Hello,
I hadn't expected that cfganal.c's reverse-CFG DFS would actually
depend on the order of the basic blocks. The attached patch fixes that
small oversight...
Bootstrapped&tested on powerpc64-unknown-linux-gnu. OK for trunk?
Ciao!
Steven
* cfganal.c (connect_infinite_loops_to_exit): Call dfs_deadend
from here.
(flow_dfs_compute_reverse_execute): Don't call it here.
Index: cfganal.c
===================================================================
--- cfganal.c (revision 193141)
+++ cfganal.c (working copy)
@@ -452,6 +452,7 @@ void
connect_infinite_loops_to_exit (void)
{
basic_block unvisited_block = EXIT_BLOCK_PTR;
+ basic_block deadend_block;
struct depth_first_search_dsS dfs_ds;
/* Perform depth-first search in the reverse graph to find nodes
@@ -467,8 +468,9 @@ connect_infinite_loops_to_exit (void)
if (!unvisited_block)
break;
- make_edge (unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
- flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
+ deadend_block = dfs_find_deadend (unvisited_block);
+ make_edge (deadend_block, EXIT_BLOCK_PTR, EDGE_FAKE);
+ flow_dfs_compute_reverse_add_bb (&dfs_ds, deadend_block);
}
flow_dfs_compute_reverse_finish (&dfs_ds);
@@ -958,7 +960,7 @@ flow_dfs_compute_reverse_execute (depth_first_sear
/* Determine if there are unvisited basic blocks. */
FOR_BB_BETWEEN (bb, last_unvisited, NULL, prev_bb)
if (!bitmap_bit_p (data->visited_blocks, bb->index))
- return dfs_find_deadend (bb);
+ return bb;
return NULL;
}
Index: testsuite/gcc.dg/pr55191.c
===================================================================
--- testsuite/gcc.dg/pr55191.c (revision 0)
+++ testsuite/gcc.dg/pr55191.c (revision 0)
@@ -0,0 +1,14 @@
+/* PR tree-optimization/55191 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int a, b;
+
+void f(void)
+{
+ b = a || b;
+
+ for(a = 0; a < 2; a++);
+ while(1);
+}
+
