[PATCH] Fix PR59822

[Richard Biener <rguenther at suse dot de>]

This should fix PR59822, us creating in valid SSA form when
hoisting a[i_2] out of a loop where i_2 is defined inside the loop.

Bootstrap / regtest running on x86_64-unknown-linux-gnu.

Richard.

2014-01-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/59822
	* tree-vect-stmts.c (hoist_defs_of_uses): New function.
	(vectorizable_load): Use it to hoist defs of uses of invariant
	loads out of the loop.

	* g++.dg/torture/pr59822.C: New testcase.

Index: gcc/tree-vect-stmts.c
===================================================================
*** gcc/tree-vect-stmts.c	(revision 206624)
--- gcc/tree-vect-stmts.c	(working copy)
*************** permute_vec_elements (tree x, tree y, tr
*** 5480,5485 ****
--- 5480,5538 ----
    return data_ref;
  }
  
+ /* Hoist the definitions of all SSA uses on STMT out of the loop LOOP,
+    inserting them on the loops preheader edge.  Returns true if we
+    were successful in doing so (and thus STMT can be moved then),
+    otherwise returns false.  */
+ 
+ static bool
+ hoist_defs_of_uses (gimple stmt, struct loop *loop)
+ {
+   ssa_op_iter i;
+   tree op;
+   bool any = false;
+ 
+   FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
+     {
+       gimple def_stmt = SSA_NAME_DEF_STMT (op);
+       if (!gimple_nop_p (def_stmt)
+ 	  && flow_bb_inside_loop_p (loop, gimple_bb (def_stmt)))
+ 	{
+ 	  /* Make sure we don't need to recurse.  While we could do
+ 	     so in simple cases when there are more complex use webs
+ 	     we don't have an easy way to preserve stmt order to fulfil
+ 	     dependencies within them.  */
+ 	  tree op2;
+ 	  ssa_op_iter i2;
+ 	  FOR_EACH_SSA_TREE_OPERAND (op2, def_stmt, i2, SSA_OP_USE)
+ 	    {
+ 	      gimple def_stmt2 = SSA_NAME_DEF_STMT (op2);
+ 	      if (!gimple_nop_p (def_stmt2)
+ 		  && flow_bb_inside_loop_p (loop, gimple_bb (def_stmt2)))
+ 		return false;
+ 	    }
+ 	  any = true;
+ 	}
+     }
+ 
+   if (!any)
+     return true;
+ 
+   FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
+     {
+       gimple def_stmt = SSA_NAME_DEF_STMT (op);
+       if (!gimple_nop_p (def_stmt)
+ 	  && flow_bb_inside_loop_p (loop, gimple_bb (def_stmt)))
+ 	{
+ 	  gimple_stmt_iterator gsi = gsi_for_stmt (def_stmt);
+ 	  gsi_remove (&gsi, false);
+ 	  gsi_insert_on_edge_immediate (loop_preheader_edge (loop), def_stmt);
+ 	}
+     }
+ 
+   return true;
+ }
+ 
  /* vectorizable_load.
  
     Check if STMT reads a non scalar data-ref (array/pointer/structure) that
*************** vectorizable_load (gimple stmt, gimple_s
*** 6384,6390 ****
  		  /* If we have versioned for aliasing then we are sure
  		     this is a loop invariant load and thus we can insert
  		     it on the preheader edge.  */
! 		  if (LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo))
  		    {
  		      if (dump_enabled_p ())
  			{
--- 6437,6444 ----
  		  /* If we have versioned for aliasing then we are sure
  		     this is a loop invariant load and thus we can insert
  		     it on the preheader edge.  */
! 		  if (LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo)
! 		      && hoist_defs_of_uses (stmt, loop))
  		    {
  		      if (dump_enabled_p ())
  			{
Index: gcc/testsuite/g++.dg/torture/pr59822.C
===================================================================
*** gcc/testsuite/g++.dg/torture/pr59822.C	(revision 0)
--- gcc/testsuite/g++.dg/torture/pr59822.C	(working copy)
***************
*** 0 ****
--- 1,14 ----
+ // { dg-do compile }
+ 
+ typedef struct rtvec_def *rtvec;
+ enum machine_mode { VOIDmode };
+ struct rtvec_def { void *elem[1]; };
+ extern void *const_tiny_rtx[2];
+ void
+ ix86_build_const_vector (enum machine_mode mode, bool vect,
+ 			 void *value, rtvec v, int n_elt)
+ {
+   int i;
+   for (i = 1; i < n_elt; ++i)
+     ((v)->elem[i]) = vect ? value : (const_tiny_rtx[(int) (mode)]);
+ }