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-rw-r--r--gcc-4.9/gcc/tree-ssa-threadupdate.c40
1 files changed, 34 insertions, 6 deletions
diff --git a/gcc-4.9/gcc/tree-ssa-threadupdate.c b/gcc-4.9/gcc/tree-ssa-threadupdate.c
index d1b289ffa..3c7df9add 100644
--- a/gcc-4.9/gcc/tree-ssa-threadupdate.c
+++ b/gcc-4.9/gcc/tree-ssa-threadupdate.c
@@ -1772,6 +1772,21 @@ duplicate_seme_region (edge entry, edge exit,
return true;
}
+/* Return true when PATH is a valid jump-thread path. */
+
+static bool
+valid_jump_thread_path (vec<jump_thread_edge *> *path)
+{
+ unsigned len = path->length ();
+
+ /* Check that the path is connected. */
+ for (unsigned int j = 0; j < len - 1; j++)
+ if ((*path)[j]->e->dest != (*path)[j+1]->e->src)
+ return false;
+
+ return true;
+}
+
/* Walk through all blocks and thread incoming edges to the appropriate
outgoing edge for each edge pair recorded in THREADED_EDGES.
@@ -1807,12 +1822,25 @@ thread_through_all_blocks (bool may_peel_loop_headers)
vec<jump_thread_edge *> *path = paths[i];
edge entry = (*path)[0]->e;
- if ((*path)[0]->type != EDGE_FSM_THREAD
- /* Do not jump-thread twice from the same block. */
- || bitmap_bit_p (threaded_blocks, entry->src->index)) {
- i++;
- continue;
- }
+ /* Only code-generate FSM jump-threads in this loop. */
+ if ((*path)[0]->type != EDGE_FSM_THREAD)
+ {
+ i++;
+ continue;
+ }
+
+ /* Do not jump-thread twice from the same block. */
+ if (bitmap_bit_p (threaded_blocks, entry->src->index)
+ /* Verify that the jump thread path is still valid: a
+ previous jump-thread may have changed the CFG, and
+ invalidated the current path. */
+ || !valid_jump_thread_path (path))
+ {
+ /* Remove invalid FSM jump-thread paths. */
+ delete_jump_thread_path (path);
+ paths.unordered_remove (i);
+ continue;
+ }
unsigned len = path->length ();
edge exit = (*path)[len - 1]->e;