* tree-optimize.c (init_tree_optimization_passes): Schedule

	pass_may_alias right after the program is renamed into SSA.
	* tree-pass.h (PROP_alias): Define.
	* tree-outof-ssa.c (pass_del_ssa): Require PROP_alias.
	* tree-sra.c (pass_sra): Likewise.
	* tree-ssa-ccp.c (pass_ccp): Likewise.
	* tree-ssa-copyrename.c (pass_rename_ssa_ccp): Likewise.
	* tree-ssa-dce.c (pass_dce): Likewise.
	* tree-ssa-dom.c (pass_dominator): Likewise.
	* tree-ssa-dse.c (pass_dse): Likewise.
	* tree-ssa-forwprop.c (pass_forwprop): Likewise.
	* tree-ssa-loop-ch.c (pass_ch): Likewise.
	* tree-ssa-phiopt.c (pass_phiopt): Likewise.
	* tree-ssa-pre.c (pass_pre): Likewise.
	* tree-tailcall.c (pass_tail_recursion): Likewise.
	* tree-ssa.c (pass_redundant_phi): Likewise.
	* tree-ssa-alias.c (aliases_computed_p): Remove.
	Update all users.
	(init_alias_info): Do not mark all type tags for renaming
	unconditionally.
	Clear may_aliases from every symbol.
	(setup_pointers_and_addressables): If a pointer has not been
	dereferenced and it had a type tag, clear it and mark the old
	tag for renaming.


testsuite/ChangeLog

	* gcc.dg/tree-ssa/20030714-2.c: Adjust number of expected
	conditionals.
	* gcc.dg/tree-ssa/20031022-1.c: Adjust number of expected
	loads.
	* gcc.dg/tree-ssa/ssa-dom-cse-1.c: Expect optimization in
	DOM1.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@85255 138bc75d-0d04-0410-961f-82ee72b054a4

22 files changed, 158 insertions, 147 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 52bbdd9a9f3..a3f30ff9d3d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,32 @@
 2004-07-28  Diego Novillo  <dnovillo@redhat.com>
 
+	* tree-optimize.c (init_tree_optimization_passes): Schedule
+	pass_may_alias right after the program is renamed into SSA.
+	* tree-pass.h (PROP_alias): Define.
+	* tree-outof-ssa.c (pass_del_ssa): Require PROP_alias.
+	* tree-sra.c (pass_sra): Likewise.
+	* tree-ssa-ccp.c (pass_ccp): Likewise.
+	* tree-ssa-copyrename.c (pass_rename_ssa_ccp): Likewise.
+	* tree-ssa-dce.c (pass_dce): Likewise.
+	* tree-ssa-dom.c (pass_dominator): Likewise.
+	* tree-ssa-dse.c (pass_dse): Likewise.
+	* tree-ssa-forwprop.c (pass_forwprop): Likewise.
+	* tree-ssa-loop-ch.c (pass_ch): Likewise.
+	* tree-ssa-phiopt.c (pass_phiopt): Likewise.
+	* tree-ssa-pre.c (pass_pre): Likewise.
+	* tree-tailcall.c (pass_tail_recursion): Likewise.
+	* tree-ssa.c (pass_redundant_phi): Likewise.
+	* tree-ssa-alias.c (aliases_computed_p): Remove.
+	Update all users.
+	(init_alias_info): Do not mark all type tags for renaming
+	unconditionally.
+	Clear may_aliases from every symbol.
+	(setup_pointers_and_addressables): If a pointer has not been
+	dereferenced and it had a type tag, clear it and mark the old
+	tag for renaming.
+
+2004-07-28  Diego Novillo  <dnovillo@redhat.com>
+
 	PR tree-optimization/16705
 	* tree-ssa-alias.c (create_global_var): Set DECL_EXTERNAL on
 	.GLOBAL_VAR.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 35a5a3aa376..8b99613999f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,12 @@
+2004-07-28  Diego Novillo  <dnovillo@redhat.com>
+
+	* gcc.dg/tree-ssa/20030714-2.c: Adjust number of expected
+	conditionals.
+	* gcc.dg/tree-ssa/20031022-1.c: Adjust number of expected
+	loads.
+	* gcc.dg/tree-ssa/ssa-dom-cse-1.c: Expect optimization in
+	DOM1.
+
 2004-07-27  Andrew Pinski  <apinski@apple.com>
 
 	* g++.dg/rtti/tinfo1.C: Correct the xfail.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20030714-2.c b/gcc/testsuite/gcc.dg/tree-ssa/20030714-2.c
index 6a43360b07f..2c8a84a494d 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/20030714-2.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/20030714-2.c
@@ -32,8 +32,8 @@ get_alias_set (t)
     }
 }
 
-/* There should be exactly four IF conditionals if we thread jumps
+/* There should be exactly three IF conditionals if we thread jumps
    properly.  */
-/* { dg-final { scan-tree-dump-times "if " 4 "dom3"} } */
+/* { dg-final { scan-tree-dump-times "if " 3 "dom3"} } */
  
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20031022-1.c b/gcc/testsuite/gcc.dg/tree-ssa/20031022-1.c
index 546e6b00759..d4f9b3c3611 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/20031022-1.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/20031022-1.c
@@ -23,5 +23,5 @@ blah (int arf)
   foo (e);
 }
 
-/* There should be two loads from entry_exit_blocks[1].pred.  */
+/* There should be one load from entry_exit_blocks[1].pred.  */
 /* { dg-final { scan-tree-dump-times "entry_exit_blocks.1..pred" 2 "dom1"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-cse-1.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-cse-1.c
index 4e4ed8c912f..52531009e67 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-cse-1.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-cse-1.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */ 
-/* { dg-options "-O2 -fdump-tree-dom2-details" } */
+/* { dg-options "-O2 -fdump-tree-dom1-details" } */
 int t(int a) __attribute__ ((const));
 void q (void);
 void
@@ -11,6 +11,5 @@ threading(int a,int b)
 	    q();
 	}
 }
-/* We should thread the jump twice and eliminate it.  Test this in
-   DOM2, after aliases have been computed.  */
-/* { dg-final { scan-tree-dump-times "Replaced.* t " 1 "dom2"} } */
+/* We should thread the jump twice and eliminate it.  */
+/* { dg-final { scan-tree-dump-times "Replaced.* t " 1 "dom1"} } */
diff --git a/gcc/tree-optimize.c b/gcc/tree-optimize.c
index d575990cce6..d41bebc618a 100644
--- a/gcc/tree-optimize.c
+++ b/gcc/tree-optimize.c
@@ -321,6 +321,7 @@ init_tree_optimization_passes (void)
   NEXT_PASS (pass_referenced_vars);
   NEXT_PASS (pass_build_pta);
   NEXT_PASS (pass_build_ssa);
+  NEXT_PASS (pass_may_alias);
   NEXT_PASS (pass_rename_ssa_copies);
   NEXT_PASS (pass_early_warn_uninitialized);
   NEXT_PASS (pass_dce);
diff --git a/gcc/tree-outof-ssa.c b/gcc/tree-outof-ssa.c
index d1899981c1f..1fef266646d 100644
--- a/gcc/tree-outof-ssa.c
+++ b/gcc/tree-outof-ssa.c
@@ -2213,7 +2213,7 @@ struct tree_opt_pass pass_del_ssa =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_SSA_TO_NORMAL,		/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   /* ??? If TER is enabled, we also kill gimple.  */
   PROP_ssa,				/* properties_destroyed */
diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index 9651c9e659b..2bf63ee77b6 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -76,6 +76,7 @@ struct tree_opt_pass
 #define PROP_ssa		(1 << 6)
 #define PROP_no_crit_edges      (1 << 7)
 #define PROP_rtl		(1 << 8)
+#define PROP_alias		(1 << 9)
 
 #define PROP_trees \
   (PROP_gimple_any | PROP_gimple_lcf | PROP_gimple_leh)
diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index 30d8e34d32b..b3fa20c6c77 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -2118,7 +2118,7 @@ struct tree_opt_pass pass_sra =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_SRA,				/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 64476ebe301..94ccd800929 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -175,13 +175,6 @@ bitmap call_clobbered_vars;
    variable).  */
 bitmap addressable_vars;
 
-/* 'true' after aliases have been computed (see compute_may_aliases).  This
-   is used by get_stmt_operands and its helpers to determine what to do
-   when scanning an operand for a variable that may be aliased.  If
-   may-alias information is still not available, the statement is marked as
-   having volatile operands.  */
-bool aliases_computed_p;
-
 /* When the program has too many call-clobbered variables and call-sites,
    this variable is used to represent the clobbering effects of function
    calls.  In these cases, all the call clobbered variables in the program
@@ -350,9 +343,6 @@ compute_may_aliases (void)
 
   /* Deallocate memory used by aliasing data structures.  */
   delete_alias_info (ai);
-
-  /* Indicate that may-alias information is now available.  */
-  aliases_computed_p = true;
 }
 
 struct tree_opt_pass pass_may_alias = 
@@ -365,7 +355,7 @@ struct tree_opt_pass pass_may_alias =
   0,					/* static_pass_number */
   TV_TREE_MAY_ALIAS,			/* tv_id */
   PROP_cfg | PROP_ssa | PROP_pta,	/* properties_required */
-  0,					/* properties_provided */
+  PROP_alias,				/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
   TODO_dump_func | TODO_rename_vars
@@ -379,6 +369,7 @@ static struct alias_info *
 init_alias_info (void)
 {
   struct alias_info *ai;
+  static bool aliases_computed_p = false;
 
   ai = xcalloc (1, sizeof (struct alias_info));
   ai->ssa_names_visited = BITMAP_XMALLOC ();
@@ -417,14 +408,8 @@ init_alias_info (void)
       for (i = 0; i < num_referenced_vars; i++)
 	{
 	  var_ann_t ann = var_ann (referenced_var (i));
-
 	  ann->is_alias_tag = 0;
-	  if (ann->type_mem_tag)
-	    {
-	      var_ann_t tag_ann = var_ann (ann->type_mem_tag);
-	      tag_ann->may_aliases = NULL;
-	      bitmap_set_bit (vars_to_rename, tag_ann->uid);
-	    }
+	  ann->may_aliases = NULL;
 	}
 
       /* Clear flow-sensitive points-to information from each SSA name.  */
@@ -450,12 +435,13 @@ init_alias_info (void)
 	      pi->is_dereferenced = 0;
 	      if (pi->pt_vars)
 		bitmap_clear (pi->pt_vars);
-	      if (pi->name_mem_tag)
-		var_ann (pi->name_mem_tag)->may_aliases = NULL;
 	    }
 	}
     }
 
+  /* Next time, we will need to reset alias information.  */
+  aliases_computed_p = true;
+
   return ai;
 }
 
@@ -1375,47 +1361,64 @@ setup_pointers_and_addressables (struct alias_info *ai)
 
       /* Add pointer variables that have been dereferenced to the POINTERS
          array and create a type memory tag for them.  */
-      if (POINTER_TYPE_P (TREE_TYPE (var))
-	  && (bitmap_bit_p (ai->dereferenced_ptrs_store, v_ann->uid)
-	      || bitmap_bit_p (ai->dereferenced_ptrs_load, v_ann->uid)))
+      if (POINTER_TYPE_P (TREE_TYPE (var)))
 	{
-	  tree tag;
-	  var_ann_t t_ann;
-
-	  /* If pointer VAR still doesn't have a memory tag associated
-	     with it, create it now or re-use an existing one.  */
-	  tag = get_tmt_for (var, ai);
-	  t_ann = var_ann (tag);
-
-	  /* The type tag will need to be renamed into SSA afterwards.
-	     Note that we cannot do this inside get_tmt_for because
-	     aliasing may run multiple times and we only create type
-	     tags the first time.  */
-	  bitmap_set_bit (vars_to_rename, t_ann->uid);
-
-	  /* Associate the tag with pointer VAR.  */
-	  v_ann->type_mem_tag = tag;
-
-	  /* If pointer VAR has been used in a store operation, then its
-	     memory tag must be marked as written-to.  */
-	  if (bitmap_bit_p (ai->dereferenced_ptrs_store, v_ann->uid))
-	    bitmap_set_bit (ai->written_vars, t_ann->uid);
-
-	  /* If pointer VAR is a global variable or a PARM_DECL, then its
-	     memory tag should be considered a global variable.  */
-	  if (TREE_CODE (var) == PARM_DECL || needs_to_live_in_memory (var))
-	    mark_call_clobbered (tag);
-
-	  /* All the dereferences of pointer VAR count as references of
-	     TAG.  Since TAG can be associated with several pointers, add
-	     the dereferences of VAR to the TAG.  We may need to grow
-	     AI->NUM_REFERENCES because we have been adding name and
-	     type tags.  */
-	  if (t_ann->uid >= VARRAY_SIZE (ai->num_references))
-	    VARRAY_GROW (ai->num_references, t_ann->uid + 10);
-
-	  VARRAY_UINT (ai->num_references, t_ann->uid)
-	      += VARRAY_UINT (ai->num_references, v_ann->uid);
+	  if ((bitmap_bit_p (ai->dereferenced_ptrs_store, v_ann->uid)
+		|| bitmap_bit_p (ai->dereferenced_ptrs_load, v_ann->uid)))
+	    {
+	      tree tag;
+	      var_ann_t t_ann;
+
+	      /* If pointer VAR still doesn't have a memory tag
+		 associated with it, create it now or re-use an
+		 existing one.  */
+	      tag = get_tmt_for (var, ai);
+	      t_ann = var_ann (tag);
+
+	      /* The type tag will need to be renamed into SSA
+		 afterwards. Note that we cannot do this inside
+		 get_tmt_for because aliasing may run multiple times
+		 and we only create type tags the first time.  */
+	      bitmap_set_bit (vars_to_rename, t_ann->uid);
+
+	      /* Associate the tag with pointer VAR.  */
+	      v_ann->type_mem_tag = tag;
+
+	      /* If pointer VAR has been used in a store operation,
+		 then its memory tag must be marked as written-to.  */
+	      if (bitmap_bit_p (ai->dereferenced_ptrs_store, v_ann->uid))
+		bitmap_set_bit (ai->written_vars, t_ann->uid);
+
+	      /* If pointer VAR is a global variable or a PARM_DECL,
+		 then its memory tag should be considered a global
+		 variable.  */
+	      if (TREE_CODE (var) == PARM_DECL || needs_to_live_in_memory (var))
+		mark_call_clobbered (tag);
+
+	      /* All the dereferences of pointer VAR count as
+		 references of TAG.  Since TAG can be associated with
+		 several pointers, add the dereferences of VAR to the
+		 TAG.  We may need to grow AI->NUM_REFERENCES because
+		 we have been adding name and type tags.  */
+	      if (t_ann->uid >= VARRAY_SIZE (ai->num_references))
+		VARRAY_GROW (ai->num_references, t_ann->uid + 10);
+
+	      VARRAY_UINT (ai->num_references, t_ann->uid)
+		+= VARRAY_UINT (ai->num_references, v_ann->uid);
+	    }
+	  else
+	    {
+	      /* The pointer has not been dereferenced.  If it had a
+		 type memory tag, remove it and mark the old tag for
+		 renaming to remove it out of the IL.  */
+	      var_ann_t ann = var_ann (var);
+	      tree tag = ann->type_mem_tag;
+	      if (tag)
+		{
+		  bitmap_set_bit (vars_to_rename, var_ann (tag)->uid);
+		  ann->type_mem_tag = NULL_TREE;
+		}
+	    }
 	}
     }
 
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 04ab19d8ff6..82479f052e6 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -245,7 +245,7 @@ struct tree_opt_pass pass_ccp =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_CCP,				/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
@@ -2704,7 +2704,7 @@ struct tree_opt_pass pass_fold_builtins =
   NULL,					/* next */
   0,					/* static_pass_number */
   0,					/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa-copyrename.c b/gcc/tree-ssa-copyrename.c
index ac7c00aa06e..2fd87e2214b 100644
--- a/gcc/tree-ssa-copyrename.c
+++ b/gcc/tree-ssa-copyrename.c
@@ -391,7 +391,7 @@ struct tree_opt_pass pass_rename_ssa_copies =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_COPY_RENAME,			/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */ 
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 1d3038fc60c..c94a2f6c6d6 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -908,7 +908,7 @@ struct tree_opt_pass pass_dce =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_DCE,				/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
@@ -924,7 +924,7 @@ struct tree_opt_pass pass_cd_dce =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_CD_DCE,			/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c
index 7382d5f8875..036706f9f37 100644
--- a/gcc/tree-ssa-dom.c
+++ b/gcc/tree-ssa-dom.c
@@ -692,7 +692,7 @@ struct tree_opt_pass pass_dominator =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_SSA_DOMINATOR_OPTS,		/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index efc7d7fbef4..26aae0cb143 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -437,7 +437,8 @@ struct tree_opt_pass pass_dse = {
   NULL,				/* next */
   0,				/* static_pass_number */
   TV_TREE_DSE,			/* tv_id */
-  PROP_cfg | PROP_ssa,		/* properties_required */
+  PROP_cfg | PROP_ssa
+    | PROP_alias,		/* properties_required */
   0,				/* properties_provided */
   0,				/* properties_destroyed */
   0,				/* todo_flags_start */
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 7df513f4e8a..2cb3b9bd20b 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -517,7 +517,8 @@ struct tree_opt_pass pass_forwprop = {
   NULL,				/* next */
   0,				/* static_pass_number */
   TV_TREE_FORWPROP,		/* tv_id */
-  PROP_cfg | PROP_ssa,		/* properties_required */
+  PROP_cfg | PROP_ssa
+    | PROP_alias,		/* properties_required */
   0,				/* properties_provided */
   0,				/* properties_destroyed */
   0,				/* todo_flags_start */
diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c
index 5794a86cd6c..ddb2438bae7 100644
--- a/gcc/tree-ssa-loop-ch.c
+++ b/gcc/tree-ssa-loop-ch.c
@@ -340,7 +340,7 @@ struct tree_opt_pass pass_ch =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_CH,				/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index bd80da33341..a9e864ed8c1 100644
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -1137,13 +1137,6 @@ get_asm_expr_operands (tree stmt, voperands_t prev_vops)
 	      add_stmt_operand (&var, stmt, opf_is_def, prev_vops);
 	    });
 
-	/* If we don't have call-clobbered nor addressable vars and we
-	   still have not computed aliasing information, just mark the
-	   statement as having volatile operands.  If the alias pass
-	   finds some, we will add them at that point.  */
-	if (!aliases_computed_p)
-	  stmt_ann (stmt)->has_volatile_ops = true;
-
 	break;
       }
 }
@@ -1159,53 +1152,42 @@ get_indirect_ref_operands (tree stmt, tree expr, int flags,
 
   if (SSA_VAR_P (ptr))
     {
-      if (!aliases_computed_p)
+      struct ptr_info_def *pi = NULL;
+
+      /* If PTR has flow-sensitive points-to information, use it.  */
+      if (TREE_CODE (ptr) == SSA_NAME
+	  && (pi = SSA_NAME_PTR_INFO (ptr)) != NULL
+	  && pi->name_mem_tag)
 	{
-	  /* If the pointer does not have a memory tag and aliases have not
-	     been computed yet, mark the statement as having volatile
-	     operands to prevent DOM from entering it in equivalence tables
-	     and DCE from killing it.  */
-	  stmt_ann (stmt)->has_volatile_ops = true;
+	  /* PTR has its own memory tag.  Use it.  */
+	  add_stmt_operand (&pi->name_mem_tag, stmt, flags, prev_vops);
 	}
       else
 	{
-	  struct ptr_info_def *pi = NULL;
-
-	  /* If we have computed aliasing already, check if PTR has
-	     flow-sensitive points-to information.  */
-	  if (TREE_CODE (ptr) == SSA_NAME
-	      && (pi = SSA_NAME_PTR_INFO (ptr)) != NULL
-	      && pi->name_mem_tag)
+	  /* If PTR is not an SSA_NAME or it doesn't have a name
+	     tag, use its type memory tag.  */
+	  var_ann_t ann;
+
+	  /* If we are emitting debugging dumps, display a warning if
+	     PTR is an SSA_NAME with no flow-sensitive alias
+	     information.  That means that we may need to compute
+	     aliasing again.  */
+	  if (dump_file
+	      && TREE_CODE (ptr) == SSA_NAME
+	      && pi == NULL)
 	    {
-	      /* PTR has its own memory tag.  Use it.  */
-	      add_stmt_operand (&pi->name_mem_tag, stmt, flags, prev_vops);
+	      fprintf (dump_file,
+		  "NOTE: no flow-sensitive alias info for ");
+	      print_generic_expr (dump_file, ptr, dump_flags);
+	      fprintf (dump_file, " in ");
+	      print_generic_stmt (dump_file, stmt, dump_flags);
 	    }
-	  else
-	    {
-	      /* If PTR is not an SSA_NAME or it doesn't have a name
-		 tag, use its type memory tag.  */
-	      var_ann_t ann;
-
-	      /* If we are emitting debugging dumps, display a warning if
-		 PTR is an SSA_NAME with no flow-sensitive alias
-		 information.  That means that we may need to compute
-		 aliasing again.  */
-	      if (dump_file
-		  && TREE_CODE (ptr) == SSA_NAME
-		  && pi == NULL)
-		{
-		  fprintf (dump_file,
-			   "NOTE: no flow-sensitive alias info for ");
-		  print_generic_expr (dump_file, ptr, dump_flags);
-		  fprintf (dump_file, " in ");
-		  print_generic_stmt (dump_file, stmt, dump_flags);
-		}
 
-	      if (TREE_CODE (ptr) == SSA_NAME)
-		ptr = SSA_NAME_VAR (ptr);
-	      ann = var_ann (ptr);
-	      add_stmt_operand (&ann->type_mem_tag, stmt, flags, prev_vops);
-	    }
+	  if (TREE_CODE (ptr) == SSA_NAME)
+	    ptr = SSA_NAME_VAR (ptr);
+	  ann = var_ann (ptr);
+	  if (ann->type_mem_tag)
+	    add_stmt_operand (&ann->type_mem_tag, stmt, flags, prev_vops);
 	}
     }
 
@@ -1272,8 +1254,6 @@ get_call_expr_operands (tree stmt, tree expr, voperands_t prev_vops)
       else if (!(call_flags & (ECF_CONST | ECF_NORETURN)))
 	add_call_read_ops (stmt, prev_vops);
     }
-  else if (!aliases_computed_p)
-    stmt_ann (stmt)->has_volatile_ops = true;
 }
 
 
@@ -1348,13 +1328,6 @@ add_stmt_operand (tree *var_p, tree stmt, int flags, voperands_t prev_vops)
 
       aliases = v_ann->may_aliases;
 
-      /* If alias information hasn't been computed yet, then
-	 addressable variables will not be an alias tag nor will they
-	 have aliases.  In this case, mark the statement as having
-	 volatile operands.  */
-      if (!aliases_computed_p && may_be_aliased (var))
-	s_ann->has_volatile_ops = true;
-
       if (aliases == NULL)
 	{
 	  /* The variable is not aliased or it is an alias tag.  */
diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index 50c845e7637..ee48b25b214 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -669,7 +669,7 @@ struct tree_opt_pass pass_phiopt =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_PHIOPT,			/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index d24ebc0b547..95ee573aa1a 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -2076,7 +2076,8 @@ struct tree_opt_pass pass_pre =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_PRE,				/* tv_id */
-  PROP_no_crit_edges | PROP_cfg | PROP_ssa,/* properties_required */
+  PROP_no_crit_edges | PROP_cfg
+    | PROP_ssa | PROP_alias,		/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
@@ -2107,7 +2108,7 @@ struct tree_opt_pass pass_fre =
   NULL,					/* next */
   0,					/* static_pass_number */
   TV_TREE_FRE,				/* tv_id */
-  PROP_no_crit_edges | PROP_cfg | PROP_ssa,/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 27b3a5b1bf0..52df86937e0 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -505,11 +505,8 @@ err:
 static void
 verify_alias_info (void)
 {
-  if (aliases_computed_p)
-    {
-      verify_flow_sensitive_alias_info ();
-      verify_flow_insensitive_alias_info ();
-    }
+  verify_flow_sensitive_alias_info ();
+  verify_flow_insensitive_alias_info ();
 }
 
 
@@ -677,7 +674,6 @@ init_tree_ssa (void)
   init_ssanames ();
   init_phinodes ();
   global_var = NULL_TREE;
-  aliases_computed_p = false;
 }
 
 
@@ -710,7 +706,6 @@ delete_tree_ssa (void)
   global_var = NULL_TREE;
   BITMAP_XFREE (call_clobbered_vars);
   call_clobbered_vars = NULL;
-  aliases_computed_p = false;
   BITMAP_XFREE (addressable_vars);
   addressable_vars = NULL;
 }
@@ -1211,7 +1206,7 @@ struct tree_opt_pass pass_redundant_phi =
   NULL,					/* next */
   0,					/* static_pass_number */
   0,					/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
diff --git a/gcc/tree-tailcall.c b/gcc/tree-tailcall.c
index d3d48f5a89b..6599cbd09e2 100644
--- a/gcc/tree-tailcall.c
+++ b/gcc/tree-tailcall.c
@@ -937,7 +937,7 @@ struct tree_opt_pass pass_tail_recursion =
   NULL,					/* next */
   0,					/* static_pass_number */
   0,					/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */
@@ -953,7 +953,7 @@ struct tree_opt_pass pass_tail_calls =
   NULL,					/* next */
   0,					/* static_pass_number */
   0,					/* tv_id */
-  PROP_cfg | PROP_ssa,			/* properties_required */
+  PROP_cfg | PROP_ssa | PROP_alias,	/* properties_required */
   0,					/* properties_provided */
   0,					/* properties_destroyed */
   0,					/* todo_flags_start */