Call finite_loop_p in RTL to get better finiteness information.

gcc/ChangeLog

2019-06-27  Kewen Lin  <linkw@gcc.gnu.org>

    PR target/62147
    * gcc/loop-iv.c (find_simple_exit): Call finite_loop_p to update finiteness.

gcc/testsuite/ChangeLog

2019-06-27  Kewen Lin  <linkw@gcc.gnu.org>

    PR target/62147
    * gcc.target/powerpc/pr62147.c: New test.

From-SVN: r272731

1 files changed, 14 insertions, 0 deletions

diff --git a/gcc/loop-iv.c b/gcc/loop-iv.c
index 82b4bdb..36f9856 100644
--- a/gcc/loop-iv.c
+++ b/gcc/loop-iv.c
@@ -61,6 +61,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "intl.h"
 #include "dumpfile.h"
 #include "rtl-iter.h"
+#include "tree-ssa-loop-niter.h"
 
 /* Possible return values of iv_get_reaching_def.  */
 
@@ -2997,6 +2998,19 @@ find_simple_exit (struct loop *loop, struct niter_desc *desc)
 	fprintf (dump_file, "Loop %d is not simple.\n", loop->num);
     }
 
+  /* Fix up the finiteness if possible.  We can only do it for single exit,
+     since the loop is finite, but it's possible that we predicate one loop
+     exit to be finite which can not be determined as finite in middle-end as
+     well.  It results in incorrect predicate information on the exit condition
+     expression.  For example, if says [(int) _1 + -8, + , -8] != 0 finite,
+     it means _1 can exactly divide -8.  */
+  if (single_exit (loop) && finite_loop_p (loop))
+    {
+      desc->infinite = NULL_RTX;
+      if (dump_file)
+	fprintf (dump_file, "  infinite updated to finite.\n");
+    }
+
   free (body);
 }