Avoid if-conversion of loops in which the data dependence analysis fails.

2010-05-26  Sebastian Pop  <sebastian.pop@amd.com>

	* tree-if-conv.c (if_convertible_loop_p): Avoid if-conversion
	of loops in which the data dependence analysis fails.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@159883 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cef95f2dde768b6ceb490921bdfb72824883a5d1..6a4bac37677f13a6ae949974ab7f6012f05ee127 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2010-05-26  Sebastian Pop  <sebastian.pop@amd.com>
+
+       * tree-if-conv.c (if_convertible_loop_p): Avoid if-conversion
+       of loops in which the data dependence analysis fails.
+
 2010-05-26  Sebastian Pop  <sebastian.pop@amd.com>
 
        * tree-if-conv.c (if_convertible_loop_p): Do not compute/free

diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 23d71a044cf00a5bdb45919b93aa6c55eedc7687..f5247a35ee79238be43f5863086a5bce98a1ca84 100644 (file)
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -623,6 +623,20 @@ if_convertible_loop_p (struct loop *loop)
        return false;
     }
 
+  /* Don't if-convert the loop when the data dependences cannot be
+     computed: the loop won't be vectorized in that case.  */
+  {
+    VEC (data_reference_p, heap) *refs = VEC_alloc (data_reference_p, heap, 5);
+    VEC (ddr_p, heap) *ddrs = VEC_alloc (ddr_p, heap, 25);
+    bool res = compute_data_dependences_for_loop (loop, true, &refs, &ddrs);
+
+    free_data_refs (refs);
+    free_dependence_relations (ddrs);
+
+    if (!res)
+      return false;
+  }
+
   calculate_dominance_info (CDI_DOMINATORS);
 
   /* Allow statements that can be handled during if-conversion.  */