From: Marion Guthmuller <marion.guthmuller@loria.fr>
Date: Fri, 9 Nov 2012 17:57:47 +0000 (+0100)
Subject: Shake up snapshot comparison : apply a new order of comparison
X-Git-Tag: v3_9_rc1~91^2~126^2~6
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/72fe27194fcb9623c09078d80efbd3b174dbc731

Shake up snapshot comparison : apply a new order of comparison
- number of chunks used in heaps
- size used in stacks
- binary/libsimgrid data segments
- heap comparison algorithm
- local variables with DWARF and libunwind

If debug log is enabled on mc_compare, comparison is done entirely otherwise comparison stops when a first difference is detected.
---

diff --git a/src/mc/mc_compare.c b/src/mc/mc_compare.c
index fbedb9d705..389ad342da 100644
--- a/src/mc/mc_compare.c
+++ b/src/mc/mc_compare.c
@@ -45,7 +45,7 @@ static size_t heap_ignore_size(void *address){
 }
 
 static int data_program_region_compare(void *d1, void *d2, size_t size){
-  int distance = 0;
+
   size_t i = 0;
   int pointer_align;
   void *addr_pointed1 = NULL, *addr_pointed2 = NULL;
@@ -58,19 +58,20 @@ static int data_program_region_compare(void *d1, void *d2, size_t size){
       if((addr_pointed1 > start_plt_binary && addr_pointed1 < end_plt_binary) || (addr_pointed2 > start_plt_binary && addr_pointed2 < end_plt_binary)){
         continue;
       }else{
-        XBT_DEBUG("Different byte (offset=%zu) (%p - %p) in data program region", i, (char *)d1 + i, (char *)d2 + i);
-        distance++;
+        if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose)){
+          XBT_VERB("Different byte (offset=%zu) (%p - %p) in data program region", i, (char *)d1 + i, (char *)d2 + i);
+          XBT_VERB("Addresses pointed : %p - %p\n", addr_pointed1, addr_pointed2);
+        }
+        return 1;
       }
     }
   }
   
-  XBT_INFO("Hamming distance between data program regions : %d", distance);
-
-  return distance;
+  return 0;
 }
 
 static int data_libsimgrid_region_compare(void *d1, void *d2, size_t size){
-  int distance = 0;
+
   size_t i = 0, ignore_size = 0;
   int pointer_align;
   void *addr_pointed1 = NULL, *addr_pointed2 = NULL;
@@ -89,33 +90,32 @@ static int data_libsimgrid_region_compare(void *d1, void *d2, size_t size){
       }else if(addr_pointed1 >= raw_heap && addr_pointed1 <= end_raw_heap && addr_pointed2 >= raw_heap && addr_pointed2 <= end_raw_heap){
         continue;
       }else{
-        XBT_DEBUG("Different byte (offset=%zu) (%p - %p) in data libsimgrid region", i, (char *)d1 + i, (char *)d2 + i);
-        XBT_DEBUG("Addresses pointed : %p - %p\n", addr_pointed1, addr_pointed2);
-        distance++;
+        if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose)){
+          XBT_VERB("Different byte (offset=%zu) (%p - %p) in data libsimgrid region", i, (char *)d1 + i, (char *)d2 + i);
+          XBT_VERB("Addresses pointed : %p - %p\n", addr_pointed1, addr_pointed2);
+        }
+        return 1;
       }
     }
   }
   
-  XBT_INFO("Hamming distance between data libsimgrid regions : %d", distance); fflush(NULL);
-  
-  return distance;
+  return 0;
 }
 
 static int heap_region_compare(void *d1, void *d2, size_t size){
   
-  int distance = 0;
   size_t i = 0;
   
   for(i=0; i<size; i++){
     if(memcmp(((char *)d1) + i, ((char *)d2) + i, 1) != 0){
-      XBT_DEBUG("Different byte (offset=%zu) (%p - %p) in heap region", i, (char *)d1 + i, (char *)d2 + i);
-      distance++;
+      if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose)){
+        XBT_VERB("Different byte (offset=%zu) (%p - %p) in heap region", i, (char *)d1 + i, (char *)d2 + i);
+      }
+      return 1;
     }
   }
   
-  XBT_INFO("Hamming distance between heap regions : %d (total size : %zu)", distance, size);
-
-  return distance;
+  return 0;
 }
 
 static void stack_region_free(stack_region_t s){
@@ -145,153 +145,174 @@ int snapshot_compare(mc_snapshot_t s1, mc_snapshot_t s2){
   
   MC_SET_RAW_MEM;
 
-  int errors = 0, i;
-  xbt_dynar_t stacks1 = xbt_dynar_new(sizeof(stack_region_t), stack_region_free_voidp);
-  xbt_dynar_t stacks2 = xbt_dynar_new(sizeof(stack_region_t), stack_region_free_voidp);
-  xbt_dynar_t equals = xbt_dynar_new(sizeof(heap_equality_t), heap_equality_free_voidp);
+  int errors = 0, i = 0;
 
-  void *heap1 = NULL, *heap2 = NULL;
-  
   if(s1->num_reg != s2->num_reg){
-    XBT_DEBUG("Different num_reg (s1 = %u, s2 = %u)", s1->num_reg, s2->num_reg);
+    if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose)){
+      XBT_VERB("Different num_reg (s1 = %u, s2 = %u)", s1->num_reg, s2->num_reg);
+    }
     return 1;
   }
 
-  for(i=0 ; i< s1->num_reg ; i++){
-    
-    if(s1->regions[i]->type != s2->regions[i]->type){
-      XBT_DEBUG("Different type of region");
-      errors++;
-    }
-    
+  int heap_index = 0, data_libsimgrid_index = 0, data_program_index = 0;
+
+  /* Get index of regions */
+  while(i < s1->num_reg){
     switch(s1->regions[i]->type){
-    case 0 :
-      /* Compare heapregion */
-      if(s1->regions[i]->size != s2->regions[i]->size){
-        XBT_DEBUG("Different size of heap (s1 = %zu, s2 = %zu)", s1->regions[i]->size, s2->regions[i]->size);
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;
-        return 1;
-      }
-      if(s1->regions[i]->start_addr != s2->regions[i]->start_addr){
-        XBT_DEBUG("Different start addr of heap (s1 = %p, s2 = %p)", s1->regions[i]->start_addr, s2->regions[i]->start_addr);
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;
-        return 1;
-      }
-      if(mmalloc_compare_heap((xbt_mheap_t)s1->regions[i]->data, (xbt_mheap_t)s2->regions[i]->data, &stacks1, &stacks2, &equals)){
-        XBT_INFO("Different heap (mmalloc_compare)");
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;  
-        return 1; 
-      }
-      heap1 = s1->regions[i]->data;
-      heap2 = s2->regions[i]->data;
+    case 0:
+      heap_index = i;
+      i++;
       break;
-    case 1 :
-      /* Compare data libsimgrid region */
-      if(s1->regions[i]->size != s2->regions[i]->size){
-        XBT_DEBUG("Different size of libsimgrid (data) (s1 = %zu, s2 = %zu)", s1->regions[i]->size, s2->regions[i]->size);
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;
-        return 1;
-      }
-      if(s1->regions[i]->start_addr != s2->regions[i]->start_addr){
-        XBT_DEBUG("Different start addr of libsimgrid (data) (s1 = %p, s2 = %p)", s1->regions[i]->start_addr, s2->regions[i]->start_addr);
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;
-        return 1;
-      }
-      if(data_libsimgrid_region_compare(s1->regions[i]->data, s2->regions[i]->data, s1->regions[i]->size) != 0){
-        XBT_INFO("Different memcmp for data in libsimgrid");
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;
-        return 1;
-      }
+    case 1:
+      data_libsimgrid_index = i;
+      i++;
+      while( i < s1->num_reg && s1->regions[i]->type == 1)
+        i++;
       break;
+    case 2:
+      data_program_index = i;
+      i++;
+      break;
+    }
+  }
 
-    case 2 :
-      /* Compare data program region */
-      if(s1->regions[i]->size != s2->regions[i]->size){
-        XBT_DEBUG("Different size of data program (s1 = %zu, s2 = %zu)", s1->regions[i]->size, s2->regions[i]->size);
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
+  /* Compare number of blocks/fragments uses in each heap */
+  size_t chunks_used1 = mmalloc_get_chunks_used((xbt_mheap_t)s1->regions[heap_index]->data);
+  size_t chunks_used2 = mmalloc_get_chunks_used((xbt_mheap_t)s2->regions[heap_index]->data);
+  if(chunks_used1 != chunks_used2){
+    if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug)){
+      XBT_DEBUG("Different number of chunks used in each heap : %zu - %zu", chunks_used1, chunks_used2);
+      errors++;
+    }else{
+      if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+        XBT_VERB("Different number of chunks used in each heap : %zu - %zu", chunks_used1, chunks_used2);
+      if(!raw_mem_set)
+        MC_UNSET_RAW_MEM;
+      return 1;
+    }
+  }
+
+  /* Compare size of stacks */
+  unsigned int cursor = 0;
+  void *addr_stack1, *addr_stack2;
+  void *sp1, *sp2;
+  size_t size_used1, size_used2;
+  while(cursor < xbt_dynar_length(stacks_areas)){
+    addr_stack1 = (char *)s1->regions[heap_index]->data + ((char *)((stack_region_t)xbt_dynar_get_as(stacks_areas, cursor, stack_region_t))->address - (char *)std_heap);
+    addr_stack2 = (char *)s2->regions[heap_index]->data + ((char *)((stack_region_t)xbt_dynar_get_as(stacks_areas, cursor, stack_region_t))->address - (char *)std_heap);
+    sp1 = ((mc_snapshot_stack_t)xbt_dynar_get_as(s1->stacks, cursor, mc_snapshot_stack_t))->stack_pointer;
+    sp2 = ((mc_snapshot_stack_t)xbt_dynar_get_as(s2->stacks, cursor, mc_snapshot_stack_t))->stack_pointer;
+    size_used1 = ((stack_region_t)xbt_dynar_get_as(stacks_areas, cursor, stack_region_t))->size - ((char*)sp1 - (char*)addr_stack1);
+    size_used2 = ((stack_region_t)xbt_dynar_get_as(stacks_areas, cursor, stack_region_t))->size - ((char*)sp2 - (char*)addr_stack2);
+    if(size_used1 != size_used2){
+      if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug)){
+        XBT_DEBUG("Different size used in stacks : %zu - %zu", size_used1, size_used2);
+        errors++;
+      }else{
+        if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+          XBT_VERB("Different size used in stacks : %zu - %zu", size_used1, size_used2);
         if(!raw_mem_set)
           MC_UNSET_RAW_MEM;
         return 1;
       }
-      if(s1->regions[i]->start_addr != s2->regions[i]->start_addr){
-        XBT_DEBUG("Different start addr of data program (s1 = %p, s2 = %p)", s1->regions[i]->start_addr, s2->regions[i]->start_addr);
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
+    }
+    cursor++;
+  }
+
+  /* Compare program data segment(s) */
+  i = data_program_index;
+  while(i < s1->num_reg && s1->regions[i]->type == 2){
+    if(data_program_region_compare(s1->regions[i]->data, s2->regions[i]->data, s1->regions[i]->size) != 0){
+      if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug)){
+        XBT_DEBUG("Different memcmp for data in program");
+        errors++;
+      }else{
+        if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+          XBT_VERB("Different memcmp for data in program");
         if(!raw_mem_set)
           MC_UNSET_RAW_MEM;
         return 1;
       }
-      if(data_program_region_compare(s1->regions[i]->data, s2->regions[i]->data, s1->regions[i]->size) != 0){
-        XBT_INFO("Different memcmp for data in program");
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
+    }
+    i++;
+  }
+
+  /* Compare libsimgrid data segment(s) */
+  i = data_libsimgrid_index;
+  while(i < s1->num_reg && s1->regions[i]->type == 1){
+    if(data_libsimgrid_region_compare(s1->regions[i]->data, s2->regions[i]->data, s1->regions[i]->size) != 0){
+      if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug)){
+        XBT_DEBUG("Different memcmp for data in libsimgrid");
+        errors++;
+      }else{
+        if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+          XBT_VERB("Different memcmp for data in libsimgrid");
         if(!raw_mem_set)
           MC_UNSET_RAW_MEM;
         return 1;
       }
-      break;
- 
     }
+    i++;
+  }
 
+  /* Compare heap */
+  xbt_dynar_t stacks1 = xbt_dynar_new(sizeof(stack_region_t), stack_region_free_voidp);
+  xbt_dynar_t stacks2 = xbt_dynar_new(sizeof(stack_region_t), stack_region_free_voidp);
+  xbt_dynar_t equals = xbt_dynar_new(sizeof(heap_equality_t), heap_equality_free_voidp);
+  
+  void *heap1 = s1->regions[heap_index]->data, *heap2 = s2->regions[heap_index]->data;
+ 
+  if(mmalloc_compare_heap((xbt_mheap_t)s1->regions[heap_index]->data, (xbt_mheap_t)s2->regions[heap_index]->data, &stacks1, &stacks2, &equals)){
+
+    if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug)){
+      XBT_DEBUG("Different heap (mmalloc_compare)");
+      errors++;
+    }else{
+
+      xbt_dynar_free(&stacks1);
+      xbt_dynar_free(&stacks2);
+      xbt_dynar_free(&equals);
+ 
+      if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+        XBT_VERB("Different heap (mmalloc_compare)");
+      if(!raw_mem_set)
+        MC_UNSET_RAW_MEM;
+      return 1;
+    } 
   }
 
   /* Stacks comparison */
-  unsigned int cursor = 0;
+  cursor = 0;
   stack_region_t stack_region1, stack_region2;
-  void *sp1, *sp2;
   int diff = 0, diff_local = 0;
 
   while(cursor < xbt_dynar_length(stacks1)){
-    XBT_DEBUG("Stack %d", cursor + 1); 
     stack_region1 = (stack_region_t)(xbt_dynar_get_as(stacks1, cursor, stack_region_t));
     stack_region2 = (stack_region_t)(xbt_dynar_get_as(stacks2, cursor, stack_region_t));
     sp1 = ((mc_snapshot_stack_t)xbt_dynar_get_as(s1->stacks, cursor, mc_snapshot_stack_t))->stack_pointer;
     sp2 = ((mc_snapshot_stack_t)xbt_dynar_get_as(s2->stacks, cursor, mc_snapshot_stack_t))->stack_pointer;
     diff = compare_stack(stack_region1, stack_region2, sp1, sp2, heap1, heap2, equals);
 
-    if(diff >0){  
+    if(diff > 0){ /* Differences may be due to padding */  
       diff_local = compare_local_variables(((mc_snapshot_stack_t)xbt_dynar_get_as(s1->stacks, cursor, mc_snapshot_stack_t))->local_variables->data, ((mc_snapshot_stack_t)xbt_dynar_get_as(s2->stacks, cursor, mc_snapshot_stack_t))->local_variables->data, equals);
       if(diff_local > 0){
-        XBT_INFO("Different local variables between stacks");
-        xbt_dynar_free(&stacks1);
-        xbt_dynar_free(&stacks2);
-        xbt_dynar_free(&equals);
-        if(!raw_mem_set)
-          MC_UNSET_RAW_MEM;
-        return 1;
-      }else{
-        XBT_INFO("Local variables are equals in stack %d", cursor + 1);
+        if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug)){
+          XBT_DEBUG("Different local variables between stacks %d", cursor + 1);
+          errors++;
+        }else{
+          xbt_dynar_free(&stacks1);
+          xbt_dynar_free(&stacks2);
+          xbt_dynar_free(&equals);
+
+          if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+            XBT_VERB("Different local variables between stacks %d", cursor + 1);
+          
+          if(!raw_mem_set)
+            MC_UNSET_RAW_MEM;
+
+          return 1;
+        }
       }
-    }else{
-      XBT_INFO("Hamming distance between stacks %d : %d", cursor + 1, diff);
     }
     cursor++;
   }
@@ -301,7 +322,8 @@ int snapshot_compare(mc_snapshot_t s1, mc_snapshot_t s2){
   xbt_dynar_free(&equals);
   if(!raw_mem_set)
     MC_UNSET_RAW_MEM;
-  return 0;
+
+  return errors > 0;
   
 }
 
@@ -341,8 +363,6 @@ static int compare_local_variables(char *s1, char *s2, xbt_dynar_t heap_equals){
   unsigned int cursor = 0;
   void *addr1, *addr2;
   char *ip1 = NULL, *ip2 = NULL;
-
-  int diff = 0;
   
   while(cursor < xbt_dynar_length(tokens1)){
     s_tokens1 = xbt_str_split(xbt_dynar_get_as(tokens1, cursor, char *), "=");
@@ -351,7 +371,8 @@ static int compare_local_variables(char *s1, char *s2, xbt_dynar_t heap_equals){
       if((strcmp(xbt_dynar_get_as(s_tokens1, 0, char *), "ip") == 0) && (strcmp(xbt_dynar_get_as(s_tokens2, 0, char *), "ip") == 0)){
         ip1 = strdup(xbt_dynar_get_as(s_tokens1, 1, char *));
         ip2 = strdup(xbt_dynar_get_as(s_tokens2, 1, char *));
-        XBT_DEBUG("Ip1 : %s, Ip2 : %s", ip1, ip2);
+        /*if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+          XBT_VERB("Instruction pointer : %s, Instruction pointer : %s", ip1, ip2);*/
       }
       if(strcmp(xbt_dynar_get_as(s_tokens1, 1, char *), xbt_dynar_get_as(s_tokens2, 1, char *)) != 0){   
         /* Ignore this variable ?  */
@@ -364,11 +385,11 @@ static int compare_local_variables(char *s1, char *s2, xbt_dynar_t heap_equals){
         addr1 = (void *) strtoul(xbt_dynar_get_as(s_tokens1, 1, char *), NULL, 16);
         addr2 = (void *) strtoul(xbt_dynar_get_as(s_tokens2, 1, char *), NULL, 16);
         if(is_heap_equality(heap_equals, addr1, addr2) == 0){
-          if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_debug))
-            XBT_DEBUG("Variable %s is different between stacks : %s - %s", xbt_dynar_get_as(s_tokens1, 0, char *), xbt_dynar_get_as(s_tokens1, 1, char *), xbt_dynar_get_as(s_tokens2, 1, char *));
-          else
-            XBT_INFO("Variable %s is different between stacks", xbt_dynar_get_as(s_tokens1, 0, char *));
-          diff++;
+          if(XBT_LOG_ISENABLED(mc_compare, xbt_log_priority_verbose))
+            XBT_VERB("Variable %s is different between stacks : %s - %s", xbt_dynar_get_as(s_tokens1, 0, char *), xbt_dynar_get_as(s_tokens1, 1, char *), xbt_dynar_get_as(s_tokens2, 1, char *));
+          xbt_dynar_free(&s_tokens1);
+          xbt_dynar_free(&s_tokens2);
+          return 1;
         }
       }
     }
@@ -379,7 +400,7 @@ static int compare_local_variables(char *s1, char *s2, xbt_dynar_t heap_equals){
 
   xbt_dynar_free(&tokens1);
   xbt_dynar_free(&tokens2);
-  return diff;
+  return 0;
   
 }
 
@@ -414,41 +435,32 @@ static int is_heap_equality(xbt_dynar_t equals, void *a1, void *a2){
 
 static int compare_stack(stack_region_t s1, stack_region_t s2, void *sp1, void *sp2, void *heap1, void *heap2, xbt_dynar_t equals){
   
-  size_t k = 0, nb_diff = 0;
+  size_t k = 0;
   size_t size_used1 = s1->size - ((char*)sp1 - (char*)s1->address);
   size_t size_used2 = s2->size - ((char*)sp2 - (char*)s2->address);
 
   int pointer_align;
   void *addr_pointed1 = NULL, *addr_pointed2 = NULL;  
-
-  if(size_used1 == size_used2){
- 
-    while(k < size_used1){
-      if(memcmp((char *)s1->address + s1->size - k, (char *)s2->address + s2->size - k, 1) != 0){
-        pointer_align = ((size_used1 - k) / sizeof(void*)) * sizeof(void*);
-        addr_pointed1 = *((void **)(((char*)s1->address + (s1->size - size_used1)) + pointer_align));
-        addr_pointed2 = *((void **)(((char*)s2->address + (s2->size - size_used2)) + pointer_align));
-        if(is_heap_equality(equals, addr_pointed1, addr_pointed2) == 0){
-          if((addr_pointed1 > std_heap) && (addr_pointed1 < (void *)((char *)std_heap + STD_HEAP_SIZE)) && (addr_pointed2 > std_heap) && (addr_pointed2 < (void *)((char *)std_heap + STD_HEAP_SIZE))){
-            if(is_free_area(addr_pointed1, (xbt_mheap_t)heap1) == 0 || is_free_area(addr_pointed2, (xbt_mheap_t)heap2) == 0){
-              //XBT_INFO("Difference at offset %zu (%p - %p)", k, (char *)s1->address + s1->size - k, (char *)s2->address + s2->size - k);
-              nb_diff++;
-            }
-          }else{
-            //XBT_INFO("Difference at offset %zu (%p - %p)", k, (char *)s1->address + s1->size - k, (char *)s2->address + s2->size - k);
-            nb_diff++;
-          } 
-        }
-      } 
-      k++;
-    }
-
-  }else{
-    XBT_INFO("Different size used between stacks");
-    return 1;
+  
+  while(k < size_used1){
+    if(memcmp((char *)s1->address + s1->size - k, (char *)s2->address + s2->size - k, 1) != 0){
+      pointer_align = ((size_used1 - k) / sizeof(void*)) * sizeof(void*);
+      addr_pointed1 = *((void **)(((char*)s1->address + (s1->size - size_used1)) + pointer_align));
+      addr_pointed2 = *((void **)(((char*)s2->address + (s2->size - size_used2)) + pointer_align));
+      if(is_heap_equality(equals, addr_pointed1, addr_pointed2) == 0){
+        if((addr_pointed1 > std_heap) && (addr_pointed1 < (void *)((char *)std_heap + STD_HEAP_SIZE)) && (addr_pointed2 > std_heap) && (addr_pointed2 < (void *)((char *)std_heap + STD_HEAP_SIZE))){
+          if(is_free_area(addr_pointed1, (xbt_mheap_t)heap1) == 0 || is_free_area(addr_pointed2, (xbt_mheap_t)heap2) == 0){
+            return 1;
+          }
+        }else{
+          return 1;
+        } 
+      }
+    } 
+    k++;
   }
-
-  return nb_diff;
+ 
+  return 0;
 }
 
 int MC_compare_snapshots(void *s1, void *s2){