-	(get_irn_op(cb) == op_EndReg) ||
-	(get_irn_op(cb) == op_EndExcept)) {
+    if ((intern_get_irn_op(cb) == op_CallBegin) ||
+	(intern_get_irn_op(cb) == op_EndReg) ||
+	(intern_get_irn_op(cb) == op_EndExcept)) {
       init_node(cb, NULL);
       init_node(get_nodes_Block(cb), NULL);
     }
+  }
 #endif
 }
 
 static INLINE void
-init_scc (ir_graph *irg) {
+init_scc_common (void) {
   current_dfn = 1;
   loop_node_cnt = 0;
+  if (!node_loop_map) node_loop_map = pmap_create();
   init_stack();
+}
+
+static INLINE void
+init_scc (ir_graph *irg) {
+  init_scc_common();
   irg_walk_graph (irg, init_node, NULL, NULL);
   /*
   irg_walk (irg, link_to_reg_end, NULL, NULL);
@@ -456,36 +557,17 @@ init_scc (ir_graph *irg) {
 
 static INLINE void
 init_ip_scc (void) {
-  current_dfn = 1;
-  loop_node_cnt = 0;
-  init_stack();
+  init_scc_common();
   cg_walk (init_node, NULL, NULL);
 }
 
-#if 0
-Works, but is inefficient.
-static INLINE void
-init_ip_scc (void) {
-  int i;
-  interprocedural_view = 1;
-  current_dfn = 1;
-  loop_node_cnt = 0;
-  init_stack();
-  for (i = 0; i < get_irp_n_irgs(); i++) {
-    current_ir_graph = get_irp_irg(i);
-    irg_walk_graph (current_ir_graph, init_node, NULL, NULL);
-    /* @@@ decrease max_visited to avoide double walks */
-  }
-}
-#endif
-
 /* Condition for breaking the recursion. */
 static bool is_outermost_Start(ir_node *n) {
   /* Test whether this is the outermost Start node.  If so
      recursion must end. */
-  if ((get_irn_op(n) == op_Block)     &&
+  if ((intern_get_irn_op(n) == op_Block)     &&
       (get_Block_n_cfgpreds(n) == 1)  &&
-      (get_irn_op(skip_Proj(get_Block_cfgpred(n, 0))) == op_Start) &&
+      (intern_get_irn_op(skip_Proj(get_Block_cfgpred(n, 0))) == op_Start) &&
       (get_nodes_Block(skip_Proj(get_Block_cfgpred(n, 0))) == n)) {
     return true;
   }
@@ -494,10 +576,10 @@ static bool is_outermost_Start(ir_node *n) {
       not possible in interprocedural view as outermost_graph is
       not necessarily the only with a dead-end start block.
       Besides current_ir_graph is not set properly. */
-  if ((get_irn_op(n) == op_Block) &&
+  if ((intern_get_irn_op(n) == op_Block) &&
       (n == get_irg_start_block(current_ir_graph))) {
     if ((!interprocedural_view)  ||
-	(current_ir_graph == outermost_ir_graph))
+    (current_ir_graph == outermost_ir_graph))
       return true;
   }
 #endif
@@ -507,12 +589,12 @@ static bool is_outermost_Start(ir_node *n) {
 /* Don't walk from nodes to blocks except for Control flow operations. */
 static INLINE int
 get_start_index(ir_node *n) {
-  if (is_cfop(n) || is_fragile_op(n) || get_irn_op(n) == op_Start)
+  if (is_cfop(n) || is_fragile_op(n) || intern_get_irn_op(n) == op_Start)
     return -1;
   else
     return 0;
 }
-
+#if 0
 /* Returns current_ir_graph and set it to the irg of predecessor index
    of node n. */
 static INLINE ir_graph *
@@ -521,13 +603,13 @@ switch_irg (ir_node *n, int index) {
 
   if (interprocedural_view) {
     /* Only Filter and Block nodes can have predecessors in other graphs. */
-    if (get_irn_op(n) == op_Filter)
+    if (intern_get_irn_op(n) == op_Filter)
       n = get_nodes_Block(n);
-    if (get_irn_op(n) == op_Block) {
+    if (intern_get_irn_op(n) == op_Block) {
       ir_node *cfop = skip_Proj(get_Block_cfgpred(n, index));
       if (is_ip_cfop(cfop)) {
-	current_ir_graph = get_irn_irg(cfop);
-	set_irg_visited(current_ir_graph, get_max_irg_visited());
+    current_ir_graph = get_irn_irg(cfop);
+    set_irg_visited(current_ir_graph, get_max_irg_visited());
       }
     }
   }
@@ -558,7 +640,7 @@ find_irg_on_stack (ir_node *n) {
 	current_ir_graph = get_irn_irg(m);
 	break;
       }
-      if (get_irn_op(m) == op_Filter) {
+      if (intern_get_irn_op(m) == op_Filter) {
 	/* Find the corresponding ip_cfop */
 	ir_node *pred = stack[i+1];
 	int j;
@@ -576,6 +658,7 @@ find_irg_on_stack (ir_node *n) {
 
   return old_current;
 }
+#endif
 
 #if 0
 static void test(ir_node *pred, ir_node *root, ir_node *this) {
@@ -598,34 +681,37 @@ static void test(ir_node *pred, ir_node *root, ir_node *this) {
 
 /* Test for legal loop header: Block, Phi, ... */
 INLINE static bool is_possible_loop_head(ir_node *n) {
-  return ((get_irn_op(n) == op_Block) ||
-	  (get_irn_op(n) == op_Phi) ||
-	  ((get_irn_op(n) == op_Filter) && interprocedural_view));
+  ir_op *op = intern_get_irn_op(n);
+  return ((op == op_Block) ||
+      (op == op_Phi) ||
+      ((op == op_Filter) && interprocedural_view));
 }
 
 /* Returns true if n is a loop header, i.e., it is a Block, Phi
    or Filter node and has predecessors within the loop and out
-   of the loop. */
+   of the loop.
+   @arg root: only needed for assertion. */
 static bool
 is_head (ir_node *n, ir_node *root)
 {
-  int i;
-  int some_outof_loop = 0,  some_in_loop = 0;
+  int i, arity;
+  int some_outof_loop = 0, some_in_loop = 0;
 
   /* Test for legal loop header: Block, Phi, ... */
   if (!is_possible_loop_head(n))
     return false;
 
   if (!is_outermost_Start(n)) {
-    for (i = get_start_index(n); i < get_irn_arity(n); i++) {
-      ir_node *pred = get_irn_n(n, i);
+    arity = intern_get_irn_arity(n);
+    for (i = get_start_index(n); i < arity; i++) {
+      ir_node *pred = intern_get_irn_n(n, i);
       assert(pred);
       if (is_backedge(n, i)) continue;
       if (!irn_is_in_stack(pred)) {
-	some_outof_loop = 1;
+    some_outof_loop = 1;
       } else {
-	assert(get_irn_uplink(pred) >= get_irn_uplink(root));
-	some_in_loop = 1;
+    assert(get_irn_uplink(pred) >= get_irn_uplink(root));
+    some_in_loop = 1;
       }
     }
   }
@@ -640,14 +726,14 @@ smallest_dfn_pred (ir_node *n, int limit)
   int i, index = -2, min = -1;
 
   if (!is_outermost_Start(n)) {
-    for (i = get_start_index(n); i < get_irn_arity(n); i++) {
-      ir_node *pred = get_irn_n(n, i);
+    int arity = intern_get_irn_arity(n);
+    for (i = get_start_index(n); i < arity; i++) {
+      ir_node *pred = intern_get_irn_n(n, i);
       assert(pred);
       if (is_backedge(n, i) || !irn_is_in_stack(pred)) continue;
-      if (get_irn_dfn(pred) >= limit
-	&& (min == -1 || get_irn_dfn(pred) < min)) {
-	index = i;
-	min = get_irn_dfn(pred);
+      if (get_irn_dfn(pred) >= limit && (min == -1 || get_irn_dfn(pred) < min)) {
+    index = i;
+    min = get_irn_dfn(pred);
       }
     }
   }
@@ -661,12 +747,13 @@ largest_dfn_pred (ir_node *n)
   int i, index = -2, max = -1;
 
   if (!is_outermost_Start(n)) {
-    for (i = get_start_index(n); i < get_irn_arity(n); i++) {
-      ir_node *pred = get_irn_n(n, i);
+    int arity = intern_get_irn_arity(n);
+    for (i = get_start_index(n); i < arity; i++) {
+      ir_node *pred = intern_get_irn_n(n, i);
       if (is_backedge (n, i) || !irn_is_in_stack(pred)) continue;
       if (get_irn_dfn(pred) > max) {
-	index = i;
-	max = get_irn_dfn(pred);
+    index = i;
+    max = get_irn_dfn(pred);
       }
     }
   }
@@ -692,24 +779,24 @@ find_tail (ir_node *n) {
   if (is_head (m, n)) {
     res_index = smallest_dfn_pred(m, 0);
     if ((res_index == -2) &&  /* no smallest dfn pred found. */
-	(n == m))
+    (n == m))
       return NULL;
   } else {
     if (m == n) return NULL;
     for (i = tos-2; ; --i) {
       m = stack[i];
       if (is_head (m, n)) {
-	res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
-	if (res_index == -2)  /* no smallest dfn pred found. */
-	  res_index = largest_dfn_pred (m);
-	break;
+    res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
+    if (res_index == -2)  /* no smallest dfn pred found. */
+      res_index = largest_dfn_pred (m);
+    break;
       }
     }
   }
   assert (res_index > -2);
 
   set_backedge (m, res_index);
-  return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
+  return is_outermost_Start(n) ? NULL : intern_get_irn_n(m, res_index);
 }
 
 
@@ -717,64 +804,83 @@ find_tail (ir_node *n) {
 
 static void scc (ir_node *n) {
   int i;
-  ir_graph *rem;
-
   if (irn_visited(n)) return;
   mark_irn_visited(n);
-  /*printf("mark: %d ", get_irn_visited(n)); DDMN(n);
-  DDME(get_irg_ent(current_ir_graph));*/
 
   /* Initialize the node */
   set_irn_dfn(n, current_dfn);      /* Depth first number for this node */
   set_irn_uplink(n, current_dfn);   /* ... is default uplink. */
-  set_irn_loop_tmp(n, NULL);
+  set_irn_loop(n, NULL);
   current_dfn ++;
-
-  /* What's this good for?
-  n->ana.scc.section = NULL;
-  */
-
   push(n);
 
+  /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
+     array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
+     so is_backedge does not access array[-1] but correctly returns false! */
+
   if (!is_outermost_Start(n)) {
-    for (i = get_start_index(n); i < get_irn_arity(n); i++) {
+    int arity = intern_get_irn_arity(n);
+    for (i = get_start_index(n); i < arity; i++) {
       ir_node *m;
       if (is_backedge(n, i)) continue;
 
-      m = get_irn_n(n, i); /*get_irn_ip_pred(n, i);*/
-      if ((!m) || (get_irn_op(m) == op_Unknown)) continue;
+      m = intern_get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
+      //if ((!m) || (intern_get_irn_op(m) == op_Unknown)) continue;
       scc (m);
-      /*return_recur(n, i);*/
-
       if (irn_is_in_stack(m)) {
-	/* Uplink of m is smaller if n->m is a backedge.
-	   Propagate the uplink to mark the loop. */
-	if (get_irn_uplink(m) < get_irn_uplink(n))
-	  set_irn_uplink(n, get_irn_uplink(m));
+    /* Uplink of m is smaller if n->m is a backedge.
+       Propagate the uplink to mark the loop. */
+    if (get_irn_uplink(m) < get_irn_uplink(n))
+      set_irn_uplink(n, get_irn_uplink(m));
       }
     }
   }
+
   if (get_irn_dfn(n) == get_irn_uplink(n)) {
-    /* This condition holds for the node with the incoming backedge. */
+    /* This condition holds for the node with the incoming backedge.
+       AS: That is: For the loop head. */
     ir_node *tail = find_tail(n);
     if (tail) {
-      /* We found a new loop! */
+      /* We found a new inner loop! */
+
+      /* This is an adaption of the algorithm from fiasco / optscc to
+       * avoid loops without Block or Phi as first node.  This should
+       * severely reduce the number of evaluations of nodes to detect
+       * a fixpoint in the heap analyses.
+       * Further it avoids loops without firm nodes that cause errors
+       * in the heap analyses. */
+#define NO_LOOPS_WITHOUT_HEAD 1
+#if NO_LOOPS_WITHOUT_HEAD
+      ir_loop *l;
+      int close;
+      if (get_loop_n_elements(current_loop) > 0) {
+    l = new_loop();
+    close = 1;
+      } else {
+    l = current_loop;
+    close = 0;
+      }
+#else
       ir_loop *l = new_loop();
+#endif
 
       /* Remove the loop from the stack ... */
       pop_scc_unmark_visit (n);
       /* and recompute it in a better order; and so that it goes into
-	 the new loop. */
-      rem = find_irg_on_stack(tail);
+     the new loop. */
+      // GL @@@ remove experimental stuff rem = find_irg_on_stack(tail);
 
       scc (tail);
-      current_ir_graph = rem;
+      // GL @@@ remove experimental stuff current_ir_graph = rem;
 
       assert (irn_visited(n));
+#if NO_LOOPS_WITHOUT_HEAD
+      if (close)
+#endif
       close_loop(l);
-
-      /*      current_loop = l; AS: This is done close_loop */
     } else {
+      /* AS: No inner loop was found. Pop all nodes from the stack
+     to the current loop. */
       pop_scc_to_loop(n);
     }
   }
@@ -785,36 +891,34 @@ static void scc (ir_node *n) {
 void construct_backedges(ir_graph *irg) {
   ir_graph *rem = current_ir_graph;
   ir_loop *head_rem;
-  int i;
 
   assert(!interprocedural_view &&
-	 "not implemented, use construct_ip_backedges");
+     "not implemented, use construct_ip_backedges");
 
   current_ir_graph = irg;
   outermost_ir_graph = irg;
 
-  init_scc(irg);
+  init_scc(current_ir_graph);
 
   current_loop = NULL;
   new_loop();  /* sets current_loop */
   head_rem = current_loop; /* Just for assertion */
 
   if (interprocedural_view) {
-    set_irg_visited(irg, inc_max_irg_visited());
+    set_irg_visited(current_ir_graph, inc_max_irg_visited());
     init_ip_walk ();
   } else {
-    inc_irg_visited(irg);
+    inc_irg_visited(current_ir_graph);
   }
 
-  scc(get_irg_end(irg));
-  for (i = 0; i < get_End_n_keepalives(get_irg_end(irg)); i++)
-    scc(get_End_keepalive(get_irg_end(irg), i));
+  scc(get_irg_end(current_ir_graph));
 
   if (interprocedural_view) finish_ip_walk();
 
   assert(head_rem == current_loop);
-  set_irg_loop(irg, current_loop);
-  assert(get_irg_loop(irg)->kind == k_ir_loop);
+  set_irg_loop(current_ir_graph, current_loop);
+  set_irg_loopinfo_state(current_ir_graph, loopinfo_consistent);
+  assert(get_irg_loop(current_ir_graph)->kind == k_ir_loop);
   /*
   irg->loops = current_loop;
   if (icfg == 1) {
@@ -828,7 +932,7 @@ void construct_backedges(ir_graph *irg) {
 }
 
 
-
+#if 0
 void construct_ip_backedges (void) {
   ir_graph *rem = current_ir_graph;
   int rem_ipv = interprocedural_view;
@@ -849,12 +953,10 @@ void construct_ip_backedges (void) {
   for (i = 0; i < get_irp_n_irgs(); i++) {
     ir_node *sb;
     current_ir_graph = get_irp_irg(i);
-    /*DDME(get_irg_ent(current_ir_graph));*/
     /* Find real entry points */
     sb = get_irg_start_block(current_ir_graph);
     if ((get_Block_n_cfgpreds(sb) > 1) ||
-	(get_nodes_Block(get_Block_cfgpred(sb, 0)) != sb)) continue;
-    /*    printf("running scc for "); DDME(get_irg_ent(current_ir_graph));   */
+    (get_nodes_Block(get_Block_cfgpred(sb, 0)) != sb)) continue;
     /* Compute scc for this graph */
     outermost_ir_graph = current_ir_graph;
     set_irg_visited(outermost_ir_graph, get_max_irg_visited());
@@ -864,24 +966,109 @@ void construct_ip_backedges (void) {
   }
 
   set_irg_loop(outermost_ir_graph, current_loop);
+  set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
   assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
 
   current_ir_graph = rem;
   interprocedural_view = rem_ipv;
 }
+#else
+void construct_ip_backedges (void) {
+  ir_graph *rem = current_ir_graph;
+  int rem_ipv = interprocedural_view;
+  int i;
+
+  outermost_ir_graph = get_irp_main_irg();
+
+  init_ip_scc();
+
+  current_loop = NULL;
+  new_loop();  /* sets current_loop */
+  interprocedural_view = 1;
+
+  inc_max_irg_visited();
+  for (i = 0; i < get_irp_n_irgs(); i++)
+    set_irg_visited(get_irp_irg(i), get_max_irg_visited());
+
+  /** We have to start the walk at the same nodes as cg_walk. **/
+  /* Walk starting at unreachable procedures. Only these
+   * have End blocks visible in interprocedural view. */
+  for (i = 0; i < get_irp_n_irgs(); i++) {
+    ir_node *sb;
+    current_ir_graph = get_irp_irg(i);
+
+    sb = get_irg_start_block(current_ir_graph);
+
+    if ((get_Block_n_cfgpreds(sb) > 1) ||
+    (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
+
+    scc(get_irg_end(current_ir_graph));
+  }
+
+  /* Check whether we walked all procedures: there could be procedures
+     with cyclic calls but no call from the outside. */
+  for (i = 0; i < get_irp_n_irgs(); i++) {
+    ir_node *sb;
+    current_ir_graph = get_irp_irg(i);
+
+    /* Test start block: if inner procedure end and end block are not
+     * visible and therefore not marked. */
+    sb = get_irg_start_block(current_ir_graph);
+    if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
+  }
+
+  /* Walk all endless loops in inner procedures.
+   * We recognize an inner procedure if the End node is not visited. */
+  for (i = 0; i < get_irp_n_irgs(); i++) {
+    ir_node *e;
+    current_ir_graph = get_irp_irg(i);
+
+    e = get_irg_end(current_ir_graph);
+    if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
+      int j;
+      /* Don't visit the End node. */
+      for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
+    }
+  }
 
+  set_irg_loop(outermost_ir_graph, current_loop);
+  set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
+  assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
 
-static void reset_backedges(ir_node *n, void *env) {
-  if (is_possible_loop_head(n))
+  current_ir_graph = rem;
+  interprocedural_view = rem_ipv;
+}
+#endif
+
+static void reset_backedges(ir_node *n) {
+  if (is_possible_loop_head(n)) {
+    int rem = interprocedural_view;
+    interprocedural_view = 1;
     clear_backedges(n);
+    interprocedural_view = 0;
+    clear_backedges(n);
+    interprocedural_view = rem;
+  }
+}
+
+static void loop_reset_backedges(ir_loop *l) {
+  int i;
+  reset_backedges(get_loop_node(l, 0));
+  for (i = 0; i < get_loop_n_nodes(l); ++i)
+    set_irn_loop(get_loop_node(l, i), NULL);
+  for (i = 0; i < get_loop_n_sons(l); ++i) {
+    loop_reset_backedges(get_loop_son(l, i));
+  }
 }
 
 /** Removes all loop information.
     Resets all backedges */
 void free_loop_information(ir_graph *irg) {
+  if (get_irg_loop(irg))
+    loop_reset_backedges(get_irg_loop(irg));
   set_irg_loop(irg, NULL);
+  set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
   /* We cannot free the loop nodes, they are on the obstack. */
-  irg_walk_graph(irg, NULL, reset_backedges, NULL);
 }
 
 
@@ -892,5 +1079,85 @@ void free_all_loop_information (void) {
   for (i = 0; i < get_irp_n_irgs(); i++) {
     free_loop_information(get_irp_irg(i));
   }
+  pmap_destroy(node_loop_map);
+  node_loop_map = NULL;
   interprocedural_view = rem;
 }
+
+
+
+
+
+/* Debug stuff *************************************************/
+
+static int test_loop_node(ir_loop *l) {
+  int i, has_node = 0, found_problem = 0;
+  loop_element le;
+
+  assert(l && l->kind == k_ir_loop);
+
+  if (get_loop_n_elements(l) == 0) {
+    printf(" Loop completely empty! "); DDML(l);
+    found_problem = 1;
+    dump_loop(l, "-ha");
+  }
+
+  le = get_loop_element(l, 0);
+  if (*(le.kind) != k_ir_node) {
+    assert(le.kind && *(le.kind) == k_ir_loop);
+    printf(" First loop element is not a node! "); DDML(l);
+    printf("                                   "); DDML(le.son);
+
+    found_problem = 1;
+    dump_loop(l, "-ha");
+  }
+
+  if ((*(le.kind) == k_ir_node) && !is_possible_loop_head(le.node)) {
+    printf(" Wrong node as head! "); DDML(l);
+    printf("                     "); DDMN(le.node);
+    found_problem = 1;
+    dump_loop(l, "-ha");
+  }
+
+  if ((get_loop_depth(l) != 0) &&
+      (*(le.kind) == k_ir_node) && !has_backedges(le.node)) {
+    printf(" Loop head has no backedges! "); DDML(l);
+    printf("                             "); DDMN(le.node);
+    found_problem = 1;
+    dump_loop(l, "-ha");
+  }
+
+  /* Recur */
+  has_node = 0;
+  for (i = 0; i < get_loop_n_elements(l); ++i) {
+    le = get_loop_element(l, i);
+    if (*(le.kind) == k_ir_node)
+      has_node++;
+    else
+      if (test_loop_node(le.son)) found_problem = 1;
+  }
+
+  if (has_node == 0) {
+    printf(" Loop has no firm node! "); DDML(l);
+    found_problem = 1;
+    dump_loop(l, "-ha");
+  }
+
+  if (get_loop_loop_nr(l) == 11819)
+    dump_loop(l, "-ha-debug");
+
+  return found_problem;
+}
+
+/** Prints all loop nodes that
+ *  - do not have any firm nodes, only loop sons
+ *  - the header is not a Phi, Block or Filter.
+ */
+void find_strange_loop_nodes(ir_loop *l) {
+  int found_problem = 0;
+  printf("\nTesting loop "); DDML(l);
+  found_problem = test_loop_node(l);
+  printf("Finished Test\n\n");
+  if (found_problem) exit(0);
+
+}