Fixed call dependency comparison for backend call ordering.

Code was taken from cmp_call_dependency in beabi.c which handles the
situation correctly.

diff --git a/ir/be/beabihelper.c b/ir/be/beabihelper.c
index 4e317a5..a7a8b6e 100644 (file)
--- a/ir/be/beabihelper.c
+++ b/ir/be/beabihelper.c
@@ -566,6 +566,7 @@ static int cmp_call_dependency(const void *c1, const void *c2)
 {
        const ir_node *n1 = *(const ir_node **) c1;
        const ir_node *n2 = *(const ir_node **) c2;
+       unsigned h1, h2;
 
        if (dependent_on(n1, n2))
                return 1;
@@ -574,8 +575,17 @@ static int cmp_call_dependency(const void *c1, const void *c2)
                return -1;
 
        /* The nodes have no depth order, but we need a total order because qsort()
-        * is not stable. */
-       return get_irn_idx(n2) - get_irn_idx(n1);
+        * is not stable.
+        *
+        * Additionally, we need to respect transitive dependencies. Consider a
+        * Call a depending on Call b and an independent Call c.
+        * We MUST NOT order c > a and b > c. */
+       h1 = get_irn_height(heights, n1);
+       h2 = get_irn_height(heights, n2);
+       if (h1 < h2) return -1;
+       if (h1 > h2) return  1;
+       /* Same height, so use a random (but stable) order */
+       return get_irn_idx(n1) - get_irn_idx(n2);
 }
 
 /**