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[PATCH]: Structure aliasing part 2


(Sorry you are going to get this twice diego, i hit send a little early,
before i added gcc-patches to the To list, and before i added the
changelog to the top of the patch)

This updates the patch with the changes Diego requested (I think i got
all of them, anyway :P).

You can turn field sensitivity off by setting the static
use_field_sensitivity to true or false.

I've got a followup patch that will remove the old aliaser.

Timings have been posted seperately, it takes roughly as much time as
the old aliaser, and can be sped up to be faster pretty easily.

Bootstrapped and regetested on i686-pc-linux-gnu.

Okay for mainline?

--Dan	
2005-04-28  Daniel Berlin  <dberlin@dberlin.org>

	* Makefile.in (OBJS-common): Add tree-ssa-structalias.o.
	* tree-flow.h (find_what_p_points_to): Add prototype.
	* tree-optimize.c (init_tree_optimization_passes): Add
	pass_build_pta and pass_del_pta.
	* tree-pass.h (pass_build_pta): New structure.
	(pass_del_pta): Ditto.
	* tree-ssa-alias.c (compute_flow_sensitive_aliasing): Disambiguate
	using new alias analyzer.
	* tree-ssa-structalias.c: New file.
	* tree-ssa-structalias.h: Ditto.
Index: Makefile.in
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Makefile.in,v
retrieving revision 1.1493
diff -u -p -r1.1493 Makefile.in
--- Makefile.in	30 May 2005 05:53:21 -0000	1.1493
+++ Makefile.in	31 May 2005 22:07:33 -0000
@@ -960,8 +960,9 @@ OBJS-common = \
  varasm.o varray.o vec.o version.o vmsdbgout.o xcoffout.o alloc-pool.o	   \
  et-forest.o cfghooks.o bt-load.o pretty-print.o $(GGC) web.o passes.o	   \
  rtl-profile.o tree-profile.o rtlhooks.o cfgexpand.o lambda-mat.o          \
+ lambda-trans.o	lambda-code.o tree-loop-linear.o tree-ssa-sink.o 	   \
  lambda-trans.o lambda-code.o tree-loop-linear.o tree-ssa-sink.o           \
- tree-vrp.o tree-stdarg.o tree-cfgcleanup.o
+ tree-vrp.o tree-stdarg.o tree-cfgcleanup.o tree-ssa-structalias.o
 
 OBJS-md = $(out_object_file)
 OBJS-archive = $(EXTRA_OBJS) $(host_hook_obj) tree-inline.o		   \
@@ -1658,6 +1659,9 @@ stor-layout.o : stor-layout.c $(CONFIG_H
    $(TREE_H) $(PARAMS_H) $(FLAGS_H) function.h $(EXPR_H) $(RTL_H) \
    $(GGC_H) $(TM_P_H) $(TARGET_H) langhooks.h $(REGS_H) gt-stor-layout.h \
    toplev.h
+tree-ssa-structalias.o: tree-ssa-structalias.c tree-ssa-structalias.h \
+   $(SYSTEM_H) $(CONFIG_H) $(GGC_H) $(TREE_H) $(TREE_FLOW_H) \
+   $(TM_H) coretypes.h cgraph.h tree-pass.h $(TIMEVAR_H)
 tree-ssa.o : tree-ssa.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
    $(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) output.h $(DIAGNOSTIC_H) \
    errors.h toplev.h function.h $(TIMEVAR_H) $(TM_H) coretypes.h \
Index: tree-flow.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-flow.h,v
retrieving revision 2.114
diff -u -p -r2.114 tree-flow.h
--- tree-flow.h	29 May 2005 13:14:42 -0000	2.114
+++ tree-flow.h	31 May 2005 22:07:33 -0000
@@ -776,6 +776,9 @@ extern bool thread_through_all_blocks (b
 tree force_gimple_operand (tree, tree *, bool, tree);
 tree force_gimple_operand_bsi (block_stmt_iterator *, tree, bool, tree);
 
+/* In tree-ssa-structalias.c */
+bool find_what_p_points_to (tree);
+
 #include "tree-flow-inline.h"
 
 #endif /* _TREE_FLOW_H  */
Index: tree-optimize.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-optimize.c,v
retrieving revision 2.103
diff -u -p -r2.103 tree-optimize.c
--- tree-optimize.c	29 May 2005 13:14:42 -0000	2.103
+++ tree-optimize.c	31 May 2005 22:07:34 -0000
@@ -395,7 +395,9 @@ init_tree_optimization_passes (void)
   NEXT_PASS (pass_referenced_vars);
   NEXT_PASS (pass_create_structure_vars);
   NEXT_PASS (pass_build_ssa);
+  NEXT_PASS (pass_build_pta);  
   NEXT_PASS (pass_may_alias);
+  NEXT_PASS (pass_del_pta);  
   NEXT_PASS (pass_rename_ssa_copies);
   NEXT_PASS (pass_early_warn_uninitialized);
 
@@ -411,7 +413,9 @@ init_tree_optimization_passes (void)
   NEXT_PASS (pass_dominator);
 
   NEXT_PASS (pass_phiopt);
+  NEXT_PASS (pass_build_pta);  
   NEXT_PASS (pass_may_alias);
+  NEXT_PASS (pass_del_pta);  
   NEXT_PASS (pass_tail_recursion);
   NEXT_PASS (pass_profile);
   NEXT_PASS (pass_ch);
Index: tree-pass.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-pass.h,v
retrieving revision 2.38
diff -u -p -r2.38 tree-pass.h
--- tree-pass.h	26 May 2005 18:14:47 -0000	2.38
+++ tree-pass.h	31 May 2005 22:07:34 -0000
@@ -219,6 +219,8 @@ extern struct tree_opt_pass pass_store_c
 extern struct tree_opt_pass pass_store_copy_prop;
 extern struct tree_opt_pass pass_vrp;
 extern struct tree_opt_pass pass_create_structure_vars;
+extern struct tree_opt_pass pass_build_pta;
+extern struct tree_opt_pass pass_del_pta;
 extern struct tree_opt_pass pass_uncprop;
 
 extern struct tree_opt_pass pass_ipa_inline;
Index: tree-ssa-alias.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-alias.c,v
retrieving revision 2.93
diff -u -p -r2.93 tree-ssa-alias.c
--- tree-ssa-alias.c	29 May 2005 13:14:42 -0000	2.93
+++ tree-ssa-alias.c	31 May 2005 22:07:34 -0000
@@ -874,7 +874,16 @@ static void
 compute_flow_sensitive_aliasing (struct alias_info *ai)
 {
   size_t i;
-
+  
+  for (i = 0; i < VARRAY_ACTIVE_SIZE (ai->processed_ptrs); i++)
+    {
+      tree ptr = VARRAY_TREE (ai->processed_ptrs, i);
+      struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
+      if (pi->pt_anything || pi->pt_vars == NULL)
+	{
+	  find_what_p_points_to (ptr);
+	}
+    }
   create_name_tags (ai);
 
   for (i = 0; i < VARRAY_ACTIVE_SIZE (ai->processed_ptrs); i++)
Index: tree-ssa-structalias.c
===================================================================
RCS file: tree-ssa-structalias.c
diff -N tree-ssa-structalias.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tree-ssa-structalias.c	31 May 2005 22:07:35 -0000
@@ -0,0 +1,3123 @@
+/* Tree based points-to analysis
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   Contributed by Daniel Berlin <dberlin@dberlin.org>
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "ggc.h"
+#include "obstack.h"
+#include "bitmap.h"
+#include "tree-ssa-structalias.h"
+#include "flags.h"
+#include "rtl.h"
+#include "tm_p.h"
+#include "hard-reg-set.h"
+#include "basic-block.h"
+#include "output.h"
+#include "errors.h"
+#include "expr.h"
+#include "diagnostic.h"
+#include "tree.h"
+#include "c-common.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+#include "varray.h"
+#include "c-tree.h"
+#include "tree-gimple.h"
+#include "hashtab.h"
+#include "function.h"
+#include "cgraph.h"
+#include "tree-pass.h"
+#include "timevar.h"
+#include "alloc-pool.h"
+#include "splay-tree.h"
+
+/* The idea behind this analyzer is to generate set constraints from the
+   program, then solve the resulting constraints in order to generate the
+   points-to sets. 
+
+   Set constraints are a way of modeling program analysis problems that
+   involve sets.  They consist of an inclusion constraint language,
+   describing the variables (each variable is a set) and operations that
+   are involved on the variables, and a set of rules that derive facts
+   from these operations.  To solve a system of set constraints, you derive
+   all possible facts under the rules, which gives you the correct sets
+   as a consequence.
+
+   See  "Efficient Field-sensitive pointer analysis for C" by "David
+   J. Pearce and Paul H. J. Kelly and Chris Hankin, at
+   http://citeseer.ist.psu.edu/pearce04efficient.html
+
+   Also see "Ultra-fast Aliasing Analysis using CLA: A Million Lines
+   of C Code in a Second" by ""Nevin Heintze and Olivier Tardieu" at
+   http://citeseer.ist.psu.edu/heintze01ultrafast.html 
+
+   There are three types of constraint expressions, DEREF, ADDRESSOF, and
+   SCALAR.  Each constraint expression consists of a constraint type,
+   a variable, and an offset.  
+   
+   SCALAR is a constraint expression type used to represent x, whether
+   it appears on the LHS or the RHS of a statement.
+   DEREF is a constraint expression type used to represent *x, whether
+   it appears on the LHS or the RHS of a statement. 
+   ADDRESSOF is a constraint expression used to represent &x, whether
+   it apepars on the LHS or the RHS of a statement.
+   
+   Each pointer variable in the program is assigned an integer id, and
+   each field of a structure variable is assigned an integer id as well.
+   
+   Structure variables are linked to their list of fields through a "next
+   field" in each variable that points to the next field in offset
+   order.  
+   Each variable for a structure field has 
+
+   1. "size", that tells the size in bits of that field.
+   2. "fullsize, that tells the size in bits of the entire structure.
+   3. "offset", that tells the offset in bits from the beginning of the
+   structure to this field.
+
+   Thus, 
+   struct f
+   {
+     int a;
+     int b;
+   } foo;
+   int *bar;
+
+   looks like
+
+   foo.a -> id 1, size 32, offset 0, fullsize 64, next foo.b
+   foo.b -> id 2, size 32, offset 32, fullsize 64, next NULL
+   bar -> id 3, size 32, offset 0, fullsize 32, next NULL
+
+   
+In order to solve the system of set constraints, the following is
+done:
+
+  1. Each constraint variable x has a solution set associated with it,
+  Sol(x).
+  
+  2. Constraints are separated into direct, copy, and complex.
+  Direct constraints are ADDRESSOF constraints that require no extra
+  processing, such as P = &Q
+  Copy constraints are those of the form P = Q.
+  Complex constraints are all the constraints involving dereferences.
+  
+  3. All direct constraints of the form P = &Q are processed, such
+  that Q is added to Sol(P) 
+
+  4. All complex constraints for a given constraint variable are stored in a
+  linked list attached to that variable's node.  
+
+  5. A directed graph is built out of the copy constraints. Each
+  constraint variable is a node in the graph, and an edge from 
+  Q to P is added for each copy constraint of the form P = Q
+  
+  6. The graph is then walked, and solution sets are
+  propagated along the copy edges, such that an edge from Q to P
+  causes Sol(P) <- Sol(P) union Sol(Q).
+  
+  7.  As we visit each node, all complex constraints associated with
+  that node are processed by adding approriate copy edges to the graph, or the
+  approriate variables to the solution set.  
+
+  8. The process of walking the graph is iterated until no solution
+  sets change.
+
+
+   Prior to walking the graph in steps 6 and 7, We perform static
+   cycle elimination on the constraint graph, as well 
+   as off-line variable substitution.
+   
+   TODO: Adding offsets to pointer-to-structures can be handled (IE not punted
+   on and turned into anything), but isn't.  You can just see what offset
+   inside the pointed-to struct it's going to access.
+   
+   TODO: Constant bounded arrays can be handled as if they were structs of the
+   same number of elements. 
+
+   TODO: Modeling heap and incoming pointers becomes much better if we
+   add fields to them as we discover them, which we could do.
+
+   TODO: We could handle unions, but to be honest, it's probably not
+   worth the pain or slowdown.  */
+
+static bool use_field_sensitive = true;
+static unsigned int create_variable_info_for (tree, const char *);
+static struct constraint_expr get_constraint_for (tree);
+static void build_constraint_graph (void);
+
+static bitmap_obstack ptabitmap_obstack;
+static bitmap_obstack iteration_obstack;
+DEF_VEC_P(constraint_t);
+DEF_VEC_ALLOC_P(constraint_t,gc);
+
+static struct constraint_stats
+{
+  unsigned int total_vars;
+  unsigned int collapsed_vars;
+  unsigned int unified_vars_static;
+  unsigned int unified_vars_dynamic;
+  unsigned int iterations;
+} stats;
+
+struct variable_info
+{
+  /* ID of this variable  */
+  unsigned int id;
+
+  /* Name of this variable */
+  const char *name;
+
+  /* Tree that this variable is associated with.  */
+  tree decl;
+
+  /* Offset of this variable, in bits, from the base variable  */
+  unsigned HOST_WIDE_INT offset;  
+
+  /* Size of the variable, in bits.  */
+  unsigned HOST_WIDE_INT size;
+
+  /* Full size of the base variable, in bits.  */
+  unsigned HOST_WIDE_INT fullsize;
+
+  /* A link to the variable for the next field in this structure.  */
+  struct variable_info *next;
+
+  /* Node in the graph that represents the constraints and points-to
+     solution for the variable.  */
+  unsigned int node;
+
+  /* True if the address of this variable is taken.  Needed for
+     variable substitution.  */
+  unsigned int address_taken:1;
+
+  /* True if this variable is the target of a dereference.  Needed for
+     variable substitution.  */
+  unsigned int indirect_target:1;
+
+  /* True if this is a variable created by the constraint analysis, such as
+     heap variables and constraints we had to break up.  */
+  unsigned int is_artificial_var:1;
+
+  /* True for variables whose size is not known or variable.  */
+  unsigned int is_unknown_size_var:1;  
+
+  /* Points-to set for this variable.  */
+  bitmap solution;
+
+  /* Variable ids represented by this node.  */
+  bitmap variables;
+
+  /* Vector of complex constraints for this node.  Complex
+     constraints are those involving dereferences.  */
+  VEC(constraint_t,gc) *complex;
+};
+typedef struct variable_info *varinfo_t;
+
+static varinfo_t first_vi_for_offset (varinfo_t, unsigned HOST_WIDE_INT);
+
+/* Pool of variable info structures.  */
+static alloc_pool variable_info_pool;
+
+DEF_VEC_P(varinfo_t);
+
+DEF_VEC_ALLOC_P(varinfo_t, gc);
+
+static VEC(varinfo_t,gc) *varmap;
+#define get_varinfo(n) VEC_index(varinfo_t, varmap, n)
+
+/* Variable that represents the unknown pointer.  */
+static varinfo_t var_anything;
+static tree anything_tree;
+static unsigned int anything_id;
+
+/* Variable that represents the NULL pointer.  */
+static varinfo_t var_nothing;
+static tree nothing_tree;
+static unsigned int nothing_id;
+
+/* Variable that represents read only memory.  */
+static varinfo_t var_readonly;
+static tree readonly_tree;
+static unsigned int readonly_id;
+
+/* Variable that represents integers.  This is used for when people do things
+   like &0->a.b.  */
+static varinfo_t var_integer;
+static tree integer_tree;
+static unsigned int integer_id;
+
+
+/* Return a new variable info structure consisting for a variable
+   named NAME, ending at id END, and using constraint graph node
+   NODE.  */
+
+static varinfo_t
+new_var_info (tree t, unsigned int id, const char *name, unsigned int node)
+{
+  varinfo_t ret = pool_alloc (variable_info_pool);
+
+  ret->id = id;
+  ret->name = name;
+  ret->decl = t;
+  ret->node = node;
+  ret->address_taken = false;
+  ret->indirect_target = false;
+  ret->is_artificial_var = false;
+  ret->is_unknown_size_var = false;
+  ret->solution = BITMAP_ALLOC (&ptabitmap_obstack);
+  bitmap_clear (ret->solution);
+  ret->variables = BITMAP_ALLOC (&ptabitmap_obstack);
+  bitmap_clear (ret->variables);
+  ret->complex = NULL;
+  ret->next = NULL;
+  return ret;
+}
+
+typedef enum {SCALAR, DEREF, ADDRESSOF} constraint_expr_type;
+
+/* An expression that appears in a constraint.  */
+
+struct constraint_expr 
+{
+  /* Constraint type.  */
+  constraint_expr_type type;
+
+  /* Variable we are referring to in the constraint.  */
+  unsigned int var;
+
+  /* Offset, in bits, of this constraint from the beginning of
+     variables it ends up referring to.
+
+     IOW, in a deref constraint, we would deref, get the result set,
+     then add OFFSET to each member.   */
+  unsigned HOST_WIDE_INT offset;
+};
+
+static struct constraint_expr do_deref (struct constraint_expr);
+
+/* Our set constraints are made up of two constraint expressions, one
+   LHS, and one RHS.  
+
+   As described in the introduction, our set constraints each represent an
+   operation between set valued variables.
+*/
+struct constraint
+{
+  struct constraint_expr lhs;
+  struct constraint_expr rhs;
+};
+
+/* List of constraints that we use to build the constraint graph from.  */
+
+static VEC(constraint_t,gc) *constraints;
+static alloc_pool constraint_pool;
+
+/* An edge in the constraint graph.  We technically have no use for
+   the src, since it will always be the same node that we are indexing
+   into the pred/succ arrays with, but it's nice for checking
+   purposes.  The edges are weighted, with a bit set in weights for
+   each edge from src to dest with that weight.  */
+
+struct constraint_edge
+{
+  unsigned int src;
+  unsigned int dest;
+  bitmap weights;
+};
+
+typedef struct constraint_edge *constraint_edge_t;
+static alloc_pool constraint_edge_pool;
+
+/* Return a new constraint edge from SRC to DEST.  */
+
+static constraint_edge_t
+new_constraint_edge (unsigned int src, unsigned int dest)
+{
+  constraint_edge_t ret = pool_alloc (constraint_edge_pool);
+  ret->src = src;
+  ret->dest = dest;
+  ret->weights = NULL;
+  return ret;
+}
+
+DEF_VEC_P(constraint_edge_t);
+DEF_VEC_ALLOC_P(constraint_edge_t,gc);
+
+
+/* The constraint graph is simply a set of adjacency vectors, one per
+   variable. succs[x] is the vector of successors for variable x, and preds[x]
+   is the vector of predecessors for variable x. 
+   IOW, all edges are "forward" edges, which is not like our CFG.  
+   So remember that
+   preds[x]->src == x, and
+   succs[x]->src == x*/
+
+struct constraint_graph
+{
+  VEC(constraint_edge_t,gc) **succs;
+  VEC(constraint_edge_t,gc) **preds;
+};
+
+typedef struct constraint_graph *constraint_graph_t;
+
+static constraint_graph_t graph;
+
+/* Create a new constraint consisting of LHS and RHS expressions.  */
+
+static constraint_t 
+new_constraint (const struct constraint_expr lhs,
+		const struct constraint_expr rhs)
+{
+  constraint_t ret = pool_alloc (constraint_pool);
+  ret->lhs = lhs;
+  ret->rhs = rhs;
+  return ret;
+}
+
+/* Print out constraint C to FILE.  */
+
+void
+dump_constraint (FILE *file, constraint_t c)
+{
+  if (c->lhs.type == ADDRESSOF)
+    fprintf (file, "&");
+  else if (c->lhs.type == DEREF)
+    fprintf (file, "*");  
+  fprintf (file, "%s", get_varinfo (c->lhs.var)->name);
+  if (c->lhs.offset != 0)
+    fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->lhs.offset);
+  fprintf (file, " = ");
+  if (c->rhs.type == ADDRESSOF)
+    fprintf (file, "&");
+  else if (c->rhs.type == DEREF)
+    fprintf (file, "*");
+  fprintf (file, "%s", get_varinfo (c->rhs.var)->name);
+  if (c->rhs.offset != 0)
+    fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->rhs.offset);
+  fprintf (file, "\n");
+}
+
+/* Print out constraint C to stderr.  */
+
+void
+debug_constraint (constraint_t c)
+{
+  dump_constraint (stderr, c);
+}
+
+/* Print out all constraints to FILE */
+
+void
+dump_constraints (FILE *file)
+{
+  int i;
+  constraint_t c;
+  for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
+    dump_constraint (file, c);
+}
+
+/* Print out all constraints to stderr.  */
+
+void
+debug_constraints (void)
+{
+  dump_constraints (stderr);
+}
+
+/* SOLVER FUNCTIONS 
+
+   The solver is a simple worklist solver, that works on the following
+   algorithm:
+   
+   sbitmap changed_nodes = all ones;
+   changed_count = number of nodes;
+   For each node that was already collapsed:
+       changed_count--;
+
+
+   while (changed_count > 0)
+   {
+     compute topological ordering for constraint graph
+  
+     find and collapse cycles in the constraint graph (updating
+     changed if necessary)
+     
+     for each node (n) in the graph in topological order:
+       changed_count--;
+
+       Process each complex constraint associated with the node,
+       updating changed if necessary.
+
+       For each outgoing edge from n, propagate the solution from n to
+       the destination of the edge, updating changed as necessary.
+
+   }  */
+
+/* Return true if two constraint expressions A and B are equal.  */
+
+static bool
+constraint_expr_equal (struct constraint_expr a, struct constraint_expr b)
+{
+  return a.type == b.type
+    && a.var == b.var
+    && a.offset == b.offset;
+}
+
+/* Return true if constraint expression A is less than constraint expression
+   B.  This is just arbitrary, but consistent, in order to give them an
+   ordering.  */
+
+static bool
+constraint_expr_less (struct constraint_expr a, struct constraint_expr b)
+{
+  if (a.type == b.type)
+    {
+      if (a.var == b.var)
+	return a.offset < b.offset;
+      else
+	return a.var < b.var;
+    }
+  else
+    return a.type < b.type;
+}
+
+/* Return true if constraint A is less than constraint B.  This is just
+   arbitrary, but consistent, in order to give them an ordering.  */
+
+static bool
+constraint_less (const constraint_t a, const constraint_t b)
+{
+  if (constraint_expr_less (a->lhs, b->lhs))
+    return true;
+  else if (constraint_expr_less (b->lhs, a->lhs))
+    return false;
+  else
+    return constraint_expr_less (a->rhs, b->rhs);
+}
+
+/* Return true if two constraints A and B are equal.  */
+  
+static bool
+constraint_equal (struct constraint a, struct constraint b)
+{
+  return constraint_expr_equal (a.lhs, b.lhs) 
+    && constraint_expr_equal (a.rhs, b.rhs);
+}
+
+
+/* Find a constraint LOOKFOR in the sorted constraint vector VEC */
+
+static constraint_t
+constraint_vec_find (VEC(constraint_t,gc) *vec,
+		     struct constraint lookfor)
+{
+  unsigned int place;  
+  constraint_t found;
+
+  if (vec == NULL)
+    return NULL;
+
+  place = VEC_lower_bound (constraint_t, vec, &lookfor, constraint_less);
+  if (place >= VEC_length (constraint_t, vec))
+    return NULL;
+  found = VEC_index (constraint_t, vec, place);
+  if (!constraint_equal (*found, lookfor))
+    return NULL;
+  return found;
+}
+
+/* Union two constraint vectors, TO and FROM.  Put the result in TO.  */
+
+static void
+constraint_set_union (VEC(constraint_t,gc) **to,
+		      VEC(constraint_t,gc) **from)
+{
+  int i;
+  constraint_t c;
+
+  for (i = 0; VEC_iterate (constraint_t, *from, i, c); i++)
+    {
+      if (constraint_vec_find (*to, *c) == NULL)
+	{
+	  unsigned int place = VEC_lower_bound (constraint_t, *to, c,
+						constraint_less);
+	  VEC_safe_insert (constraint_t, gc, *to, place, c);
+	}
+    }
+}
+
+/* Take a solution set SET, add OFFSET to each member of the set, and
+   overwrite SET with the result when done.  */
+
+static void
+solution_set_add (bitmap set, unsigned HOST_WIDE_INT offset)
+{
+  bitmap result = BITMAP_ALLOC (&iteration_obstack);
+  unsigned int i;
+  bitmap_iterator bi;
+
+  EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+    {
+      /* If this is a properly sized variable, only add offset if it's
+	 less than end.  Otherwise, it is globbed to a single
+	 variable.  */
+      
+      if ((get_varinfo (i)->offset + offset) < get_varinfo (i)->fullsize)
+	{
+	  unsigned HOST_WIDE_INT fieldoffset = get_varinfo (i)->offset + offset;
+	  varinfo_t v = first_vi_for_offset (get_varinfo (i), fieldoffset);
+	  bitmap_set_bit (result, v->id);
+	}
+      else if (get_varinfo (i)->is_artificial_var 
+	       || get_varinfo (i)->is_unknown_size_var)
+	{
+	  bitmap_set_bit (result, i);
+	}
+    }
+  
+  bitmap_copy (set, result);  
+  BITMAP_FREE (result);
+}
+
+/* Union solution sets TO and FROM, and add INC to each member of FROM in the
+   process.  */
+
+static bool
+set_union_with_increment  (bitmap to, bitmap from, unsigned HOST_WIDE_INT inc)
+{
+  if (inc == 0)
+    return bitmap_ior_into (to, from);
+  else
+    {
+      bitmap tmp;
+      bool res;
+
+      tmp = BITMAP_ALLOC (&iteration_obstack);
+      bitmap_copy (tmp, from);
+      solution_set_add (tmp, inc);
+      res = bitmap_ior_into (to, tmp);
+      BITMAP_FREE (tmp);
+      return res;
+    }
+}
+
+/* Insert constraint C into the list of complex constraints for VAR.  */
+
+static void
+insert_into_complex (unsigned int var, constraint_t c)
+{
+  varinfo_t vi = get_varinfo (var);
+  unsigned int place = VEC_lower_bound (constraint_t, vi->complex, c,
+					constraint_less);
+  VEC_safe_insert (constraint_t, gc, vi->complex, place, c);
+}
+
+
+/* Compare two constraint edges A and B, return true if they are equal.  */
+
+static bool
+constraint_edge_equal (struct constraint_edge a, struct constraint_edge b)
+{
+  return a.src == b.src && a.dest == b.dest;
+}
+
+/* Compare two constraint edges, return true if A is less than B */
+
+static bool
+constraint_edge_less (const constraint_edge_t a, const constraint_edge_t b)
+{
+  if (a->dest < b->dest)
+    return true;
+  else if (a->dest == b->dest)
+    return a->src < b->src;
+  else
+    return false;
+}
+
+/* Find the constraint edge that matches LOOKFOR, in VEC.
+   Return the edge, if found, NULL otherwise.  */
+
+static constraint_edge_t 
+constraint_edge_vec_find (VEC(constraint_edge_t,gc) *vec, 
+			  struct constraint_edge lookfor)
+{
+  unsigned int place;  
+  constraint_edge_t edge;
+
+  place = VEC_lower_bound (constraint_edge_t, vec, &lookfor, 
+			   constraint_edge_less);
+  edge = VEC_index (constraint_edge_t, vec, place);
+  if (!constraint_edge_equal (*edge, lookfor))
+    return NULL;
+  return edge;
+}
+
+/* Condense two variable nodes into a single variable node, by moving
+   all associated info from SRC to TO.  */
+
+static void 
+condense_varmap_nodes (unsigned int to, unsigned int src)
+{
+  varinfo_t tovi = get_varinfo (to);
+  varinfo_t srcvi = get_varinfo (src);
+  unsigned int i;
+  constraint_t c;
+  bitmap_iterator bi;
+  
+  /* the src node, and all its variables, are now the to node.  */
+  srcvi->node = to;
+  EXECUTE_IF_SET_IN_BITMAP (srcvi->variables, 0, i, bi)
+    get_varinfo (i)->node = to;
+  
+  /* Merge the src node variables and the to node variables.  */
+  bitmap_set_bit (tovi->variables, src);
+  bitmap_ior_into (tovi->variables, srcvi->variables);
+  bitmap_clear (srcvi->variables);
+  
+  /* Move all complex constraints from src node into to node  */
+  for (i = 0; VEC_iterate (constraint_t, srcvi->complex, i, c); i++)
+    {
+      /* In complex constraints for node src, we may have either
+	 a = *src, and *src = a.  */
+      
+      if (c->rhs.type == DEREF)
+	c->rhs.var = to;
+      else
+	c->lhs.var = to;
+    }
+  constraint_set_union (&tovi->complex, &srcvi->complex);
+  srcvi->complex = NULL;
+}
+
+/* Erase EDGE from GRAPH.  This routine only handles self-edges
+   (e.g. an edge from a to a).  */
+
+static void
+erase_graph_self_edge (constraint_graph_t graph, struct constraint_edge edge)
+{
+  VEC(constraint_edge_t,gc) *predvec = graph->preds[edge.src];
+  VEC(constraint_edge_t,gc) *succvec = graph->succs[edge.dest];
+  unsigned int place;
+  gcc_assert (edge.src == edge.dest);
+
+  /* Remove from the successors.  */
+  place = VEC_lower_bound (constraint_edge_t, succvec, &edge, 
+			   constraint_edge_less);
+  
+  /* Make sure we found the edge.  */
+#ifdef ENABLE_CHECKING
+  {
+    constraint_edge_t tmp = VEC_index (constraint_edge_t, succvec, place);
+    gcc_assert (constraint_edge_equal (*tmp, edge));
+  }
+#endif
+  VEC_ordered_remove (constraint_edge_t, succvec, place);
+
+  /* Remove from the predecessors.  */
+  place = VEC_lower_bound (constraint_edge_t, predvec, &edge,
+			   constraint_edge_less);
+
+  /* Make sure we found the edge.  */
+#ifdef ENABLE_CHECKING
+  {
+    constraint_edge_t tmp = VEC_index (constraint_edge_t, predvec, place);
+    gcc_assert (constraint_edge_equal (*tmp, edge));
+  }
+#endif
+  VEC_ordered_remove (constraint_edge_t, predvec, place);
+}
+
+/* Remove edges involving NODE from GRAPH.  */
+
+static void
+clear_edges_for_node (constraint_graph_t graph, unsigned int node)
+{
+  VEC(constraint_edge_t,gc) *succvec = graph->succs[node];
+  VEC(constraint_edge_t,gc) *predvec = graph->preds[node];
+  constraint_edge_t c;
+  int i;
+  
+  /* Walk the successors, erase the associated preds.  */
+  for (i = 0; VEC_iterate (constraint_edge_t, succvec, i, c); i++)
+    if (c->dest != node)
+      {
+	unsigned int place;
+	struct constraint_edge lookfor;
+	lookfor.src = c->dest;
+	lookfor.dest = node;
+	place = VEC_lower_bound (constraint_edge_t, graph->preds[c->dest], 
+				 &lookfor, constraint_edge_less);
+	VEC_ordered_remove (constraint_edge_t, graph->preds[c->dest], place);
+      }
+  /* Walk the preds, erase the associated succs.  */
+  for (i =0; VEC_iterate (constraint_edge_t, predvec, i, c); i++)
+    if (c->dest != node)
+      {
+	unsigned int place;
+	struct constraint_edge lookfor;
+	lookfor.src = c->dest;
+	lookfor.dest = node;
+	place = VEC_lower_bound (constraint_edge_t, graph->succs[c->dest],
+				 &lookfor, constraint_edge_less);
+	VEC_ordered_remove (constraint_edge_t, graph->succs[c->dest], place);
+      }    
+  
+  graph->preds[node] = NULL;
+  graph->succs[node] = NULL;
+}
+
+static bool edge_added = false;
+  
+/* Add edge NEWE to the graph.  */
+
+static bool
+add_graph_edge (constraint_graph_t graph, struct constraint_edge newe)
+{
+  unsigned int place;
+  unsigned int src = newe.src;
+  unsigned int dest = newe.dest;
+  VEC(constraint_edge_t,gc) *vec;
+
+  vec = graph->preds[src];
+  place = VEC_lower_bound (constraint_edge_t, vec, &newe, 
+			   constraint_edge_less);
+  if (place == VEC_length (constraint_edge_t, vec)
+      || VEC_index (constraint_edge_t, vec, place)->dest != dest)
+    {
+      constraint_edge_t edge = new_constraint_edge (src, dest);
+      bitmap weightbitmap;
+
+      weightbitmap = BITMAP_ALLOC (&ptabitmap_obstack);
+      edge->weights = weightbitmap;
+      VEC_safe_insert (constraint_edge_t, gc, graph->preds[edge->src], 
+		       place, edge);
+      edge = new_constraint_edge (dest, src);
+      edge->weights = weightbitmap;
+      place = VEC_lower_bound (constraint_edge_t, graph->succs[edge->src],
+			       edge, constraint_edge_less);
+      VEC_safe_insert (constraint_edge_t, gc, graph->succs[edge->src], 
+		       place, edge);
+      edge_added = true;
+      return true;
+    }
+  else
+    return false;
+}
+
+
+/* Return the bitmap representing the weights of edge LOOKFOR */
+
+static bitmap
+get_graph_weights (constraint_graph_t graph, struct constraint_edge lookfor)
+{
+  constraint_edge_t edge;
+  unsigned int src = lookfor.src;
+  VEC(constraint_edge_t,gc) *vec;
+  vec = graph->preds[src];
+  edge = constraint_edge_vec_find (vec, lookfor);
+  gcc_assert (edge != NULL);
+  return edge->weights;
+}
+
+
+/* Merge GRAPH nodes FROM and TO into node TO.  */
+
+static void
+merge_graph_nodes (constraint_graph_t graph, unsigned int to, 
+		   unsigned int from)
+{
+  VEC(constraint_edge_t,gc) *succvec = graph->succs[from];
+  VEC(constraint_edge_t,gc) *predvec = graph->preds[from];
+  int i;
+  constraint_edge_t c;
+  
+  /* Merge all the predecessor edges.  */
+
+  for (i = 0; VEC_iterate (constraint_edge_t, predvec, i, c); i++)
+    {
+      unsigned int d = c->dest;
+      struct constraint_edge olde;
+      struct constraint_edge newe;
+      bitmap temp;
+      bitmap weights;
+      if (c->dest == from)
+	d = to;
+      newe.src = to;
+      newe.dest = d;
+      add_graph_edge (graph, newe);
+      olde.src = from;
+      olde.dest = c->dest;
+      temp = get_graph_weights (graph, olde);
+      weights = get_graph_weights (graph, newe);
+      bitmap_ior_into (weights, temp);
+    }
+  
+  /* Merge all the successor edges.  */
+  for (i = 0; VEC_iterate (constraint_edge_t, succvec, i, c); i++)
+    {
+      unsigned int d = c->dest;
+      struct constraint_edge olde;
+      struct constraint_edge newe;
+      bitmap temp;
+      bitmap weights;
+      if (c->dest == from)
+	d = to;
+      newe.src = d;
+      newe.dest = to;
+      add_graph_edge (graph, newe);
+      olde.src = c->dest;
+      olde.dest = from;
+      temp = get_graph_weights (graph, olde);
+      weights = get_graph_weights (graph, newe);
+      bitmap_ior_into (weights, temp);
+    }
+  clear_edges_for_node (graph, from);
+}
+
+/* Add a graph edge to GRAPH, going from TO to FROM, with WEIGHT, if
+   it doesn't exist in the graph already.
+   Return false if the edge already existed, true otherwise.  */
+
+static bool
+int_add_graph_edge (constraint_graph_t graph, unsigned int to, 
+		    unsigned int from, unsigned HOST_WIDE_INT weight)
+{
+  if (to == from && weight == 0)
+    {
+      return false;
+    }
+  else
+    {
+      bool r;
+      struct constraint_edge edge;
+      edge.src = to;
+      edge.dest = from;
+      r = add_graph_edge (graph, edge);
+      r |= !bitmap_bit_p (get_graph_weights (graph, edge), weight);
+      bitmap_set_bit (get_graph_weights (graph, edge), weight);
+      return r;
+    }
+}
+
+
+/* Return true if LOOKFOR is an existing graph edge.  */
+
+static bool
+valid_graph_edge (constraint_graph_t graph, struct constraint_edge lookfor)
+{
+  return constraint_edge_vec_find (graph->preds[lookfor.src], lookfor) != NULL;
+}
+
+
+/* Build the constraint graph.  */
+
+static void
+build_constraint_graph (void)
+{
+  int i = 0;
+  constraint_t c;
+
+  graph = ggc_alloc (sizeof (struct constraint_graph));
+  graph->succs = ggc_alloc_cleared (VEC_length (varinfo_t, varmap) * sizeof (*graph->succs));
+  graph->preds = ggc_alloc_cleared (VEC_length (varinfo_t, varmap) * sizeof (*graph->preds));
+  for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
+    {
+      struct constraint_expr lhs = c->lhs;
+      struct constraint_expr rhs = c->rhs;
+      if (lhs.type == DEREF)
+	{
+	  /* *x = y or *x = &y (complex) */
+	  if (rhs.type == ADDRESSOF || rhs.var > anything_id)
+	    insert_into_complex (lhs.var, c);
+	}
+      else if (rhs.type == DEREF)
+	{
+	  /* !ANYTHING = *y */
+	  if (lhs.var > anything_id) 
+	    insert_into_complex (rhs.var, c);
+	}
+      else if (rhs.type == ADDRESSOF)
+	{
+	  /* x = &y */
+	  bitmap_set_bit (get_varinfo (lhs.var)->solution, rhs.var);
+	}
+      else if (rhs.var > anything_id && lhs.var > anything_id)
+	{
+	  /* Ignore 0 weighted self edges, as they can't possibly contribute
+	     anything */
+	  if (lhs.var != rhs.var || rhs.offset != 0 || lhs.offset != 0)
+	    {
+	      
+	      struct constraint_edge edge;
+	      edge.src = lhs.var;
+	      edge.dest = rhs.var;
+	      /* x = y (simple) */
+	      add_graph_edge (graph, edge);
+	      bitmap_set_bit (get_graph_weights (graph, edge),
+			      rhs.offset);
+	    }
+	  
+	}
+    }
+}
+/* Changed variables on the last iteration.  */
+static unsigned int changed_count;
+static sbitmap changed;
+
+DEF_VEC_I(uint);
+DEF_VEC_ALLOC_I(uint,heap);
+
+/* Strongly Connected Component visitation info.  */
+
+struct scc_info
+{
+  sbitmap visited;
+  sbitmap in_component;
+  int current_index;
+  unsigned int *visited_index;
+  VEC(uint,heap) *scc_stack;
+  VEC(uint,heap) *unification_queue;
+};
+
+
+/* Recursive routine to find strongly connected components in GRAPH.
+   
+   This is Tarjan's strongly connected component finding algorithm, as
+   modified by Nuutila to keep only non-root nodes on the stack.  
+   The algorithm can be found in "On finding the strongly connected
+   connected components in a directed graph" by Esko Nuutila and Eljas
+   Soisalon-Soininen, in Information Processing Letters volume 49,
+   number 1, pages 9-14.  */
+
+static void
+scc_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
+{
+  constraint_edge_t c;
+  int i;
+
+  gcc_assert (get_varinfo (n)->node == n);
+  SET_BIT (si->visited, n);
+  RESET_BIT (si->in_component, n);
+  si->visited_index[n] = si->current_index ++;
+  
+  /* Visit all the successors.  */
+  for (i = 0; VEC_iterate (constraint_edge_t, graph->succs[n], i, c); i++)
+    {
+      /* We only want to find and collapse the zero weight edges. */
+      if (bitmap_bit_p (c->weights, 0))
+	{
+	  unsigned int w = c->dest;
+	  if (!TEST_BIT (si->visited, w))
+	    scc_visit (graph, si, w);
+	  if (!TEST_BIT (si->in_component, w))
+	    {
+	      unsigned int t = get_varinfo (w)->node;
+	      unsigned int nnode = get_varinfo (n)->node;
+	      if (si->visited_index[t] < si->visited_index[nnode])
+		{
+		  get_varinfo (n)->node = t;
+		}
+	    }
+	}
+    }
+  
+  /* See if any components have been identified.  */
+  if (get_varinfo (n)->node == n)
+    {
+      unsigned int t = si->visited_index[n];
+      SET_BIT (si->in_component, n);
+      while (VEC_length (uint, si->scc_stack) != 0 
+	     && t < si->visited_index[VEC_last (uint, si->scc_stack)])
+	{
+	  unsigned int w = VEC_pop (uint, si->scc_stack);
+	  get_varinfo (w)->node = n;
+	  SET_BIT (si->in_component, w);
+	  /* Mark this node for collapsing.  */
+	  VEC_safe_push (uint, heap, si->unification_queue, w);
+	} 
+    }
+  else
+    VEC_safe_push (uint, heap, si->scc_stack, n);
+}
+
+/* Collapse two variables into one variable.  */
+
+static void
+collapse_nodes (constraint_graph_t graph, unsigned int to, unsigned int from)
+{
+  bitmap tosol, fromsol;
+  struct constraint_edge edge;
+
+
+  condense_varmap_nodes (to, from);
+  tosol = get_varinfo (to)->solution;
+  fromsol = get_varinfo (from)->solution;
+  bitmap_ior_into (tosol, fromsol);
+  merge_graph_nodes (graph, to, from);
+  edge.src = to;
+  edge.dest = to;
+  if (valid_graph_edge (graph, edge))
+    {
+      bitmap weights = get_graph_weights (graph, edge);
+      bitmap_clear_bit (weights, 0);
+      if (bitmap_empty_p (weights))
+	erase_graph_self_edge (graph, edge);
+    }
+  bitmap_clear (fromsol);
+  get_varinfo (to)->address_taken |= get_varinfo (from)->address_taken;
+  get_varinfo (to)->indirect_target |= get_varinfo (from)->indirect_target;
+}
+
+
+/* Unify nodes that we have found to be part of a cycle.  */
+
+static void
+process_unification_queue (constraint_graph_t graph, struct scc_info *si,
+			   bool update_changed)
+{
+  size_t i = 0;
+  bitmap tmp = BITMAP_ALLOC (update_changed ? &iteration_obstack : NULL);
+  bitmap_clear (tmp);
+
+  /* We proceed as follows:
+
+     For each component in the queue (components are delineated by
+     when current_queue_element->node != next_queue_element->node):
+
+        rep = representative node for component
+
+        For each node (tounify) to be unified in the component,
+           merge the solution for tounify into tmp bitmap
+
+           clear solution for tounify
+
+           merge edges from tounify into rep
+
+	   merge complex constraints from tounify into rep
+
+	   update changed count to note that tounify will never change
+	   again
+
+	Merge tmp into solution for rep, marking rep changed if this
+	changed rep's solution.
+	
+	Delete any 0 weighted self-edges we now have for rep.
+  */
+
+  while (i != VEC_length (uint, si->unification_queue))
+    {
+      unsigned int tounify = VEC_index (uint, si->unification_queue, i);
+      unsigned int n = get_varinfo (tounify)->node;
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Unifying %s to %s\n", 
+		 get_varinfo (tounify)->name,
+		 get_varinfo (n)->name);
+      if (update_changed)
+	stats.unified_vars_dynamic++;
+      else
+	stats.unified_vars_static++;
+      bitmap_ior_into (tmp, get_varinfo (tounify)->solution);
+      merge_graph_nodes (graph, n, tounify);
+      condense_varmap_nodes (n, tounify);
+      
+      if (update_changed && TEST_BIT (changed, tounify))
+	{
+	  RESET_BIT (changed, tounify);
+	  if (!TEST_BIT (changed, n))
+	    SET_BIT (changed, n);
+	  else
+	    {
+	      gcc_assert (changed_count > 0);
+	      changed_count--;
+	    }
+	}
+
+      bitmap_clear (get_varinfo (tounify)->solution);
+      ++i;
+
+      /* If we've either finished processing the entire queue, or
+	 finished processing all nodes for component n, update the solution for
+	 n.  */
+      if (i == VEC_length (uint, si->unification_queue)
+	  || get_varinfo (VEC_index (uint, si->unification_queue, i))->node != n)
+	{
+	  struct constraint_edge edge;
+
+	  /* If the solution changes because of the merging, we need to mark
+	     the variable as changed.  */
+	  if (bitmap_ior_into (get_varinfo (n)->solution, tmp))
+	    {
+	      if (update_changed && !TEST_BIT (changed, n))
+		{
+		  SET_BIT (changed, n);
+		  changed_count++;
+		}
+	    }
+	  bitmap_clear (tmp);
+	  edge.src = n;
+	  edge.dest = n;
+	  if (valid_graph_edge (graph, edge))
+	    {
+	      bitmap weights = get_graph_weights (graph, edge);
+	      bitmap_clear_bit (weights, 0);
+	      if (bitmap_empty_p (weights))
+		erase_graph_self_edge (graph, edge);
+	    }
+	}
+    }
+  BITMAP_FREE (tmp);
+}
+
+/* Information needed to compute the topological ordering of a graph.  */
+
+struct topo_info
+{
+  /* sbitmap of visited nodes.  */
+  sbitmap visited;
+  /* Array that stores the topological order of the graph, *in
+     reverse*.  */
+  VEC(uint,heap) *topo_order;
+};
+
+/* Initialize and return a topological info structure.  */
+
+static struct topo_info *
+init_topo_info (void)
+{
+  size_t size = VEC_length (varinfo_t, varmap);
+  struct topo_info *ti = xmalloc (sizeof (struct topo_info));
+  ti->visited = sbitmap_alloc (size);
+  sbitmap_zero (ti->visited);
+  ti->topo_order = VEC_alloc (uint, heap, 1);
+  return ti;
+}
+
+/* Free the topological sort info pointed to by TI.  */
+
+static void
+free_topo_info (struct topo_info *ti)
+{
+  sbitmap_free (ti->visited);
+  VEC_free (uint, heap, ti->topo_order);
+  free (ti);
+}
+
+/* Visit the graph in topological order, and store the order in the
+   topo_info structure.  */
+
+static void
+topo_visit (constraint_graph_t graph, struct topo_info *ti,
+	    unsigned int n)
+{
+  VEC(constraint_edge_t,gc) *succs = graph->succs[n];
+  constraint_edge_t c;
+  int i;
+  SET_BIT (ti->visited, n);
+  for (i = 0; VEC_iterate (constraint_edge_t, succs, i, c); i++)
+    {
+      if (!TEST_BIT (ti->visited, c->dest))
+	topo_visit (graph, ti, c->dest);
+    }
+  VEC_safe_push (uint, heap, ti->topo_order, n);
+}
+
+/* Return true if variable N + OFFSET is a legal field of N.  */
+
+static bool 
+type_safe (unsigned int n, unsigned HOST_WIDE_INT *offset)
+{
+  varinfo_t ninfo = get_varinfo (n);
+
+  /* For things we've globbed to single variables, any offset into the
+     variable acts like the entire variable, so that it becomes offset
+     0.  */
+  if (n == anything_id
+      || ninfo->is_artificial_var
+      || ninfo->is_unknown_size_var)
+    {
+      *offset = 0;
+      return true;
+    }
+  return n > anything_id 
+    && (get_varinfo (n)->offset + *offset) < get_varinfo (n)->fullsize;
+}
+
+/* Process a constraint C that represents *x = &y.  */
+
+static void
+do_da_constraint (constraint_graph_t graph ATTRIBUTE_UNUSED,
+		  constraint_t c, bitmap delta)
+{
+  unsigned int rhs = c->rhs.var;
+  unsigned HOST_WIDE_INT offset = c->lhs.offset;
+  unsigned int j;
+  bitmap_iterator bi;
+
+  /* For each member j of Delta (Sol(x)), add x to Sol(j)  */
+  EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
+    {
+      if (type_safe (j, &offset))
+	{
+	/* *x != NULL && *x != ANYTHING*/
+	  varinfo_t v;
+	  unsigned int t;
+	  bitmap sol;
+	  unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + offset;
+	  v = first_vi_for_offset (get_varinfo (j), fieldoffset);
+	  t = v->node;
+	  sol = get_varinfo (t)->solution;
+	  if (!bitmap_bit_p (sol, rhs))
+	    {		  
+	      bitmap_set_bit (sol, rhs);
+	      if (!TEST_BIT (changed, t))
+		{
+		  SET_BIT (changed, t);
+		  changed_count++;
+		}
+	    }
+	}
+      else if (dump_file)
+	fprintf (dump_file, "Untypesafe usage in do_da_constraint.\n");
+      
+    }
+}
+
+/* Process a constraint C that represents x = *y, using DELTA as the
+   starting solution.  */
+
+static void
+do_sd_constraint (constraint_graph_t graph, constraint_t c,
+		  bitmap delta)
+{
+  unsigned int lhs = get_varinfo (c->lhs.var)->node;
+  unsigned HOST_WIDE_INT roffset = c->rhs.offset;
+  bool flag = false;
+  bitmap sol = get_varinfo (lhs)->solution;
+  unsigned int j;
+  bitmap_iterator bi;
+  
+  /* For each variable j in delta (Sol(y)), add    
+     an edge in the graph from j to x, and union Sol(j) into Sol(x).  */
+  EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
+    {
+      if (type_safe (j, &roffset))
+	{
+	  varinfo_t v;
+	  unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + roffset;
+	  unsigned int t;
+
+	  v = first_vi_for_offset (get_varinfo (j), fieldoffset);	  
+	  t = v->node;
+	  if (int_add_graph_edge (graph, lhs, t, 0))
+	    flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);	  
+	}
+      else if (dump_file)
+	fprintf (dump_file, "Untypesafe usage in do_sd_constraint\n");
+      
+    }
+
+  /* If the LHS solution changed, mark the var as changed.  */
+  if (flag)
+    {
+      get_varinfo (lhs)->solution = sol;
+      if (!TEST_BIT (changed, lhs))
+	{
+	  SET_BIT (changed, lhs);
+	  changed_count++;
+	}
+    }    
+}
+
+/* Process a constraint C that represents *x = y.  */
+
+static void
+do_ds_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
+{
+  unsigned int rhs = get_varinfo (c->rhs.var)->node;
+  unsigned HOST_WIDE_INT loff = c->lhs.offset;
+  unsigned HOST_WIDE_INT roff = c->rhs.offset;
+  bitmap sol = get_varinfo (rhs)->solution;
+  unsigned int j;
+  bitmap_iterator bi;
+
+  /* For each member j of delta (Sol(x)), add an edge from y to j and
+     union Sol(y) into Sol(j) */
+  EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
+    {
+      if (type_safe (j, &loff))
+	{
+	  varinfo_t v;
+	  unsigned int t;
+	  unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + loff;
+
+	  v = first_vi_for_offset (get_varinfo (j), fieldoffset);
+	  t = v->node;
+	  if (int_add_graph_edge (graph, t, rhs, roff))
+	    {
+	      bitmap tmp = get_varinfo (t)->solution;
+	      if (set_union_with_increment (tmp, sol, roff))
+		{
+		  get_varinfo (t)->solution = tmp;
+		  if (t == rhs)
+		    {
+		      sol = get_varinfo (rhs)->solution;
+		    }
+		  if (!TEST_BIT (changed, t))
+		    {
+		      SET_BIT (changed, t);
+		      changed_count++;
+		    }
+		}
+	    }
+	}    
+      else if (dump_file)
+	fprintf (dump_file, "Untypesafe usage in do_ds_constraint\n");
+    }
+}
+
+/* Handle a non-simple (simple meaning requires no iteration), non-copy
+   constraint (IE *x = &y, x = *y, and *x = y).  */
+   
+static void
+do_complex_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
+{
+  if (c->lhs.type == DEREF)
+    {
+      if (c->rhs.type == ADDRESSOF)
+	{
+	  /* *x = &y */
+	  do_da_constraint (graph, c, delta);
+	}
+      else
+	{
+	  /* *x = y */
+	  do_ds_constraint (graph, c, delta);
+	}
+    }
+  else
+    {
+      /* x = *y */
+      do_sd_constraint (graph, c, delta);
+    }
+}
+
+/* Initialize and return a new SCC info structure.  */
+
+static struct scc_info *
+init_scc_info (void)
+{
+  struct scc_info *si = xmalloc (sizeof (struct scc_info));
+  size_t size = VEC_length (varinfo_t, varmap);
+
+  si->current_index = 0;
+  si->visited = sbitmap_alloc (size);
+  sbitmap_zero (si->visited);
+  si->in_component = sbitmap_alloc (size);
+  sbitmap_ones (si->in_component);
+  si->visited_index = xcalloc (sizeof (unsigned int), size + 1);
+  si->scc_stack = VEC_alloc (uint, heap, 1);
+  si->unification_queue = VEC_alloc (uint, heap, 1);
+  return si;
+}
+
+/* Free an SCC info structure pointed to by SI */
+
+static void
+free_scc_info (struct scc_info *si)
+{  
+  sbitmap_free (si->visited);
+  sbitmap_free (si->in_component);
+  free (si->visited_index);
+  VEC_free (uint, heap, si->scc_stack);
+  VEC_free (uint, heap, si->unification_queue);
+  free(si); 
+}
+
+
+/* Find cycles in GRAPH that occur, using strongly connected components, and
+   collapse the cycles into a single representative node.  if UPDATE_CHANGED
+   is true, then update the changed sbitmap to note those nodes whose
+   solutions have changed as a result of collapsing.  */
+
+static void
+find_and_collapse_graph_cycles (constraint_graph_t graph, bool update_changed)
+{
+  unsigned int i;
+  unsigned int size = VEC_length (varinfo_t, varmap);
+  struct scc_info *si = init_scc_info ();
+
+  for (i = 0; i != size; ++i)
+    if (!TEST_BIT (si->visited, i) && get_varinfo (i)->node == i)
+      scc_visit (graph, si, i);
+  process_unification_queue (graph, si, update_changed);
+  free_scc_info (si);
+}
+
+/* Compute a topological ordering for GRAPH, and store the result in the
+   topo_info structure TI.  */
+
+static void 
+compute_topo_order (constraint_graph_t graph,
+		    struct topo_info *ti)
+{
+  unsigned int i;
+  unsigned int size = VEC_length (varinfo_t, varmap);
+  
+  for (i = 0; i != size; ++i)
+    if (!TEST_BIT (ti->visited, i) && get_varinfo (i)->node == i)
+      topo_visit (graph, ti, i);
+}
+
+/* Return true if bitmap B is empty, or a bitmap other than bit 0 is set. */
+
+static bool
+bitmap_other_than_zero_bit_set (bitmap b)
+{
+  unsigned int i;
+  bitmap_iterator bi;
+
+  if (bitmap_empty_p (b))
+    return false;
+  EXECUTE_IF_SET_IN_BITMAP (b, 1, i, bi)
+    return true;
+  return false;
+}
+
+/* Perform offline variable substitution.
+   
+   This is a linear time way of identifying variables that must have
+   equivalent points-to sets, including those caused by static cycles,
+   and single entry subgraphs, in the constraint graph.
+
+   The technique is described in "Off-line variable substitution for
+   scaling points-to analysis" by Atanas Rountev and Satish Chandra,
+   in "ACM SIGPLAN Notices" volume 35, number 5, pages 47-56.  */
+
+static void
+perform_var_substitution (constraint_graph_t graph)
+{
+  struct topo_info *ti = init_topo_info ();
+ 
+  /* Compute the topological ordering of the graph, then visit each
+     node in topological order.  */
+  compute_topo_order (graph, ti);
+ 
+  while (VEC_length (uint, ti->topo_order) != 0)
+    {
+      unsigned int i = VEC_pop (uint, ti->topo_order);
+      unsigned int pred;
+      varinfo_t vi = get_varinfo (i);
+      bool okay_to_elim = false;
+      unsigned int root = VEC_length (varinfo_t, varmap);
+      VEC(constraint_edge_t,gc) *predvec = graph->preds[i];
+      constraint_edge_t ce;
+      bitmap tmp;
+
+      /* We can't eliminate things whose address is taken, or which is
+	 the target of a dereference.  */
+      if (vi->address_taken || vi->indirect_target)
+	continue;
+
+      /* See if all predecessors of I are ripe for elimination */
+      for (pred = 0; VEC_iterate (constraint_edge_t, predvec, pred, ce); pred++)
+	{
+	  bitmap weight;
+	  unsigned int w;
+	  weight = get_graph_weights (graph, *ce);
+	
+	  /* We can't eliminate variables that have non-zero weighted
+	     edges between them.  */
+	  if (bitmap_other_than_zero_bit_set (weight))
+	    {
+	      okay_to_elim = false;
+	      break;
+	    }
+	  w = get_varinfo (ce->dest)->node;
+	  /* We can't eliminate the node if one of the predecessors is
+	     part of a different strongly connected component.  */
+	  if (!okay_to_elim)
+	    {
+	      root = w;
+	      okay_to_elim = true;
+	    }
+	  else if (w != root)
+	    {
+	      okay_to_elim = false;
+	      break;
+	    }
+	  /* Theorem 4 in Rountev and Chandra: If i is a direct node,
+	     then Solution(i) is a subset of Solution (w), where w is a
+	     predecessor in the graph.  
+	     Corrolary: If all predecessors of i have the same
+	     points-to set, then i has that same points-to set as
+	     those predecessors.  */
+	  tmp = BITMAP_ALLOC (NULL);
+	  bitmap_and_compl (tmp, get_varinfo (i)->solution,
+			    get_varinfo (w)->solution);
+	  if (!bitmap_empty_p (tmp))
+	    {
+	      okay_to_elim = false;
+	      BITMAP_FREE (tmp);
+	      break;
+	    }
+	  BITMAP_FREE (tmp);
+	}
+      /* See if the root is different than the original node. 
+	 If so, we've found an equivalence.  */
+      if (root != get_varinfo (i)->node && okay_to_elim)
+	{
+	  /* Found an equivalence */
+	  get_varinfo (i)->node = root;
+	  collapse_nodes (graph, root, i);
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    fprintf (dump_file, "Collapsing %s into %s\n",
+		     get_varinfo (i)->name,
+		     get_varinfo (root)->name);
+	  stats.collapsed_vars++;
+	}
+    }
+  free_topo_info (ti);
+}
+
+/* Solve the constraint graph GRAPH using our worklist solver.  */
+
+static void
+solve_graph (constraint_graph_t graph)
+{
+  unsigned int size = VEC_length (varinfo_t, varmap);
+  unsigned int i;
+
+  changed_count = size;
+  changed = sbitmap_alloc (size);
+  sbitmap_ones (changed);
+  
+  /* The already collapsed/unreachable nodes will never change, so we
+     need to  account for them in changed_count.  */
+  for (i = 0; i < size; i++)
+    if (get_varinfo (i)->node != i)
+      changed_count--;
+  
+  while (changed_count > 0)
+    {
+      unsigned int i;
+      struct topo_info *ti = init_topo_info ();
+      stats.iterations++;
+      
+      bitmap_obstack_initialize (&iteration_obstack);
+      
+      if (edge_added)
+	{
+	  /* We already did cycle elimination once, when we did variable
+	     substitution, so we don't need it again for the first iteration.  */
+	  if (stats.iterations > 1)
+	    find_and_collapse_graph_cycles (graph, true);
+	  
+	  edge_added = false;
+	}
+      compute_topo_order (graph, ti);
+      while (VEC_length (uint, ti->topo_order) != 0)
+	{
+	  i = VEC_pop (uint, ti->topo_order);
+	  gcc_assert (get_varinfo (i)->node == i);
+
+	  /* If the node has changed, we need to process the
+	     complex constraints and outgoing edges again.  */
+	  if (TEST_BIT (changed, i))
+	    {
+	      unsigned int j;
+	      constraint_t c;
+	      constraint_edge_t e;
+	      bitmap solution;
+	      VEC(constraint_t,gc) *complex = get_varinfo (i)->complex;
+	      VEC(constraint_edge_t,gc) *succs;
+
+	      RESET_BIT (changed, i);
+	      changed_count--;
+
+	      /* Process the complex constraints */
+	      solution = get_varinfo (i)->solution;
+	      for (j = 0; VEC_iterate (constraint_t, complex, j, c); j++)
+		do_complex_constraint (graph, c, solution);
+
+	      /* Propagate solution to all successors.  */
+	      succs = graph->succs[i];
+	      for (j = 0; VEC_iterate (constraint_edge_t, succs, j, e); j++)
+		{
+		  bitmap tmp = get_varinfo (e->dest)->solution;
+		  bool flag = false;
+		  unsigned int k;
+		  bitmap weights = e->weights;
+		  bitmap_iterator bi;
+
+		  gcc_assert (!bitmap_empty_p (weights));
+		  EXECUTE_IF_SET_IN_BITMAP (weights, 0, k, bi)
+		    flag |= set_union_with_increment (tmp, solution, k);
+
+		  if (flag)
+		    {
+		      get_varinfo (e->dest)->solution = tmp;		    
+		      if (!TEST_BIT (changed, e->dest))
+			{
+			  SET_BIT (changed, e->dest);
+			  changed_count++;
+			}
+		    }
+		}
+	    }
+	}
+      free_topo_info (ti);
+      bitmap_obstack_release (&iteration_obstack);
+    }
+  sbitmap_free (changed);
+}
+
+
+/* CONSTRAINT AND VARIABLE GENERATION FUNCTIONS */
+
+/* Map from trees to variable ids.  */    
+static htab_t id_for_tree;
+
+typedef struct tree_id
+{
+  tree t;
+  unsigned int id;
+} *tree_id_t;
+
+/* Hash a tree id structure.  */
+
+static hashval_t 
+tree_id_hash (const void *p)
+{
+  const tree_id_t ta = (tree_id_t) p;
+  return htab_hash_pointer (ta->t);
+}
+
+/* Return true if the tree in P1 and the tree in P2 are the same.  */
+
+static int
+tree_id_eq (const void *p1, const void *p2)
+{
+  const tree_id_t ta1 = (tree_id_t) p1;
+  const tree_id_t ta2 = (tree_id_t) p2;
+  return ta1->t == ta2->t;
+}
+
+/* Insert ID as the variable id for tree T in the hashtable.  */
+
+static void 
+insert_id_for_tree (tree t, int id)
+{
+  void **slot;
+  struct tree_id finder;
+  tree_id_t new_pair;
+  
+  finder.t = t;
+  slot = htab_find_slot (id_for_tree, &finder, INSERT);
+  gcc_assert (*slot == NULL);
+  new_pair = xmalloc (sizeof (struct tree_id));
+  new_pair->t = t;
+  new_pair->id = id;
+  *slot = (void *)new_pair;
+}
+
+/* Find the variable id for tree T in the hashtable.  If T does not
+   exist in the hash table, return false, otherwise, return true and
+   set *ID to the id we found.  */
+
+static bool
+lookup_id_for_tree (tree t, unsigned int *id)
+{
+  tree_id_t pair;
+  struct tree_id finder;
+
+  finder.t = t;
+  pair = htab_find (id_for_tree,  &finder);
+  if (pair == NULL)
+    return false;
+  *id = pair->id;
+  return true;
+}
+
+/* Return a printable name for DECL  */
+
+static const char *
+alias_get_name (tree decl)
+{
+  const char *res = get_name (decl);
+  char *temp;
+  int num_printed = 0;
+
+  if (res != NULL)
+    return res;
+
+  res = "NULL";
+  if (TREE_CODE (decl) == SSA_NAME)
+    {
+      num_printed = asprintf (&temp, "%s_%u", 
+			      alias_get_name (SSA_NAME_VAR (decl)),
+			      SSA_NAME_VERSION (decl));
+    }
+  else if (DECL_P (decl))
+    {
+      num_printed = asprintf (&temp, "D.%u", DECL_UID (decl));
+    }
+  if (num_printed > 0)
+    {
+      res = ggc_strdup (temp);
+      free (temp);
+    }
+  return res;
+}
+
+/* Find the variable id for tree T in the hashtable.
+   If T doesn't exist in the hash table, create an entry for it.  */
+
+static unsigned int
+get_id_for_tree (tree t)
+{
+  tree_id_t pair;
+  struct tree_id finder;
+
+  finder.t = t;
+  pair = htab_find (id_for_tree,  &finder);
+  if (pair == NULL)
+    return create_variable_info_for (t, alias_get_name (t));
+  
+  return pair->id;
+}
+
+/* Get a constraint expression from an SSA_VAR_P node.  */
+
+static struct constraint_expr
+get_constraint_exp_from_ssa_var (tree t)
+{
+  struct constraint_expr cexpr;
+
+  gcc_assert (SSA_VAR_P (t) || DECL_P (t));
+
+  /* For parameters, get at the points-to set for the actual parm
+     decl.  */
+  if (TREE_CODE (t) == SSA_NAME 
+      && TREE_CODE (SSA_NAME_VAR (t)) == PARM_DECL 
+      && default_def (SSA_NAME_VAR (t)) == t)
+    return get_constraint_exp_from_ssa_var (SSA_NAME_VAR (t));
+
+  cexpr.type = SCALAR;
+  
+  if (TREE_READONLY (t))
+    {
+      cexpr.type = ADDRESSOF;
+      cexpr.var = readonly_id;
+    }
+  else
+    cexpr.var = get_id_for_tree (t);    
+    
+  cexpr.offset = 0;
+  return cexpr;
+}
+
+/* Process a completed constraint T, and add it to the constraint
+   list.  */
+
+static void
+process_constraint (constraint_t t)
+{
+  struct constraint_expr rhs = t->rhs;
+  struct constraint_expr lhs = t->lhs;
+  
+  gcc_assert (rhs.var < VEC_length (varinfo_t, varmap));
+  gcc_assert (lhs.var < VEC_length (varinfo_t, varmap));
+
+  /* ANYTHING == ANYTHING is pointless.  */
+  if (lhs.var == anything_id && rhs.var == anything_id)
+    return;
+
+  /* If we have &ANYTHING = something, convert to SOMETHING = &ANYTHING) */
+  else if (lhs.var == anything_id && lhs.type == ADDRESSOF)
+    {
+      rhs = t->lhs;
+      t->lhs = t->rhs;
+      t->rhs = rhs;
+      process_constraint (t);
+    }   
+  /* This can happen in our IR with things like n->a = *p */
+  else if (rhs.type == DEREF && lhs.type == DEREF && rhs.var != anything_id)
+    {
+      /* Split into tmp = *rhs, *lhs = tmp */
+      tree rhsdecl = get_varinfo (rhs.var)->decl;
+      tree pointertype = TREE_TYPE (rhsdecl);
+      tree pointedtotype = TREE_TYPE (pointertype);
+      tree tmpvar = create_tmp_var_raw (pointedtotype, "doubledereftmp");
+      struct constraint_expr tmplhs = get_constraint_exp_from_ssa_var (tmpvar);
+      
+      /* If this is an aggregate of known size, we should have passed
+	 this off to do_structure_copy, and it should have broken it
+	 up.  */
+      gcc_assert (!AGGREGATE_TYPE_P (pointedtotype) 
+		  || get_varinfo (rhs.var)->is_unknown_size_var);
+      
+      process_constraint (new_constraint (tmplhs, rhs));
+      process_constraint (new_constraint (lhs, tmplhs));
+    }
+  else if (rhs.type == ADDRESSOF)
+    {
+      varinfo_t vi;
+      gcc_assert (rhs.offset == 0);
+      
+      for (vi = get_varinfo (rhs.var); vi != NULL; vi = vi->next)
+	vi->address_taken = true;
+
+      VEC_safe_push (constraint_t, gc, constraints, t);
+    }
+  else
+    {
+      if (lhs.type != DEREF && rhs.type == DEREF)
+	get_varinfo (lhs.var)->indirect_target = true;
+      VEC_safe_push (constraint_t, gc, constraints, t);
+    }
+}
+
+
+/* Return the position, in bits, of FIELD_DECL from the beginning of its
+   structure.  */
+
+static unsigned HOST_WIDE_INT
+bitpos_of_field (const tree fdecl)
+{
+  return (tree_low_cst (DECL_FIELD_OFFSET (fdecl), 1) * 8) 
+    + tree_low_cst (DECL_FIELD_BIT_OFFSET (fdecl), 1);
+}
+
+/* Given a COMPONENT_REF, return the constraint_expr for it.  */
+
+static struct constraint_expr
+get_constraint_for_component_ref (tree t)
+{
+  struct constraint_expr result;
+  HOST_WIDE_INT bitsize;
+  HOST_WIDE_INT bitpos;
+  tree offset;
+  enum machine_mode mode;
+  int unsignedp;
+  int volatilep;
+  tree forzero;
+  
+  result.offset = 0;
+  result.type = SCALAR;
+  result.var = 0;
+
+  /* Some people like to do cute things like take the address of
+     &0->a.b */
+
+  forzero = t;
+  while (!SSA_VAR_P (forzero) && !CONSTANT_CLASS_P (forzero))
+      forzero = TREE_OPERAND (forzero, 0);
+
+  if (CONSTANT_CLASS_P (forzero) && integer_zerop (forzero)) 
+    {
+      result.offset = 0;
+      result.var = integer_id;
+      result.type = SCALAR;
+      return result;
+    }
+ 
+  t = get_inner_reference (t, &bitsize, &bitpos, &offset, &mode,
+			   &unsignedp, &volatilep, false);
+  result = get_constraint_for (t);
+
+  /* This can also happen due to weird offsetof type macros.  */
+  if (TREE_CODE (t) != ADDR_EXPR && result.type == ADDRESSOF)
+    result.type = SCALAR;
+  
+  /* If we know where this goes, then yay. Otherwise, booo. */
+
+  if (offset == NULL && bitsize != -1)
+    {
+      result.offset = bitpos;
+    }	
+  else
+    {
+      result.var = anything_id;
+      result.offset = 0;      
+    }
+
+  if (result.type == SCALAR)
+    {
+      /* In languages like C, you can access one past the end of an
+	 array.  You aren't allowed to dereference it, so we can
+	 ignore this constraint. When we handle pointer subtraction,
+	 we may have to do something cute here.  */
+      
+      if (result.offset < get_varinfo (result.var)->fullsize)	
+	result.var = first_vi_for_offset (get_varinfo (result.var), 
+					  result.offset)->id;
+      else
+	if (dump_file && (dump_flags & TDF_DETAILS))
+	  fprintf (dump_file, "Access to past the end of variable, ignoring\n");
+      result.offset = 0;
+    }
+  
+  return result;
+}
+
+/* Dereference the constraint expression CONS, and return the result.
+   DEREF (ADDRESSOF) = SCALAR
+   DEREF (SCALAR) = DEREF
+   DEREF (DEREF) = (temp = DEREF1; result = DEREF(temp))
+   This is needed so that we can handle dereferencing DEREF constraints.  */
+
+static struct constraint_expr
+do_deref (struct constraint_expr cons)
+{
+  if (cons.type == SCALAR)
+    {
+      cons.type = DEREF;
+      return cons;
+    }
+  else if (cons.type == ADDRESSOF)
+    {
+      cons.type = SCALAR;
+      return cons;
+    }
+  else if (cons.type == DEREF)
+    {
+      tree tmpvar = create_tmp_var_raw (ptr_type_node, "derefmp");
+      struct constraint_expr tmplhs = get_constraint_exp_from_ssa_var (tmpvar);
+      process_constraint (new_constraint (tmplhs, cons));
+      cons.var = tmplhs.var;
+      return cons;
+    }
+  gcc_unreachable ();
+}
+
+/* Given a TREE, return the constraint expression for it.  */
+
+static struct constraint_expr
+get_constraint_for (tree t)
+{
+  struct constraint_expr temp;
+
+  /* x = integer is all glommed to a single variable, which doesn't point to
+     anything by itself.
+     That is, of course, unless it is an integer constant being treated as a
+     pointer, in which case, we will return that this is really the addressof
+     anything.  This happens below, since it will fall into the default case.
+     
+     The only case we know something about an integer treated like a pointer
+     is when it is the NULL pointer, and then we just say it points to NULL.
+     */
+  if (TREE_CODE (t) == INTEGER_CST
+      && !POINTER_TYPE_P (TREE_TYPE (t)))
+    {
+      temp.var = integer_id;
+      temp.type = SCALAR;
+      temp.offset = 0;
+      return temp;
+    }
+  else if (TREE_CODE (t) == INTEGER_CST
+	   && integer_zerop (t))
+    {
+      temp.var = nothing_id;
+      temp.type = ADDRESSOF;
+      temp.offset = 0;
+      return temp;
+    }
+
+  switch (TREE_CODE_CLASS (TREE_CODE (t)))
+    {
+    case tcc_expression:
+      {
+	switch (TREE_CODE (t))
+	  {
+	  case ADDR_EXPR:
+	    {
+	      temp = get_constraint_for (TREE_OPERAND (t, 0));
+	       if (temp.type == DEREF)
+		 temp.type = SCALAR;
+	       else
+		 temp.type = ADDRESSOF;
+	      return temp;
+	    }
+	    break;
+	  case CALL_EXPR:
+	    
+	    /* XXX: In interprocedural mode, if we didn't have the
+	       body, we would need to do *each pointer argument =
+	       &ANYTHING added.
+	    */
+
+	    if (call_expr_flags (t) & (ECF_MALLOC | ECF_MAY_BE_ALLOCA))
+	      {
+		tree heapvar = create_tmp_var_raw (ptr_type_node, "HEAP");
+		temp.var = create_variable_info_for (heapvar,
+						     alias_get_name (heapvar));
+		
+		get_varinfo (temp.var)->is_artificial_var = 1;
+		temp.type = ADDRESSOF;
+		temp.offset = 0;
+		return temp;
+	      }
+	    /* FALLTHRU */
+	  default:
+	    {
+	      temp.type = ADDRESSOF;
+	      temp.var = anything_id;
+	      temp.offset = 0;
+	      return temp;
+	    }
+	  }
+      }
+    case tcc_reference:
+      {
+	switch (TREE_CODE (t))
+	  {
+	  case INDIRECT_REF:
+	    {
+	      temp = get_constraint_for (TREE_OPERAND (t, 0));
+	      temp = do_deref (temp);
+	      return temp;
+	    }
+	  case ARRAY_REF:
+	  case COMPONENT_REF:
+	    temp = get_constraint_for_component_ref (t);
+	    return temp;
+	  default:
+	    {
+	      temp.type = ADDRESSOF;
+	      temp.var = anything_id;
+	      temp.offset = 0;
+	      return temp;
+	    }
+	  }
+      }
+    case tcc_unary:
+      {
+	switch (TREE_CODE (t))
+	  {
+	  case NOP_EXPR:
+	  case CONVERT_EXPR:
+	  case NON_LVALUE_EXPR:
+	    {
+	      tree op = TREE_OPERAND (t, 0);
+	      
+	      /* Cast from non-pointer to pointers are bad news for us.
+		 Anything else, we see through */
+	      if (!(POINTER_TYPE_P (TREE_TYPE (t))  &&
+		    ! POINTER_TYPE_P (TREE_TYPE (op))))
+		return get_constraint_for (op);
+	    }
+	  default:
+	    {
+	      temp.type = ADDRESSOF;
+	      temp.var = anything_id;
+	      temp.offset = 0;
+	      return temp;
+	    }
+	  }
+      }
+    case tcc_exceptional:
+      {
+	switch (TREE_CODE (t))
+	  {
+	  case PHI_NODE:	   
+	    return get_constraint_for (PHI_RESULT (t));
+	  case SSA_NAME:
+	    return get_constraint_exp_from_ssa_var (t);
+	  default:
+	    {
+	      temp.type = ADDRESSOF;
+	      temp.var = anything_id;
+	      temp.offset = 0;
+	      return temp;
+	    }
+	  }
+      }
+    case tcc_declaration:
+      return get_constraint_exp_from_ssa_var (t);
+    default:
+      {
+	temp.type = ADDRESSOF;
+	temp.var = anything_id;
+	temp.offset = 0;
+	return temp;
+      }
+    }
+}
+
+
+/* Handle the structure copy case where we have a simple structure copy
+   between LHS and RHS that is of SIZE (in bits) 
+  
+   For each field of the lhs variable (lhsfield)
+     For each field of the rhs variable at lhsfield.offset (rhsfield)
+       add the constraint lhsfield = rhsfield
+*/
+
+static void
+do_simple_structure_copy (const struct constraint_expr lhs,
+			  const struct constraint_expr rhs,
+			  const unsigned HOST_WIDE_INT size)
+{
+  varinfo_t p = get_varinfo (lhs.var);
+  unsigned HOST_WIDE_INT pstart,last;
+
+  pstart = p->offset;
+  last = p->offset + size;
+  for (; p && p->offset < last; p = p->next)
+    {
+      varinfo_t q;
+      struct constraint_expr templhs = lhs;
+      struct constraint_expr temprhs = rhs;
+      unsigned HOST_WIDE_INT fieldoffset;
+
+      templhs.var = p->id;            
+      q = get_varinfo (temprhs.var);
+      fieldoffset = p->offset - pstart;
+      q = first_vi_for_offset (q, q->offset + fieldoffset);
+      temprhs.var = q->id;
+      process_constraint (new_constraint (templhs, temprhs));
+    }
+}
+
+
+/* Handle the structure copy case where we have a  structure copy between a
+   aggregate on the LHS and a dereference of a pointer on the RHS
+   that is of SIZE (in bits) 
+  
+   For each field of the lhs variable (lhsfield)
+       rhs.offset = lhsfield->offset
+       add the constraint lhsfield = rhs
+*/
+
+static void
+do_rhs_deref_structure_copy (const struct constraint_expr lhs,
+			     const struct constraint_expr rhs,
+			     const unsigned HOST_WIDE_INT size)
+{
+  varinfo_t p = get_varinfo (lhs.var);
+  unsigned HOST_WIDE_INT pstart,last;
+  pstart = p->offset;
+  last = p->offset + size;
+
+  for (; p && p->offset < last; p = p->next)
+    {
+      varinfo_t q;
+      struct constraint_expr templhs = lhs;
+      struct constraint_expr temprhs = rhs;
+      unsigned HOST_WIDE_INT fieldoffset;
+
+
+      if (templhs.type == SCALAR)
+	templhs.var = p->id;      
+      else
+	templhs.offset = p->offset;
+      
+      q = get_varinfo (temprhs.var);
+      fieldoffset = p->offset - pstart;      
+      temprhs.offset += fieldoffset;
+      process_constraint (new_constraint (templhs, temprhs));
+    }
+}
+
+/* Handle the structure copy case where we have a  structure copy between a
+   aggregate on the RHS and a dereference of a pointer on the LHS
+   that is of SIZE (in bits) 
+  
+   For each field of the rhs variable (rhsfield)
+       lhs.offset = rhsfield->offset
+       add the constraint lhs = rhsfield
+*/
+
+static void
+do_lhs_deref_structure_copy (const struct constraint_expr lhs,
+			     const struct constraint_expr rhs,
+			     const unsigned HOST_WIDE_INT size)
+{
+  varinfo_t p = get_varinfo (rhs.var);
+  unsigned HOST_WIDE_INT pstart,last;
+  pstart = p->offset;
+  last = p->offset + size;
+
+  for (; p && p->offset < last; p = p->next)
+    {
+      varinfo_t q;
+      struct constraint_expr templhs = lhs;
+      struct constraint_expr temprhs = rhs;
+      unsigned HOST_WIDE_INT fieldoffset;
+
+
+      if (temprhs.type == SCALAR)
+	temprhs.var = p->id;      
+      else
+	temprhs.offset = p->offset;
+      
+      q = get_varinfo (templhs.var);
+      fieldoffset = p->offset - pstart;      
+      templhs.offset += fieldoffset;
+      process_constraint (new_constraint (templhs, temprhs));
+    }
+}
+
+/* Handle aggregate copies by expanding into copies of the respective
+   fields of the structures.  */
+
+static void
+do_structure_copy (tree lhsop, tree rhsop)
+{
+  struct constraint_expr lhs, rhs, tmp;
+  varinfo_t p;
+  unsigned HOST_WIDE_INT lhssize;
+  unsigned HOST_WIDE_INT rhssize;
+
+  lhssize = TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (lhsop)));
+  rhssize = TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (rhsop)));
+  lhs = get_constraint_for (lhsop);  
+  rhs = get_constraint_for (rhsop);
+  
+  /* If we have special var = x, swap it around.  */
+  if (lhs.var <= integer_id && rhs.var > integer_id)
+    {
+      tmp = lhs;
+      lhs = rhs;
+      rhs = tmp;
+    }
+  
+  /* If the RHS is a special var, set all the LHS fields to that
+     special var.  */
+  if (rhs.var <= integer_id)
+    {
+      for (p = get_varinfo (lhs.var); p; p = p->next)
+	{
+	  struct constraint_expr templhs = lhs;
+	  struct constraint_expr temprhs = rhs;
+	  if (templhs.type == SCALAR )
+	    templhs.var = p->id;
+	  else
+	    templhs.offset += p->offset;
+	  process_constraint (new_constraint (templhs, temprhs));
+	}
+    }
+  else
+    {
+      
+      if (rhs.type == SCALAR && lhs.type == SCALAR)  
+	do_simple_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
+      else if (lhs.type != DEREF && rhs.type == DEREF)
+	do_rhs_deref_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
+      else if (lhs.type == DEREF && rhs.type != DEREF)
+	do_lhs_deref_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
+      else
+	{
+	  tree rhsdecl = get_varinfo (rhs.var)->decl;
+	  tree pointertype = TREE_TYPE (rhsdecl);
+	  tree pointedtotype = TREE_TYPE (pointertype);
+	  tree tmpvar;
+	  gcc_assert (rhs.type == DEREF && lhs.type == DEREF);
+	  tmpvar = create_tmp_var_raw (pointedtotype, "structcopydereftmp");
+	  lhs = get_constraint_for (tmpvar);
+	  do_rhs_deref_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
+	  rhs = lhs;
+	  lhs = get_constraint_for (lhsop);
+	  do_lhs_deref_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
+	}
+    }
+}
+
+/* Return true if REF, a COMPONENT_REF, has an INDIRECT_REF somewhere
+   in it.  */
+
+static inline bool
+ref_contains_indirect_ref (tree ref)
+{
+  while (handled_component_p (ref))
+    {
+      if (TREE_CODE (ref) == INDIRECT_REF)
+	return true;
+      ref = TREE_OPERAND (ref, 0);
+    }
+  return false;
+}
+
+/*  Tree walker that is the heart of the aliasing infrastructure.
+    TP is a pointer to the current tree.
+    WALK_SUBTREES specifies whether to continue traversing subtrees or
+    not.
+    Returns NULL_TREE when we should stop.
+    
+    This function is the main part of the constraint builder. It
+    walks the trees, calling the appropriate building functions
+    to process various statements.  */
+
+static void
+find_func_aliases (tree t)
+{
+  struct constraint_expr lhs, rhs;
+  switch (TREE_CODE (t))
+    {      
+    case PHI_NODE:
+      {
+	int i;
+	/* Only care about pointers and structures containing
+	   pointers.  */
+	if (POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (t)))
+	    || AGGREGATE_TYPE_P (TREE_TYPE (PHI_RESULT (t))))
+	  {
+	    lhs = get_constraint_for (PHI_RESULT (t));
+	    for (i = 0; i < PHI_NUM_ARGS (t); i++)
+	      {
+		rhs = get_constraint_for (PHI_ARG_DEF (t, i));
+		process_constraint (new_constraint (lhs, rhs));
+	      }
+	  }
+      }
+      break;
+    case MODIFY_EXPR:
+      {
+	tree lhsop = TREE_OPERAND (t, 0);
+	tree rhsop = TREE_OPERAND (t, 1);
+	int i;	
+	if (AGGREGATE_TYPE_P (TREE_TYPE (lhsop)) 
+	    && AGGREGATE_TYPE_P (TREE_TYPE (rhsop)))
+	  {
+	    do_structure_copy (lhsop, rhsop);
+	  }
+	else
+	  {
+	    /* Only care about operations with pointers, structures containing
+	       pointers, dereferences, and call expressions*/
+	    if (POINTER_TYPE_P (TREE_TYPE (lhsop))
+		|| AGGREGATE_TYPE_P (TREE_TYPE (lhsop))
+		|| ref_contains_indirect_ref (lhsop)
+		|| TREE_CODE (rhsop) == CALL_EXPR)
+	      {
+		
+		lhs = get_constraint_for (lhsop);
+		switch (TREE_CODE_CLASS (TREE_CODE (rhsop)))
+		  {
+		    /* RHS that consist of unary operations,
+		       exceptional types, or bare decls/constants, get
+		       handled directly by get_constraint_for.  */ 
+		  case tcc_reference:
+		  case tcc_declaration:
+		  case tcc_constant:
+		  case tcc_exceptional:
+		  case tcc_expression:
+		  case tcc_unary:
+		    {
+		      rhs = get_constraint_for (rhsop);
+		      process_constraint (new_constraint (lhs, rhs));
+		    }
+		    break;
+		    /* other classes, we walk each operator */
+		  default:
+		    for (i = 0; i < TREE_CODE_LENGTH (TREE_CODE (rhsop)); i++)
+		      {
+			tree op = TREE_OPERAND (rhsop, i);
+			rhs = get_constraint_for (op);
+			process_constraint (new_constraint (lhs, rhs));
+		      }
+		  }      
+	      }
+	  }
+      }
+      break;
+    default:
+      break;
+    }
+}
+
+/* Find the first varinfo in the same variable as START that overlaps with
+   OFFSET.
+   Effectively, walk the chain of fields for the variable START to find the
+   first field that overlaps with OFFSET.
+   Abort if we can't find one.  */
+
+static varinfo_t 
+first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
+{
+  varinfo_t curr = start;
+  while (curr)
+    {
+      /* We may not find a variable in the field list with the actual
+	 offset when when we have glommed a structure to a variable.
+	 In that case, however, offset should still be within the size
+	 of the variable. */
+      if (offset >= curr->offset && offset < (curr->offset +  curr->size))
+	return curr;
+      curr = curr->next;
+    }
+  gcc_unreachable ();
+}
+
+/* Insert the varinfo FIELD into the field list for BASE, ordered by
+   offset.  */
+
+static void
+insert_into_field_list (varinfo_t base, varinfo_t field)
+{
+  varinfo_t prev = base;
+  varinfo_t curr = base->next;
+  
+  if (curr == NULL)
+    {
+      prev->next = field;
+      field->next = NULL;
+    }
+  else
+    {
+      while (curr)
+	{
+	  if (field->offset <= curr->offset)
+	    break;
+	  prev = curr;
+	  curr = curr->next;
+	}
+      field->next = prev->next;
+      prev->next = field;
+    }
+}
+
+/* This structure is simply used during pushing fields onto the fieldstack
+   to track the offset of the field, since bitpos_of_field gives it relative
+   to its immediate containing type, and we want it relative to the ultimate
+   containing object.  */
+
+typedef struct fieldoff
+{
+  tree field;
+  HOST_WIDE_INT offset;  
+} fieldoff_s;
+
+DEF_VEC_O (fieldoff_s);
+DEF_VEC_ALLOC_O(fieldoff_s,heap);
+
+/* qsort comparison function for two fieldoff's PA and PB */
+
+static int 
+fieldoff_compare (const void *pa, const void *pb)
+{
+  const fieldoff_s *foa = (const fieldoff_s *)pa;
+  const fieldoff_s *fob = (const fieldoff_s *)pb;
+  HOST_WIDE_INT foasize, fobsize;
+  
+  if (foa->offset != fob->offset)
+    return foa->offset - fob->offset;
+
+  foasize = TREE_INT_CST_LOW (DECL_SIZE (foa->field));
+  fobsize = TREE_INT_CST_LOW (DECL_SIZE (fob->field));
+  return foasize - fobsize;
+}
+
+
+/* Given a TYPE, and a vector of field offsets FIELDSTACK, push all the fields
+   of TYPE onto fieldstack, recording their offsets along the way.
+   OFFSET is used to keep track of the offset in this entire structure, rather
+   than just the immediately containing structure.  Returns the number
+   of fields pushed.
+   HAS_UNION is set to true if we find a union type as a field of
+   TYPE.  */
+
+static int
+push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack, 
+			     HOST_WIDE_INT offset, bool *has_union)
+{
+  tree field;
+  int count = 0;
+
+  for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
+    if (TREE_CODE (field) == FIELD_DECL)
+      {
+	bool push = false;
+	
+	if (TREE_CODE (TREE_TYPE (field)) == QUAL_UNION_TYPE
+	    || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
+	  *has_union = true;
+	
+	if (!var_can_have_subvars (field))
+	  push = true;
+	else if (!(push_fields_onto_fieldstack
+		   (TREE_TYPE (field), fieldstack,
+		    offset + bitpos_of_field (field), has_union))
+		 && DECL_SIZE (field)
+		 && !integer_zerop (DECL_SIZE (field)))
+	  /* Empty structures may have actual size, like in C++. So
+	     see if we didn't push any subfields and the size is
+	     nonzero, push the field onto the stack */
+	  push = true;
+	
+	if (push)
+	  {
+	    fieldoff_s *pair;
+
+	    pair = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
+	    pair->field = field;
+	    pair->offset = offset + bitpos_of_field (field);
+	    count++;
+	  }
+      }
+  return count;
+}
+
+static void
+make_constraint_to_anything (varinfo_t vi)
+{
+  struct constraint_expr lhs, rhs;
+  
+  lhs.var = vi->id;
+  lhs.offset = 0;
+  lhs.type = SCALAR;
+  
+  rhs.var = anything_id;
+  rhs.offset =0 ;
+  rhs.type = ADDRESSOF;
+  process_constraint (new_constraint (lhs, rhs));
+}
+
+
+/* Create a varinfo structure for NAME and DECL, and add it to the varmap.
+   This will also create any variable infos necessary for fields of DECL.  */
+
+static unsigned int
+create_variable_info_for (tree decl, const char *name)
+{
+  unsigned int index = VEC_length (varinfo_t, varmap);
+  varinfo_t vi;
+  tree decltype = TREE_TYPE (decl);
+  bool notokay = false;
+  subvar_t svars;
+  bool is_global = DECL_P (decl) ? is_global_var (decl) : false;
+
+  VEC (fieldoff_s,heap) *fieldstack = NULL;
+  
+  if (var_can_have_subvars (decl) && use_field_sensitive)
+    {
+      push_fields_onto_fieldstack (decltype, &fieldstack, 0, &notokay);
+      if (notokay)
+	VEC_free (fieldoff_s, heap, fieldstack);
+    }
+
+  /* If this variable already has subvars, just create the variables for the
+     subvars and we are done.
+     NOTE: This assumes things haven't generated uses of previously
+     unused structure fields.  */
+  if (use_field_sensitive 
+      && !notokay 
+      && var_can_have_subvars (decl) 
+      && var_ann (decl)      
+      && (svars = get_subvars_for_var (decl)))
+    {
+      subvar_t sv;
+      varinfo_t base = NULL;
+      unsigned int firstindex = index;
+
+      for (sv = svars; sv; sv = sv->next)
+	{
+	  /* For debugging purposes, this will print the names of the
+	     fields as "<var>.<offset>.<size>"
+	     This is only for debugging purposes.  */
+#define PRINT_LONG_NAMES
+#ifdef PRINT_LONG_NAMES
+	  char *tempname;
+	  const char *newname;
+
+	  asprintf (&tempname, "%s." HOST_WIDE_INT_PRINT_DEC "."HOST_WIDE_INT_PRINT_DEC, alias_get_name (decl), sv->offset, sv->size);
+	  newname = ggc_strdup (tempname);
+	  free (tempname);
+	  vi = new_var_info (sv->var, index, newname, index);
+#else
+	  vi = new_var_info (sv->var, index, alias_get_name (sv->var), index);
+#endif
+	  vi->decl = sv->var;
+	  vi->fullsize = TREE_INT_CST_LOW (TYPE_SIZE (decltype));
+	  vi->size = sv->size;
+	  vi->offset = sv->offset;
+	  if (!base)
+	    {
+	      base = vi;
+	      insert_id_for_tree (decl, index);
+	    }
+	  else
+	    {
+	      insert_into_field_list (base, vi);
+	    }
+	  insert_id_for_tree (sv->var, index);  
+	  VEC_safe_push (varinfo_t, gc, varmap, vi);
+	  if (is_global)
+	    make_constraint_to_anything (vi);
+	  index++;
+	  
+	}
+      return firstindex;
+    }
+  
+
+  /* If the variable doesn't have subvars, we may end up needing to
+     sort the field list and create fake variables for all the
+     fields.  */
+  vi = new_var_info (decl, index, name, index);
+  vi->decl = decl;
+  vi->offset = 0;
+  if (!TYPE_SIZE (decltype) 
+      || TREE_CODE (TYPE_SIZE  (decltype)) != INTEGER_CST
+      || TREE_CODE (decltype) == ARRAY_TYPE
+      || TREE_CODE (decltype) == UNION_TYPE
+      || TREE_CODE (decltype) == QUAL_UNION_TYPE)
+    {
+      vi->is_unknown_size_var = true;
+      vi->fullsize = ~0;
+      vi->size = ~0;
+    }
+  else
+    {
+      vi->fullsize = TREE_INT_CST_LOW (TYPE_SIZE (decltype));
+      vi->size = vi->fullsize;
+    }
+  
+  insert_id_for_tree (vi->decl, index);  
+  VEC_safe_push (varinfo_t, gc, varmap, vi);
+  if (is_global)
+    make_constraint_to_anything (vi);
+
+  stats.total_vars++;
+  if (use_field_sensitive 
+      && !notokay 
+      && !vi->is_unknown_size_var 
+      && var_can_have_subvars (decl))
+    {
+      unsigned int newindex = VEC_length (varinfo_t, varmap);
+      fieldoff_s *fo = NULL;
+      unsigned int i;
+      tree field;
+
+      for (i = 0; !notokay && VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
+	{
+	  if (!DECL_SIZE (fo->field) 
+	      || TREE_CODE (DECL_SIZE (fo->field)) != INTEGER_CST
+	      || TREE_CODE (TREE_TYPE (fo->field)) == ARRAY_TYPE
+	      || fo->offset < 0)
+	    {
+	      notokay = true;
+	      break;
+	    }
+	}
+      qsort (VEC_address (fieldoff_s, fieldstack), 
+	     VEC_length (fieldoff_s, fieldstack), 
+	     sizeof (fieldoff_s),
+	     fieldoff_compare);
+
+      if (VEC_length (fieldoff_s, fieldstack) != 0)
+	fo = VEC_index (fieldoff_s, fieldstack, 0);
+
+      if (fo == NULL || notokay)
+	{
+	  vi->is_unknown_size_var = 1;
+	  vi->fullsize = ~0;
+	  vi->size = ~0;
+	  VEC_free (fieldoff_s, heap, fieldstack);
+	  return index;
+	}
+      
+      field = fo->field;
+      gcc_assert (bitpos_of_field (field) == 0);
+      vi->size = TREE_INT_CST_LOW (DECL_SIZE (field));
+      for (i = 1; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
+	{
+	  varinfo_t newvi;
+	  const char *newname;
+	  char *tempname;
+
+	  field = fo->field;
+	  newindex = VEC_length (varinfo_t, varmap);
+	  asprintf (&tempname, "%s.%s", vi->name, alias_get_name (field));
+	  newname = ggc_strdup (tempname);
+	  free (tempname);
+	  newvi = new_var_info (decl, newindex, newname, newindex);
+	  newvi->offset = fo->offset;
+	  newvi->size = TREE_INT_CST_LOW (DECL_SIZE (field));
+	  newvi->fullsize = vi->fullsize;
+	  insert_into_field_list (vi, newvi);
+	  VEC_safe_push (varinfo_t, gc, varmap, newvi);
+	  if (is_global)
+	    make_constraint_to_anything (newvi);
+
+	  stats.total_vars++;	  
+	}
+      VEC_free (fieldoff_s, heap, fieldstack);
+    }
+  return index;
+}
+
+/* Print out the points-to solution for VAR to FILE.  */
+
+void
+dump_solution_for_var (FILE *file, unsigned int var)
+{
+  varinfo_t vi = get_varinfo (var);
+  unsigned int i;
+  bitmap_iterator bi; 
+  
+  fprintf (file, "%s = {", vi->name);
+  EXECUTE_IF_SET_IN_BITMAP (get_varinfo (vi->node)->solution, 0, i, bi)
+    {
+      fprintf (file, "%s,", get_varinfo (i)->name);
+    }
+  fprintf (file, "}\n");
+}
+
+/* Print the points-to solution for VAR to stdout.  */
+
+void
+debug_solution_for_var (unsigned int var)
+{
+  dump_solution_for_var (stdout, var);
+}
+
+/* Create varinfo structures for all of the variables in the
+   function for intraprocedural mode.  */
+
+static void
+intra_create_variable_infos (void)
+{
+  tree t;
+  /* For each incoming argument arg, ARG = &ANYTHING */
+  for (t = DECL_ARGUMENTS (current_function_decl);
+       t;
+       t = TREE_CHAIN (t))
+    {
+      struct constraint_expr lhs;
+      struct constraint_expr rhs;
+      varinfo_t p;
+      
+      lhs.offset = 0;
+      lhs.type = SCALAR;
+      lhs.var  = create_variable_info_for (t, alias_get_name (t));
+      
+      get_varinfo (lhs.var)->is_artificial_var = true;
+      rhs.var = anything_id;
+      rhs.type = ADDRESSOF;
+      rhs.offset = 0;
+
+      for (p = get_varinfo (lhs.var); p; p = p->next)
+	{
+	  struct constraint_expr temp = lhs;
+	  temp.var = p->id;
+	  process_constraint (new_constraint (temp, rhs));
+	}
+    }	
+
+}
+
+/* Set bits in INTO corresponding to the variable uids in solution set
+   FROM  */
+
+static void
+set_uids_in_ptset (bitmap into, bitmap from)
+{
+  unsigned int i;
+  bitmap_iterator bi;
+
+  EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
+    {
+      varinfo_t vi = get_varinfo (i);
+
+      /* We may end up with labels in the points-to set because people
+	 take their address, and they are _DECL's.  */
+      if (TREE_CODE (vi->decl) == VAR_DECL 
+	  || TREE_CODE (vi->decl) == PARM_DECL)
+	bitmap_set_bit (into, var_ann (vi->decl)->uid);
+    }
+}
+static int have_alias_info = false;
+
+/* Given a pointer variable P, fill in its points-to set, or return
+   false if we can't.  */
+
+bool
+find_what_p_points_to (tree p)
+{
+  unsigned int id = 0;
+  if (!have_alias_info)
+    return false;
+  if (lookup_id_for_tree (p, &id))
+    {
+      varinfo_t vi = get_varinfo (id);
+      
+      if (vi->is_artificial_var)
+	return false;
+
+      /* See if this is a field or a structure */
+      if (vi->size != vi->fullsize)
+	{
+	  if (!var_can_have_subvars (vi->decl)
+	      || get_subvars_for_var (vi->decl) == NULL)
+	    return false;
+	} 
+      else
+	{
+	  struct ptr_info_def *pi = get_ptr_info (p);
+	  unsigned int i;
+	  bitmap_iterator bi;
+
+	  /* This variable may have been collapsed, let's get the real
+	     variable.  */
+	  vi = get_varinfo (vi->node);
+	  
+	  /* Make sure there aren't any artificial vars in the points
+             to set.  XXX: Note that we need to translate our heap
+             variables to something.  */ 
+	  EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
+	    {
+	      if (get_varinfo (i)->is_artificial_var)
+		return false;
+	    }
+	  pi->pt_anything = false;
+	  if (!pi->pt_vars)
+	    pi->pt_vars = BITMAP_GGC_ALLOC ();
+	  set_uids_in_ptset (pi->pt_vars, vi->solution);
+	  return true;
+	}
+    }
+  return false;
+}
+
+/* Initialize things necessary to perform PTA */
+
+static void
+init_alias_vars (void)
+{
+  bitmap_obstack_initialize (&ptabitmap_obstack);
+}
+
+/* Dump the points-to information to OUTFILE.  */
+
+static void
+dump_sa_points_to_info (FILE *outfile)
+{
+  
+  unsigned int i;
+  if (dump_flags & TDF_STATS)
+    {
+      fprintf (outfile, "Stats:\n");
+      fprintf (outfile, "Total vars:%d\n", stats.total_vars);
+      fprintf (outfile, "Statically unified vars:%d\n", stats.unified_vars_static);
+      fprintf (outfile, "Collapsed vars:%d\n", stats.collapsed_vars);
+      fprintf (outfile, "Dynamically unified vars:%d\n", stats.unified_vars_dynamic);
+      fprintf (outfile, "Iterations:%d\n", stats.iterations);
+    }
+  for (i = 0; i < VEC_length (varinfo_t, varmap); i++)
+    dump_solution_for_var (outfile, i);
+}
+
+
+/* Initialize the always-existing constraint variables for NULL
+   ANYTHING, READONLY, and INTEGER */
+
+static void
+init_base_vars (void)
+{
+  struct constraint_expr lhs, rhs;
+  /* Create the NULL variable, used to represent that a variable points
+     to NULL.  */
+  nothing_tree = create_tmp_var_raw (void_type_node, "NULL");
+  var_nothing = new_var_info (nothing_tree, 0, "NULL", 0);
+  insert_id_for_tree (nothing_tree, 0);
+  var_nothing->is_artificial_var = 1;
+  var_nothing->offset = 0;
+  var_nothing->size = ~0;
+  var_nothing->fullsize = ~0;
+  nothing_id = 0;
+  VEC_safe_push (varinfo_t, gc, varmap, var_nothing);
+
+  /* Create the ANYTHING variable, used to represent that a variable
+     points to some unknown piece of memory.  */
+  anything_tree = create_tmp_var_raw (void_type_node, "ANYTHING");
+  var_anything = new_var_info (anything_tree, 1, "ANYTHING", 1); 
+  insert_id_for_tree (anything_tree, 1);
+  var_anything->is_artificial_var = 1;
+  var_anything->size = ~0;
+  var_anything->offset = 0;
+  var_anything->next = NULL;
+  var_anything->fullsize = ~0;
+  anything_id = 1;
+
+  /* anything points to anything. This makes deref constraints just
+     work.  */
+  
+  VEC_safe_push (varinfo_t, gc, varmap, var_anything);
+  lhs.type = SCALAR;
+  lhs.var = anything_id;
+  lhs.offset = 0;
+  rhs.type = ADDRESSOF;
+  rhs.var = anything_id;
+  rhs.offset = 0;
+  var_anything->address_taken = true;
+  process_constraint (new_constraint (lhs, rhs));
+
+  
+  /* Create the READONLY variable, used to represent that a variable
+     points to readonly memory.  */
+  readonly_tree = create_tmp_var_raw (void_type_node, "READONLY");
+  var_readonly = new_var_info (readonly_tree, 2, "READONLY", 2);
+  var_readonly->is_artificial_var = 1;
+  var_readonly->offset = 0;
+  var_readonly->size = ~0;
+  var_readonly->fullsize = ~0;
+  var_readonly->next = NULL;
+  insert_id_for_tree (readonly_tree, 2);
+  readonly_id = 2;
+  VEC_safe_push (varinfo_t, gc, varmap, var_readonly);
+
+  /* readonly memory points to anything, in order to make deref easier.  */
+  lhs.type = SCALAR;
+  lhs.var = readonly_id;
+  lhs.offset = 0;
+  rhs.type = ADDRESSOF;
+  rhs.var = anything_id;
+  rhs.offset = 0;
+  var_readonly->address_taken = true;
+  
+  process_constraint (new_constraint (lhs, rhs));
+  
+  /* Create the INTEGER variable, used to represent that a variable points
+     to an INTEGER.  */
+  integer_tree = create_tmp_var_raw (void_type_node, "INTEGER");
+  var_integer = new_var_info (integer_tree, 3, "INTEGER", 3);
+  insert_id_for_tree (integer_tree, 3);
+  var_integer->is_artificial_var = 1;
+  var_integer->size = ~0;
+  var_integer->fullsize = ~0;
+  var_integer->offset = 0;
+  var_integer->next = NULL;
+  integer_id = 3;
+  VEC_safe_push (varinfo_t, gc, varmap, var_integer);
+}  
+
+/* Create points-to sets for the current function.  */
+
+static void
+create_alias_vars (void)
+{
+  basic_block bb;
+
+  
+  init_alias_vars ();
+
+  constraint_pool = create_alloc_pool ("Constraint pool", 
+				       sizeof (struct constraint), 30);
+  variable_info_pool = create_alloc_pool ("Variable info pool",
+					  sizeof (struct variable_info), 30);
+  constraint_edge_pool = create_alloc_pool ("Constraint edges",
+					    sizeof (struct constraint_edge), 30);
+  
+  constraints = VEC_alloc (constraint_t, gc, 8);
+  varmap = VEC_alloc (varinfo_t, gc, 8);
+  id_for_tree = htab_create (10, tree_id_hash, tree_id_eq, free);
+  memset (&stats, 0, sizeof (stats));
+  
+  init_base_vars ();
+
+  intra_create_variable_infos ();
+  /* Now walk all statements and derive aliases.  */
+  FOR_EACH_BB (bb)
+    {
+      block_stmt_iterator bsi; 
+      tree phi;
+      for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
+	if (is_gimple_reg (PHI_RESULT (phi)))
+	  find_func_aliases (phi);
+      for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+	find_func_aliases (bsi_stmt (bsi));
+    }
+
+  build_constraint_graph ();
+  if (dump_file)
+    {
+      fprintf (dump_file, "Constraints:\n");
+      dump_constraints (dump_file);
+    }
+  if (dump_file)
+    fprintf (dump_file, "Collapsing static cycles and doing variable substitution:\n");
+  find_and_collapse_graph_cycles (graph, false);
+  perform_var_substitution (graph);
+  if (dump_file)
+    fprintf (dump_file, "Solving graph:\n");
+  solve_graph (graph);
+
+  if (dump_file)
+    dump_sa_points_to_info (dump_file);
+  
+  have_alias_info = true;
+}
+
+struct tree_opt_pass pass_build_pta = 
+{
+  "pta",				/* name */
+  NULL,					/* gate */
+  create_alias_vars,			/* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  TV_TREE_PTA,				/* tv_id */
+  PROP_cfg,				/* properties_required */
+  PROP_pta,				/* properties_provided */
+  0,					/* properties_destroyed */
+  0,					/* todo_flags_start */
+  0,                                    /* todo_flags_finish */
+  0					/* letter */
+};
+ 
+
+/* Delete created points-to sets.  */
+
+static void
+delete_alias_vars (void)
+{
+  htab_delete (id_for_tree);
+  free_alloc_pool (variable_info_pool);
+  free_alloc_pool (constraint_pool); 
+  free_alloc_pool (constraint_edge_pool);
+  bitmap_obstack_release (&ptabitmap_obstack);
+  have_alias_info = false;
+}
+
+struct tree_opt_pass pass_del_pta = 
+{
+  NULL,                                 /* name */
+  NULL,					/* gate */
+  delete_alias_vars,			/* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  TV_TREE_PTA,				/* tv_id */
+  PROP_pta,				/* properties_required */
+  0,					/* properties_provided */
+  PROP_pta,				/* properties_destroyed */
+  0,					/* todo_flags_start */
+  0,                                    /* todo_flags_finish */
+  0					/* letter */
+};
+
+
+
Index: tree-ssa-structalias.h
===================================================================
RCS file: tree-ssa-structalias.h
diff -N tree-ssa-structalias.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tree-ssa-structalias.h	31 May 2005 22:07:35 -0000
@@ -0,0 +1,33 @@
+/* Tree based points-to analysis
+   Copyright (C) 2002, 2003 Free Software Foundation, Inc.
+   Contributed by Daniel Berlin <dberlin@dberlin.org>
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#ifndef TREE_ALIAS_COMMON
+#define TREE_ALIAS_COMMON
+
+struct constraint;
+typedef struct constraint *constraint_t;
+extern void dump_constraint (FILE *, constraint_t);
+extern void dump_constraints (FILE *);
+extern void debug_constraint (constraint_t);
+extern void debug_constraints (void);
+extern void dump_solution_for_var (FILE *, unsigned int);
+extern void debug_solution_for_var (unsigned int);
+#endif /* TREE_ALIAS_COMMON */

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