[ tree-ssa] PRE problem

[law@redhat.com]

In message <1077304036.3169.162.camel@localhost.localdomain>, Diego Novillo wri
tes:
 >
 >See if this (untested) patch fixes your problem.  We were not calling
 >propagate_value in generate_expr_as_of_bb.  This fixes PR14153, but I
 >haven't checked other places in PRE where we may be doing the same.
I think something like this is what we need:

I'm primarily concerned about having EREF_STMT pointing to NULL in the
case where we could not generate the expression.  I just don't know the
code well enough to know if that might trigger undesirable effects.


I believe we also want to make propagate_copy static and only export the more
generic propagate_value.


Index: tree-ssa-pre.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-ssa-pre.c,v
retrieving revision 1.1.4.129
diff -c -p -r1.1.4.129 tree-ssa-pre.c
*** tree-ssa-pre.c	30 Jan 2004 13:14:18 -0000	1.1.4.129
--- tree-ssa-pre.c	20 Feb 2004 19:45:00 -0000
*************** static tree create_ephi_node (basic_bloc
*** 142,148 ****
  static inline int opnum_of_phi (tree, int);
  static inline int opnum_of_ephi (const tree, const edge);
  static tree subst_phis (struct expr_info *, tree, basic_block, basic_block);
! static void generate_expr_as_of_bb (tree, basic_block, basic_block);
  static void generate_vops_as_of_bb (tree, basic_block, basic_block);
  static void rename_1 (struct expr_info *);
  static void process_delayed_rename (struct expr_info *, tree, tree);
--- 142,148 ----
  static inline int opnum_of_phi (tree, int);
  static inline int opnum_of_ephi (const tree, const edge);
  static tree subst_phis (struct expr_info *, tree, basic_block, basic_block);
! static bool generate_expr_as_of_bb (tree, basic_block, basic_block);
  static void generate_vops_as_of_bb (tree, basic_block, basic_block);
  static void rename_1 (struct expr_info *);
  static void process_delayed_rename (struct expr_info *, tree, tree);
*************** opnum_of_phi (tree phi, int j)
*** 1202,1210 ****
  /* Generate EXPR as it would look in basic block PRED (using the phi in
     block BB).  We do this by replacing the variables with the phi
     argument definitions for block J if they are defined by a phi in
!    block BB.  */
  
! static void
  generate_expr_as_of_bb (tree expr, basic_block pred, basic_block bb)
  {
    use_optype uses = STMT_USE_OPS (expr);
--- 1202,1213 ----
  /* Generate EXPR as it would look in basic block PRED (using the phi in
     block BB).  We do this by replacing the variables with the phi
     argument definitions for block J if they are defined by a phi in
!    block BB.
  
!    Return TRUE if we were able to generate the expression, otherwise
!    return otherwise.  */
! 
! static bool
  generate_expr_as_of_bb (tree expr, basic_block pred, basic_block bb)
  {
    use_optype uses = STMT_USE_OPS (expr);
*************** generate_expr_as_of_bb (tree expr, basic
*** 1223,1229 ****
  	    {
  	      int opnum = opnum_of_phi (phi, pred->index);
  	      tree p = PHI_ARG_DEF (phi, opnum);
! 	      *vp = p;
  	      if (!phi_ssa_name_p (p))
  		replaced_constants = true;
  	      break;
--- 1226,1234 ----
  	    {
  	      int opnum = opnum_of_phi (phi, pred->index);
  	      tree p = PHI_ARG_DEF (phi, opnum);
! 	      if (! may_propagate_copy (*vp, p))
! 		return false;
! 	      propagate_value (vp, p);
  	      if (!phi_ssa_name_p (p))
  		replaced_constants = true;
  	      break;
*************** subst_phis (struct expr_info *ei, tree Z
*** 1285,1291 ****
    create_stmt_ann (stmt_copy);
    modify_stmt (stmt_copy);
    get_stmt_operands (stmt_copy);
!   generate_expr_as_of_bb (stmt_copy, pred, bb);
    set_bb_for_stmt (stmt_copy, bb);
    modify_stmt (stmt_copy);
    get_stmt_operands (stmt_copy);
--- 1290,1297 ----
    create_stmt_ann (stmt_copy);
    modify_stmt (stmt_copy);
    get_stmt_operands (stmt_copy);
!   if (!  generate_expr_as_of_bb (stmt_copy, pred, bb))
!     return NULL;
    set_bb_for_stmt (stmt_copy, bb);
    modify_stmt (stmt_copy);
    get_stmt_operands (stmt_copy);
*************** process_delayed_rename (struct expr_info
*** 1528,1535 ****
  	    {
  	      tree tmp_use = EPHI_ARG_PRED (exp_phi, opnd_num);	     
  	      EREF_STMT (tmp_use) = newexp;
! 	      if (same_e_version_phi_result (ei, def, newexp,
! 					     tmp_use))
  		{
  		  
  		  if (EREF_INJURED (tmp_use))
--- 1534,1541 ----
  	    {
  	      tree tmp_use = EPHI_ARG_PRED (exp_phi, opnd_num);	     
  	      EREF_STMT (tmp_use) = newexp;
! 	      if (newexp
! 		  && same_e_version_phi_result (ei, def, newexp, tmp_use))
  		{
  		  
  		  if (EREF_INJURED (tmp_use))
*************** process_delayed_rename (struct expr_info
*** 1563,1571 ****
  	  else if (TREE_CODE (def) == EUSE_NODE && !EUSE_PHIOP (def))
  	    {
  	      bool injured = false;
! 	      if (same_e_version_real_occ_phi_opnd (ei, def, 
! 						    bb_for_stmt (use),
! 						    opnd_num, newexp, &injured))
  		{
  		  tree tmp_use = EPHI_ARG_PRED (exp_phi, opnd_num);
  		  EPHI_ARG_HAS_REAL_USE (exp_phi, opnd_num) = true;
--- 1569,1580 ----
  	  else if (TREE_CODE (def) == EUSE_NODE && !EUSE_PHIOP (def))
  	    {
  	      bool injured = false;
! 	      if (newexp
! 		  && same_e_version_real_occ_phi_opnd (ei, def, 
! 						       bb_for_stmt (use),
! 						       opnd_num,
! 						       newexp,
! 						       &injured))
  		{
  		  tree tmp_use = EPHI_ARG_PRED (exp_phi, opnd_num);
  		  EPHI_ARG_HAS_REAL_USE (exp_phi, opnd_num) = true;