re PR tree-optimization/54458 (ICE get_loop_body, at cfgloop.c:830)

2012-09-04  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/54458
	* tree-ssa-threadupdate.c (thread_through_loop_header): If we
	turn the loop into one with multiple latches mark it so.

	* gcc.dg/torture/pr54458.c: New testcase.

From-SVN: r190918

gcc/ChangeLog

+2012-09-04  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/54458
+	* tree-ssa-threadupdate.c (thread_through_loop_header): If we
+	turn the loop into one with multiple latches mark it so.
+
 2012-09-04  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
 
 	PR target/54220

gcc/testsuite/ChangeLog

+2012-09-04  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/54458
+	* gcc.dg/torture/pr54458.c: New testcase.
+
 2012-09-04  Christophe Lyon  <christophe.lyon@linaro.org>
 
 	* gcc.target/arm/neon-vext.c: New test.

gcc/testsuite/gcc.dg/torture/pr54458.c

+/* { dg-do compile } */
+
+unsigned int a, b, c;
+
+void
+foo (unsigned int x)
+{
+  do
+    {
+      if (a == 0 ? 1 : 1 % a)
+	for (; b; b--)
+	  lab:;
+      else
+	while (x)
+	  ;
+      if (c)
+	goto lab;
+    }
+  while (1);
+}

gcc/tree-ssa-threadupdate.c

@@ -1037,11 +1037,21 @@ thread_through_loop_header (struct loop *loop, bool may_peel_loop_headers)
 	}
       free (bblocks);
 
+      /* If the new header has multiple latches mark it so.  */
+      FOR_EACH_EDGE (e, ei, loop->header->preds)
+	if (e->src->loop_father == loop
+	    && e->src != loop->latch)
+	  {
+	    loop->latch = NULL;
+	    loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
+	  }
+
       /* Cancel remaining threading requests that would make the
 	 loop a multiple entry loop.  */
       FOR_EACH_EDGE (e, ei, header->preds)
 	{
 	  edge e2;
+
 	  if (e->aux == NULL)
 	    continue;