[patch, vectorizer] Fix PR tree-optimization/38529

[Ira Rosen <IRAR at il dot ibm dot com>]

Hi,

This patch fixes an ICE in the vectorizer that occurs in case that a def is
in the inner loop and its use is in the outer loop (which is being
vectorized). The problem is that the vectorized definitions were not
recorded for such uses.

Bootstrapped with vectorization enabled and regtested on
powerpc64-suse-linux.
O.K. for 4.3 and 4.4?

Thanks,
Ira

ChangeLog entry:

2008-12-16  Dorit Nuzman  <dorit@il.ibm.com>
            Ira Rosen  <irar@il.ibm.com>

      PR tree-optimization/38529
      * tree-vect-transform (vect_transform_stmt): Handle inner-loop stmts
      whose DEF is used in the loop-nest that is being vectorized, but
outside
      the immediately enclosing loop.

testsuite/ChangeLog entry:

2008-12-16  Dorit Nuzman  <dorit@il.ibm.com>
            Ira Rosen  <irar@il.ibm.com>

      PR tree-optimization/38529
      * gcc.dg/vect/pr38529.c: New.


Index: tree-vect-transform.c
===================================================================
--- tree-vect-transform.c       (revision 142762)
+++ tree-vect-transform.c       (working copy)
@@ -7047,6 +7047,8 @@ vect_transform_stmt (gimple stmt, gimple
   stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
   gimple orig_stmt_in_pattern;
   bool done;
+  loop_vec_info loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_info);
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);

   switch (STMT_VINFO_TYPE (stmt_info))
     {
@@ -7130,6 +7132,52 @@ vect_transform_stmt (gimple stmt, gimple;
        }
     }

+  /* Handle inner-loop stmts whose DEF is used in the loop-nest that
+     is being vectorized, but outside the immediately enclosing loop.  */
+  if (vec_stmt
+      && nested_in_vect_loop_p (loop, stmt)
+      && STMT_VINFO_TYPE (stmt_info) != reduc_vec_info_type
+      && (STMT_VINFO_RELEVANT (stmt_info) == vect_used_in_outer
+          || STMT_VINFO_RELEVANT (stmt_info) ==
vect_used_in_outer_by_reduction))
+    {
+      struct loop *innerloop = loop->inner;)
+      imm_use_iterator imm_iter;
+      use_operand_p use_p;
+      VEC(gimple,heap) *phis = NULL;>
+      tree scalar_dest;
+      gimple exit_phi;;
+      int i;
+
+      if (vect_print_dump_info (REPORT_DETAILS))
+       fprintf (vect_dump, "Record the vdef for outer-loop
vectorization.");
+
+      /* Find the relevant loop-exit phi-node, and reord the vec_stmt
there;
+        (to be used when vectorizing outer-loop stmts that use the DEF of
+        STMT).  */
+      if (gimple_code (stmt) == GIMPLE_PHI)
+       scalar_dest = PHI_RESULT (stmt);
+      else
+        scalar_dest = gimple_assign_lhs (stmt);
+
+      phis = VEC_alloc (gimple, heap, 10);
+      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, scalar_dest)
+       {
+         if (!flow_bb_inside_loop_p (innerloop, gimple_bb (USE_STMT
(use_p))))
+           {
+             exit_phi = USE_STMT (use_p);
+             VEC_quick_push (gimple, phis, exit_phi);
+           }
+       }
+
+      for (i = 0; VEC_iterate (gimple, phis, i, exit_phi); i++)
+       {
+         stmt_vec_info stmt_vinfo = vinfo_for_stmt (exit_phi);)
+         STMT_VINFO_VEC_STMT (stmt_vinfo) = vec_stmt;
+        }
+    }
+
+  /* Handle stmts whose DEF is used outside the loop-nest that is
+     being vectorized.  */
   if (STMT_VINFO_LIVE_P (stmt_info)
       && STMT_VINFO_TYPE (stmt_info) != reduc_vec_info_type)
     {
Index: testsuite/gcc.dg/vect/pr38529.c!
===================================================================
--- testsuite/gcc.dg/vect/pr38529.c     (revision 0)
+++ testsuite/gcc.dg/vect/pr38529.c     (revision 0)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_float } */
+
+float a[4];
+
+void foo();
+{
+  int i, j;
+
+  for (i = 0; i < 4; ++i)
+    for (j = 0; j < 17; ++j)
+      a[i] = 0;
+}
+}
+/* { dg-final { scan-tree-dump-times "OUTER LOOP VECTORIZED" 1 "vect"  } }
*/)
+/* { dg-final { cleanup-tree-dump "vect" } } */
+