isl_tab: don't create new undo records during rollback

diff --git a/isl_tab.c b/isl_tab.c
index cdb950b..4f2e783 100644 (file)
--- a/isl_tab.c
+++ b/isl_tab.c
@@ -51,6 +51,7 @@ struct isl_tab *isl_tab_alloc(struct isl_ctx *ctx,
        tab->need_undo = 0;
        tab->rational = 0;
        tab->empty = 0;
+       tab->in_undo = 0;
        tab->bottom.type = isl_tab_undo_bottom;
        tab->bottom.next = NULL;
        tab->top = &tab->bottom;
@@ -484,6 +485,8 @@ static void pivot(struct isl_ctx *ctx,
        var = var_from_col(ctx, tab, col);
        var->is_row = 0;
        var->index = col;
+       if (tab->in_undo)
+               return;
        for (i = tab->n_redundant; i < tab->n_row; ++i) {
                if (isl_int_is_zero(mat->row[i][2 + col]))
                        continue;
@@ -1701,6 +1704,7 @@ int isl_tab_rollback(struct isl_ctx *ctx, struct isl_tab *tab,
        if (!tab)
                return -1;
 
+       tab->in_undo = 1;
        for (undo = tab->top; undo && undo != &tab->bottom; undo = next) {
                next = undo->next;
                if (undo == snap)
@@ -1708,6 +1712,7 @@ int isl_tab_rollback(struct isl_ctx *ctx, struct isl_tab *tab,
                perform_undo(ctx, tab, undo);
                free(undo);
        }
+       tab->in_undo = 0;
        tab->top = undo;
        if (!undo)
                return -1;

diff --git a/isl_tab.h b/isl_tab.h
index 1df42e1..e747a9f 100644 (file)
--- a/isl_tab.h
+++ b/isl_tab.h
@@ -93,6 +93,7 @@ struct isl_tab {
        unsigned need_undo : 1;
        unsigned rational : 1;
        unsigned empty : 1;
+       unsigned in_undo : 1;
 };
 
 struct isl_tab *isl_tab_alloc(struct isl_ctx *ctx,