[PATCH] Fix PR65935

[Richard Biener <rguenther at suse dot de>]

The following fixes PR65935 where the vectorizer is confused after
SLP operands swapping to see the stmts in the IL with unswapped
operands.  As we already swap for different def-kinds just swap
for other swaps as well.

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

Richard.

2015-05-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/65935
	* tree-vect-slp.c (vect_build_slp_tree): If we swapped operands
	then make sure to apply that swapping to the IL.

	* gcc.dg/vect/pr65935.c: New testcase.

Index: gcc/tree-vect-slp.c
===================================================================
*** gcc/tree-vect-slp.c	(revision 222758)
--- gcc/tree-vect-slp.c	(working copy)
*************** vect_build_slp_tree (loop_vec_info loop_
*** 1081,1093 ****
  		dump_printf (MSG_NOTE, "%d ", j);
  	      }
  	  dump_printf (MSG_NOTE, "\n");
! 	  /* And try again ... */
  	  if (vect_build_slp_tree (loop_vinfo, bb_vinfo, &child,
  				   group_size, max_nunits, loads,
  				   vectorization_factor,
! 				   matches, npermutes, &this_tree_size,
  				   max_tree_size))
  	    {
  	      oprnd_info->def_stmts = vNULL;
  	      SLP_TREE_CHILDREN (*node).quick_push (child);
  	      continue;
--- 1081,1105 ----
  		dump_printf (MSG_NOTE, "%d ", j);
  	      }
  	  dump_printf (MSG_NOTE, "\n");
! 	  /* And try again with scratch 'matches' ... */
! 	  bool *tem = XALLOCAVEC (bool, group_size);
  	  if (vect_build_slp_tree (loop_vinfo, bb_vinfo, &child,
  				   group_size, max_nunits, loads,
  				   vectorization_factor,
! 				   tem, npermutes, &this_tree_size,
  				   max_tree_size))
  	    {
+ 	      /* ... so if successful we can apply the operand swapping
+ 		 to the GIMPLE IL.  This is necessary because for example
+ 		 vect_get_slp_defs uses operand indexes and thus expects
+ 		 canonical operand order.  */
+ 	      for (j = 0; j < group_size; ++j)
+ 		if (!matches[j])
+ 		  {
+ 		    gimple stmt = SLP_TREE_SCALAR_STMTS (*node)[j];
+ 		    swap_ssa_operands (stmt, gimple_assign_rhs1_ptr (stmt),
+ 				       gimple_assign_rhs2_ptr (stmt));
+ 		  }
  	      oprnd_info->def_stmts = vNULL;
  	      SLP_TREE_CHILDREN (*node).quick_push (child);
  	      continue;
Index: gcc/testsuite/gcc.dg/vect/pr65935.c
===================================================================
*** gcc/testsuite/gcc.dg/vect/pr65935.c	(revision 0)
--- gcc/testsuite/gcc.dg/vect/pr65935.c	(working copy)
***************
*** 0 ****
--- 1,63 ----
+ /* { dg-do run } */
+ /* { dg-additional-options "-O3" } */
+ /* { dg-require-effective-target vect_double } */
+ 
+ #include "tree-vect.h"
+ 
+ extern void abort (void);
+ extern void *malloc (__SIZE_TYPE__);
+ 
+ struct site {
+     struct {
+ 	struct {
+ 	    double real;
+ 	    double imag;
+ 	} e[3][3];
+     } link[32];
+     double phase[32];
+ } *lattice;
+ int sites_on_node;
+ 
+ void rephase (void)
+ {
+   int i,j,k,dir;
+   struct site *s;
+   for(i=0,s=lattice;i<sites_on_node;i++,s++)
+     for(dir=0;dir<32;dir++)
+       for(j=0;j<3;j++)for(k=0;k<3;k++)
+ 	{
+ 	  s->link[dir].e[j][k].real *= s->phase[dir];
+ 	  s->link[dir].e[j][k].imag *= s->phase[dir];
+ 	}
+ }
+ 
+ int main()
+ {
+   int i,j,k;
+   check_vect ();
+   sites_on_node = 1;
+   lattice = malloc (sizeof (struct site) * sites_on_node);
+   for (i = 0; i < 32; ++i)
+     {
+       lattice->phase[i] = i;
+       for (j = 0; j < 3; ++j)
+ 	for (k = 0; k < 3; ++k)
+ 	  {
+ 	    lattice->link[i].e[j][k].real = 1.0;
+ 	    lattice->link[i].e[j][k].imag = 1.0;
+ 	    __asm__ volatile ("" : : : "memory");
+ 	  }
+     }
+   rephase ();
+   for (i = 0; i < 32; ++i)
+     for (j = 0; j < 3; ++j)
+       for (k = 0; k < 3; ++k)
+ 	if (lattice->link[i].e[j][k].real != i
+ 	    || lattice->link[i].e[j][k].imag != i)
+ 	  abort ();
+   return 0;
+ }
+ 
+ /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "slp1" } } */
+ /* { dg-final { cleanup-tree-dump "slp1" } } */
+ /* { dg-final { cleanup-tree-dump "vect" } } */