isl_tab: store index of variable in undo record instead of pointer to variable

The row of variables might get reallocated between pushing the undo
record and performing the undo, invalidating the pointer.

diff --git a/isl_tab.c b/isl_tab.c
index 6aaedc0..a8e4e02 100644 (file)
--- a/isl_tab.c
+++ b/isl_tab.c
@@ -387,7 +387,12 @@ static void push(struct isl_tab *tab,
                return;
        }
        undo->type = type;
-       undo->var = var;
+       if (!var)
+               undo->var_index = 0;
+       else if (var->is_row)
+               undo->var_index = tab->row_var[var->index];
+       else
+               undo->var_index = tab->col_var[var->index];
        undo->next = tab->top;
        tab->top = undo;
 }
@@ -1717,34 +1722,35 @@ static void unrelax(struct isl_tab *tab, struct isl_tab_var *var)
 
 static void perform_undo(struct isl_tab *tab, struct isl_tab_undo *undo)
 {
+       struct isl_tab_var *var = var_from_index(tab, undo->var_index);
        switch(undo->type) {
        case isl_tab_undo_empty:
                tab->empty = 0;
                break;
        case isl_tab_undo_nonneg:
-               undo->var->is_nonneg = 0;
+               var->is_nonneg = 0;
                break;
        case isl_tab_undo_redundant:
-               undo->var->is_redundant = 0;
+               var->is_redundant = 0;
                tab->n_redundant--;
                break;
        case isl_tab_undo_zero:
-               undo->var->is_zero = 0;
+               var->is_zero = 0;
                tab->n_dead--;
                break;
        case isl_tab_undo_allocate:
-               if (!undo->var->is_row) {
-                       if (!max_is_manifestly_unbounded(tab, undo->var))
-                               to_row(tab, undo->var, 1);
-                       else if (!min_is_manifestly_unbounded(tab, undo->var))
-                               to_row(tab, undo->var, -1);
+               if (!var->is_row) {
+                       if (!max_is_manifestly_unbounded(tab, var))
+                               to_row(tab, var, 1);
+                       else if (!min_is_manifestly_unbounded(tab, var))
+                               to_row(tab, var, -1);
                        else
-                               to_row(tab, undo->var, 0);
+                               to_row(tab, var, 0);
                }
-               drop_row(tab, undo->var->index);
+               drop_row(tab, var->index);
                break;
        case isl_tab_undo_relax:
-               unrelax(tab, undo->var);
+               unrelax(tab, var);
                break;
        }
 }

diff --git a/isl_tab.h b/isl_tab.h
index 4db65a7..5a7c96d 100644 (file)
--- a/isl_tab.h
+++ b/isl_tab.h
@@ -27,7 +27,7 @@ enum isl_tab_undo_type {
 
 struct isl_tab_undo {
        enum isl_tab_undo_type  type;
-       struct isl_tab_var      *var;
+       int                     var_index;
        struct isl_tab_undo     *next;
 };