bryanhundven@2943: ------------------------------------------------------------------------
bryanhundven@2943: r186424 | vries | 2012-04-13 18:44:18 +0200 (Fri, 13 Apr 2012) | 12 lines
bryanhundven@2943: 
bryanhundven@2943: 2012-04-13  Tom de Vries  <tom@codesourcery.com>
bryanhundven@2943: 
bryanhundven@2943: 	Backport from mainline r186418.
bryanhundven@2943: 
bryanhundven@2943: 	2012-04-13  Tom de Vries  <tom@codesourcery.com>
bryanhundven@2943: 
bryanhundven@2943: 	* tree-ssa-tail-merge.c (gsi_advance_bw_nondebug_nonlocal): Add
bryanhundven@2943: 	parameters vuse and vuse_escaped.
bryanhundven@2943: 	(find_duplicate): Init vuse1, vuse2 and vuse_escaped.  Pass to
bryanhundven@2943: 	gsi_advance_bw_nondebug_nonlocal.  Return if vuse_escaped and
bryanhundven@2943: 	vuse1 != vuse2.
bryanhundven@2943: 
bryanhundven@2943: ------------------------------------------------------------------------
bryanhundven@2943: Index: gcc/tree-ssa-tail-merge.c
bryanhundven@2943: ===================================================================
bryanhundven@2943: --- gcc-4.7.0/gcc/tree-ssa-tail-merge.c	(revision 186423)
bryanhundven@2943: +++ gcc-4.7.0/gcc/tree-ssa-tail-merge.c	(revision 186424)
bryanhundven@2943: @@ -1123,18 +1123,31 @@
bryanhundven@2943:      }
bryanhundven@2943:  }
bryanhundven@2943:  
bryanhundven@2943: -/* Let GSI skip backwards over local defs.  */
bryanhundven@2943: +/* Let GSI skip backwards over local defs.  Return the earliest vuse in VUSE.
bryanhundven@2943: +   Return true in VUSE_ESCAPED if the vuse influenced a SSA_OP_DEF of one of the
bryanhundven@2943: +   processed statements.  */
bryanhundven@2943:  
bryanhundven@2943:  static void
bryanhundven@2943: -gsi_advance_bw_nondebug_nonlocal (gimple_stmt_iterator *gsi)
bryanhundven@2943: +gsi_advance_bw_nondebug_nonlocal (gimple_stmt_iterator *gsi, tree *vuse,
bryanhundven@2943: +				  bool *vuse_escaped)
bryanhundven@2943:  {
bryanhundven@2943:    gimple stmt;
bryanhundven@2943: +  tree lvuse;
bryanhundven@2943:  
bryanhundven@2943:    while (true)
bryanhundven@2943:      {
bryanhundven@2943:        if (gsi_end_p (*gsi))
bryanhundven@2943:  	return;
bryanhundven@2943:        stmt = gsi_stmt (*gsi);
bryanhundven@2943: +
bryanhundven@2943: +      lvuse = gimple_vuse (stmt);
bryanhundven@2943: +      if (lvuse != NULL_TREE)
bryanhundven@2943: +	{
bryanhundven@2943: +	  *vuse = lvuse;
bryanhundven@2943: +	  if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_DEF))
bryanhundven@2943: +	    *vuse_escaped = true;
bryanhundven@2943: +	}
bryanhundven@2943: +
bryanhundven@2943:        if (!(is_gimple_assign (stmt) && local_def (gimple_get_lhs (stmt))
bryanhundven@2943:  	    && !gimple_has_side_effects (stmt)))
bryanhundven@2943:  	return;
bryanhundven@2943: @@ -1150,9 +1163,11 @@
bryanhundven@2943:  {
bryanhundven@2943:    gimple_stmt_iterator gsi1 = gsi_last_nondebug_bb (bb1);
bryanhundven@2943:    gimple_stmt_iterator gsi2 = gsi_last_nondebug_bb (bb2);
bryanhundven@2943: +  tree vuse1 = NULL_TREE, vuse2 = NULL_TREE;
bryanhundven@2943: +  bool vuse_escaped = false;
bryanhundven@2943:  
bryanhundven@2943: -  gsi_advance_bw_nondebug_nonlocal (&gsi1);
bryanhundven@2943: -  gsi_advance_bw_nondebug_nonlocal (&gsi2);
bryanhundven@2943: +  gsi_advance_bw_nondebug_nonlocal (&gsi1, &vuse1, &vuse_escaped);
bryanhundven@2943: +  gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
bryanhundven@2943:  
bryanhundven@2943:    while (!gsi_end_p (gsi1) && !gsi_end_p (gsi2))
bryanhundven@2943:      {
bryanhundven@2943: @@ -1161,13 +1176,20 @@
bryanhundven@2943:  
bryanhundven@2943:        gsi_prev_nondebug (&gsi1);
bryanhundven@2943:        gsi_prev_nondebug (&gsi2);
bryanhundven@2943: -      gsi_advance_bw_nondebug_nonlocal (&gsi1);
bryanhundven@2943: -      gsi_advance_bw_nondebug_nonlocal (&gsi2);
bryanhundven@2943: +      gsi_advance_bw_nondebug_nonlocal (&gsi1, &vuse1, &vuse_escaped);
bryanhundven@2943: +      gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
bryanhundven@2943:      }
bryanhundven@2943:  
bryanhundven@2943:    if (!(gsi_end_p (gsi1) && gsi_end_p (gsi2)))
bryanhundven@2943:      return;
bryanhundven@2943:  
bryanhundven@2943: +  /* If the incoming vuses are not the same, and the vuse escaped into an
bryanhundven@2943: +     SSA_OP_DEF, then merging the 2 blocks will change the value of the def,
bryanhundven@2943: +     which potentially means the semantics of one of the blocks will be changed.
bryanhundven@2943: +     TODO: make this check more precise.  */
bryanhundven@2943: +  if (vuse_escaped && vuse1 != vuse2)
bryanhundven@2943: +    return;
bryanhundven@2943: +
bryanhundven@2943:    if (dump_file)
bryanhundven@2943:      fprintf (dump_file, "find_duplicates: <bb %d> duplicate of <bb %d>\n",
bryanhundven@2943:  	     bb1->index, bb2->index);