[PATCH][4.7] Fix PR57864

[Richard Biener <rguenther at suse dot de>]

This backports a piece of

2012-09-24  Richard Guenther  <rguenther@suse.de>

       * tree-ssa-pre.c (bitmap_find_leader, create_expression_by_pieces,
       find_or_generate_expression): Remove dominating stmt argument.
       (find_leader_in_sets, phi_translate_1, bitmap_find_leader,
       create_component_ref_by_pieces_1, create_component_ref_by_pieces,
       do_regular_insertion, do_partial_partial_insertion): Adjust.
       (compute_avail): Do not set uids.

to the 4.7 branch.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to
the branch (and the testcase added to 4.8, 4.9 and trunk).

Richard.

2014-05-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/57864
	* tree-ssa-pre.c (phi_translate_1): Backport NAME case
	simplification from mainline.  Do not lookup the VN
	value-number here.

	* gcc.dg/torture/pr57864.c: New testcase.

Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c	(revision 210104)
--- gcc/tree-ssa-pre.c	(working copy)
*************** phi_translate_1 (pre_expr expr, bitmap_s
*** 1756,1794 ****
  
      case NAME:
        {
- 	gimple phi = NULL;
- 	edge e;
- 	gimple def_stmt;
  	tree name = PRE_EXPR_NAME (expr);
! 
! 	def_stmt = SSA_NAME_DEF_STMT (name);
  	if (gimple_code (def_stmt) == GIMPLE_PHI
  	    && gimple_bb (def_stmt) == phiblock)
- 	  phi = def_stmt;
- 	else
- 	  return expr;
- 
- 	e = find_edge (pred, gimple_bb (phi));
- 	if (e)
  	  {
! 	    tree def = PHI_ARG_DEF (phi, e->dest_idx);
! 	    pre_expr newexpr;
! 
! 	    if (TREE_CODE (def) == SSA_NAME)
! 	      def = VN_INFO (def)->valnum;
  
  	    /* Handle constant. */
  	    if (is_gimple_min_invariant (def))
  	      return get_or_alloc_expr_for_constant (def);
  
! 	    if (TREE_CODE (def) == SSA_NAME && ssa_undefined_value_p (def))
! 	      return NULL;
! 
! 	    newexpr = get_or_alloc_expr_for_name (def);
! 	    return newexpr;
  	  }
        }
-       return expr;
  
      default:
        gcc_unreachable ();
--- 1756,1781 ----
  
      case NAME:
        {
  	tree name = PRE_EXPR_NAME (expr);
! 	gimple def_stmt = SSA_NAME_DEF_STMT (name);
! 	/* If the SSA name is defined by a PHI node in this block,
! 	   translate it.  */
  	if (gimple_code (def_stmt) == GIMPLE_PHI
  	    && gimple_bb (def_stmt) == phiblock)
  	  {
! 	    edge e = find_edge (pred, gimple_bb (def_stmt));
! 	    tree def = PHI_ARG_DEF (def_stmt, e->dest_idx);
  
  	    /* Handle constant. */
  	    if (is_gimple_min_invariant (def))
  	      return get_or_alloc_expr_for_constant (def);
  
! 	    return get_or_alloc_expr_for_name (def);
  	  }
+ 	/* Otherwise return it unchanged - it will get cleaned if its
+ 	   value is not available in PREDs AVAIL_OUT set of expressions.  */
+ 	return expr;
        }
  
      default:
        gcc_unreachable ();
Index: gcc/testsuite/gcc.dg/torture/pr57864.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr57864.c	(revision 0)
--- gcc/testsuite/gcc.dg/torture/pr57864.c	(working copy)
***************
*** 0 ****
--- 1,37 ----
+ /* { dg-do compile } */
+ 
+ union U {
+     double val;
+     union U *ptr;
+ };
+ 
+ union U *d;
+ double a;
+ int b;
+ int c;
+ 
+ static void fn1(union U *p1, int p2, _Bool p3)
+ {
+     union U *e;
+ 
+     if (p2 == 0)
+ 	a = ((union U*)((unsigned long)p1 & ~1))->val;
+ 
+     if (b) {
+ 	e = p1;
+     } else if (c) {
+ 	e = ((union U*)((unsigned long)p1 & ~1))->ptr;
+ 	d = e;
+     } else {
+ 	e = 0;
+ 	d = ((union U*)0)->ptr;
+     }
+ 
+     fn1 (e, 0, 0);
+     fn1 (0, 0, p3);
+ }
+ 
+ void fn2 (void)
+ {
+   fn1 (0, 0, 0);
+ }