[PATCH] Fix PR39358, some more wrong PTA

[Richard Guenther]

This PR uncovers that on the trunk we fail to identify the
ESCAPED = *ESCAPED constraint properly and thus mis-compute
the escaped solution and the rest.

Fixed with the following, bootstrapped and tested on 
x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2009-03-04  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/39358
	* tree-ssa-structalias.c (do_sd_constraint): Fix check for
	escaped_id and callused_id.
	(solve_graph): Likewise.

	* g++.dg/warn/Wstrict-aliasing-bogus-escape-2.C: New testcase.
	* g++.dg/warn/Wstrict-aliasing-bogus-escape-3.C: Likewise.

Index: gcc/tree-ssa-structalias.c
===================================================================
*** gcc/tree-ssa-structalias.c	(revision 144599)
--- gcc/tree-ssa-structalias.c	(working copy)
*************** do_sd_constraint (constraint_graph_t gra
*** 1524,1531 ****
       of a variable can also reach all other fields of the variable
       we simply have to expand the solution to contain all sub-fields
       if one sub-field is contained.  */
!   if (c->rhs.var == escaped_id
!       || c->rhs.var == callused_id)
      {
        bitmap vars = NULL;
        /* In a first pass record all variables we need to add all
--- 1524,1531 ----
       of a variable can also reach all other fields of the variable
       we simply have to expand the solution to contain all sub-fields
       if one sub-field is contained.  */
!   if (c->rhs.var == find (escaped_id)
!       || c->rhs.var == find (callused_id))
      {
        bitmap vars = NULL;
        /* In a first pass record all variables we need to add all
*************** do_sd_constraint (constraint_graph_t gra
*** 1594,1602 ****
  	  /* Merging the solution from ESCAPED needlessly increases
  	     the set.  Use ESCAPED as representative instead.
  	     Same for CALLUSED.  */
! 	  else if (get_varinfo (t)->id == escaped_id
! 		   || get_varinfo (t)->id == callused_id)
! 	    flag |= bitmap_set_bit (sol, get_varinfo (t)->id);
  	  else if (add_graph_edge (graph, lhs, t))
  	    flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
  	}
--- 1594,1603 ----
  	  /* Merging the solution from ESCAPED needlessly increases
  	     the set.  Use ESCAPED as representative instead.
  	     Same for CALLUSED.  */
! 	  else if (get_varinfo (t)->id == find (escaped_id))
! 	    flag |= bitmap_set_bit (sol, escaped_id);
! 	  else if (get_varinfo (t)->id == find (callused_id))
! 	    flag |= bitmap_set_bit (sol, callused_id);
  	  else if (add_graph_edge (graph, lhs, t))
  	    flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
  	}
*************** solve_graph (constraint_graph_t graph)
*** 2516,2523 ****
  
  	      if (!solution_empty
  		  /* Do not propagate the ESCAPED/CALLUSED solutions.  */
! 		  && i != escaped_id
! 		  && i != callused_id)
  		{
  		  bitmap_iterator bi;
  
--- 2517,2524 ----
  
  	      if (!solution_empty
  		  /* Do not propagate the ESCAPED/CALLUSED solutions.  */
! 		  && i != find (escaped_id)
! 		  && i != find (callused_id))
  		{
  		  bitmap_iterator bi;
  
Index: gcc/testsuite/g++.dg/warn/Wstrict-aliasing-bogus-escape-2.C
===================================================================
*** gcc/testsuite/g++.dg/warn/Wstrict-aliasing-bogus-escape-2.C	(revision 0)
--- gcc/testsuite/g++.dg/warn/Wstrict-aliasing-bogus-escape-2.C	(revision 0)
***************
*** 0 ****
--- 1,19 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -Wstrict-aliasing" } */
+ 
+ #include<list>
+ 
+ struct A
+ {
+   virtual ~A();
+ };
+ 
+ A* foo();
+ 
+ void bar(std::list<int> x)
+ {
+   std::list<int> y = x;
+   if (*y.rbegin())
+     delete foo();
+ }
+ 
Index: gcc/testsuite/g++.dg/warn/Wstrict-aliasing-bogus-escape-3.C
===================================================================
*** gcc/testsuite/g++.dg/warn/Wstrict-aliasing-bogus-escape-3.C	(revision 0)
--- gcc/testsuite/g++.dg/warn/Wstrict-aliasing-bogus-escape-3.C	(revision 0)
***************
*** 0 ****
--- 1,35 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -Wstrict-aliasing" } */
+ 
+ struct Node_base {};
+ 
+ struct Node : Node_base
+ {
+   int data;
+ };
+ 
+ struct List
+ {
+   Node_base node, *prev;
+ 
+   List() : prev(&node) { xyz(); }
+ 
+   void xyz();
+ 
+   int back() { return static_cast<Node*>(prev)->data; }
+ };
+ 
+ struct A
+ {
+   virtual ~A();
+ };
+ 
+ A* foo();
+ 
+ void bar()
+ {
+   List y;
+   if (y.back())
+     delete foo();
+ }
+