[PATCH] Fix tree-data-ref DDR_LOOP_NEST handling (PR tree-optimization/29330)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

As vec.h documentation states, vectors at least when they use safe push
shouldn't be passed around using value, but using reference, because a safe
push might realloc them.  This is what happens in the attached testcase,
compute_data_dependences_for_loop allocates initially a 3 entry vector
but as there are 4 nested loops, the vector is reallocated, but
compute_data_dependences_for_loop isn't aware of that and still
reuses the old pointer.  This is fixed by the
find_loop_nest_1/find_loop_nest/compute_data_dependences_for_loop
hunks.  When looking around the code, I also find that the loop_nest
vector is never freed, so we have a memory leak (it is a tiny bit tricky,
because all the loops share the same loop_nest vector), free_data_ref
could use a DR_FREE_ACCESS_FNS macro which does exactly what free_data_ref
was doing and the macro was unused, and lastly tree-loop-linear.c forgot
to free various data structures if it decided to bail after
compute_data_dependences_for_loop was called.
Tested on x86_64-linux.

Ok for trunk?
The tree-loop-linear.c change is also applicable to 4.1 branch (i.e.
we are leaking memory there too), is that part ok for 4.1 too?

2006-10-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/29330
	* tree-data-ref.c (free_data_ref): Use DR_FREE_ACCESS_FNS macro.
	(initialize_data_dependence_relation): Clear DDR_LOOP_NEST pointer
	on newly allocated ddrs.
	(find_loop_nest_1, find_loop_nest): Change LOOP_NEST to a pointer
	to VEC (loop_p, heap) pointer.
	(compute_data_dependences_for_loop): Adjust caller.
	(free_dependence_relations): Free DDR_LOOP_NEST.

	* tree-loop-linear.c (linear_transform_loops): Don't forget to
	free DEPENDENCE_RELATIONS and DATAREFS.

	* gcc.dg/pr29330.c: New test.

--- gcc/tree-data-ref.c.jj	2006-10-05 00:28:42.000000000 +0200
+++ gcc/tree-data-ref.c	2006-10-06 16:04:39.000000000 +0200
@@ -1913,11 +1913,7 @@ analyze_offset (tree offset, tree *invar
 static void
 free_data_ref (data_reference_p dr)
 {
-  if (DR_TYPE(dr) == ARRAY_REF_TYPE)
-    VEC_free (tree, heap, dr->object_info.access_fns);
-  else
-    VEC_free (tree, heap, dr->first_location.access_fns);
-
+  DR_FREE_ACCESS_FNS (dr);
   free (dr);
 }
 
@@ -2171,6 +2167,7 @@ initialize_data_dependence_relation (str
   res = XNEW (struct data_dependence_relation);
   DDR_A (res) = a;
   DDR_B (res) = b;
+  DDR_LOOP_NEST (res) = NULL;
 
   if (a == NULL || b == NULL)
     {
@@ -4205,7 +4202,7 @@ find_data_references_in_loop (struct loo
 /* Recursive helper function.  */
 
 static bool
-find_loop_nest_1 (struct loop *loop, VEC (loop_p, heap) *loop_nest)
+find_loop_nest_1 (struct loop *loop, VEC (loop_p, heap) **loop_nest)
 {
   /* Inner loops of the nest should not contain siblings.  Example:
      when there are two consecutive loops,
@@ -4224,7 +4221,7 @@ find_loop_nest_1 (struct loop *loop, VEC
   if (loop->next)
     return false;
 
-  VEC_safe_push (loop_p, heap, loop_nest, loop);
+  VEC_safe_push (loop_p, heap, *loop_nest, loop);
   if (loop->inner)
     return find_loop_nest_1 (loop->inner, loop_nest);
   return true;
@@ -4236,9 +4233,9 @@ find_loop_nest_1 (struct loop *loop, VEC
    appear in the classic distance vector.  */
 
 static bool
-find_loop_nest (struct loop *loop, VEC (loop_p, heap) *loop_nest)
+find_loop_nest (struct loop *loop, VEC (loop_p, heap) **loop_nest)
 {
-  VEC_safe_push (loop_p, heap, loop_nest, loop);
+  VEC_safe_push (loop_p, heap, *loop_nest, loop);
   if (loop->inner)
     return find_loop_nest_1 (loop->inner, loop_nest);
   return true;
@@ -4265,7 +4262,7 @@ compute_data_dependences_for_loop (struc
      is not computable, give up without spending time to compute other
      dependences.  */
   if (!loop_nest
-      || !find_loop_nest (loop_nest, vloops)
+      || !find_loop_nest (loop_nest, &vloops)
       || find_data_references_in_loop (loop, datarefs) == chrec_dont_know)
     {
       struct data_dependence_relation *ddr;
@@ -4435,10 +4432,22 @@ free_dependence_relations (VEC (ddr_p, h
 {
   unsigned int i;
   struct data_dependence_relation *ddr;
+  VEC (loop_p, heap) *loop_nest = NULL;
 
   for (i = 0; VEC_iterate (ddr_p, dependence_relations, i, ddr); i++)
-    free_dependence_relation (ddr);
+    {
+      if (ddr == NULL)
+	continue;
+      if (loop_nest == NULL)
+	loop_nest = DDR_LOOP_NEST (ddr);
+      else
+	gcc_assert (DDR_LOOP_NEST (ddr) == NULL
+		    || DDR_LOOP_NEST (ddr) == loop_nest);
+      free_dependence_relation (ddr);
+    }
 
+  if (loop_nest)
+    VEC_free (loop_p, heap, loop_nest);
   VEC_free (ddr_p, heap, dependence_relations);
 }
 
--- gcc/tree-loop-linear.c.jj	2006-10-05 12:02:47.000000000 +0200
+++ gcc/tree-loop-linear.c	2006-10-06 15:07:24.000000000 +0200
@@ -308,7 +308,7 @@ linear_transform_loops (struct loops *lo
 	{
 	  if (dump_file)
 	   fprintf (dump_file, "Won't transform loop. Optimal transform is the identity transform\n");
-	  continue;
+	  goto free_and_continue;
 	}
 
       /* Check whether the transformation is legal.  */
@@ -316,15 +316,15 @@ linear_transform_loops (struct loops *lo
 	{
 	  if (dump_file)
 	    fprintf (dump_file, "Can't transform loop, transform is illegal:\n");
-	  continue;
+	  goto free_and_continue;
 	}
 
       before = gcc_loopnest_to_lambda_loopnest (loops, loop_nest, &oldivs,
 						&invariants);
 
       if (!before)
-	continue;
-            
+	goto free_and_continue;
+
       if (dump_file)
 	{
 	  fprintf (dump_file, "Before:\n");
@@ -346,6 +346,7 @@ linear_transform_loops (struct loops *lo
       if (dump_file)
 	fprintf (dump_file, "Successfully transformed loop.\n");
 
+    free_and_continue:
       free_dependence_relations (dependence_relations);
       free_data_refs (datarefs);
     }
--- gcc/testsuite/gcc.dg/pr29330.c.jj	2006-10-06 15:13:23.000000000 +0200
+++ gcc/testsuite/gcc.dg/pr29330.c	2006-10-06 15:12:55.000000000 +0200
@@ -0,0 +1,15 @@
+/* PR tree-optimization/29330 */
+/* { dg-do compile } */
+/* { dg-options "-O -ftree-loop-linear" } */
+
+int buf[2][2][2][2];
+
+void
+f (void)
+{
+  for (int a = 0; a < 2; ++a)
+    for (int b = 0; b < 2; ++b)
+      for (int c = 0; c < 2; ++c)
+	for (int d = 0; d < 2; ++d)
+	  buf[a][b][c][d] = 0;
+}

	Jakub