re PR tree-optimization/87609 (miscompilation with restrict and loop)

2019-02-22  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/87609
	* tree-core.h (tree_base): Document special clique values.
	* tree-inline.c (remap_dependence_clique): Do not use the
	special clique value of one.
	(maybe_set_dependence_info): Use clique one.
	(clear_dependence_clique): New callback.
	(compute_dependence_clique): Clear clique one from all refs
	before assigning it (again).

From-SVN: r269097

gcc/ChangeLog

+2019-02-22  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/87609
+	* tree-core.h (tree_base): Document special clique values.
+	* tree-inline.c (remap_dependence_clique): Do not use the
+	special clique value of one.
+	(maybe_set_dependence_info): Use clique one.
+	(clear_dependence_clique): New callback.
+	(compute_dependence_clique): Clear clique one from all refs
+	before assigning it (again).
+
 2019-02-21  Martin Sebor  <msebor@redhat.com>
 
 	* doc/extend.texi (__clear_cache): Correct signature.

gcc/tree-core.h

@@ -1032,7 +1032,9 @@ struct GTY(()) tree_base {
        expression trees and specify known data non-dependences.  For
        two memory references in a function they are known to not
        alias if dependence_info.clique are equal and dependence_info.base
-       are distinct.  */
+       are distinct.  Clique number zero means there is no information,
+       clique number one is populated from function global information
+       and thus needs no remapping on transforms like loop unrolling.  */
     struct {
       unsigned short clique;
       unsigned short base;

gcc/tree-inline.c

@@ -911,7 +911,12 @@ remap_dependence_clique (copy_body_data *id, unsigned short clique)
   bool existed;
   unsigned short &newc = id->dependence_map->get_or_insert (clique, &existed);
   if (!existed)
-    newc = ++cfun->last_clique;
+    {
+      /* Clique 1 is reserved for local ones set by PTA.  */
+      if (cfun->last_clique == 0)
+	cfun->last_clique = 1;
+      newc = ++cfun->last_clique;
+    }
   return newc;
 }
 

gcc/tree-ssa-structalias.c

@@ -7495,7 +7495,11 @@ maybe_set_dependence_info (gimple *, tree base, tree, void *data)
       if (MR_DEPENDENCE_CLIQUE (base) == 0)
 	{
 	  if (clique == 0)
-	    clique = ++cfun->last_clique;
+	    {
+	      if (cfun->last_clique == 0)
+		cfun->last_clique = 1;
+	      clique = 1;
+	    }
 	  if (restrict_var->ruid == 0)
 	    restrict_var->ruid = ++last_ruid;
 	  MR_DEPENDENCE_CLIQUE (base) = clique;
@@ -7506,12 +7510,42 @@ maybe_set_dependence_info (gimple *, tree base, tree, void *data)
   return false;
 }
 
+/* Clear dependence info for the clique DATA.  */
+
+static bool
+clear_dependence_clique (gimple *, tree base, tree, void *data)
+{
+  unsigned short clique = (uintptr_t)data;
+  if ((TREE_CODE (base) == MEM_REF
+       || TREE_CODE (base) == TARGET_MEM_REF)
+      && MR_DEPENDENCE_CLIQUE (base) == clique)
+    {
+      MR_DEPENDENCE_CLIQUE (base) = 0;
+      MR_DEPENDENCE_BASE (base) = 0;
+    }
+
+  return false;
+}
+
 /* Compute the set of independend memory references based on restrict
    tags and their conservative propagation to the points-to sets.  */
 
 static void
 compute_dependence_clique (void)
 {
+  /* First clear the special "local" clique.  */
+  basic_block bb;
+  if (cfun->last_clique != 0)
+    FOR_EACH_BB_FN (bb, cfun)
+      for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
+	   !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gimple *stmt = gsi_stmt (gsi);
+	  walk_stmt_load_store_ops (stmt, (void *)(uintptr_t) 1,
+				    clear_dependence_clique,
+				    clear_dependence_clique);
+	}
+
   unsigned short clique = 0;
   unsigned short last_ruid = 0;
   bitmap rvars = BITMAP_ALLOC (NULL);