diff -pruN origsrc/gcc-4.5.0/gcc/unwind-dw2-fde.c src/gcc-4.5.0/gcc/unwind-dw2-fde.c
--- origsrc/gcc-4.5.0/gcc/unwind-dw2-fde.c	2009-09-20 12:03:33.000000000 +0100
+++ src/gcc-4.5.0/gcc/unwind-dw2-fde.c	2010-04-19 04:28:35.406250000 +0100
@@ -37,6 +37,8 @@ see the files COPYING3 and COPYING.RUNTI
 #include "gthr.h"
 #endif
 
+#define __debug_unwind_enabled (0)
+
 /* The unseen_objects list contains objects that have been registered
    but not yet categorized in any way.  The seen_objects list has had
    its pc_begin and count fields initialized at minimum, and is sorted
@@ -840,6 +842,8 @@ binary_search_unencoded_fdes (struct obj
   struct fde_vector *vec = ob->u.sort;
   size_t lo, hi;
 
+  if (__debug_unwind_enabled) printf ("search fdes ob %p: vec %p count %d\n", ob, vec, vec->count);
+
   for (lo = 0, hi = vec->count; lo < hi; )
     {
       size_t i = (lo + hi) / 2;
@@ -849,6 +853,8 @@ binary_search_unencoded_fdes (struct obj
       memcpy (&pc_begin, (const void * const *) f->pc_begin, sizeof (void *));
       memcpy (&pc_range, (const uaddr *) f->pc_begin + 1, sizeof (uaddr));
 
+if (__debug_unwind_enabled) printf ("fde#%d (%p): pc_begin %p pc_range %p\n", i, f, pc_begin, (void *)pc_range);
+
       if (pc < pc_begin)
 	hi = i;
       else if (pc >= pc_begin + pc_range)
@@ -856,7 +862,7 @@ binary_search_unencoded_fdes (struct obj
       else
 	return f;
     }
-
+if (__debug_unwind_enabled) printf ("**not found\n");
   return NULL;
 }
 
@@ -977,6 +983,8 @@ _Unwind_Find_FDE (void *pc, struct dwarf
   /* Linear search through the classified objects, to find the one
      containing the pc.  Note that pc_begin is sorted descending, and
      we expect objects to be non-overlapping.  */
+  if (__debug_unwind_enabled) printf ("Search seen obs for pc %p: Bases t %p, d %p, func %p\n", 
+	pc, bases->tbase, bases->dbase, bases->func);
   for (ob = seen_objects; ob; ob = ob->next)
     if (pc >= ob->pc_begin)
       {
@@ -987,6 +995,8 @@ _Unwind_Find_FDE (void *pc, struct dwarf
       }
 
   /* Classify and search the objects we've not yet processed.  */
+  if (__debug_unwind_enabled) printf ("Search unseen obs for pc %p: Bases t %p, d %p, func %p\n", 
+	pc, bases->tbase, bases->dbase, bases->func);
   while ((ob = unseen_objects))
     {
       struct object **p;
@@ -1022,6 +1032,15 @@ _Unwind_Find_FDE (void *pc, struct dwarf
       read_encoded_value_with_base (encoding, base_from_object (encoding, ob),
 				    f->pc_begin, &func);
       bases->func = (void *) func;
+
+  if (__debug_unwind_enabled) printf ("Found fde %p: Bases t %p, d %p, func %p\n", 
+	f, bases->tbase, bases->dbase, bases->func);
+
+    }
+    else
+    {
+  if (__debug_unwind_enabled) printf ("No fde %p: Bases t %p, d %p, func %p\n", 
+	f, bases->tbase, bases->dbase, bases->func);
     }
 
   return f;
diff -pruN origsrc/gcc-4.5.0/gcc/unwind-dw2.c src/gcc-4.5.0/gcc/unwind-dw2.c
--- origsrc/gcc-4.5.0/gcc/unwind-dw2.c	2010-01-20 08:13:50.000000000 +0000
+++ src/gcc-4.5.0/gcc/unwind-dw2.c	2010-04-19 04:28:35.421875000 +0100
@@ -79,6 +79,7 @@ struct _Unwind_Context
 
 /* Byte size of every register managed by these routines.  */
 static unsigned char dwarf_reg_size_table[DWARF_FRAME_REGISTERS+1];
+#define __debug_unwind_enabled (0)
 
 
 /* Read unaligned data from the instruction buffer.  */
@@ -370,7 +371,7 @@ extract_cie_info (const struct dwarf_cie
       fs->retaddr_column = (_Unwind_Word)utmp;
     }
   fs->lsda_encoding = DW_EH_PE_omit;
-
+if (__debug_unwind_enabled) printf ("extract cie: augmentation '%c'\n", *aug);
   /* If the augmentation starts with 'z', then a uleb128 immediately
      follows containing the length of the augmentation field following
      the size.  */
@@ -386,6 +387,7 @@ extract_cie_info (const struct dwarf_cie
   /* Iterate over recognized augmentation subsequences.  */
   while (*aug != '\0')
     {
+if (__debug_unwind_enabled) printf ("handle augmentation '%c'\n", *aug);
       /* "L" indicates a byte showing how the LSDA pointer is encoded.  */
       if (aug[0] == 'L')
 	{
@@ -423,6 +425,7 @@ extract_cie_info (const struct dwarf_cie
 	return ret;
     }
 
+if (__debug_unwind_enabled) printf ("extract cie: augmentation done\n");
   return ret ? ret : p;
 }
 
@@ -1568,9 +1571,25 @@ uw_identify_context (struct _Unwind_Cont
     return _Unwind_GetCFA (context) + _Unwind_IsSignalFrame (context);
 }
 
+static _Unwind_Reason_Code 
+debug_unwind_trace (struct _Unwind_Context *ctx, void *arg)
+{
+  fflush (NULL);
+  printf ("_Unwind_Context %p\n", ctx);
+  printf ("    cfa %p  ra %p  lsda %p\n", ctx->cfa, ctx->ra, ctx->lsda);
+  printf (" bases: t %p d %p func %p\n", ctx->bases.tbase, ctx->bases.dbase, ctx->bases.func);
+  printf ("\n");
+  fflush (NULL);
+  return _URC_NO_REASON;
+}
 
 #include "unwind.inc"
 
+void debug_dump_stack_trace (void *arg)
+{
+  _Unwind_Backtrace (debug_unwind_trace, arg);
+}
+
 #if defined (USE_GAS_SYMVER) && defined (SHARED) && defined (USE_LIBUNWIND_EXCEPTIONS)
 alias (_Unwind_Backtrace);
 alias (_Unwind_DeleteException);
diff -pruN origsrc/gcc-4.5.0/gcc/unwind.inc src/gcc-4.5.0/gcc/unwind.inc
--- origsrc/gcc-4.5.0/gcc/unwind.inc	2009-04-09 16:00:19.000000000 +0100
+++ src/gcc-4.5.0/gcc/unwind.inc	2010-04-19 04:28:35.421875000 +0100
@@ -96,8 +96,9 @@ _Unwind_RaiseException(struct _Unwind_Ex
 
       /* Set up fs to describe the FDE for the caller of cur_context.  The
 	 first time through the loop, that means __cxa_throw.  */
+if (__debug_unwind_enabled) printf ("Ctx: ra %p\n", cur_context.ra);
       code = uw_frame_state_for (&cur_context, &fs);
-
+if (__debug_unwind_enabled) printf ("... code %d, perso %p\n", code, fs.personality);
       if (code == _URC_END_OF_STACK)
 	/* Hit end of stack with no handler found.  */
 	return _URC_END_OF_STACK;
@@ -112,6 +113,7 @@ _Unwind_RaiseException(struct _Unwind_Ex
 	{
 	  code = (*fs.personality) (1, _UA_SEARCH_PHASE, exc->exception_class,
 				    exc, &cur_context);
+if (__debug_unwind_enabled) printf ("perso returns code %d\n", code);
 	  if (code == _URC_HANDLER_FOUND)
 	    break;
 	  else if (code != _URC_CONTINUE_UNWIND)