[PATCH] Fix PR64406

[Richard Biener]

When a optimization pass in the loop pipeline moves stmts between
loops or removes loops we have to reset the SCEV cache to not
have stale CHREC_LOOPs.  This patch does it for loop distribution
for which I have a testcase.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2015-01-13  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/64406
        * tree-loop-distibution.c (pass_loop_distribution::execute):
        Reset the SCEV hashtable if we distributed anything.

        * gcc.dg/pr64406.c: New testcase.

Index: gcc/tree-loop-distribution.c
===================================================================
--- gcc/tree-loop-distribution.c        (revision 219520)
+++ gcc/tree-loop-distribution.c        (working copy)
@@ -1838,6 +1851,9 @@ out:
 
   if (changed)
     {
+      /* Cached scalar evolutions now may refer to wrong or non-existing
+        loops.  */
+      scev_reset_htab ();
       mark_virtual_operands_for_renaming (fun);
       rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
     }
Index: gcc/testsuite/gcc.dg/pr64406.c
===================================================================
--- gcc/testsuite/gcc.dg/pr64406.c      (revision 0)
+++ gcc/testsuite/gcc.dg/pr64406.c      (working copy)
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-O -ftree-loop-distribute-patterns -fno-tree-loop-ivcanon 
-fno-tree-loop-vectorize -ftree-vectorize" } */
+
+unsigned in[72];
+
+void bar (unsigned out[], unsigned ia[]);
+
+void
+foo ()
+{
+  int i;
+  unsigned out[72], ia[8];
+  for (i = 0; i < 8; i++)
+    {
+      out[i * 8] = in[i * 8] + 5;
+      out[i * 8 + 1] = in[i * 8 + 1] + 6;
+      out[i * 8 + 2] = in[i * 8 + 2] + 7;
+      out[i * 8 + 3] = in[i * 8 + 3] + 8;
+      out[i * 8 + 4] = in[i * 8 + 4] + 9;
+      out[i * 8 + 5] = in[i * 8 + 5] + 10;
+      out[i * 8 + 6] = in[i * 8 + 6] + 11;
+      out[i * 8 + 7] = in[i * 8 + 7] + 12;
+      ia[i] = in[i];
+    }
+  bar (out, ia);
+}