re PR tree-optimization/58343 (ICE in dfs_enumerate_from, at cfganal.c:1036)

	PR tree-optimization/58343
	* tree-ssa-threadupdate.c (thread_block): Identify and disable
	jump threading requests through loop headers buried in the middle
	of a jump threading path.

	* tree-ssa-threadedge.c (thread_around_empty_blocks): Fix thinko
	in return value/type.

	* gcc.c-torture/compile/pr58343.c: New test.

From-SVN: r202441

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cd91607f9b78bef9f3cc495219ce695946d201e6..4607dd63a68085bb5ad41c8336af95cafc2d4b61 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2013-09-10  Jeff Law  <law@redhat.com>
+
+       PR tree-optimization/58343
+       * tree-ssa-threadupdate.c (thread_block): Identify and disable
+       jump threading requests through loop headers buried in the middle
+       of a jump threading path.
+
+       * tree-ssa-threadedge.c (thread_around_empty_blocks): Fix thinko
+       in return value/type.
+
 2013-09-10  Jakub Jelinek  <jakub@redhat.com>
 
        PR rtl-optimization/58365

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fe91b24808fbbafdd8d84c139bcf227e8145291e..1e5f483d20ada3fcb5e2b7a837613d1e84eb673f 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2013-09-10  Jeff Law  <law@redhat.com>
+
+       * gcc.c-torture/compile/pr58343.c: New test.
+
 2013-09-10  Jakub Jelinek  <jakub@redhat.com>
 
        PR rtl-optimization/58365

diff --git a/gcc/testsuite/gcc.c-torture/compile/pr58343.c b/gcc/testsuite/gcc.c-torture/compile/pr58343.c
new file mode 100644 (file)
index 0000000..cdd2ce9
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr58343.c
@@ -0,0 +1,15 @@
+int a;
+
+int main ()
+{
+  int b = a; 
+
+  for (a = 1; a > 0; a--)
+    ;
+
+ lbl:
+  if (b && a)
+    goto lbl; 
+
+  return 0;
+}

diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
index f2051d7e7d00f271152a2153b1e6925ec035e71f..14bc4e37329d8af16f1e1ce0e6d909d87354b06e 100644 (file)
--- a/gcc/tree-ssa-threadedge.c
+++ b/gcc/tree-ssa-threadedge.c
@@ -764,7 +764,7 @@ thread_around_empty_blocks (edge taken_edge,
      when threading.  Thus they can not have visible side effects such
      as PHI nodes.  */
   if (!gsi_end_p (gsi_start_phis (bb)))
-    return NULL;
+    return false;
 
   /* Skip over DEBUG statements at the start of the block.  */
   gsi = gsi_start_nondebug_bb (bb);

diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index 8e40f6668cf52dbf602403495421d190abb1f448..3c3d3bc80f0aeab7cefcf3e01e1db3bdd771ceb8 100644 (file)
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -640,14 +640,36 @@ thread_block (basic_block bb, bool noloop_only)
       else
        e2 = THREAD_TARGET (e);
 
-      if (!e2
+      if (!e2 || noloop_only)
+       {
          /* If NOLOOP_ONLY is true, we only allow threading through the
-            header of a loop to exit edges.  */
-         || (noloop_only
-             && bb == bb->loop_father->header
+            header of a loop to exit edges. 
+
+            There are two cases to consider.  The first when BB is the
+            loop header.  We will attempt to thread this elsewhere, so
+            we can just continue here.  */
+
+         if (bb == bb->loop_father->header
              && (!loop_exit_edge_p (bb->loop_father, e2)
-                 || THREAD_TARGET2 (e))))
-       continue;
+                 || THREAD_TARGET2 (e)))
+           continue;
+
+
+         /* The second occurs when there was loop header buried in a jump
+            threading path.  We do not try and thread this elsewhere, so
+            just cancel the jump threading request by clearing the AUX
+            field now.  */
+         if (bb->loop_father != e2->src->loop_father
+             && !loop_exit_edge_p (e2->src->loop_father, e2))
+           {
+             /* Since this case is not handled by our special code
+                to thread through a loop header, we must explicitly
+                cancel the threading request here.  */
+             free (e->aux);
+             e->aux = NULL;
+             continue;
+           }
+       }
 
       if (e->dest == e2->src)
        update_bb_profile_for_threading (e->dest, EDGE_FREQUENCY (e),